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. 2020 Jul 9;15(7):e0235211. doi: 10.1371/journal.pone.0235211

Prevalence and socio-demographic correlates of accelerometer measured physical activity levels of school-going children in Kampala city, Uganda

Bernadette Nakabazzi 1,2,*, Lucy-Joy M Wachira 1, Adewale L Oyeyemi 3, Ronald Ssenyonga 4, Vincent O Onywera 1
Editor: Javier Brazo-Sayavera5
PMCID: PMC7347200  PMID: 32645010

Abstract

Background

The current international physical activity guidelines for health recommend children to engage in at least 60 minutes of moderate-to-vigorous physical activity (MVPA) daily. Yet, accurate prevalence estimates of physical activity levels of children are unavailable in many African countries due to the dearth of accelerometer-measured physical activity data. The aim of this study was to describe the prevalence and examine the socio-demographic correlates of accelerometer-measured physical activity among school-going children in Kampala city, Uganda.

Methods

A cross-sectional study design was used to recruit a sample of 10–12 years old school-going children (n = 256) from 7 primary schools (3 public schools and 4 private schools) in Kampala city, Uganda. Sedentary time, light-intensity physical activity (LPA), moderate-intensity physical activity (MPA) and vigorous-intensity physical activity (VPA) were measured by accelerometers (ActiGraph GT3X+ [Pensacola, Florida, USA]) over a seven-day period. Socio-demographic factors were assessed by a parent/guardian questionnaire. Weight status was generated from objectively measured height and weight and computed as body mass index (BMI). Multi-level logistic regressions identified socio-demographic factors that were associated with meeting physical activity guidelines.

Results

Children’s sedentary time was 9.8±2.1 hours/day and MVPA was 56±25.7 minutes/day. Only 36.3% of the children (38.9% boys, 34.3% girls) met the physical activity guidelines. Boys, thin/normal weight and public school children had significantly higher mean daily MVPA levels. Socio-demographic factors associated with odds of meeting physical activity guidelines were younger age (OR = 0.68; 95% CI = 0.55–0.84), thin/normal weight status (OR = 4.08; 95% CI = 1.42–11.76), and socioeconomic status (SES) indicators such as lower maternal level of education (OR = 2.43; 95% CI = 1.84–3.21) and no family car (OR = 0.31; 95% CI = 0.17–0.55).

Conclusion

Children spent a substantial amount of time sedentary and in LPA and less time in MVPA. Few children met the physical activity guidelines. Lower weight status, lower maternal education level and no family car were associated with meeting physical activity guidelines. Effective interventions and policies to increase physical activity among school-going children in Kampala, are urgently needed.

Introduction

Childhood physical activity is associated with numerous physical, psycho-social and cognitive health benefits [1,2]. All levels of physical activity; LPA, MPA and VPA are important [2]. LPA contributes the most to overall physical activity and may be easier for children to engage in; however, higher physical activity intensity levels (MVPA) are consistently associated with greater health benefits [2,3]. In this regard, the World Health Organisation (WHO) [4] and some countries such as United States of America (USA) [5], Canada [6], Australia [7] and United Kingdom (UK) [8] have established and revised physical activity guidelines for children. The international physical activity guidelines recommend children to accumulate at least 60 minutes of MVPA each day to acquire the health benefits. However, even with known health benefits associated with regular participation in physical activity, global estimates show that 81% of children aged 11 to 17 years are not sufficiently active [9]. In 2016, Sallis and colleagues found no evidence of global increases in physical activity [10]. A recent study on global trends in insufficient physical activity among adolescents also found that 4 in every 5 adolescents aged 11 to 17 years did not meet the current physical activity guidelines [11]. Also across Europe, a harmonized analysis of accelerometer-measured physical activity revealed that two thirds of European children and adolescents were not sufficiently active [12]. The global pattern of insufficient physical activity in children has also been observed in Sub-Saharan African countries [13,14,15,16] particularly in urban areas. For example, in neighbouring Nairobi city results from the International Study of Childhood Obesity, Lifestyle and the Environment study (ISCOLE) showed that only 12.6% of the children 10 to 11 years old met the physical activity guidelines [17]. This is an indication that insufficient physical activity is still a current global public health problem. Findings from a recent systematic review and meta-analysis of longitudinal studies also showed that physical activity starts to decline in childhood [18]. Promoting physical activity during childhood is therefore a public health priority because this behavior persists into adolescence and adulthood [19]. However, a recent study on global trends in insufficient physical activity among children [11] and a publication on physical activity report cards from nine low-and middle-income countries (LMICs) [20], found a challenging data gap particularly in accelerometer-measured physical activity. Therefore, there is an urgent need for quality data to better describe children’s physical activity and associated factors. Accurate measurement of children’s physical activity is also key to continued surveillance and formulation of informed interventions and polices.

Technological advances in past two decades have increased the use of accelerometers to quantify children’s physical activity [21]. Accelerometers are an alternative to self-reporting methods like questionnaires that are subject to recall bias and are not recommended for use among children because of their limited reading and comprehension skills due to their age [22,23]. Recall-based measures may also not accurately capture the sporadic and short-burst patterns of children’s physical activity and LPA [24,25]. Accelerometers provide a valid and reliable measure of patterns as well as total physical activity among children [26,27]. Despite the increase in the use of accelerometers to quantify children’s physical activity in large population studies, especially in high income countries (HICs) [28,29,30], there are relatively fewer studies that have used accelerometers in low income countries (LICs) [11,20]. Accelerometer-measured physical activity data was also non-existent in school-going children in Kampala city, Uganda. Theron and Santorino in 2009 used photographic methods to study physical activity of Ugandan youth in Mbarara and found that they participated in physical activity for 1 to 2 hours/week [31]. Analysis of self-reported secondary data from the Global School-based Students Health Survey (GSHS) showed that most Ugandan adolescents aged 13 to 15 years were inactive [32]. A pilot study among urban and rural school going children 10 to 16 years old from central Uganda, reported varied physical activity engaged in (such as active travel to school, sport-related, house chores and muscle-strengthening activities). However, the study used self-reporting measures [33]. Therefore, there was a need for accelerometer-measured physical activity data, to describe children’s physical activity levels and identify the proportion of children who complied with the physical activity guidelines in Kampala city, Uganda.

Children’s physical activity is consistently associated with various socio-demographic factors [29,34,35,36]. Various studies that used both objective and recall-based measures of physical activity consistently reported sex differences in physical activity favouring boys [11,17,29,34,35,36,37]. Children’s physical activity has also been found to decline with increasing age [18,29], nevertheless non-significant associations have also been reported [38]. Physical activity is frequently reported to be lower among overweight/obese children [13,29,35,39,40,41]. Studies on associations between SES and children’s physical activity have generated inconsistent results. For example, in HICs, children from high socio-economic status (HSES) families were more likely to meet physical activity guidelines [34] whereas in LICs children from low socio-economic status (LSES) were more likely to meet physical activity guidelines [17]. Physical activity is also lower among children from families that own cars [42,43,44,45]. However, there are inconsistent findings on the associations between parental education level and children’s physical activity [17,36,42,45]. Therefore, there is still need for more research assessing the sociodemographic correlates of children’s physical activity levels, particularly in LICs countries like Uganda where little research has been conducted [11,20]. The present study thus helped to identify children that required immediate intervention

To our knowledge, there is no study that has used accelerometers to measure physical activity levels among school-going children in Kampala city, Uganda. Therefore, the present study assessed the prevalence of accelerometer-measured physical activity intensity levels, compliance with the WHO, 2010 physical activity guidelines and sociodemographic correlates of physical activity among school-going children in Kampala city, Uganda.

Materials and methods

Design and participants recruitment

This was a cross-sectional study of a representative sample of school-going children aged 10–12 years old in Kampala city, Uganda. As children aged 10 to 12 years old are transiting from childhood to adolescence, they gain some autonomy in decision making which may be critical to declines in their physical activity [46,47]. Kampala city is the capital and largest city in Uganda covering an area of 182 km2 with population of 1,516,210 residents from diverse ethnic groups and SES [48]. Kampala comprises of five administrative divisions, that is Nakawa, Makindye, Rubaga, Central and Kawempe [49]. Participants were selected using a multistage random sampling method. In stage one, we randomly selected two out of the five divisions (Central and Nakawa); from which 7 primary schools (3 public schools and 4 private schools) were randomly selected. One classroom from any one grade (5th through 7th) was randomly selected and all children from the selected classroom, except those who had physical and health conditions that limited their participation in physical activity were invited to participate in this study. Ethical approval to conduct the study was obtained from the Uganda National Council of Science and Technology (SS4340) and Kenyatta University Ethical Review Board (PKU/619/1703). Permission to access schools was granted by the Directorate of Education and Social Services, Kampala Capital City Authority (KCCA). The respective school head teachers, approved the school’s participation in the study. A parent/guardian provided written informed consent for themselves and their child in addition to written assent from the child. Data were collected during school sessions from May 2017 through August 2018

Measures

Accelerometry

Children wore a tri-axial ActiGraph GT3X+ (Pensacola, Florida, USA) accelerometer on the right hip using an elastic belt for 7 consecutive days including 2 weekend days. A 24-hour wear protocol was employed to increase compliance [28,50]; and as such children were requested to wear the monitor all the time except when engaging in water-based activities like swimming and bathing. ActiGraph accelerometers are reliable and valid measures of children’s physical activity [21,26]. Using Actilife software (version 6.13.3) (ActiGraph, Pensacola, Florida, USA) the fully charged accelerometers were initialized to collect second to second movement counts at midnight following the first day that the children received the accelerometers; at a samplings rate of 80 HZ. Data were downloaded using ActiLife v6.13.3 (ActiGraph, Pensacola, Florida, USA) in raw format as GT3+ files and AGD files with 1 second epoch. The 24-hour protocol required sleep time to be identified and accounted for before evaluating wake wear time and generating physical activity variables of interest [51,52]. We used the Sadeh algorithm, which is in built into the sleep scoring function in ActiLife software to identify individualised daily sleep on set and offset time for each valid day for each child [53]; this is a valid method for removal of sleep [54]. Daily sleep on set and offset time was used to create time filters in CSV files (Excel Microsoft co-operation, 2016). Time filtered files for the wake period were created and used to identify non wear time and wear time. We defined non-wear as 20 minutes of consecutive 0 counts. Sufficient wear time was determined as 4 days including 1 weekend day with ≥ 10 hours/day. The time spent in different levels of movement intensity were generated basing on the Evenson cut points as: Sedentary time (≤ 25 counts/15 s), LPA (26–573 counts/15 s), MPA (574–1002 counts/15 s) and VPA (≥1003 counts/15 s) [55]. These cut-offs have been recommended as the most accurate for classifying children’s physical activity levels [56]. Time spent in MVPA was calculated as the sum of MPA and VPA. Children were classified as meeting the physical activity guidelines (sufficiently active) if their mean amount of time spent in MVPA/day was ≥60 minutes in accordance to the WHO, 2010 physical activity recommendations [4].

Anthropometry

Each child had their height (to the nearest 0.1 cm) and body weight (to the nearest 0.1Kg) measured without shoes and with minimal clothing, using a portable stadiometer (Seca 213 portable stadiometer, Hamburg, Germany) and a digital weighing scale (Seca 869 portable electronic digital weighing scale, Hamburg, Germany) respectively following a standardised procedure. Weight status was calculated as BMI (kilograms per meter squared) and children were categorised as thin/normal weight and overweight/obese using the WHO, 2007 age and gender specific BMI percentiles [57].

