Abstract
Background
Although previous evidence has shown that physical activity and physical fitness lower the level of psychological distress, little is known of simultaneous associations between of physical activity and physical fitness and with psychological distress, especially in young adults. Therefore, the main purpose of the present study was to explore both separate and simultaneous association between physical activity and physical fitness with psychological distress.
Methods
Participants in this cross-sectional study were 2,100 university students (1,041 men and 1,059 women) chosen from eight faculties in the city of Zagreb. Physical activity, physical fitness and psychological distress were assessed using structured questionnaires. The associations were examined using logistic regression analysis.
Results
After adjusting for gender, body-mass index, self-rated health, material status, binge drinking, chronic disease/s and sleep quality, “insufficient” physical activity (OR = 2.60; 95% CI [1.92–3.52]) and “lower” levels of physical fitness (tertile 2; OR = 1.94; 95% CI [1.25–3.01] and tertile 1; OR = 2.59; 95% CI [1.65–4.08]) remained associated with “high” psychological distress. When physical activity and physical fitness were entered simultaneously into the model, “insufficient” physical activity (OR = 2.35; 95% CI [1.72–3.21]) and “lower” levels of physical fitness (tertile 2; OR = 1.77; 95% CI [1.24–2.77] and tertile 1; OR = 2.00; 95% CI [1.26–3.20]) remained associated with “high” psychological distress.
Conclusion
Our study shows that both “insufficient” physical activity and “lower” levels of physical fitness are associated with “high” psychological distress, even after adjusting for numerous covariates. Therefore, special policies aiming to increase the levels of physical activity and fitness are warranted.
Keywords: Mental health, Associations, Logistic regression, Youth, Activity
Introduction
Mental health disorders have become one of the main public health problems worldwide, with special increasing prevalence among youth (Costello et al., 2003). Approximately 30% of children and adolescents present mental disorders in the United States (Costello et al., 2003). In Croatia, the prevalence of mental disorders among youth is 15.7% (Rudan et al., 2005), girls experienced high psychological distress more frequently in the last 30 days, compared with boys (33% vs. 16%) (Novak & Kawacki, 2015). In general, psychological distress is a term frequently used to describe the experience of unpleasant emotions and feelings that influence on everyday functioning (Perales, del Pozo-Cruz & del Pozo-Cruz, 2014) and has been consistently associated with cardiovascular (Mensah & Collins, 2015), metabolic (Newcomer, 2007) and musculoskeletal (Patten, Williams & Wang, 2006) diseases, cancer (Kisely, Crowe & Lawrence, 2013) and overall mortality (Walker, McGee & Druss, 2015).
Treatment for depression is antidepressant medication (Richey & Krystal, 2011), which is expensive with potential side effects. Nevertheless, regular physical activity may serve as a protective factor against mental disorders. Physical activity is defined as “any bodily movement produced by skeletal muscles that results in energy expenditure and can be categorized into occupation, sports, conditioning, household, or other activities” (Caspersen, Powell & Christenson, 1985). The health benefits of physical activity on mental health have been well-documented (World Health Organization, 2010). Specifically, Larun et al. (2006) in their meta-analytical review showed, that vigorous physical activity had small effect in reducing anxiety or depression symptoms in youth. One meta-analysis showed that overall effects of physical activity on mental health were small, yet significant and indicated that physical activity led to improvements of mental health outcomes in children (Ahn & Fedewa, 2011). To determine causal direction, one longitudinal study showed that the number of hours spent in physical activity per week at age 15–16 was negatively associated with emotional symptoms in boys, yet no associations were found in girls (Sagatun et al., 2007). The same study also showed, that boys and girls who spent 5–7 h of physical activity per week at the same age had the least mental difficulties reported after a three-year of follow-up (Sagatun et al., 2007). While physical activity is related to the body movement, physical fitness represents “a set of attributes that people have or achieve” (Caspersen, Powell & Christenson, 1985). In general, physical fitness has two components: (1) health-related and (2) skill-related, where each component has a set of sub-components (Caspersen, Powell & Christenson, 1985). Similar studies aiming to explore the associations between physical fitness and psychological distress have also shown, that young adults with higher levels of cardio-respiratory, strength and flexibility fitness (Pozuelo-Carrascosa et al., 2017; Jeoung, Hong & Lee, 2013) have significantly lower levels of mental health disorders, compared to their peers with lower levels of fitness and higher levels of mental health disorders.
