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. Author manuscript; available in PMC: 2017 Jun 1.
Published in final edited form as: J Phys Act Health. 2016 Jun;13(6 Suppl 1):S29–S34. doi: 10.1123/jpah.2015-0728

Youth Energy Expenditure During Common Free-Living Activities and Treadmill Walking

John M Schuna Jr 1,6, Tiago V Barreria 2,6, Daniel S Hsia 3, William D Johnson 4, Catrine Tudor-Locke 5,6
PMCID: PMC5108056  NIHMSID: NIHMS826010  PMID: 27392374

Abstract

Background

Energy expenditure (EE) estimates for a broad age range of youth performing a variety of activities are needed.

Methods

106 participants (6-18 years) completed 6 free-living activities (seated rest, movie watching, coloring, stair climbing, basketball dribbling, jumping jacks) and up to 9 treadmill walking bouts (13.4-120.7 m/min; 13.4 m/min increments). Breath-by-breath oxygen uptake (VO2) was measured using the COSMED K4b2 and EE was quantified as youth metabolic equivalents (METy1:VO2/measured resting VO2, METy2:VO2/estimated resting VO2). Age trends were evaluated with ANOVA.

Results

Seated movie watching produced the lowest mean METy1 (6-9 year-olds: 0.94±0.13) and METy2 values (13-15 year-olds: 1.10±0.19) and jumping jacks produced the highest mean METy1 (13-15 year-olds: 6.89±1.47) and METy2 values (16-18 year-olds: 8.61±2.03). Significant age-related variability in METy1 and METy2 were noted for 8 and 2 of the 15 evaluated activities, respectively.

Conclusions

Descriptive EE data presented herein will augment the Youth Compendium of Physical Activities.

INTRODUCTION

Over 20 years have passed since the introduction of the Compendium of Physical Activities, and the original publication,1 in conjunction with subsequent updates,2,3 have collectively received more than 5,000 citations (Web of Science™, accessed 16 December 2015). The compendium provides standardized estimates of energy expenditure (EE) across a broad array of activities, represented in absolute terms as metabolic equivalents (METs). MET values contained within the compendium are applicable to adult populations and typically used to describe the metabolic cost of self-reported behaviors in epidemiological research.1-3

More recently, a youth compendium (now referred to as the Youth Compendium of Physical Activities) was introduced to catalog EE estimates for children and adolescents.4 At present, there remains a need to expand the assembled activities and age ranges represented within the Youth Compendium of Physical Activities. Therefore, the primary purpose of this study was to provide descriptive data of measured EE in children and adolescents during common free-living activities and treadmill walking. We also examined the age independence of several candidate EE metrics across the completed activities.

METHODS

Participants

A convenience sample of 106 children and adolescents (6-18 years) from Louisiana participated in the study. Participants were recruited using email advertisements, health fair presentations, and via word-of-mouth. The Pennington Biomedical Research Center Institutional Review Board approved all study protocols. Before participation, informed parental consent and assent were obtained for 6-17 year-old participants, and informed consent was obtained for 18 year-old participants. The study was prospectively registered at ClinicalTrials.gov before enrollment began (NCT01989104).

Activities

Participants completed laboratory-based free-living activities and ambulatory treadmill bouts while oxygen uptake (VO2) was measured. A 4-hour fast (no food or caloric/caffeinated beverages) was required and a 10-minute seated washout period preceded the protocol. Participants then completed 3 seated activities by resting motionless, watching a movie, and coloring in a book. A series of up to 10 ambulatory treadmill bouts (0% grade) followed the seated activities, beginning at 13.4 m/min (0.80 km/h) and increasing in 13.4 m/min increments to a maximum of 134.1 m/min (8.05 km/h). Treadmill testing was terminated following the bout when the participant naturally began running. Participants then completed simulated stair climbing (stepping up-and-down on a 19.69 cm step at 88 bpm), basketball dribbling while ambulating at a self-selected speed (continuous movement around a 12 m course), and jumping jacks (126 bpm). Each activity lasted 5 minutes and was preceded by a 2-minute washout period, except for the transition following the final treadmill bout where a 5-minute washout period was given to ensure VO2 returned close to resting values before completing the remaining activities.