Socio-demographics

A validated questionnaire assessing children and parents’ socio-demographics and neighbourhood built environment [58] was completed by parents/guardians. In this paper, questions that captured children and parents’ socio-demographic factors were analysed. Parents reported their children’s date of birth (from which the child’s actual age at the time of the study was generated) and sex. The questionnaire also captured information about parents’ age, sex, marital status, level of education; number of cars at home and the number of children and youth aged 6 to 17years in their homes.

Recruitment and completion rate

Using the Daniel (1999) formula [59], and an expected prevalence of 21.4% obtained from a previous study by Millstein and colleagues [60] a sample size of 254 was generated. However, because the children were to be sampled in clusters by divisions and schools, the above sample size was multiplied by a design effect of 2 [61] which produced a required sample size of 500 children. To further allow for children who may fail to provide valid and/or incomplete data the enrolment target was set to 600 children. A sample of 600 children received a study package that contained an introduction letter, parent informed consent form, child assent form and a parent/guardian questionnaire to take home to their parents/guardians. Of the 600 children who were invited to participate, 400 (66.7%) had parents/guardians who completed the questionnaire and 328 (54.6%) parental/guardian consented for their children to participate in accelerometry and anthropometric assessment. Of the 328 children who obtained parental consent to wear devices, 256 had valid accelerometry data and were therefore retained for analysis. The response rate was 42.7%. We further assessed demographic characteristics of children who had valid accelerometry results (n = 256) and compared them to those who had complete questionnaire data (n = 400) and found no differences.

Data analysis

Continuous data such as accelerometer counts were summarised as means and standard deviations while categorical data such as sex were presented as frequencies and percentages. To test for statistical differences between physical activity intensity levels and children’s socio-demographic factors, Student’s t-tests with unequal variance for factors with two levels and analysis of variance (ANOVA) for factors with more than two levels were used. The two tests were run after testing for assumptions such as equality of variance using the variance ratio test and the Bartlett’s test for the t-test and ANOVA respectively. A multi-level mixed effect logistic regression model adjusted for clustering at division and school level was used to examine associations between compliance with physical activity guidelines and each of the socio-demographic variables. We used a backward model fitting technique and set the inclusion into the multivariable model at a p<0.2 and also included other factors highlighted in literature such as age and sex. Statistical significance was set at p<0.05 and all data were analysed using STATA statistical software Version 14.2.

Results

Accelerometer para-data

The para-data presented in Fig 1 was generated during the process of accelerometry enrolment, data collection, management and processing [62]. Of the 400 hundred children who returned complete parent/guardian questionnaires, 328 (82%) obtained parent/guardian consent to participate in accelerometry. The children who met the study age criteria were 312. During the entire study, 309 children were monitored; 285 children wore the monitor once whereas 24 children had additional monitoring. After retrieval of monitors and data download 41 data files were invalid mainly due to insufficient wear (31 files), malfunction (7 accelerometers) and loss (3 accelerometers). The final locked data set had 256 files with valid wake wearing time (78% of the children who had parental consent).

Fig 1. Participant flow chart reflecting accelerometry stages of participant enrollment, data collection, data processing and reasons for data loss at each stage (adapted from Tudor-Locke et al. 2015).

Fig 1

Participant characteristics

Children and parent/guardian characteristics are summarised in Table 1. The study sample comprised 256 children/parent pairs who completed the survey and had valid accelerometer-measured physical activity data. Most of the children attended private schools (58.3%) versus public schools (41.7%). More than half of the children were females (55.9%). Majority of the children were aged 10 and 11 years old (71.5%). Approximately three quarters of the children were of thin/normal weight (79.3%). More than half (58.6%) of parent/guardian respondents were females. Most of the parents/guardians (47.1%) were in the age range of 31 to 40 years old. One in every five parents/guardians were married or living with a partner. Majority of the parents had attained a diploma/degree/postgraduate level of education (74.2%); 70.3% of the families owned a car; and most of the households studied (62.1%) had 2 to 4 children aged 0 to 17 years old. Children wore accelerometers for an average of 15.6 hours/day and 6.5 days and out of the 24 hours and 7 days respectively.

Table 1. Children and parents/guardians characteristics.

Characteristics Type of school n(%) Overall N(%)
Private (n = 150) Public (n = 106) Overall (N = 256)
Children’s characteristics
Sex
Male 75 (25.8) 38 (14.8) 113 (44.1)
Female 75 (29.3) 68 (26.6) 143 (55.9)
Age (years)
10 69 (27.0) 20 (7.8) 88 (34.8)
11 56 (21.9) 38 (14.8) 94 (36.7)
12 25 (9.8) 48 (18.7) 74 (28.5)
Weight status (Calculated as BMI)
Overweight/Obese 47 (18.4) 6 (2.3) 53 (20.7)
Thin/Normal weight 103 (40.2) 100 (39.1) 203 (79.3)
Parents/guardian characteristics
Sex
Male 63 (24.6) 43 (16.8) 106 (41.4)
Female 87 (34.0) 63 (24.6) 150 (58.6)
Marital status
Married/Living with partner 128 (50.0) 79 (30.9) 207 (80.9)
Single/Widowed/Divorced 22 (8.6) 27 (10.6) 49 (19.1)
Age
21–30 5 (2.1) 12 (5.0) 17 (7.1)
31–40 70 (29.4) 42 (17.6) 112 (47.1)
41–50 55 (23.1) 42 (17.6) 97 (40.8)
51–66 7 (2.9) 5 (2.1) 12 (5.0)
Level of education
Diploma/Degree/Postgraduate 140 (54.7) 50 (19.5) 190 (74.2)
Certificate (Ordinary and Advanced level) 10 (3.91) 56 (21.9) 66 (25.8)
Number of cars at home
None 12 (4.7) 64 (25.0) 76 (29.7)
One 65 (25.4) 31 (12.1) 96 (37.5)
More than one 73 (28.5) 11 (4.3) 84 (32.8)
Number of youths in the Household
0–1 30 (11.7) 13 (5.1) 43 (16.8)
2–4 97 (37.9) 62 (24.2) 159 (62.1)
5+ 23 (9.0) 31 (12.1) 54 (21.1)
Accelerometry wear
*Wear time in hours per day 16.1 (6.0) 14.9 (1.3) 15.6 (4.7)
*Wear days 6.2 (1.0) 6.3 (1.1) 6.3 (1.1)

Data presented as counts and (%) and * means (standard deviation), N = total sample size, n = group sample size, BMI = Body Mass Index.

Physical activity intensity levels by sex, age, type of school and weight status

The children spent most of their time sedentary (9.8±2.1 hours/day), which accounted for 64% of their wake time. They spent another 4.5±0.8 hours /day in LPA and 56±25.7 minutes/day in MVPA with more time accumulated in MPA (38.6±16 minutes/day). Children attending private schools accumulated more sedentary time (P<0.001) compared to their peers from public schools. Children’s LPA was significantly different by age (p<0.05). We found significant sex differences in MPA (p<0.05) and VPA (P<0.001), with boys engaging in more MPA and VPA than girls. We also found significant differences in MPA (p<0.001) and VPA (p<0.001) by type of school; children attending public schools accumulated 16.4 and 9.3 more minutes/day of MPA and VPA respectively compared to their peers attending private schools. Thin/normal weight children had significantly higher amounts of MPA (p<0.001) and VPA (P<0.001) compared to overweight/obese children (Table 2).

Table 2. Average daily minutes of physical activity at various intensity levels by age, sex, type of school and weight status.

Physical Activity intensity levels (Mean [SD])
Sedentary time P-value LPA P-value
Overall 590.6 (124.0) 273 (48.3)
Sex#
Male 606.1 (146.6) 0.089 272.5 (48.0) 0.783
Female 578.4 (101.6) 274 (48.8)
Age^
10 591.0 (112.0) 0.995 283.3 (44.2) 0.020
11 591.2 (142.6) 272.9 (50.4)
12 589.4 (113.5) 262.1 (48.6)
Type of School#
Private 617.4 (142.1) <0.001* 277.1 (45.4) 0.155
Public 552.6 (78.7) 268.3 (52.1)
Weight status#
Overweight/obese 614.4 (144.2) 0.117 275.3 (47.6) 0.758
Thin/normal weight 584.4 (117.8) 272.9 (48.6)
MPA P-value VPA P-value
Overall 38.6 (16.0) 17.3 (12.3)
Sex#
Male 39.4 (16.3) 0.002 20.7 (15.2) <0.001*
Female 37.9 (15.8) 14.9 (8.7)
Age^
10 36.9 (13.9) 0.459 15.9 (8.2) 0.090
11 39.4 (17.9) 17.0 (11.0)
12 39.6 (16.0) 20.0 (17.1)
Type of School#
Private 31.8 (12.1) <0.001* 13.6 (7.0) <0.001*
Public 48.2 (16.0) 22.9 (15.8)
Weight status#
Overweight/Obese 30.0 (10.9) <0.001 11.6 (6.6) <0.001
Thin/normal weight 40.8 (16.4) 19.0 (13.0)

SES = socio-economic status, HSES = High socio-economic status, LSES = Low socio-economic status. Analysis: mean difference,

T-Test#,

One-way ANOVA^,

*p<0.001

Children’s compliance with physical activity recommendations

WHO (2010) [4] recommends that children accumulate at least 60 minutes of MVPA daily. Table 3 shows children’s compliance with these recommendations by age, sex, type of school and weight status. Only 36.3% of the 256 children participated in ≥ 60 minutes/day of MVPA. Significantly more males (38.9%) than females (34.3%) accumulated recommended MVPA. Significantly more children from public schools (62.3%) than their peers from private schools (18%), met the physical activity guidelines. Significantly more thin/normal weight children (42.9%) engaged in sufficient amounts of physical activity than overweight/obese children (11.3%).

Table 3. Compliance with physical activity guidelines by children’s sociodemographics.

Characteristic Sufficient PA Insufficient PA P-value
Overall n (%) n (%)
93 (36.3%) 163 (63.7%)
Sex
Male n = 113 44 (38.9) 69 (61.1) <0.001*
Female n = 143 49 (34.3) 94 (65.7)
Age
10 years n = 88 29 (32.6) 60 (67.4)
11 years n = 94 35 (37.2) 59 (62.8) 0.064
12 years n = 74 29 (39.7) 44 (60.3)
School Type
Private n = 150 27 (18) 123 (82) <0.001*
Public n = 106 66 (62.3) 40 (37.7)
Body Weight Status
Overweight/obese 6 (11.3) 47 (88.7) <0.001*
Thin/normal weight 87 (42.9) 116 (57.1)

PA = physical activity, n = subtotal,

* p<0.001.