Previous studies have tried to explain the complexity and mutual processes of biological and psychological factors that physical activity has on mental health (Faulkner & Taylor, 2009). In terms of biological factors, physical activity has beneficial effects on neurotransmitters (monoamines, dopamine, endorphin), which play an important role in regulating stress and emotions and rewarding motivation (Paluska & Schwenk, 2000). Psychological factors include self-esteem, self-efficacy and distraction, and physical activity/fitness play an important role in increasing such perceptions (Ekeland et al., 2004).
Thus, according to the literature, it is well-established, that both physical activity and physical fitness have beneficial role on mental health. However, little is known about the relationship these two potential factors with mental health in young adults. Young adulthood is characterized by the onset of which mental health problems start to occur (Kessler et al., 2005). On the other hand, it has been reported that 40% of young adults from United States do not meet the recommendations of National physical activity guidelines (150 min of moderate or 75 min of vigorous physical activity weekly) leading to excessive weight gain (Malhotra et al., 2013) and other diseases (Warburton, Nicol & Bredin, 2006).
Since young adults represent a risk group for higher levels of mental health disorders and lower levels of physical activity, it is necessary to explore these associations. Therefore, the main purpose of the present study was to explore both separate and simultaneous associations of physical activity and physical fitness with psychological distress in a large sample of young adults.
Materials and Methods
Participants
This study was conducted among university students in Zagreb, the capital city of Croatia with approximately 1,000,000 citizens. The University of Zagreb is composed of 33 faculties (departments) and between 65,000 and 70,000 students attend the University every year. A random sampling approach was used to select faculties. At the first stage, we randomly selected eight out of 33 faculties. The randomization was done with replacement, where each faculty had unique number and was drawn from the box. At the second stage, we contacted teachers from each faculty to help us organize the sampling procedure. A recruitment announcement was sent via emails and e-newsletter to the teachers with a request to pass the study information to students. All eight faculties agreed to take part in the study, representing 2,320 students enrolled in the 2017 academic year. Of these, 2,100 students (1,041 men and 1,059 women, aged 18–24 years) provided full data (90.5%) and were enrolled in further analysis. Students came from a variety of social (psychology, political sciences, economy and business), technical (computing, information technologies, electrical engineering, civil engineering, mechanical engineering, graphics arts and naval architecture) and health-related (medical doctors, physiotherapists, nurses) sciences. Before the main analysis, we examined the differences between the participants and non-participants in terms of gender, age, body-mass index, self-rated health and psychological distress. No significant differences were observed and no potential bias was made (p = 0.21–0.74). All the analysis and procedures were anonymous and in accordance with the Declaration of Helsinki and approved by the Institutional Review Board of the Faculty of Kinesiology (Ethics code: 16/2017). Also, all participants gave their written informed consent for participation in the study.
Outcome variable
Psychological distress was assessed by using Kessler’s six-item questionnaire: (1) “How often during the past 30 days did you feel nervous?,” (2) “How often during the past 30 days did you feel hopeless?,” (3) “How often during the past 30 days did you feel restless or fidgety?,” (4) “How often during the past 30 days did you feel so depressed that nothing could cheer you up?,” (5) “How often during the past 30 days did you feel that everything was an effort?” and (6) “How often during the past 30 days did you feel worthless?” (Kessler et al., 2003). Each question is scored from zero (none of the time) to four (all of the time). Scores of each question are summed up ranging from zero to 24, with lower score indicating lower level of psychological distress. Kessler et al. (2003) showed that responses <13 points vs. ≥13 points discriminated participants without and with psychological distress.