Measures

Weight and body fat percentage were measured to the nearest 0.1 kg and 0.1%, respectively, using an integrated scale and bioelectrical impedance analyzer (Tanita SC-240; Tanita, Tokyo, Japan). Height was measured shoeless to the nearest 0.1 cm using a stadiometer (Harpenden; Holtain, Crosswell, United Kingdom). Body mass index (BMI) was calculated by dividing weight by height squared (kg/m2). Reference data from the Centers for Disease Control and Prevention were used to calculate BMI percentiles.5

Respiratory gas concentrations and flow volumes were measured during all activities using the portable COSMED K4b2 (COSMED, Rome, Italy). A silicone face mask directed respiratory gases through an external housing where breath-by-breath gas sampling and turbine-based flow volume measurements were taken. Prior to each testing session, the K4b2 was calibrated according to the manufacturer’s instructions. Measurements from the K4b2 were transmitted wirelessly and saved to a laptop computer.

Recorded breaths within each minute were averaged to yield a minute-by-minute data file. Absolute and mass-specific VO2 (L/min and ml/kg/min, respectively) were calculated. We also computed youth METs (mass-specific VO2 / resting mass-specific VO2) as this metric has been shown to provide balance in attenuating the age- and sex-dependence of youth EE estimates across a range of activities.6 Youth METs were derived in 2 forms: 1) METy1: (mass-specific VO2 / measured resting mass-specific VO2) and, 2) METy2: (mass-specific VO2 / estimated resting mass-specific VO2). Measured resting VO2 corresponded to the seated rest testing phase while estimated resting VO2 was calculated using the Schofield equation (resting EE converted to mass-specific VO2).7 The average value from minutes 4 and 5 of each activity was used for analysis. For all seated activities, average values from minutes 4 and 5 were considered steady-state. Steady-state ascertainments among the remaining activities were evaluated by inspecting the variability of breath-by-breath data from minutes 4 and 5. Minutes with mean absolute VO2 variability < 10% were deemed steady-state. As treadmill walking was one of the specific foci of this study, we eliminated data from treadmill bouts where running occurred.

Data Analyses

Descriptive statistics were computed to characterize the sample. For each activity, differences in metabolic measures between 4 age categories (6-9, 10-12, 13-15, and 16-18 years) were evaluated using one-way ANOVA. Follow-up pairwise comparisons were conducted using the Tukey-Kramer method. All analyses were performed using R (version 3.2.2). Due to the large number of hypothesis tests conducted, we conservatively defined statistical significance as p < 0.001.

RESULTS

Of the 1,696 possible activity bouts ([106 participants X 6 free-living activities] + [106 participants X 10 treadmill bouts]), we excluded 316 treadmill bouts (participant began running or bout was not completed), 18 active free-living bouts (bout was not completed), and 1 bout during seated rest (K4b2 malfuntion). Of the remaining 1,361 bouts, we further excluded data from 152 bouts not meeting our predetermined steady-state criteria. In all, the remaining 1,209 bouts available for analysis represented 88.9% of the original non-missing observations.

Descriptive characteristics are presented in Table 1. The mean age was 12.0±3.7 years and 58.5%, 15.1%, and 26.4% of the sample were non-overweight (BMI<85th percentile), overweight (85th percentile ≤BMI< 95th percentile), or obese (BMI≥95th percentile), respectively. The sample was racially/ethnically heterogeneous as 37.7%, 59.4%, and 2.8% identified as African-American, Caucasian, or other race/ethnicity, respectively. The sample’s BMI and race/ethnic characteristics were roughly comparable to previously published state-level estimates in Louisiana (2-19 year-old obesity prevalence: 29.0%; race/ethnic distribution - African-American: 32.3%, Caucasian: 64.0%, other race/ethnicity: 3.7%).8,9

Table 1.