Socio-demographics correlates of children’s physical activity

Socio-demographic factors associated with meeting physical activity guidelines were presented in Table 4. In the unadjusted model, four of the children and parents’ characteristics were significantly associated with meeting physical activity guidelines. Specifically, children were more likely to meet physical activity guidelines if they attended a public school (OR = 7.5; 95% CI = 4.24–13.32), were thin/normal weight (OR = 5.88; 95% CI = 2.30–15.00); or if their mothers reported a lower level of education (OR = 3.64; 95% CI = 2.12–6.24). Lower odds of meeting guidelines were noted for children from families that owned a car (OR = 0.23; 95% CI = 0.14–0.38). In the fully adjusted model, the observed associations of weight status, maternal level of education and car ownership remained significant and their effect size remained nearly unchanged. Specifically, thin/normal weight children (OR = 4.08; 95% CI = 1.42–11.76) and children whose mothers reported lower levels of education (OR = 2.43; 95% CI = 1.84–3.21) were more likely to meet the physical activity guidelines. However, lower odds of meeting physical activity guidelines were noted in children aged 12 years (OR = 0.68; 95% CI = 0.55–0.84) and those from families that owned a car (OR = 0.31; 95% CI = 0.17–0.55). Sex was not significantly associated with meeting physical activity guidelines.

Table 4. Multi-level logistic regression results for associations between children’s socio-demographics and compliance to physical activity guidelines.

Characteristics Physical Activity Guidelines n (%) Crude OR (95% CI) P-value Adjusted OR (95%CI) P-Value
Sufficient PA Insufficient PA
**Type of School
Private 27 (18.0) 123 (82.0) 1.00
Public 66 (62.3) 40 (37.7) 7.52(4.24,13.32) <0.001*
Sex
Female 49 (34.3) 94 (65.7) 1.00 1.00
Male 44 (38.9) 69 (61.1) 1.22 (0.71,2.11) 0.469 1.7 (0.98,2.97) 0.061
Age (years)
10 29 (32.6) 60 (67.4) 1.00 1.00
11 35 (37.2) 59 (62.8) 1.23 (0.86,1.74) 0.252 0.86 (0.43,1.72) 0.661
12 29 (39.7) 44 (60.3) 1.36 (0.55,3.41) 0.507 0.68 (0.55, 0.84) <0.001*
Weight status
Overweight/obese 6 (11.3) 47 (88.7) 1.00 1.00
Normal weight 87 (42.9) 116 (57.1) 5.88 (2.30, 15.00) <0.001* 4.08 (1.42,11.76) 0.009
Marital status
Married/Living with partner 70 (33.8) 137 (66.2) 1.00 1.00
Single/Widowed/Divorced 23 (46.9) 26 (53.1) 1.73 (0.79,3.77) 0.167 1.14 (0.54,2.41) 0.732
Mother’s education level
Diploma/Degree/Postgraduate 54 (28.4) 136 (71.6) 1.00 1.00
Certificate (Ordinary and Advanced level 39 (59.1) 27 (40.9) 3.64 (2.12, 6.24) <0.001* 2.43 (1.84,3.21) <0.001*
Number of cars at home
None 47 (61.8) 29 (38.2) 1.00 1.00
One 26 (27.1) 70 (72.9) 0.23 (0.14,0.38) <0.001* 0.30 (0.22,0.40) <0.001*
More than one 20 (23.8) 64 (76.2) 0.19 (0.05,0.76) 0.019 0.31 (0.17,0.55) <0.001*
Children and youths(6 to 17 years) in the Household
0–1 15 (34.9) 28 (65.1) 1.00
2–4 54 (34.0) 105 (66.0) 0.96 (0.48,1.90) 0.907
5+ 24 (44.4) 30 (55.6) 1.49 (0.53,4.21) 0.448

n = subtotal, ** clustered at school level,

* p<0.001.

Discussion

The current study assessed accelerometer-measured physical activity intensity levels, compliance with physical activity guidelines and socio-demographic correlates of meeting physical activity guidelines among 10 to 12 years old school-going children in Kampala, city Uganda. The results showed that children spent most of their time sedentary (64%) and in LPA and less time in MVPA. Only 36.3% met the physical activity guidelines, with the proportion of meeting physical activity guidelines lower among girls, private school and overweight/obese children. The adjusted model showed that thin/normal weight children and children whose mothers reported a lower level of education were greater than twice as likely to meet physical activity guidelines; whereas older children and children from families that owned a car had lower odds of meeting physical activity guidelines.

In line with our results, literature shows that a typical physical activity pattern for children comprise of >40% sedentary time [63,64], a substantial amount of time in LPA [3,16,38,63] and <5% of wake time in MVPA [2]. For example, in a review study, Elmesmari et al. reported that children spent >70% of their wake time in sedentary pursuits [65]. In Dakar Senegal, Diouf et al. reported 65% sedentary time among school children 8 to 11 years old [16]. Among Kenyan children, Ojiambo and colleagues found that 72% of children’s wake time was sedentary time [14]; whereas Muthuri et al. reported 6.6 hours of sedentary time [17]. This is worrying because sedentary time plays a major role on poor health and overall mortality independent of participation in physical activity [66,67]. Also, sedentary time competes for time children spend in physical activity which may hinder them from achieving the set physical activity guidelines [68,69]. Sedentary time was particularly high among overweight/obese children. Likewise, in a systematic review, Elmesmari et al., found that sedentary time was significantly higher in obese than non-obese groups [65].

The consistent finding that LPA contributes a substantial amount to children’s physical activity is supported by findings of the current study [3,17,38,39]. LPA is linked to cardio-metabolic health in children and may be an easier substitute for sedentary time due to its light intensity [2,39]. However, higher intensity physical activity (MPA & VPA) is linked to greater health benefits [1,2,70], particularly VPA which is favourable for obesity prevention [2,38,39,40]. However, similar to literature, our results showed that children spent less time in MVPA, the highest percentage coming from MPA [16,17,38,39]. Although children may not be able to sustain high intensity physical activity for a long period of time, shorter bouts of VPA may have greater health benefits than longer bouts of MPA [3,70]. Therefore, interventions programs focusing on increasing physical activity levels (MVPA) and decrease sedentary time are needed.

The average time spent in MVPA among school-going children in Kampala was 56 minutes/day which was less than the recommended minimum of 60 minutes/day. Only 36.3% of the children met the WHO, 2010 physical activity guidelines. Literature also shows that children do not engage in sufficient amounts of MVPA [9,10,11,16,17,29,30,41]. For example, results from ISCOLE, Kenya, showed that children aged 9 to 11 years recorded an average of 36 minutes/day of MVPA, and only 12.6% of the children met the physical activity guidelines [17]. Differences in MVPA by children’s characteristics revealed that girls, private school and overweight/obese children were less likely to meet the physical activity guidelines. Sex differences in children’s MVPA favoring boys have been consistently reported in literature [11,16,17,29,34,35,41,71] and the present study confirms these findings. Cultural factors may explain the sex differences in children’s MVPA [2]. Culture determines the roles taken on by boys and girls which influences their physical activity behaviour and interests [72,73]. Furthermore, boys have higher independent mobility which provides them with more opportunities to engage in physical activity [74]. Similar to results from the ISCOLE study conducted in Nairobi Kenya, a higher percentage of children in public schools accumulated more MVPA compered to their peers in private schools [17]. The results of our study were in line with those from previous studies that a higher proportion of thin/normal weight children meet physical activity guidelines compared to their overweight/obese peers [35,39,65].

Physical activity was inversely correlated with children’s weight status; specifically, overweight/obese children were unlikely to meet physical activity guidelines. This finding is consistent with literature [17,29,35,39,65]. Nevertheless, among urban and rural children aged 11 to 16 years in Uganda, high weight status was associated with sufficient physical activity; however, the highest weight status identified in this study was normal weight [33]. Inconsistent associations between physical activity and weight status have also been reported [75] whereas some studies found no significant associations [71]. The inconsistent findings may be due to the different criteria used to define weight status (WHO, US Centre for Disease Control and Prevention [CDC] and International Obesity Task Force [IOTF]) which give different estimates [65]. Our findings should also be viewed with caution due to a possibility of reverse causation.

The observation that older children were less likely to meet physical activity guidelines is consistent with previous studies demonstrating that children’s physical activity declines with increasing age [18,29,70]. LSES (as indicated by low maternal level of education and no family car) was positively associated with meeting physical activity guidelines. A review of studies from Sub-Saharan Africa [15] other studies [1317] reported similar results. On the contrary, studies from HICs [34,36,41,43] reported positive associations between children’s physical activity and HSES. The contradictory results may be explained by the different proxy indicators used to assess SES [76]. In addition, in LICs like Uganda it may be a necessity rather than a choice for children from LSES families to engage in physical activity; whereas for children from HSES families, technological advances like car ownership may hinder their participation in physical activity, and for them to be active may require a more deliberate initiative [77]. The Negative association between higher levels of maternal education and children’s physical activity found in this study have been reported elsewhere [17,38,45,78]. Crawford and colleagues proposed that highly educated mothers may not have time to model physical activity behaviour for their children because of full time employment [79]. Results of the current study also showed an inverse association between owning a car and meeting physical activity guidelines. Similar findings have been reported elsewhere [43,45]. Owning one or more cars is a disincentive to active travel which is a major contributor to children’s physical activity [17,43,45,71,80].

Therefore, there is need for developing effective strategies and policies with the aim of increasing physical activity levels among school going children in Kampala city and Uganda. This may be achieved by implementing strategies and policies that have been proposed by various global and regional organisations including those of the Active Healthy Kids Global Alliance (AHKGA) in the fight against the insufficient physical activity among children [81,82]. The current study further highlighted the need for nationally representative physical activity data. The Ministry of Education and Sports in Uganda should fund the development and release of a national report card on physical activity for children in Uganda for surveillance and promotion of physical activity among Ugandan children.

A particular strength of this study was the use of accelerometers to measure children’s physical activity which provided a more robust assessment than self-report measures. This is also the first study of this kind to be conducted in Uganda. However, when using accelerometers there are some limitations in quantifying physical activity of children who engage in swimming, cycling, and activities that predominantly involve upper body movements and weight lifting [83,84]; therefore, we may have underestimated children’s physical activity. However, according to the education abstract, 2014 children in Uganda rarely engage in cycling and swimming [83]. We also used the more liberal criteria in which participating in an average of ≥60 minutes of MVPA on all measured days was considered sufficient physical activity. It is likely that some of the children were not meeting the ≥ 60 minutes of MVPA on all 7days of the week as stated in the guidelines [4]. The study is also not nationally representative; therefore, the results cannot be generalized to all school-going children in Ugandan. The current study findings should be interpreted with caution given the cross sectional design which makes it impossible to infer causality and the low response rate

Conclusion

In conclusion the current study findings revealed that children spend substantial time in sedentary pursuits and LPA and less time in MVPA. Most of the children in did not meet the physical activity guidelines of ≥60 minutes of MVPA every day. MVPA was higher among boys, public school and thin/normal weight children. Specific interventions are needed to help children in Kampala city to increase their physical activity levels; particularly girls, overweight/obese children, and children from families that have highly educated parents and own cars. Although the response rate was relatively low, this study may be important for surveillance and serve as a model for a nationwide study.

Supporting information

S1 Appendix. Data set.

(XLSX)

Acknowledgments

The authors appreciate the Directorate of Education and Social Services, Kampala Capital City Authority (KCCA) for permitting them to access schools. We appreciate the research assistants who greatly contributed to data collection. We are also grateful to all school head teachers, teachers, parents/guardians and children who participated in this study. We thank the Physical Activity and Health Laboratory at the University of Massachusetts Amherst, USA for support on accelerometry data management and interpretation.