Physical activity
To assess physical activity in the last seven days, we used International Physical Activity questionnaire, a reliable and valid instrument designed to measure physical activity in respondents between ages 18 and 65 (Craig et al., 2003). Specifically, this measure assesses the types of intensity of physical activity during the day to estimate total physical activity measured in metabolic equivalent units-min/week. We created a dichotomized variable, where “sufficiently active” participants participated in at least (1) 150 min/week in moderate physical activity or (2) 75 min of vigorous physical activity or (3) an equivalent combination of both compared with “insufficiently active” participants (World Health Organization, 2010).
Physical fitness
Self-rated physical fitness was assessed by using one-time question: “How would you rate your physical fitness?” ranging from one (very poor) to 10 (excellent) (Plante, LeCaptain & McLain, 2000). This measure has previously been correlated with measures of objective physical fitness and perceived well-being (Plante, Lantis & Checa, 1998) and used in similar studies (Gerber et al., 2010).
Covariates
Previous studies have shown, that body-mass index, socioeconomic status, alcohol consumption, having a long-term health condition, self-rated health and sleep quality are known or suspected to influence psychological distress and we included them as covariates in the analysis (Novak & Kawacki, 2015; Perales, del Pozo-Cruz & del Pozo-Cruz, 2014; Sagatun et al., 2007). Participants self-reported their height in meters (m) and weight in kilograms (kg), from which body-mass index (kg/m2) was calculated. Before the study began, we had chosen 35 men and 40 women to validate self-reported height and weight with the objective measure taken by trained survey staff. Pearson’s coefficient of correlation showed excellent relationship between two measures in men (r = 0.96) and women (r = 0.97). For the purpose of this study, we divided body-mass index score into two categories: (1) normal (<25 kg/m2) vs. (2) overweight/obesity (≥25 kg/m2). Although not appropriate as a clinical tool, self-reported BMI serves as a valid tool for epidemiological surveys, especially in young adults (Meyer et al., 2012). Self-rated health was assessed using one-item question: “How would you rate your health?” Answers were arranged along a Likert-type scale as follows: (1) very poor, (2) poor, (3) fair, (4) good and (5) excellent. For the purpose of this study, we dichotomized the outcome variable into “good” (fair, good and excellent) vs. “poor” (very poor and poor) self-rated health (Štefan et al., 2017). Material status was assessed by one question: “How would you perceive your material status, based on your parents’ occupation?” Responses were: (1) low, (2) medium and (3) high. We created two categories as follows: (1) low and (2) medium/high. Binge alcohol consumption was assessed by one question: “How often do you have (for men) five or more and (for women) four or more drinks on one occasion?” (Peltzer & Pengpid, 2016). Those who had (for men) five or more and (for women) four or more drinks on one occasion were categorized as “Yes,” compared to “No” group who had less drinks on one occasion. The presence or absence of a chronic disease was asked by one-item question: “Have you ever been told by a doctor, that you suffer from any kind of chronic disease?” with “Yes” and “No” answers. To assess sleep quality, we asked about current self-perceived state of sleep quality: “How would you perceive your sleep quality?” Answers were arranged across a four-item scale as follows: (1) very good, (2) good, (3) poor and (4) very poor. Very good and good collapsed into “good” and poor and very poor into “poor” sleep quality.
Data analysis
Basic descriptive statistics of the study participants are presented as frequencies (N) and percentages (%). Differences between categorical variables between “low” and “high” psychological distress were analyzed using Chi-square test. To explore the associations between physical activity and physical fitness with psychological distress, we performed a set of logistic regression analyses. We calculated odd ratios (ORs) with 95% confidence intervals (95% CIs). “High” psychological distress was the main outcome of the present study. First, we explored the association between “insufficient” physical activity and “high” psychological distress in model 1. Second, we explored the association between “low” physical fitness and “high” psychological distress. Since physical fitness was assessed by a 10-item scale, we calculated median and interquartile range (25th and 75th percentile range), in order to categorize participants into three groups (tertiles): (1) <25th percentile as “low,” (2) 25th–75th percentiles as “medium” and (3) >75th percentile as “high” physical fitness. Finally, we entered both physical activity and physical fitness simultaneously into the model (model 3). Significance was set up at α ≤ 0.05 and it was one-sided. All the analysis were performed in Statistical Package for Social Sciences Software, ver. 22 (IBM Corp., Armonk, NY, USA).