Descriptive characteristics.

Stratification n Age
(years)		 Weight
(kg)		 Height
(cm)		 BMI
(kg/m2)		 BMI
Percentile		 Percent Body
Fat
Total 106 12.0 ± 3.7 53.8 ± 22.6 152.8 ± 16.6 22.2 ± 6.5 67.2 ± 30.4 25.3 ± 11.0
Boys 53 12.0 ± 3.7 54.4 ± 22.3 154.5 ± 18.5 22.0 ± 5.9 66.9 ± 32.0 22.4 ± 11.2
Girls 53 12.1 ± 3.6 53.2 ± 23.0 151.1 ± 14.5 22.5 ± 7.1 67.5 ± 29.0 28.1 ± 10.0
 
6-9y 32 (16B, 16G) 7.6 ± 1.1 34.5 ± 13.1 132.9 ± 8.7 19.2 ± 5.3 66.4 ± 32.7 24.7 ± 9.8
10-12y 25 (13B, 12G) 11.0 ± 0.8 48.9 ± 12.6 152.0 ± 8.1 21.1 ± 4.7 67.8 ± 31.0 24.7 ± 9.2
13-15y 26 (12B, 14G) 14.0 ± 0.8 68.0 ± 17.6 163.6 ± 8.6 25.3 ± 5.8 78.7 ± 21.2 29.3 ± 10.7
16-18y 23 (12B, 11G) 17.0 ± 0.9 69.7 ± 24.4 169.0 ± 8.2 24.4 ± 8.3 54.6 ± 31.8 22.2 ± 13.6
 
African-
American		 40 (21B, 19G) 11.7 ± 3.7 56.2 ± 24.6 152.0 ± 16.0 23.5 ± 7.2 76.0 ± 26.7 28.1 ± 11.4
Caucasian 63 (30B, 33G) 12.3 ± 3.7 52.7 ± 21.3 153.5 ± 17.0 21.7 ± 6.0 61.8 ± 32.0 23.6 ± 10.6
Other 3 (2B, 1G) 10.3 ± 3.5 41.8 ± 20.6 147.3 ± 21.5 18.4 ± 3.3 63.4 ± 17.0 21.5 ± 6.2
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Notes. Values presented as counts and M ± SD. B = boys; G = girls; BMI = body mass index. BMI percentiles for each participant were calculated using reference data from the Centers for Disease Control and Prevention growth charts

Age-group stratified mean values of absolute VO2, mass-specific VO2, METy1, and METy2 during the 6 free-living activities are presented in Table 2. Significant age-related differences in absolute VO2 were observed for all activities, except seated rest and coloring, as age tended to be positively associated with absolute VO2. Mass-specific VO2 also significantly differed across age groups for most of the free-living activities, with the exception of jumping jacks; however, age was inversely associated with mass-specific VO2. Less variability in METy1 and METy2 values was observed as significant age-related differences were only noted for stair climbing and jumping jacks with METy1 and seated rest and coloring with METy2. Age was positively associated with METy1 values among those free-living activities with noted significant differences; however, there did not appear to be any consistent relationship between age and METy2 values across the tested free-living activities.

Table 2.

Oxygen uptake (VO2) and youth METs during common free-living activities.