Data Availability

All relevant data are within the manuscript and its Supporting Information files.

Funding Statement

The PhD project was funded by the African Development Bank-Higher Education in Science and Technology (AfDB-HEST), Makerere University, Kampala

References

  • 1.Janssen I, Leblanc A. Systematic review of the health benefits of physical activity in school-aged children and youth. Int. J. Behav. Nutr. Phys. Act. 2010; 7:40 10.1186/1479-5868-7-40 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Poitras VJ, Gray CE, Borghese MM, Carson V, Chaput J-P, Janssen I, et al. Systematic review of the relationships between objectively measured physical activity and health indicators in school-aged children and youth. Appl. Physiol. Nutr. Metab. 2016; 41(6): S197–S239. 10.1139/apnm-2015-0663 [DOI] [PubMed] [Google Scholar]
  • 3.Carson V, Ridgers ND, Howard B J, Winkler EA, Healy GN, Owen N, et al. Light-intensity physical activity and cardio metabolic biomarkers in US adolescents. PLoS ONE. 2013, 8 (8): e71417 10.1371/journal.pone.0071417 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4.World Health Organization (WHO). Global recommendations on physical activity for health. 2010. Geneva, Switzerland. [PubMed] [Google Scholar]
  • 5.United States Department of Health and Human Services. Physical Activity Guidelines for Americans. 2018. Washington, DC. [Google Scholar]
  • 6.Tremblay MS, Warburton DER, Janssen I, Paterson DH, Latimer AE, Rhodes RE, et al. New Canadian physical activity guidelines. Appl. Physiol. Nutr. Metab. 2011; 36(1): 36–46. 10.1139/H11-009 [DOI] [PubMed] [Google Scholar]
  • 7.Australian Government. Make your move—sit less—be active for live. Australia’s Physical Activity & Sedentary Behaviour Guidelines for Children (5–12 years) and young people (13–17 years). 2012. Commonwealth of Australia, Department of Health and Ageing.
  • 8.Department of Health. Start active, stay active: a report on physical activity for health from the four home countries' Chief Medical Officers. London, UK. 2011; Department of Health,
  • 9.Hallal PC, Andersen LB, Bull FC, Guthold R, Haskell W, Ekelund U, et al. Global physical activity levels: surveillance progress, pitfalls, and prospects. Lancet. 2012; 380 (9838): 247–57. 10.1016/S0140-6736(12)60646-1 [DOI] [PubMed] [Google Scholar]
  • 10.Sallis J, Bull F, Guthold R, Heath GW, Inoue S, Kelly P, et al. Progress in physical activity over the Olympic quadrennium. Lancet. 2016; 388:1325–36. 10.1016/S0140-6736(16)30581-5 [DOI] [PubMed] [Google Scholar]
  • 11.Guthold R, Stevens GA, Riley LM, Bull FC. Global trends in insufficient physical activity among adolescents: a pooled analysis of 298 population-based surveys with 1·6 million participants. Lancet Child Adolesc. Health. 2020;4(1):23–35. 10.1016/S2352-4642(19)30323-2 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 12.Steene-Johannessen J, Hansen BH, Dalene KE, et al. Variations in accelerometry measured physical activity and sedentary time across Europe—harmonized analyses of 47,497 children and adolescents. Int J Behav Nutr Phys Act. 2020;17(1):38 Published 2020 Mar 18. 10.1186/s12966-020-00930-x [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 13.Onywera VO, Adamo KB, Sheel AW, Waudo JN, Boit MK, Tremblay MS. Emerging evidence of the physical activity transition in Kenya. J Phys Act Health. 2012. May; 9(4):554–62. 10.1123/jpah.9.4.554 [DOI] [PubMed] [Google Scholar]
  • 14.Ojiambo RM, Easton C, Casajus JA, Konstabel K, Reilly JJ, Pitsiladis Y. Effect of urbanization on objectively measured physical activity levels, sedentary time, and indices of adiposity in Kenyan adolescents. J Phys Act Health. 2012; 9:115–123. 10.1123/jpah.9.1.115 [DOI] [PubMed] [Google Scholar]
  • 15.Muthuri SK, Wachira LJM, Leblanc AG, Francis CE, Sampson M, Onywera VO, et al. Temporal trends and correlates of physical activity, sedentary behaviour, and physical fitness among school-aged children in Sub-Saharan Africa: a systematic review. Int J Environ Res Public Health. 2014; 11: 3327–3359. 10.3390/ijerph110303327 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 16.Diouf A, Thiam M, Idohou-Dossou N, Diongue O, Megne N, Diallo K, Sembene PM, Wade S. Physical activity level and sedentary behaviours among public school children in Dakar (Senegal) measured by PAQ-C and accelerometer: preliminary results. Int J Environ Res Public Health. 2016;13(10):998 10.3390/ijerph13100998 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 17.Muthuri SK, Wachira LJM, Onywera VO, Tremblay MS. Correlates of objectively measured overweight/ obesity and physical activity in Kenyan school children: results from ISCOLE-Kenya. BMC Public Health. 2014. May 24; 14:436 10.1186/1471-2458-14-436 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 18.Farooq A, Martin A, Janssen X, Wilson MG, Gibson A-M, Hughes A, Reilly JJ. Longitudinal changes in moderate-to-vigorous-intensity physical activity in children and adolescents: A systematic review and meta-analysis. Obes Rev. 2019; 1–15. 10.1111/obr.12753 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 19.Telama R, Yang X, Leskinen E, Kankaanpa A, Hirvensalo M, Tammelin T. et al. Tracking of physical activity from early childhood through youth into adulthood. Med Sci Sports Exerc. 2014; 46(5): 955–962. 10.1249/MSS.0000000000000181 [DOI] [PubMed] [Google Scholar]
  • 20.Manyanga T, Barnes JD, Abdeta C, Adeneyi AF, Bhawra J, Draper CE, et al. Indicators of Physical Activity Among Children and Youth in 9 Countries with Low to Medium Human Development Indices: A Global Matrix 3.0 Paper. J Phys Act Health. 2018; 15(Suppl2): S274–S283. 10.1123/jpah.2018-0370 [DOI] [PubMed] [Google Scholar]
  • 21.Cain KL, Conway TL, Adams MA, Husak LE, Sallis JF. Comparison of older and newer generations of ActiGraph accelerometers with the normal filter and the low frequency extension. Int J Behav Nutr Phys Act. 2013; 10:51 10.1186/1479-5868-10-51 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 22.Welk GJ, Corbin CB, Dale D. Measurement issues in the assessment of physical activity in children. Res Q Exerc Sport. 2000; 71(2): S59–73. [PubMed] [Google Scholar]
  • 23.Ainsworth B, Cahalin L, Buman M, Ross R. The current state of physical activity assessment tools. Prog Cardiovasc Dis. 2015; 57: 387–395. 10.1016/j.pcad.2014.10.005 [DOI] [PubMed] [Google Scholar]
  • 24.Tremblay MS, Esliger DW, Tremblay A, Colley R. Incidental movement, lifestyle-embedded activity and sleep: new frontiers in physical activity assessment. Can. J. Publ. Health. 2007; 98(Suppl. 2): 208–217. [PubMed] [Google Scholar]
  • 25.Hänggi JM, Phillips LRS, Rowlands AV. Validation of the ActiGraph in children and comparison with the GT1M ActiGraph. J Sci Med Sport. 2013; 16: 40–44. 10.1016/j.jsams.2012.05.012 [DOI] [PubMed] [Google Scholar]
  • 26.Plasqui G, Westerterp KR. Physical activity assessment with accelerometers: an evaluation against doubly labeled water. Obesity. 2007; 15: 2371–2379. 10.1038/oby.2007.281 [DOI] [PubMed] [Google Scholar]
  • 27.Trost SG. Measurement of physical activity in children and adolescents. Am J Lifestyle Med. 2000; 1 (4). [Google Scholar]
  • 28.Katzmarzyk PT, Barreira TV, Broyles ST, Champagne CM, Chaput JP, Fogelholm M, et al. The International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE): design and methods. BMC Public Health. 2013; 13:900 10.1186/1471-2458-13-900 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 29.Cooper AR, Goodman A, Page AS, Sherar LB, Esliger DW, van Sluij EMF, et al. Objectively measured physical activity and sedentary time in youth: The International children's accelerometry database (ICAD). Int J Behav Nutr Phys Act. 2015; 12:113 10.1186/s12966-015-0274-5 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 30.Doherty A, Jackson D, Hammerla N, Plots T, Olivier P, Granit MH, et al. Large scale population assessment of physical activity using wrist worn accelerometers: The UK biobank study. PLoS ONE. 2017; 12, e0169649 10.1371/journal.pone.0169649 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 31.Tharenos CL, Santorino D. Photographing Ugandan physical activity: Perspectives from Mbararan youth. Prog Community Health Partnersh. 2009; 3 (2): 97–98. 10.1353/cpr.0.0070 [DOI] [PubMed] [Google Scholar]
  • 32.Peltzer K, Pengpid S. Overweight and obesity and associated factors among school-aged adolescents in Ghana and Uganda. Int J Environ Res Public Health. 2011; 8:3859–3870. 10.3390/ijerph8103859 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 33.Christoph MJ, Grigsby-Toussaint DS, Baingana R, Ntambi JM. Physical Activity, Sleep, and BMI Percentile in Rural and Urban Ugandan Youth. Ann Glob Health. 2017;83(2):311–319. 10.1016/j.aogh.2017.04.005 [DOI] [PubMed] [Google Scholar]
  • 34.Currie C, Zanotti C, Morgan A, Currie D, de Looze M, Roberts C, et al. Social determinants of health and well-being among young people. Health Behavior in School-aged Children (HBSC) study: International report from the 2009/2010 survey. Health Policy for Children and Adolescents, 6. Copenhagen, 2012; WHO Regional Office for Europe.
  • 35.Li X, Kearney PM, Keane E, Harrington JM, Fitzgerald AP. Levels and sociodemographic correlates of accelerometer-based physical activity in Irish children: a cross-sectional study. J Epidemiol Community Health 2017; 71:521–527. 10.1136/jech-2016-207691 [DOI] [PubMed] [Google Scholar]
  • 36.Sallis JF, Prochaska JJ, Taylor WC. A review of correlates of physical activity of children and adolescents. Med Sci Sports Exerc. 2000; 32 (5): 963–975. 10.1097/00005768-200005000-00014 [DOI] [PubMed] [Google Scholar]
  • 37.Weinberg D, Stevens GWJ, Bucksch J, Inchley J, de Looze M. Do country-level environmental factors explain cross-national variation in adolescent physical activity? A multilevel study in 29 European countries. BMC Public Health. 2019; 19:680 10.1186/s12889-019-6908-9 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 38.Wilkie HJ, Standage M, Gillison FB, Cumming SP, Katzmarzyk P T. Correlate of intensity-specific physical activity in children aged 9–11 years: a multilevel analysis of UK data from the International Study of Childhood Obesity, Lifestyle and the Environment. Br Med J. 2018; 8: e018373 doi: 10.1136/ bmjopen-2017-01837 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 39.Schwarzfischer P, Gruszfeld D, Socha P, Luque V, Closa-Monasterolo R, Rousseaux D, et al. Longitudinal analysis of physical activity, sedentary behavior and anthropometric measures from ages 6 to 11 years. Int J Behav Nutr Phys Act. 2018; 15:126 10.1186/s12966-018-0756-3 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 40.Jiménez-Pavón D, Fernández-Vazquez A, Alexy U, Pedrero R, Cuenca-Garcia M, Polito A, Vanhelst J, et al. Association of objectively measured physical activity with body components in European adolescents. BMC Public Health. 2013; 13, 667 10.1186/1471-2458-13-667 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 41.Riso E-M, Kull M, Mooses K, Jurimae J. physical activity, sedentary time and sleep duration: associations with body composition in 10-12-year-old Estonian school children. BMC Public Health. 2018; 18:496 10.1186/s12889-018-5406-9 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 42.Baskin ML, Thind H, Affuso O, Gary LC, LaGory M, Hwang S. Predictors of moderate-to-vigorous physical activity (MVPA) in African American young adolescents. Ann Behav Med. 2013; 45 (01): S142–150. 10.1007/s12160-012-9437-7 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 43.van Sluijs EMF, Ekulund U, Hansen BH, Panter J, Sharp SJ, Sherar LB et al. Family car ownership and activity in young people: cross-sectional and longitudinal analyses using the International Children's Accelerometry Database. The Lancet. 2018, 392, S89 10.1016/S0140-6736(18)32105-6 [DOI] [Google Scholar]