Results
Basic descriptive statistics of the study participants are presented in Table 1. The prevalence of “high” psychological distress was 10.6%, while 22.6% and 28.2% of the study participants were “insufficiently” active and were in the “lowest” physical fitness group. We found that higher percentage of “insufficiently” active participants and those with “lower” levels of physical fitness reported having “high” psychological distress in the last 30 days. Also, higher percentage of women, those participants who reported having poor self-rated health, low material status, binge drinking, having a chronic disease and poor/very poor sleep had “high” psychological distress in the last 30 days.
Table 1. Basic descriptive statistics of the study participants, Croatia (2017).
| Study variables | Total sample (N = 2,100) | Low psychological distress (N = 1,878) | High psychological distress (N = 222) | p-value* |
|---|---|---|---|---|
| N (%) | N (%) | N (%) | ||
| Physical activity | ||||
| Sufficient | 1,626 (77.4) | 1,502 (92.4) | 124 (7.6) | |
| Insufficient | 474 (22.6) | 376 (20.0) | 98 (80.0) | <0.001 |
| Physical fitness | ||||
| Tertile 3 (highest) | 601 (28.6) | 572 (95.2) | 29 (4.8) | |
| Tertile 2 | 907 (43.2) | 809 (90.2) | 98 (10.8) | |
| Tertile 1 (lowest) | 592 (28.2) | 497 (84.0) | 95 (16.0) | <0.001 |
| Gender | ||||
| Men | 1,041 (49.6) | 975 (93.7) | 66 (6.3) | |
| Women | 1,059 (50.4) | 903 (85.3) | 156 (14.7) | <0.001 |
| Body-mass index | ||||
| Normal | 1,765 (84.0) | 1,577 (89.3) | 188 (10.7) | |
| Overweight/obesity | 335 (16.0) | 301 (89.9) | 34 (10.1) | 0.847 |
| Self-rated health | ||||
| Good | 1,935 (92.1) | 1,750 (90.4) | 185 (9.6) | |
| Poor | 165 (7.9) | 120 (77.6) | 37 (22.4) | <0.001 |
| Material status | ||||
| Middle/high | 2,048 (97.5) | 1,839 (89.8) | 209 (10.2) | |
| Low | 52 (2.5) | 39 (75.0) | 13 (25.0) | 0.002 |
| Binge drinking | ||||
| No | 1,530 (72.9) | 1,391 (90.9) | 139 (9.1) | |
| Yes | 570 (27.1) | 487 (85.4) | 83 (14.6) | <0.001 |
| Chronic disease/s | ||||
| No | 1,905 (90.7) | 1,721 (90.3) | 184 (9.7) | |
| Yes | 195 (9.3) | 157 (80.5) | 38 (19.5) | <0.001 |
| Sleep quality | ||||
| Very good/good | 687 (32.7) | 658 (95.8) | 29 (4.2) | |
| Poor/very poor | 1,413 (67.3) | 1,220 (86.3) | 192 (13.7) | <0.001 |
Note:
Chi-square test.
The associations between physical activity, physical fitness and psychological distress are presented in Table 2. In model 1, “insufficient” physical activity (OR = 2.60; 95% CI [1.92–3.52]) was associated with “high” psychological distress. In model 2, those participants in lower tertiles (tertile 2; OR = 1.94; 95% CI [1.25–3.01] and tertile 1; OR = 2.59; 95% CI [1.65–4.08]) were more likely to experience “high” psychological distress. Finally, when both physical activity and physical fitness were entered simultaneously into the model (model 3), OR for “insufficient” physical activity (OR = 2.35; 95% CI [1.72–3.21]) and for “lower” levels of physical fitness (tertile 2; OR = 1.77; 95% CI [1.14–2.77] and tertile 1; OR = 2.00; 95% CI [1.26–3.20]) decreased, but remained associated with “high” psychological distress. All three models were adjusted for gender, body-mass index, self-rated health, material status, binge drinking, chronic disease/s and sleep quality. The association between physical fitness and physical activity was moderate (r = 0.33, p < 0.001) and variance inflation factors test showed no multicollinearity (1.00–1.10).