Activity n Absolute VO2
(L/min)		 Min-Max Mass-specific
VO2
(ml/kg/min)		 Min-Max METy1 Min-Max METy2 Min-Max
Seated Rest
 6-9y 31 0.24 ± 0.04 0.17-0.33 7.55 ± 1.87a 3.60-10.82 1 - 1.43 ± 0.25a 0.97-1.88
 10-12y 25 0.26 ± 0.05 0.19-0.40 5.63 ± 1.45b 3.57-8.71 1 - 1.33 ± 0.25ab 0.88-1.92
 13-15y 26 0.27 ± 0.04 0.17-0.36 4.22 ± 1.17b 2.29-6.53 1 - 1.16 ± 0.22b 0.77-1.54
 16-18y 23 0.29 ± 0.06 0.19-0.40 4.34 ± 1.00b 1.90-6.08 1 - 1.22 ± 0.21ab 0.75-1.56
Movie
Watching
 6-9y 32† 0.22 ± 0.04a 0.15-0.29 7.08 ± 2.00a 2.76-10.94 0.94 ± 0.13 0.60-1.37 1.34 ± 0.27 0.63-1.97
 10-12y 25 0.25 ± 0.04ab 0.17-0.35 5.39 ± 1.38b 3.60-7.78 0.96 ± 0.10 0.70-1.15 1.28 ± 0.25 0.89-1.75
 13-15y 26 0.26 ± 0.05ab 0.19-0.36 4.00 ± 1.10b 2.22-6.89 0.96 ± 0.10 0.74-1.20 1.10 ± 0.19 0.79-1.62
 16-18y 23 0.28 ± 0.04b 0.21-0.37 4.27 ± 1.03b 1.88-5.72 0.99 ± 0.13 0.72-1.25 1.20 ± 0.22 0.74-1.60
Coloring
 6-9y 32† 0.28 ± 0.06 0.18-0.40 8.70 ± 2.37a 3.10-14.40 1.17 ± 0.20 0.68-1.60 1.66 ± 0.34a 0.71-2.36
 10-12y 25 0.31 ± 0.06 0.22-0.41 6.56 ± 1.83b 4.56-10.81 1.17 ± 0.16 0.91-1.49 1.55 ± 0.34ab 1.14-2.45
 13-15y 26 0.31 ± 0.06 0.25-0.50 4.83 ± 1.12b 2.64-7.84 1.17 ± 0.18 0.87-1.62 1.33 ± 0.20b 0.94-1.85
 16-18y 23 0.34 ± 0.07 0.23-0.50 5.21 ± 1.25b 2.17-7.02 1.21 ± 0.18 0.90-1.58 1.47 ± 0.30ab 0.85-1.99
Stair
Climbing
 6-9y 27† 0.77 ± 0.15a 0.50-1.02 23.41 ± 4.00a 17.56-34.78 3.20 ± 0.57a 2.29-4.18 4.51 ± 0.56 3.53-5.70
 10-12y 24 1.02 ± 0.24ab 0.39-1.53 21.46 ± 4.56ab 10.00-29.47 3.91 ± 0.86ab 2.09-5.70 5.11 ± 0.97 2.32-6.91
 13-15y 25 1.28 ± 0.33b 0.67-2.35 18.79 ± 2.99b 13.63-25.50 4.75 ± 1.02b 2.32-6.59 5.29 ± 0.78 3.26-7.00