  • 44.Oyeyemi AL, Ishaku CM, Oyekola J, Wakawa HD, Lawan A, Yakubu S, et al. Patterns and associated factors of physical activity among adolescents in Nigeria. 2016, PLoS ONE 11(2): e0150142 10.1371/journal.pone.0150142 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 45.Pouliou T, Sera F, Griffiths L, Joshi H, Geraci M, Cortina-Borja M, et al. Environmental influences on children's physical activity. J Epidemiol Community Health. 2015;69(1):77–85. 10.1136/jech-2014-204287 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 46.Brooke HL, Atkin AJ, Corder K, Ekelund U, van Sluijs EM. Changes in time-segment specific physical activity between ages 10 and 14 years: A longitudinal observational study. J Sci Med Sport. 2016;19(1):29–34. 10.1016/j.jsams.2014.10.003 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 47.Corder K, Sharp SJ, Atkin AJ, Griffith SJ, Jones AP, Ekelund U, et al. Change in objectively measured physical activity during the transition to adolescence. Br J Sports Med. 2015;49(11):730–736. 10.1136/bjsports-2013-093190 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 48.Uganda Bureau of Statistics (UBOS). Uganda National Housing Survey 2012/2013.Kampala-Uganda. 2014; UBOS. Retrieved from http://www.ubos.org. Accessed November 10th 2019.
  • 49.Kampala Capital City Authority (KCCA): Strategic plan 2014/15–2018/19. Laying a foundation for Kampala city transformation. Retrieved from http://www.kcca.go.ug
  • 50.Tudor-Locke C, Barreira TV, Schuna JM, Mire EF, Chaput JP, Fogelholm M, et al. Improving wear time compliance with a 24-hour waist-worn accelerometer protocol in the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE). Int J Behav Nutr Phys Act. 2015; 12:172. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 51.Tudor-Locke C, Barreira TV, Schuna JM, Mire EF, Katzmarzyk PT. Fully automated waist-worn accelerometer algorithm for detecting children’s sleep-period time separate from 24-h physical activity or sedentary behaviors. App Physiol, Nutr Metab. 2014; 39(1):53–57 [DOI] [PubMed] [Google Scholar]
  • 52.Meredith-Jones K, Williams S, Galland B, Kennedy G, Taylor R. 24 h Accelerometry: impact of sleep-screening methods on estimates of sedentary behaviour and physical activity while awake. J Sports Sci. 2016; 34:7,679–685. 10.1080/02640414.2015.1068438 [DOI] [PubMed] [Google Scholar]
  • 53.Sadeh A, Sharkey KM, Carskadon MA. Activity-based sleep wake identification: An empirical test of methodological issues. Sleep. 1994; 17(3):201–207. 10.1093/sleep/17.3.201 [DOI] [PubMed] [Google Scholar]
  • 54.Galland BC, Taylor BJ, Elder DE, Herbison P. Normal sleep patterns in infants and children: A systematic review of observational studies. Sleep Med Rev. 2012; 16(3): 213–222 10.1016/j.smrv.2011.06.001 [DOI] [PubMed] [Google Scholar]
  • 55.Evenson KR, Catellier DJ, Gill K, Ondrak KS, McMurray RG. Calibration of two objective measures of physical activity for children. J Sports Sci. 2008; 26(14):1557–65. 10.1080/02640410802334196 [DOI] [PubMed] [Google Scholar]
  • 56.Trost SG, Loprinzi PD, Moore R, Pfeiffer KA. Comparison of accelerometer cut points for predicting activity intensity in youth. Med Sci Sports Exerc. 2011; 43:1360–8. 10.1249/MSS.0b013e318206476e [DOI] [PubMed] [Google Scholar]
  • 57.de Oni M, Onyango AW, Borghi E, Siyam A, Nishida C, Siekmann J. Development of a WHO growth reference for school-aged children and adolescents. World Health Organization. 2007; 85:660e7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 58.Oyeyemi AL, Kasoma SS, Onywera VO, Assah F, Adedoyin RA, Conway TL, et al. NEWS for Africa: adaptation and reliability of a built environment questionnaire for physical activity in seven African countries. Int J Behav Nutr Phys Act. 2016; 13:33 10.1186/s12966-016-0357-y [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 59.Daniel WW, & Cross CL. Biostatistics: A Foundation for Analysis in the Health Sciences. 2013, 10th edition. New York: John Wiley & Sons [Google Scholar]
  • 60.Millstein RA, Strobel J, Kerr J, Sallis JF, Norman GJ, Durant N, et al. Home, school, and neighborhood environment factors and youth physical activity. Pediatr Exerc Sci, 2011; 23 (4), 487–503. 10.1123/pes.23.4.487 [DOI] [PubMed] [Google Scholar]
  • 61.Cochran WG. Sampling Techniques. 1977, 3rd edition. New York: John Wiley & Sons. [Google Scholar]
  • 62.Tudor-Locke C, Mire EF, Dentro KN, Barreira T, Schuna JM, Zhao P, et al. A model for presenting accelerometer Para data in large scale studies: ISCOLE. Int J Behav Nutr Phys Act. 2015b; 12:52 10.1186/s12966-015-0213-5 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 63.Colley RC, Garriguet D, Janssen I, Craig CL, Clarke J, Tremblay MS. Physical activity of Canadian children and youth: accelerometer results from the 2007 to 2009 Canadian Health Measures Survey. Health Rep. 2011;22(1):15–23. [PubMed] [Google Scholar]
  • 64.Chaput JP, Carson V, Gray C E, Tremblay MS. Importance of all movement behaviors in a 24-hour period for overall health. Int J Environ Res Public Health. 2014; 11(12):12575–81. 10.3390/ijerph111212575 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 65.Elmesmari R, Martin A, Reilly JJ, Paton JY. Comparison of accelerometer measured levels of physical activity and sedentary time between obese and non-obese children and adolescents: a systematic review. BMC Pediatr. 2018; 18:106 10.1186/s12887-018-1031-0 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 66.Carson V, Hunter S, Kuzik N, Gray CE, Poitras VJ, Chaput JP, et al. Systematic review of sedentary behavior and health indicators in school-aged children and youth: an update. App Physiol, Nutr Metab. 2016; 41: S240–65. 10.1139/apnm-2015-0630. [DOI] [PubMed] [Google Scholar]
  • 67.Tremblay MS, LeBlanc AG, Kho ME, Saunders TJ, Larouche R, Colley RC, et al. Systematic review of sedentary behaviour and health indicators in school-aged children and youth. Int J Behav Nutr Phys Act. 2011; 8:98 10.1186/1479-5868-8-98 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 68.Olds T, Blunden S, Petkov J, Forchino F. The relationships between sex, age, geography and time in bed in adolescents: a meta-analysis of data from 23 countries. Sleep Med Rev. 2010;14(6):371–8. 10.1016/j.smrv.2009.12.002 [DOI] [PubMed] [Google Scholar]
  • 69.LeBlanc AG, Katzmarzyk PT, Barreira TV, Broyles ST, Chaput JP, Church TS, et al. Correlates of total sedentary time and screen time in 9-11year-old children around the world: The international study of childhood obesity, lifestyle and the environment. PLoS ONE. 2015; 10: e0129622 10.1371/journal.pone.0129622 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 70.Carson V, Rinaldi RL, Torrance B, Maximova K, Ball GD, Majumdar SR, et al. Vigorous physical activity and longitudinal associations with cardio metabolic risk factors in youth. Int. J. Obes. 2014. 38(1): 16–21. doi: 10.1038/ ijo.2013.135 [DOI] [PubMed] [Google Scholar]
  • 71.Gomes TN, Katzmarzyk P., Hedeker D, Fogelholm M, Standage M, Onywera VO, et al. Correlates of compliance with recommended levels of physical activity in children. Sci. Rep. 2017; 7:16507 10.1038/s41598-017-16525-9 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 72.Fueyo JL, Garcia LMT, Mamondi V, Alencar GP, Florindo AA, Berra S. Neighborhood and family perceived environments associated with children's physical activity and body mass index. Prev Med. 2016; 82: 35–41 10.1016/j.ypmed.2015.11.005 [DOI] [PubMed] [Google Scholar]
  • 73.Oyeyemi AL, Ishaku CM, Deforche B, Oyeyemi AY, DeBourdeaudhuij I, Van Dyck D. Perception of built environmental factors and physical activity among adolescents in Nigeria. Int J Behav Nutr Phys Act. 2014; 11:56 10.1186/1479-5868-11-56 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 74.De Meester F, Van Dyck D, De Bourdeaudhuij I, Cardon G. Parental perceived neighborhood attributes: associations with active transport and physical activity among 10-12-year-old children and the mediating role of independent mobility. BMC Public Health. 2014; 14, 631 10.1186/1471-2458-14-631 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 75.Biddle SJH, Atkin AJ, Cavill N, Foster C. Correlates of physical activity in youth: A review of quantitative systematic reviews. Int Rev Sport Exerc Psychol. 2011; 4(1), 25–49. 10.1080/1750984X.2010. 548528. [DOI] [Google Scholar]
  • 76.Sterdt E, Liersch S, Walter U. Correlates of physical activity of children and adolescents: A systematic review of reviews. Health Educ J. 2014; 73 (1): 72–89. 10.1177/0017896912469578 [DOI] [Google Scholar]
  • 77.Bauman AE, Reis RS, Sallis JF, Wells JC, Loos RJF, Martin BW. Correlates of physical activity: why are some people physically active and others not? Lancet. 2012; 380:258–71. 10.1016/S0140-6736(12)60735-1 [DOI] [PubMed] [Google Scholar]
  • 78.Sherar LB, Griffin TP, Ekelund U, Cooper AR, Esliger DW, Van Sluij EMF et al. Association between maternal education and objectively measured physical activity and sedentary time in adolescents. J Epidemiol Community Health. 2016; 70:541–548. 10.1136/jech2015-205763 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 79.Crawford D, Cleland V, Timperio A, Salmon J, Andrianopoulos N, Roberts R, et al. The longitudinal influence of home and neighbourhood environments on children’s body mass index and physical activity over 5 years: the CLAN study. Int J Obes. 2010; 34:1177–87. [DOI] [PubMed] [Google Scholar]
  • 80.Oyeyemi AL, Larouche R. Prevalence and correlates of active transportation in developing countries In: Larouche R. Children’s active transportation. Cambridge: Elsevier; 2018; p.173–91. 10.1016/B978-0-12-811931-0.00012-0 [DOI] [Google Scholar]
  • 81.Matthews CE. Calibration of accelerometer output for adults. Med Sci Sports Exerc. 2005; 37: S512–522. 10.1249/01.mss.0000185659.11982.3d [DOI] [PubMed] [Google Scholar]
  • 82.Aubert S, Barnes JD, Abdeta C, Abi Nader P, Adeniyi AF, Aguilar-Farias N, et al. Global Matrix 3.0 Physical Activity Report Card Grades for Children and Youth: Results and Analysis from 49 Countries. J Phys Act Health. 2018;15(S2): S251‐S273. 10.1123/jpah.2018-0472 [DOI] [PubMed] [Google Scholar]
  • 83.World Health Organization. Draft WHO Global Action Plan on Physical Activity 2018–2030. Geneva, Switzerland: World Health Organization; Vol 2011 2017. [Google Scholar]
  • 84.Corder K, Brage S, Ekelund U. Accelerometers and pedometers: methodology and clinical application. Curr Opin Clin Nutr Metab Care. 2007; 10(5):597–603. 10.1097/MCO.0b013e328285d883 [DOI] [PubMed] [Google Scholar]
  • 85.The Republic of Uganda, Ministry of Education, Science, Technology and Sports. Statistical Abstract, 2014. Education planning and policy analysis department.