Table 2. Odd ratios for high psychological distress of the study participants, Croatia (2017).
| Study variables | Physical activity and psychological distress | Physical fitness and psychological distress | Physical activity and physical fitness with psychological distress |
|---|---|---|---|
| OR (95% CI) | OR (95% CI) | OR (95% CI) | |
| Physical activity | |||
| Sufficient | 1.00 | 1.00 | |
| Insufficient | 2.60 (1.92–3.52)*** | 2.35 (1.72–3.21)*** | |
| Physical fitness | |||
| Tertile 3 (highest) | 1.00 | 1.00 | |
| Tertile 2 | 1.94 (1.25–3.01)** | 1.77 (1.14–2.77)* | |
| Tertile 1 (lowest) | 2.59 (1.65–4.08)*** | 2.00 (1.26–3.20)** | |
| Gender | |||
| Men | 1.00 | 1.00 | 1.00 |
| Women | 2.18 (1.57–3.02)*** | 2.17 (1.57–3.01)*** | 2.00 (1.44–2.78)*** |
| Body-mass index | |||
| Normal | 1.00 | 1.00 | 1.00 |
| Overweight/obesity | 1.09 (0.71–1.67) | 1.01 (0.66–1.55) | 1.02 (0.66–1.57) |
| Self-rated health | |||
| Good | 1.00 | 1.00 | 1.00 |
| Poor | 2.13 (1.38–3.30)*** | 2.03 (1.31–3.12)*** | 2.04 (1.31–3.16)*** |
| Material status | |||
| Middle/high | 1.00 | 1.00 | 1.00 |
| Low | 2.32 (1.14–4.74)* | 2.12 (1.04–4.33)* | 2.22 (1.08–4.53)* |
| Binge drinking | |||
| No | 1.00 | 1.00 | 1.00 |
| Yes | 1.71 (1.26–2.33)*** | 1.76 (1.30–2.38)*** | 1.75 (1.28–2.93)** |
| Chronic disease/s | |||
| No | 1.00 | 1.00 | 1.00 |
| Yes | 1.91 (1.26–2.89)*** | 1.96 (1.30–2.95)*** | 1.94 (1.28–2.93)** |
| Sleep quality | |||
| Very good/good | 1.00 | 1.00 | 1.00 |
| Poor/very poor | 3.44 (2.28–5.19)*** | 3.34 (2.22–5.04)*** | 3.29 (2.18–4.98)*** |
Notes:
Model 1: Examines the associations of physical activity with psychological distress adjusted for gender, body-mass index, self-rated health, material status, binge drinking, chronic disease/s and sleep quality.
Model 2: Examines the associations of physical fitness with psychological distress adjusted for gender, body-mass index, self-rated health, material status, binge drinking, chronic disease/s and sleep quality.
Model 3: Examines the associations of physical activity and physical fitness entered simultaneously into the model with psychological distress adjusted for gender, body-mass index, self-rated health, material status, binge drinking, chronic disease/s and sleep quality.
p < 0.05.
p < 0.01.
p < 0.01.
Discussion
The main purpose of the present study was to explore both separate and simultaneous associations between physical activity and physical fitness and psychological distress in a large sample of young adults. Both “insufficient” physical activity and “lower” levels of physical fitness were associated with “high” psychological distress after adjusting for gender, body-mass index, self-rated health, material status, binge drinking, chronic disease/s and sleep quality.