 16-18y 22 1.22 ± 0.35b 0.71-2.5 18.58 ± 2.74b 13.12-25.44 4.29 ± 0.90b 2.96-6.32 5.22 ± 0.78 3.17-7.21
Basketball
 6-9y 29† 0.87 ± 0.19a 0.46-1.17 27.06 ± 5.44a 17.81-39.54 3.67 ± 0.71 2.46-5.06 5.16 ± 0.84 3.78-6.99
 10-12y 22 1.05 ± 0.20ab 0.69-1.58 22.17 ± 4.40ab 15.34-30.74 3.99 ± 0.71 2.80-5.48 5.28 ± 0.83 3.82-6.89
 13-15y 25 1.12 ± 0.23b 0.71-1.91 17.13 ± 3.97bc 11.61-24.66 4.09 ± 0.79 2.49-5.95 4.70 ± 0.77 3.51-6.10
 16-18y 19 1.03 ± 0.27ab 0.60-1.83 15.78 ± 3.26c 9.78-21.49 3.54 ± 0.69 2.57-4.97 4.41 ± 0.80 3.04-6.11
Jumping
Jacks
 6-9y 18 1.08 ± 0.24a 0.64-1.50 34.81 ± 8.12 25.91-55.62 4.60 ± 0.90a 3.03-6.12 6.56 ± 1.18 4.68-9.66
 10-12y 16 1.53 ± 0.38ab 0.97-2.48 33.72 ± 7.65 20.31-48.93 5.69 ± 1.40ab 3.39-9.19 7.71 ± 1.46 5.06-10.80
 13-15y 15 1.93 ± 0.48b 1.23-3.05 30.19 ± 8.25 18.97-48.39 6.89 ± 1.47b 4.33-9.08 8.23 ± 1.71 5.92-11.70
 16-18y 18 1.94 ± 0.61b 1.15-3.69 31.13 ± 8.79 18.98-52.04 6.82 ± 1.61b 4.77-11.12 8.61 ± 2.03 5.12-13.89
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Notes. Values presented as M ± SD. METy1 = youth metabolic equivalents calculated as mass-specific VO2 divided by measured resting mass-specific VO2. METy2 = youth metabolic equivalents calculated as mass-specific VO2 divided by estimated resting mass-specific VO2 (using the Schofield equation). Estimated mean resting mass-specific VO2 values for 6-9, 10-12, 13-15, and 16-18 year-olds were 5.19 ± 0.67, 4.20 ± 0.51, 3.60 ± 0.44, and 3.53 ± 0.43 ml/kg/min, respectively. Mean values with different superscript letters within each activity are significantly different at p < 0.001.