Decision Letter 0

Javier Brazo-Sayavera

24 Feb 2020

PONE-D-20-00496

Prevalence and sociodemographic correlates of accelerometer measured physical activity levels of school-going children in Kampala city, Uganda.

PLOS ONE

Dear Ms Nakabazzi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

The current manuscript describes PA patterns among children from Uganda. There is a lack of information of this type in countries from Africa, so it is to important to create evidence in the scientific literature. However, our reviewers consider that the document should be improved deeply. In this sense, I strongly recommend you to meet all the suggestions they provide throughout the revision letters in order to have a manuscript that could be published.

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Reviewer #1: No

Reviewer #2: Partly

**********

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Reviewer #1: No

Reviewer #2: I Don't Know

**********

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Reviewer #1: Yes

Reviewer #2: Yes

**********

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Reviewer #1: Yes

Reviewer #2: Yes

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Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Abstract:

----------

* Line 23 (and throughout the manuscript): Could the authors please use the term "device-based" instead of "objective"? The so-called "objective measurement" of physical activity includes several subjective calls to make by the researchers (which device to use, which analysis algorithm to use, input acceleration signal, cut-offs, etc.).

*Results (lines 36/37): For sedentary behaviour and MVPA, were data normally distributed? What were the standard deviations for the estimates?

*Results (lines 38/40): Were probability ratios measured or odds ratio? From the 95% CIs (0.71 - 2.11), looks like this estimate is not statistically significant.

*Results (lines 39/40): Please define a term before using the abbreviated form. LSES = low SES? HSES = high-SES?

Conclusion (line 45): It seems like the authors are assuming that sedentary time would be displaced by physical activity, which can happen. However, as this paper is about the prevalence and socio-demographic correlates of physical activity, it may not be ideal for making the assumption here in the Abstract!

Introduction:

---------------

* Line 63 (ref 9): The authors could consider citing a more recent paper about the prevalence of insufficient physical activity among children and adolescents: Guthold et al 2020 Global trends in insufficient physical activity among adolescents: a pooled analysis of 298 population-based surveys with 1·6 million participants. The Lancet Child & Adolescent Health 4:23-35. This study has data from 16 sub-Saharan African countries. The authors should consider re-framing their study background using information from this study.

* Line 68 (ref 12): This is a debated area. The authors should use "stronger" evidence - meta-analysis, systematic review - to support their statement.

* Line 98: The term "subjective measure" should be "recall-based measure" or "questionnaire-based measure".

* Line 106: The authors should acknowledge that "overweight and obesity" is not an SES measure.

Materials and methods:

--------------------------

* Design and Participants Recruitment subsection (line starting on 119): The authors should justify studying this age group. The recommendation for 60 min/d physical activity is for 5-17-year-old children and adolescents. Why did the authors study only children those aged 10-12 years?

* Design and Participants Recruitment subsection (line 127): So, everyone in those classrooms was eligible to participate. Were there any exclusion criteria? Did the authors ask any question about health conditions that, potentially, restrict some students' physical activity participation?

* Design and Participants Recruitment subsection (line 133): Could the authors please clarify what "during school sessions" mean? Were data not collected during holidays?

* Participants' Sociodemographics subsection (about SES measure; lines 168/170): I am not aware of how public-private schools operate in Kampala, and how they are viewed concerning SES. There might be several reasons for studying in a public school. I am unsure if this is an appropriate measure of SES -- this is an unusual approach to me. The authors may consider labelling this variable as "Type of school" not as a proxy for SES.

* Recruitment and Completion rate subsection: How did the authors calculate the sample size for this study?

* Data Analysis subsection (lines 182/183): Did the authors check if the data were normally distributed. If data were not normally disturbed, mean and SD would not be the appropriate summary statistics, the median and interquartile range would be.

* Data Analysis subsection (line 186): Could the authors please confirm all relevant assumptions for ANOVA were met?

* Data Analysis subsection (line 188): Did the regression model adjust for the nested nature of the data (i.e., a multilevel model)? Was this at the level of the division or also at the level of the school, or classroom? As the students are nested at different levels during their selection process, how the analyses account for this clustering?

* Data Analysis subsection (lines 188/191): Did the authors include all these variables in the model? Did the authors check for collinearity? It is likely that SES (i.e., type of school), maternal education, and car ownership would have multi-collinearity as these perhaps measure the same (or a similar) construct. Including all these three variables in the same model may make the model unstable and may not give correct estimates. How did the authors build their model? Did the authors run any post-estimation diagnostic test for their model?

* Data Analysis subsection (line 190): Weight status is not a socio-demographic variable.

Results:

---------

* Table 1: Is there any reason to describe the participants by their type of school?

* Line 249: I think the right way to express this is "Significantly more males (38.9%) than females (34.3%) accumulated recommended MVPA". The same applies to the rest of the paragraph.

* Table 4 (in general): I wonder why the authors presented crude ORs.

* Table 4 (variable sex): From the 95% CIs for "sex" (0.71 - 2.11) it seems like the p-value should not be 0.046.

* Table 4 (variable weight status): Some numbers in the cells are too small to run a logistic regression analysis. The CIs for the obese group is very wide and perhaps suggest that the model was unstable. I am not sure if combining the overweight and obese group into one would help.

Discussion (in general):

---------------------------

The methodological aspects of the paper needs to be revisited before discussing the findings.

Reviewer #2: Please refer to the attached reviewer comments, suggestions and questions. I think this is an important manuscript but it needs some important revisions prior to publication in my opinion. I am not sure the main statistical approach of using bivariate logistic regression was the best given the hierarchical (Individual, classroom, school) nature of these data. Although school environment is included in the analysis, the classroom is not. In light of the foregoing, I hesitate to render final judgement as to the statistical rigor of the analyses. I suggested a number of corrections hence my selecting partly on whether the manuscript is technically sound.

**********

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Attachment

Submitted filename: review comments.docx

PLoS One. 2020 Jul 9;15(7):e0235211. doi: 10.1371/journal.pone.0235211.r002

Author response to Decision Letter 0


22 Apr 2020

We are grateful to the editor and the two reviewers for their numerous and detailed comments on our manuscript.

Please find below our responses to each point raised by the academic editor and reviewers. In particular, the methods section has been expanded and made clear also we have re-analysed the data and made relevant changes to the discussion.

We believe that we have addressed all the concerns and our manuscript has greatly improved for publication.

Sincerely,

On behalf of all the authors,

Bernadette Nakabazzi

Academic Editor:

No comments provided

Reviewer #1

Abstract

1. Line 23 (and throughout the manuscript): Could the authors please use the term "device-based" instead of "objective"? The so-called "objective measurement" of physical activity includes several subjective calls to make by the researchers (which device to use, which analysis algorithm to use, input acceleration signal, cut-offs, etc.).

As requested we have changed the term “objective” and instead used “accelerometer measured” on line 23 and throughout the manuscript in the revised version. We did this to further specify the devise used to measure physical activity in the study.

2. Results (lines 36/37): For sedentary behaviour and MVPA, were data normally distributed? What were the standard deviations for the estimates?

Yes, the data were normally distributed evidence shown below (Comment 6 in the materials and methods section). We have also included the standard deviations for the estimates in the revised version line 36/37 to read; Children’s sedentary time was 9.8±2.1 hours/day and MVPA was 56±25.7 minutes/day.

3. Results (lines 38/40): Were probability ratios measured or odds ratio? From the 95% CIs (0.71 - 2.11), looks like this estimate is not statistically significant.

We measured odds ratios and this has been corrected in the revised version line 40 to 43.

Yes, the estimate was not statistically significant. The p-value is 0.469 it was a typing error. We have corrected this error.

4. Results (lines 39/40): Please define a term before using the abbreviated form. LSES = low SES? HSES = high-SES?

We thank the reviewer for pointing this out, we have corrected it (line 41/43) in the revised version.

5. Conclusion (line 45): It seems like the authors are assuming that sedentary time would be displaced by physical activity, which can happen. However, as this paper is about the prevalence and socio-demographic correlates of physical activity, it may not be ideal for making the assumption here in the Abstract!

We agree with this and have made necessary corrections, because the correlates of sedentary time were not assessed in the current study (line 54 revised version)

Introduction

6. Line 63 (ref 9): The authors could consider citing a more recent paper about the prevalence of insufficient physical activity among children and adolescents: Guthold et al 2020 Global trends in insufficient physical activity among adolescents: a pooled analysis of 298 population-based surveys with 1·6 million participants. The Lancet Child & Adolescent Health 4:23-35. This study has data from 16 sub-Saharan African countries. The authors should consider re-framing their study background using information from this study.

We thank the reviewer for suggesting this very important recent paper, we have included the information particularly the global statistics, those for Sub Saharan Africa (SSA) and the gender differences. We noted that the study generated most findings from self-reported data, which covered only 36% of the population in SSA and the trend of data were skewed to high income countries. Also the Global School-based Students Health Survey (GSHS) carried out in Uganda which informed this study focused on adolescents 13 to 17 years old.

However, we have re-phrased the study background as requested (Line 73/75 and 86/87 in revised version).

7. Line 68 (ref 12): This is a debated area. The authors should use "stronger" evidence - meta-analysis, systematic review - to support their statement.

We have deleted this statement, given that the study is focusing on physical activity and not sedentary time as noted in reviewer comment 5 above. We could also not identify a systematic review or meta-analysis to support the statement.