†

Sample size is reduced by 1 participant for METy1 data due to missing measured resting VO2.

Age-group stratified mean values of absolute VO2, mass-specific VO2, METy1, and METy2 during treadmill walking are presented in Table 3. All participants that attempted the tenth treadmill bout (134.1 m/min) began running at this speed; therefore, we restrict our presentation to only those 9 speeds ≤ 120.7 m/min. Absolute VO2 significantly differed across age groups at all speeds between 13.4 and 93.9 m/min, as age tended to be positively associated with absolute VO2. Significant age-related differences were also noted for mass-specific VO2 at all speeds between 13.4 and 93.9 m/min. However, age was inversely associated with mass-specific VO2. Significant differences in METy1 values between age groups were observed at all speeds between 26.8 and 93.9 m/min, as age tended to demonstrate a positive relationship with METy1. No significant age-related differences in METy2 values were noted across any of the evaluated speeds.

Table 3.

Oxygen uptake (VO2) and youth METs during treadmill walking.

Treadmill
Speed		 n Absolute VO2
(L/min)		 Min-Max Mass-specific
VO2
(ml/kg/min)		 Min-Max METy1 Min-Max METy2 Min-Max
13.4 m/min
 6-9y 19 0.40 ± 0.11a 0.27-0.70 12.54 ± 2.55a 8.26-17.58 1.62 ± 0.28 1.18-2.30 2.38 ± 0.33 1.88-3.05
 10-12y 18 0.48 ± 0.08ab 0.39-0.68 10.25 ± 2.06ab 7.25-14.07 1.86 ± 0.25 1.61-2.63 2.43 ± 0.35 1.80-3.13
 13-15y 23 0.52 ± 0.13ab 0.26-0.91 7.96 ± 1.65b 3.72-10.14 1.96 ± 0.34 1.31-2.55 2.19 ± 0.37 1.15-2.78
 16-18y 17 0.56 ± 0.14b 0.35-0.95 8.46 ± 1.19b 6.28-10.64 1.94 ± 0.37 1.34-2.77 2.38 ± 0.29 1.89-3.05
26.8 m/min
 6-9y 27† 0.45 ± 0.12a 0.28-0.86 13.76 ± 2.73a 8.11-18.55 1.85 ± 0.34a 1.25-2.82 2.62 ± 0.37 1.85-3.48
 10-12y 19 0.56 ± 0.10ab 0.42-0.82 11.45 ± 2.23ab 8.23-15.84 2.13 ± 0.31ab 1.66-2.97 2.77 ± 0.40 2.05-3.52
 13-15y 23 0.62 ± 0.14b 0.44-1.10 9.48 ± 1.56b 6.20-12.25 2.27 ± 0.38ab 1.52-3.07 2.58 ± 0.30 1.99-3.27
 16-18y 20 0.66 ± 0.16b 0.39-1.09 9.60 ± 1.89b 6.16-12.52 2.32 ± 0.50b 1.54-3.33 2.72 ± 0.42 2.12-3.55
40.2 m/min
 6-9y 22† 0.52 ± 0.14a 0.34-0.96 15.12 ± 2.58a 10.17-19.23 2.09 ± 0.37a 1.36-3.13 2.94 ± 0.32 2.32-3.73
 10-12y 17 0.63 ± 0.12ab 0.46-0.92 12.49 ± 1.99ab 9.55-15.78 2.33 ± 0.34ab 1.79-3.08 3.08 ± 0.36 2.38-3.72
 13-15y 22 0.71 ± 0.18ab 0.48-1.33 10.78 ± 1.91b 7.26-13.93 2.58 ± 0.51ab 1.66-3.72 2.95 ± 0.40 2.33-3.97
 16-18y 21 0.76 ± 0.20b 0.47-1.37 11.30 ± 2.07b 7.59-15.87 2.68 ± 0.56b 1.99-3.98 3.19 ± 0.47 2.53-4.21
53.6 m/min
 6-9y 22† 0.58 ± 0.11a 0.39-0.78 17.77 ± 3.34a 12.62-24.07 2.37 ± 0.38a 1.49-3.02 3.40 ± 0.42 2.75-4.18
 10-12y 19 0.72 ± 0.13ab 0.56-1.12 14.77 ± 2.24ab 10.47-17.63 2.72 ± 0.49ab 1.95-3.82 3.55 ± 0.38 2.77-4.36
 13-15y 23 0.81 ± 0.20b 0.55-1.45 12.37 ± 2.08b 8.85-15.78 2.95 ± 0.56ab 1.88-4.06 3.43 ± 0.48 2.65-4.61
 16-18y 21 0.86 ± 0.24b 0.52-1.56 12.50 ± 1.98b 9.71-15.73 3.05 ± 0.69b 2.34-5.19 3.54 ± 0.45 2.89-4.46
67.1 m/min
 6-9y 21 0.65 ± 0.14a 0.46-0.90 19.77 ± 3.48a 14.83-27.03 2.69 ± 0.51a 1.74-3.59 3.82 ± 0.48 3.08-4.70
 10-12y 19 0.85 ± 0.17ab 0.63-1.29 17.62 ± 2.80ab 12.64-24.35 3.24 ± 0.70ab 2.21-4.53 4.24 ± 0.54 3.51-5.52
 13-15y 24 0.97 ± 0.22b 0.66-1.66 14.68 ± 2.16b 10.46-18.18 3.53 ± 0.66b 2.27-4.68 4.04 ± 0.50 3.18-5.00
 16-18y 20 0.94 ± 0.26b 0.56-1.81 14.28 ± 2.13b 10.99-18.26 3.31 ± 0.66ab 2.45-4.71 4.01 ± 0.54 3.12-4.93
80.5 m/min
 6-9y 16 0.77 ± 0.17a 0.56-1.10 22.68 ± 4.17a 16.88-30.74 3.07 ± 0.61a 1.97-4.23 4.40 ± 0.52 3.55-5.34
 10-12y 20 0.98 ± 0.20ab 0.70-1.42 20.35 ± 3.09ab 15.71-26.96 3.74 ± 0.80ab 2.49-5.53 4.85 ± 0.62 4.05-6.63
 13-15y 24 1.16 ± 0.25b 0.75-1.88 17.22 ± 2.48b 12.06-20.73 4.23 ± 0.74b 2.60-5.50 4.81 ± 0.55 3.65-5.99
 16-18y 19 1.07 ± 0.30ab 0.66-2.16 16.61 ± 2.01b 12.92-20.59 3.86 ± 0.83ab 2.98-5.60 4.61 ± 0.52 3.65-5.77
93.9 m/min
 6-9y 10 0.85 ± 0.17a 0.67-1.26 28.01 ± 4.59a 23.19-36.26 3.43 ± 0.72a 2.46-4.79 5.26 ± 0.57 4.52-6.10
 10-12y 20 1.12 ± 0.22ab 0.82-1.71 24.37 ± 3.61ab 18.76-32.37 4.41 ± 0.94ab 3.13-6.43 5.73 ± 0.72 4.77-7.85
 13-15y 21 1.37 ± 0.33b 0.94-2.29 20.50 ± 2.75b 15.58-24.47 5.03 ± 0.85b 3.26-6.39 5.69 ± 0.70 4.13-6.83
 16-18y 20 1.31 ± 0.36b 0.85-2.71 20.40 ± 2.62b 15.36-25.22 4.71 ± 0.99ab 3.46-6.87 5.66 ± 0.68 4.66-7.01
107.3 m/min
 6-9y 4 1.00 ± 0.19 0.75-1.16 32.06 ± 7.49 26.16-43.03 3.99 ± 0.64 3.40-4.88 6.11 ± 1.01 5.05-7.47
 10-12y 12 1.37 ± 0.30 1.03-2.13 28.61 ± 3.04 24.06-35.07 5.37 ± 1.38 3.61-7.83 6.84 ± 0.69 6.09-7.89
 13-15y 19 1.61 ± 0.40 1.17-2.81 24.41 ± 3.96 17.21-32.74 5.95 ± 1.01 4.04-7.85 6.73 ± 0.83 5.33-8.59
 16-18y 16 1.60 ± 0.53 1.07-3.46 24.89 ± 3.72 18.56-32.33 5.58 ± 1.23 4.19-8.75 6.84 ± 0.98 5.54-9.16
120.7 m/min
 6-9y 0 - - - - - - -
 10-12y 2 1.39 ± 0.03 1.37-1.41 29.74 ± 1.25 28.85-30.62 5.79 ± 0.49 5.44-6.14 7.16 ± 0.52 6.80-7.52
 13-15y 6 2.26 ± 0.63 1.75-3.33 32.17 ± 2.93 28.60-35.49 7.43 ± 1.34 5.44-9.31 8.43 ± 0.91 7.50-9.92
 16-18y 6 1.70 ± 0.28 1.25-1.98 26.28 ± 1.14 24.74-28.05 6.31 ± 1.22 5.10-8.24 7.65 ± 0.37 7.18-8.23
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Notes. Values presented as M ± SD. METy1 = youth metabolic equivalents calculated as mass-specific VO2 divided by measured resting mass-specific VO2. METy2 = youth metabolic equivalents calculated as mass-specific VO2 divided by estimated resting mass-specific VO2 (using the Schofield equation). Estimated mean resting mass-specific VO2 values for 6-9, 10-12, 13-15, and 16-18 year-olds were 5.19 ± 0.67, 4.20 ± 0.51, 3.60 ± 0.44, and 3.53 ± 0.43 ml/kg/min, respectively. Mean values with different superscript letters within each treadmill speed are significantly different at p < 0.001.