8. Line 98: The term "subjective measure" should be "recall-based measure" or "questionnaire-based measure".

Line 116/117 in the revised version; The term “subjective measure has been replaced with “recall-based measures”

9. Line 106: The authors should acknowledge that "overweight and obesity" is not an SES measure.

Children’s physical activity is consistently associated with various sociodemographic factors [29,34,35,36]. Various studies that used both objective and recall-based measures of physical activity consistently reported sex differences in physical activity favouring boys [11,17,29,34,35,36,37]. Children’s physical activity has also been found to decline with increasing age [18,29], nevertheless non-significant associations have also been reported [38]. Physical activity is frequently reported to be lower among overweight and obese children [13, 29,35,39,40,41]. Studies on associations between SES and children’s physical activity have generated inconsistent results. For example, in HICs, children from HSES families were more likely to meet physical activity guidelines [34] whereas in SSA children from HSES were unlikely to meet physical activity guidelines [17]. Physical activity is also lower among children from families that own cars [42,43,44,45]. However, there are inconsistent findings on the associations between parental education level and children’s physical activity [17, 36, 42,45]. Therefore, there is still need for more research assessing the sociodemographic correlates of children’s physical activity levels, particularly in SSA countries like Uganda where little research has been conducted [11,20]. The present study thus helped to identify children that required immediate intervention

Materials and methods:

1. Design and Participants Recruitment subsection (line starting on 119): The authors should justify studying this age group. The recommendation for 60 min/d physical activity is for 5-17-year-old children and adolescents. Why did the authors study only children those aged 10-12 years?

We thank the reviewer for pointing out this, we have made a justification for studying this age group in line 145/147 in the revised version to read as;

As children aged 10 to 12 years old are transiting from childhood to adolescence, they gain some autonomy in decision making which is critical to declines in their physical activity [43,44].

Younger participants have not gained independence in choosing and guiding their activities and behaviour and are still greatly influenced (restricted by parents and guardians for several reasons). Older children are greatly influenced by the pubertal growth spurt which could have influenced several aspects also tested in our study such as weight and adiposity status

2. Design and Participants Recruitment subsection (line 127): So, everyone in those classrooms was eligible to participate. Were there any exclusion criteria? Did the authors ask any question about health conditions that, potentially, restrict some students' physical activity participation?

The classroom approach was meant to be as inclusive as possible so that learners do not feel left out apart from those that had conditions likely to interfere with physical activity at the time of study.

We excluded children who had physical and health conditions that limited their participation in physical activity (Line 154/155 in the revised edition)

3. Design and Participants Recruitment subsection (line 133): Could the authors please clarify what "during school sessions" mean? Were data not collected during holidays?

During school session means the data were collected when children were in school and not during holidays.

The objective was to assess the children’s’ typical physical activity behaviour and since children spend most of their time in school the study also focused on school season (i.e. activity before school starts, during school program, after school ends and weekends) to later advise school based interventions.

4. Participants' Sociodemographics subsection (about SES measure; lines 168/170): I am not aware of how public-private schools operate in Kampala, and how they are viewed concerning SES. There might be several reasons for studying in a public school. I am unsure if this is an appropriate measure of SES -- this is an unusual approach to me. The authors may consider labelling this variable as "Type of school" not as a proxy for SES.

We thank the reviewer for pointing this out. We have labelled this variable as type of school. However, we have used maternal level of education and car ownership as indicators of SES; that is high maternal level of education (diploma/degree/postgraduate) and households with one or more cars to represent HSES and low maternal level of education (Ordinary level/advanced level) and households with no cars for LSES.

5. Recruitment and Completion rate subsection: How did the authors calculate the sample size for this study?

We used the Daniel (1999) formula to generate a sample size of 254. However, because the children were to be sampled in clusters by divisions and schools, the above sample size was multiplied by a design effect of 2 (Conchran,1977) which produced a required sample size of 500 children. To further allow for children who may fail to provide valid and/or incomplete data the enrolment target was set to 600 children (line 209/2140) in the revised version

6. Data Analysis subsection (lines 182/183): Did the authors check if the data were normally distributed. If data were not normally disturbed, mean and SD would not be the appropriate summary statistics, the median and interquartile range would be.

Yes, the authors check for normal distribution using two methods the graphical and statistical. Both are presented below, the graph points normal distribution and the Schapiro Wilk test gave a p-value of 0.140 both showing normal distribution.

7. Data Analysis subsection (line 186): Could the authors please confirm all relevant assumptions for ANOVA were met?

Yes, the all relevant assumptions where tested for and met.

1. Normality- we used the raw data and not the normality of the errors and arrived at the same result. The example of age is shown in the graph below

2. Independence,

Data were independent.

3. Homoscedasticity, Using the Bartlett’s test as shown below for the age variable.

8. Data Analysis subsection (line 188): Did the regression model adjust for the nested nature of the data (i.e., a multilevel model)? Was this at the level of the division or also at the level of the school, or classroom? As the students are nested at different levels during their selection process, how the analyses account for this clustering?

Yes, the regression model did adjust for the nested nature of the data. We used a Multilevel mixed-effects logistic regression where we adjusted for both division and school (Line 231/236 in revised edition), as shown below.

melogit outcome exposure || division || school:, or

9. Data Analysis subsection (lines 188/191): Did the authors include all these variables in the model? Did the authors check for collinearity? It is likely that SES (i.e., type of school), maternal education, and car ownership would have multi-collinearity as these perhaps measure the same (or a similar) construct. Including all these three variables in the same model may make the model unstable and may not give correct estimates. How did the authors build their model? Did the authors run any post-estimation diagnostic test for their model?

Yes, we checked for collinearity using the Variance Inflation Factor (VIF)s by variable as well as the overall VIF value. All these were not much greater than one suggesting no collinearity among the variables modelled.

We used the backward model building technique which allowed all variables to be evaluated at the start thus minimising negative confounding and ruling out collinearity as well as instability of the model. We also used the Akaike's and Schwarz's Bayesian information criteria (AIC and BIC) as post estimation to assess whether the final model was better than those previously fitted on our data.

10. Data Analysis subsection (line 190): Weight status is not a socio-demographic variable.

Yes, we agree with the reviewer, however weight status in the present study was used as a primary characteristic of children.

Results:

1. Table 1: Is there any reason to describe the participants by their type of school?

Yes, because at the design of the study, there was evidence of disparities between the two types of schools especially in terms of commuting to and from school; which directly contributed to the outcome that we sought to measure that is physical activity. Therefore, this description provides an assessment on whether there could have been any marked differences in the type of school across the factors studied such as weight status where most overweight and obese children were from private schools. This provides context for interpretation of our results.

2. Line 249: I think the right way to express this is "Significantly more males (38.9%) than females (34.3%) accumulated recommended MVPA". The same applies to the rest of the paragraph.

We thank the reviewer for pointing out this, we have revised the paragraph to read; Significantly more males (38.9%) than females (34.3%) accumulated recommended MVPA. Significantly more children from public schools (62.3%) than their peers from private schools (18%), met the physical activity guidelines. Significantly more thin/normal weight children (42.9%) engaged in sufficient amounts of physical activity than overweight/obese children (11.3%). (Line 299/300 and 306/309 revised edition)

3. Table 4 (in general): I wonder why the authors presented crude ORs.

We have corrected this and presented both crude and adjusted OR (Table 4 revised edition)

4. Table 4 (variable sex): From the 95% CIs for "sex" (0.71 - 2.11) it seems like the p-value should not be 0.046.

Yes, this p-value was not 0.046, this was a typing error. We have corrected this and the p-value was 0.469.

5. Table 4 (variable weight status): Some numbers in the cells are too small to run a logistic regression analysis. The CIs for the obese group is very wide and perhaps suggest that the model was unstable. I am not sure if combining the overweight and obese group into one would help.

We thank the reviewer for this suggestion, yes some numbers are too small, we have combined the thin and normal weight group and the overweight and obese groups. We also found a similar problem with the maternal level of education and combined ordinary level and advanced level, and diploma, degree and postgraduate.

Discussion (in general):

The methodological aspects of the paper needs to be revisited before discussing the findings.

We have made the necessary revisions in the methodology as requested and re-revised the discussion as presented in the revised version (Line 346/432).

Reviewer #2:

Please refer to the attached reviewer comments, suggestions and questions. I think this is an important manuscript but it needs some important revisions prior to publication in my opinion. I am not sure the main statistical approach of using bivariate logistic regression was the best given the hierarchical (Individual, classroom, school) nature of these data. Although school environment is included in the analysis, the classroom is not. In light of the foregoing, I hesitate to render final judgement as to the statistical rigor of the analyses. I suggested a number of corrections hence my selecting partly on whether the manuscript is technically sound.

Overall comment: In this study, the authors describe the prevalence and examine the sociodemographic correlates of accelerometer measured physical activity levels among school-going children in Kampala, Uganda. Using a multistage random sampling method, the authors recruited 256 participants from 7 primary schools. In my view, this is an important study which is timely and provides much needed objective data on childhood physical activity in a LMIC. The school environment plays an important if not a very significant role in children’s physical activity behaviors. I have identified important issues that the authors should consider making to improve their manuscript. Some parts of the methods should be expanded and made clear for the readers. Please consider having another co-author read through your manuscript for editorial reasons. There are several small but meaningful errors such as acronyms and wrong brackets for references that should be addressed

Introduction

1. Once you have defined Physical activity as PA, Moderate-to-Vigorous Intensity Physical activity as MVPA etc., after the first time you use the acronyms, try to be consistent and do not revert to spelling out the whole word and vice versa. It is something the authors should address throughout the manuscript.

We thank the reviewer for pointing out this, it has been corrected throughout the revised version. We have changed PA into physical activity and used it throughout the manuscript.

2. Please add “for children” on line 59: after the phrase…revised their PA guidelines.

As requested we have added “for children” on line 69 in the revised version.

3. Line 62: after health benefits, could you please add something like “associated with regular participation in PA.

As requested we have added “associated with regular participation in physical activity” (line 72 in the revised version).

4. Line 64: delete the word ‘also’ after Sallis and colleagues.

As requested we have deleted the word “also” after Sallis and colleagues (line 74 in the revised version)

5. Add a comma after the phrase …literature shows that in children, …

The whole sentence was removed because it was not supported by a review study and the current study did not focus on sedentary time.

6. References 13,14,15 on line 70, have different brackets to the rest of the references

We thank the reviewer for pointing out this and have put the square brackets (line 80 in the revised version).

7. The sentence starting on line 82 to 85 may need to be revised. Are you suggesting that all children have limited cognition, or do you mean limited reading comprehension skills due to their age?

We meant limited reading and comprehension skills. This has been corrected in the revised version to read; Accelerometers are an alternative to self-report methods like questionnaires that are subject to recall bias and are not recommended for use among children because of their limited reading and comprehension skills due to their age [22,23]. (line 96/98)

8. When referring to children, it reads a bit odd to repeatedly say ‘in’ maybe consider using ‘among’

We have changed “in” to “among”, and used it throughout the manuscript.

9. References 13,26,31, line 100 and reference 35 on line 103 have different form of brackets

We thank the reviewer for pointing out this and have put the square brackets (references [13, 14, 15, 16] line 81 and reference [38] line 120 in the revised version).

10. Is HSES the same as SES? If so, please use the same acronym throughout your manuscript. Otherwise define HSES the first time you use it and then be consistent after that.

High socio economic status (HSES) is different from socioeconomic status (SES). We thank the reviewer for pointing this out, we have used the same acronym throughout the manuscript.

11. You use the acronym LICs on line 112, but I am not sure it has been defined before this mention

We have defined the acronym LICs on line 105 in the revised version and used it through out the manuscript.

12. Line 115, consider rewording to say: Therefore, the present study….

We have reworded as suggested on line 138 in the revised version

Methods

1. Consider starting the methods section with “This is a cross-sectional study of a representative sample of school-going children aged 10-12 years old in Kampala, Uganda”.

We thank the reviewer for pointing out this, it has been considered in the revised version on line 149.

2. Could you please substitute the word ‘tribes’ with perhaps ‘ethnic groups’? The word tribes has colonial connotations

We have substituted the word “tribe” with “ethnic group” on line 134 in the revised version.

3. How did you differentiate between awake non wear time and sleep time given that you are using a 24-hour protocol? Did you just lump possible sleep time and awake non wear time together because in your study you were not interested in measuring sleep duration? If so, please make that clear in your methods

We thank the reviewer for pointing out this, to address the reviewer’s concerns we have included information explaining this in the revised version (line 175/181) as shown here:

4. There is debate about the accuracy of classifying children over 5 years old as being ‘underweight’ rather than being ‘thin’ based on BMI z scores. Have authors thought The 24-hour protocol required sleep time to be identified and accounted for before evaluating wake wear time and generating physical activity variables of interest [51,52]. We used the Sadeh algorithm, which is in built into the sleep scoring function in ActiLife software to identify individualised daily sleep on set and offset time for each valid day for each child [53]; this is a valid method for removal of sleep [54]. Daily sleep on set and offset time was used to create time filters in CSV files (Excel Microsoft co-operation, 2016). Time filtered files for the wake period were created and used to identify non wear time and wear time.

5. about the implications of this give their reference to WHO 2007 BMI percentiles which uses thinness for the age group being studied here?

We have corrected this throughout the manuscript, however due to the small numbers of thin children we have combined them with normal weight to thin/normal weight.

6. Was the questionnaire validated for this population? If so please make that clear in your description of the questionnaire.

We thank the reviewer for this important question. The questionnaire was validated among adults in Uganda. We have cleared this and included it in the description of the questionnaire on line 199 in the revised version. A validated questionnaire assessing children and parents’ socio-demographics and neighbourhood built environment [58] was completed by parents/guardians

7. Please clarify your recruitment and response rate. Are you calculating the percentages of children with consent out of 400 or the 600? If you are calculating it from 600 then your percentages are off. The first one 66.7% is accurate but the next two need to be described accurately. For example, you could say “of the 600 who were invited to participate, 400 (66.7%) had parents who completed questionnaires…etc.

We have corrected this to read; Of the 600 children who were invited to participate, 400 (66.7%) had parents/guardians who completed the questionnaire and 328 (54.6%) parental/guardian consented for their children to participate in accelerometry and anthropometric assessment. Of the 328 children who obtained parental consent to wear devices, 256 (78%) had valid accelerometry data and were therefore retained for analysis. (Line 216/223 in the revised version).

8. Was there a specific reason for authors to use bivariate logistic regression as opposed to some hierarchical model which would be more robust to account for the clustering at the school and classroom levels?

We used a Multilevel mixed-effects logistic regression where we adjusted for both school and division (line 231/232 in the revised version). This accounted for the hierarchical element in the data.

melogit outcome exposure || division || school:, or

Results

1. Generally, it may be better to avoid the use or terms such as ‘almost’ and rather use approximately, about, close to…etc

We thank the reviewer for pointing out this, it has been considered throughout the manuscript.

2. Be consistent, either use numbers or words when writing numerical data in text. For example ‘One in every 5 parents/guardians’…may be better to just say one in every five…

We have corrected this in the revised version (Line 262)

3. Do you mean approximately ‘equal numbers by age’? You have three ages and as such could not be ‘even’.

We thank the reviewer for pointing this out we have corrected it to read; Most of the children were aged 10 and 11 years old (71.5%). (line 258 in the revised version)

4. Table 1: Overweight is one word.

We have corrected it; however due to the small numbers we have combined overweight and obese children.

5. Consider using the ‘merge cells’ function to make your sub-heading lines one line in tables.

We have merged the cells as suggested throughout the manuscript.

6. You are using children/participants interchangeably in your results section. Could you please pick one and be consistent with it.

We thank the reviewer for pointing out this inconsistency, we have used the word children throughout the manuscript.

7. Line 230: ‘Overall on average the children spent...’ seem awkward... can you consider revising for readability?

We have revised the sentence to read; Most of the families studied (62.1%) had 2 to 4 children aged 0 to 17 years old. (line 275) revised version

8. The sentence on lines 251 starting with ‘Males…’ is awkward, consider rephrasing it.

We have rephrased the sentence to read; Significantly more males (38.9%) than females (34.3%) accumulated recommended volumes of MVPA. (line 299 revised version

Discussion

1. Do you think that it was overweight/obesity that caused the participants to be more sedentary or that it was the sedentariness that led to being overweight/obese? Reverse causality is a possibility isn’t it? What is your comment?

The current study was not a causality study, we only sought to determine possible associations. However, it is true that reverse causality is highly possible and also the two aspects can still exist in a population. Therefore, future studies are required to further examine this. (also see comment in the revised version line 319).

Generally, well done, consider revising some statements which are awkwardly worded throughout the discussion.

We thank the reviewer for pointing out this, we have revised the awkwardly worded statements throughout the discussion as suggested.

Attachment

Submitted filename: Response to Reviewers.docx

Decision Letter 1

Javier Brazo-Sayavera

4 May 2020

PONE-D-20-00496R1

Prevalence and sociodemographic correlates of accelerometer measured physical activity levels of school-going children in Kampala city, Uganda.

PLOS ONE

Dear Ms Nakabazzi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Kind regards,

Javier Brazo-Sayavera, Ph.D.

Academic Editor

PLOS ONE

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Very well done with addressing my comments. There are some minor typos, grammatical errors, and issues with the use of uppercase and lowercase letters. I'm sure the editorial office will pick these issues up during copy editing and proofreading.

I have (almost) no further comments; just a few suggestions for the authors to consider:

1. If possible, avoid the use of "inactive" or "inactivity", instead, use "insufficiently active" or "insufficient activity". A healthy person can not be inactive, I guess.

2. Please clarify the response rate issue - clearly state "The response rate was XX%". Consider adding a few sentences about a seemingly low-response rate in the discussion (limitations) section.

3. In the Discussion section, please comment on the policy implications of these findings. How the results can be instrumental in informing active lifestyle strategies in Uganda, what policy initiatives may be required, how the government can align their efforts with the global community, e.g., WHO, Active Healthy Kids Global Alliance. The authors may wish to read Aubert et al. (2018) Global Matrix 3.0 Physical activity report card grades for children and youth: Results and analysis from 49 countries. Journal of Physical Activity and Health 15 (Supplement 2), S251-S273. I would encourage the authors to add a dedicated paragraph on "Implications for future research and policy" in the Discussion section before the Limitations of the study (no subheading required).

Reviewer #2: The authors have sufficiently addressed all comments and questions I raised. I have no further questions nor concerns with this manuscript.

**********

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Reviewer #2: No

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PLoS One. 2020 Jul 9;15(7):e0235211. doi: 10.1371/journal.pone.0235211.r004

Author response to Decision Letter 1


10 Jun 2020

Academic Editor:

No comments provided

Reviewer #1

A. Very well done with addressing my comments. There are some minor typos, grammatical errors, and issues with the use of uppercase and lowercase letters. I'm sure the editorial office will pick these issues up during copy editing and proofreading.

We thank the reviewer for pointing out this, we have addressed the typing and grammatical errors, and the use of upper case and lower case throughout the manuscript.

B. I have (almost) no further comments; just a few suggestions for the authors to consider:

1. If possible, avoid the use of "inactive" or "inactivity", instead, use "insufficiently active" or "insufficient activity". A healthy person cannot be inactive, I guess.

We thank the reviewer for this suggestion, it has been corrected throughout the revised version. We have changed the words “inactive or Inactivity” to “insufficiently active or insufficient activity” and used them throughout the manuscript.

2. Please clarify the response rate issue - clearly state "The response rate was XX%". Consider adding a few sentences about a seemingly low-response rate in the discussion (limitations) section.

We thank the reviewer for pointing this out we have clarified the response rate issue and clearly stated it as; “The response rate was 42.7% (line 199-200 in the revised version). Also the low response rate has been included in the study limitations (line 398 in the revised version).

3. In the Discussion section, please comment on the policy implications of these findings. How the results can be instrumental in informing active lifestyle strategies in Uganda, what policy initiatives may be required, how the government can align their efforts with the global community, e.g., WHO, Active Healthy Kids Global Alliance. The authors may wish to read Aubert et al. (2018) Global Matrix 3.0 Physical activity report card grades for children and youth: Results and analysis from 49 countries. Journal of Physical Activity and Health 15 (Supplement 2), S251-S273. I would encourage the authors to add a dedicated paragraph on "Implications for future research and policy" in the Discussion section before the Limitations of the study (no subheading required).

We thank the reviewer for suggesting this very important paper, we have included a paragraph in the discussion section on strategies to increase physical activity and policy implications of the current study results to read as;

“Therefore, there is need for developing effective strategies and policies with the aim of increasing physical activity levels among school going children in Kampala city and Uganda. This may be achieved by implementing strategies and policies that have been proposed by various global and regional organisations including those of the Active Healthy Kids Global Alliance (AHKGA) in the fight against the insufficient physical activity among children [81,82]. The current study further highlighted the need for nationally representative physical activity data. The Ministry of Education and Sports in Uganda should fund the development and release of a national report card on physical activity for children in Uganda for surveillance and promotion of physical activity among Ugandan children”.

Reviewer # 2

The authors have sufficiently addressed all comments and questions I raised. I have no further questions nor concerns with this manuscript.

Attachment

Submitted filename: Rebuttal letter.docx

Decision Letter 2

Javier Brazo-Sayavera

11 Jun 2020

Prevalence and sociodemographic correlates of accelerometer measured physical activity levels of school-going children in Kampala city, Uganda.

PONE-D-20-00496R2

Dear Dr. Nakabazzi,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Javier Brazo-Sayavera, Ph.D.

Academic Editor

PLOS ONE

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: No further comments for the authors. The authors have done a wonderful job addressing my comments on the previous version of the manuscript.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Acceptance letter

Javier Brazo-Sayavera

29 Jun 2020

PONE-D-20-00496R2

Prevalence and socio-demographic correlates of accelerometer measured physical activity levels of school-going children in Kampala city, Uganda

Dear Dr. Nakabazzi:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Javier Brazo-Sayavera

Academic Editor

PLOS ONE

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    S1 Appendix. Data set.

    (XLSX)

    Attachment

    Submitted filename: review comments.docx

    Attachment

    Submitted filename: Response to Reviewers.docx

    Attachment

    Submitted filename: Rebuttal letter.docx

    Data Availability Statement

    All relevant data are within the manuscript and its Supporting Information files.


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