†

Sample size is reduced by 1 participant for METy1 data due to missing measured resting VO2.

DISCUSSION

The descriptive data we have presented are novel, and we know of no single study which has reported children and adolescents’ steady-state EE estimates across the complete set of walking speeds evaluated herein. Moreover, no published studies have reported steady-state EE estimates among children and adolescents 6-18 years of age for the specific set of common free-living activities we evaluated. In light of these observations, our comparative discourse is limited. However, these data serve as a needed addition to previous assemblages of children and adolescents’ measured EE during various sedentary and physical activities.4

Of the candidate EE metrics evaluated herein, the METy2 appeared to be least associated with age, as age-related differences were only observed among 2 of the study’s 15 activities. This finding is consistent with previous work by McMurray et al.6 which demonstrated that the METy2 (using estimated resting VO2 as the denominator) tended to be less associated with age and sex across a range of activities than absolute, mass-specific, or net VO2 measures. Interestingly, METy1 demonstrated greater variability across age groups than did METy2, which is likely attributable to the greater age-related variation in directly measured resting VO2 (seated rest: 1.90-10.82 ml/kg/min) used in METy1 calculations than in estimated resting VO2 (2.54-6.39 ml/kg/min) used in METy2 calculations. Further research is needed to better understand how the formulation of youth METs influences the metric’s relationship with children and adolescents’ age, sex, body composition, and other physical characteristics.

We have presented estimates of measured steady-state EE during 15 different activities from a diverse sample of youth. The assembled data herein will inform future pediatric-related epidemiological research and augment the Youth Compendium of Physical Activities.

Acknowledgements

The authors thank Nancy Rajapho, Melissa Lupo, Stefany Achee, and Courtney Hancock for their assistance with this project.

Funding Source

This work was supported by a grant from the Eunice-Kennedy Shriver National Institute of Child Health and Human Development (NIH-NICHD 1R21HD073807-01A1). Dr. Johnson also received partial support from NIH-NIGMS (1 U54 GM104940) which funds the Louisiana Clinical and Translational Science Center.

Footnotes

The authors declare they have no competing interests.

Note: This submission pertains to the 2016 NCCOR supplement

References

  • 1.Ainsworth BE, Haskell WL, Leon AS, et al. Compendium of physical activities: classification of energy costs of human physical activities. Med Sci Sports Exerc. 1993;25(1):71–80. doi: 10.1249/00005768-199301000-00011. [DOI] [PubMed] [Google Scholar]
  • 2.Ainsworth BE, Haskell WL, Whitt MC, et al. Compendium of physical activities: an update of activity codes and MET intensities. Med Sci Sports Exerc. 2000;32(9 Suppl):S498–504. doi: 10.1097/00005768-200009001-00009. [DOI] [PubMed] [Google Scholar]
  • 3.Ainsworth BE, Haskell WL, Herrmann SD, et al. 2011 Compendium of Physical Activities: a second update of codes and MET values. Med Sci Sports Exerc. 2011;43(8):1575–1581. doi: 10.1249/MSS.0b013e31821ece12. [DOI] [PubMed] [Google Scholar]
  • 4.Ridley K, Ainsworth BE, Olds TS. Development of a compendium of energy expenditures for youth. Int J Behav Nutr Phys Act. 2008;5:45. doi: 10.1186/1479-5868-5-45. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 5.Kuczmarski RJ, Ogden CL, Grummer-Strawn LM, et al. CDC growth charts: United States. Adv Data. 2000;(314):1–27. [PubMed] [Google Scholar]
  • 6.McMurray RG, Butte NF, Crouter SE, et al. Exploring metrics to express energy expenditure of physical activity in youth. PLoS ONE. 2015;10(6):e0130869. doi: 10.1371/journal.pone.0130869. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 7.Schofield WN. Predicting basal metabolic rate, new standards and review of previous work. Hum Nutr Clin Nutr. 1985;39(Suppl 1):5–41. [PubMed] [Google Scholar]
  • 8.U.S. Census Bureau, Population Division . Annual Estimates of the Resident Population by Sex, Race, and Hispanic Origin for the United States, States, and Counties: April 1, 2010 to July 1, 2014. U.S. Census Bureau; Suitland, MD: 2015. [Google Scholar]
  • 9.State of Louisiana, Department of Health and Hospitals . Obesity. Department of Health and Hospitals; Baton Rouge, LA: 2015. [Google Scholar]

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