Our results are in line with previous studies aiming to explore the associations between physical activity/fitness and mental health (Sagatun et al., 2007; World Health Organization, 2010; Larun et al., 2006; Pozuelo-Carrascosa et al., 2017; Jeoung, Hong & Lee, 2013). Specifically, Sagatun et al. (2007), in their three-year longitudinal study, showed that weekly hours of physical activity were negatively associated with emotional symptoms or peer problems only in boys, but not in girls. As mentioned before, mental health is a complex state comprised of behavioral, psychological and social components (Paluska & Schwenk, 2000; Ekeland et al., 2004; Bandura, 1977). A few previous studies have shown, that participants, who are engaged in regular physical activity displays much less inhibition in social behavior (Kirkcaldy, Shephard & Siefen, 2002) and scored lower on psychological discomfort captured by loneliness, hopelessness and shyness (Page & Tucker, 1994) compared to their physically inactive peers. In addition to physical activity, studies aiming to explore the associations between physical fitness and mental health disorders have shown that higher levels of cardio-respiratory, strength and flexibility fitness are significantly associated with decreased mental health disorders, compared to participants with lower levels of physical fitness (Pozuelo-Carrascosa et al., 2017; Jeoung, Hong & Lee, 2013). Our results confirmed strong negative association between self-perceived physical fitness and psychological distress, that is, “lower” levels of physical fitness were associated with “high” psychological distress.
The mechanism underlying the association between physical activity/fitness and mental health is not clearly understood (Blake, 2012). Previous meta-analytical reviews have shown small clinical effect that physical activity has on mental health (Larun et al., 2006; Ahn & Fedewa, 2011; Rimer et al., 2012). Although small, positive benefits of physical activity on health outcomes have been well-documented (Warburton, Nicol & Bredin, 2006). In terms of mental health, physical activity serves as beneficial factor for neurotransmitters in the brain, leading to increased levels of motivation and positive emotions and reducing stress and pain (Paluska & Schwenk, 2000; Ekeland et al., 2004; Bandura, 1977). Our results also showed that among numerous factors we adjusted for, the strongest association was between “very poor/poor” sleep quality and “high” psychological distress, which is similar to other studies (Feng et al., 2014). Such associations between sleep quality and psychological distress could be mediated by physical activity which regulates temperature following exercise and the onset of sleep declines through vasodilatation of peripheral heat dissipation (Driver & Taylor, 2000). In that way, by affecting on sleep quality, physical activity decreases psychological distress and improves behavioral and emotional regulations.
Our study has some limitations. First, we used a cross-sectional design, in order to determine the associations between physical activity and physical fitness with psychological distress. To determine the causality, Reichenheim & Coutinho (2010) reported that the main outcome of the study should be frequent and might be different among subjects, due to a dynamic population. Second, we used subjective measures to assess psychological distress, physical activity, physical fitness and other covariates. However, self-reported measures are largely used in epidemiological studies. But, for better precision, future studies should use direct measurement method (motor and functional fitness tests) over a longer period of time, in order to track and establish causal direction of the association between physical activity/fitness and psychological distress.
Conclusion
Our results show strong associations between “insufficient” physical activity and “lower” levels of physical fitness with “high” psychological distress in a large sample of young adults. Findings of this study should be taken into account when establishing and implementing special strategies and policies that leverage higher participation in physical activity in order to decrease “high” psychological distress.
Supplemental Information
Acknowledgments
We would like to thank teachers and students for their enthusiastic participation in the study.
Funding Statement
The authors received no funding for this work.
Additional Information and Declarations
Competing Interests
Goran Sporiš is an Academic Editor for PeerJ.
Author Contributions
Lovro Štefan conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.
Goran Sporiš conceived and designed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.
Tomislav Krističević conceived and designed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.
Ethics
The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers):
All the analysis and procedures were anonymous and in accordance with the Declaration of Helsinki and approved by the Institutional Review Board of the Faculty of Kinesiology (Ethics code: 16/2017).
Data Availability
The following information was supplied regarding data availability:
The raw data are provided as a Supplemental File.
References
- Ahn & Fedewa (2011).Ahn S, Fedewa AL. A meta-analysis of the relationship between children’s physical activity and mental health. Journal of Pediatric Psychology. 2011;36(4):385–397. doi: 10.1093/jpepsy/jsq107. [DOI] [PubMed] [Google Scholar]
- Bandura (1977).Bandura A. Self-efficacy: toward a unifying theory of behavioral change. Psychological Review. 1977;84(2):191–215. doi: 10.1037//0033-295x.84.2.191. [DOI] [PubMed] [Google Scholar]
- Blake (2012).Blake H. Physical activity and exercise in the treatment of depression. Frontiers in Psychiatry. 2012;3:106. doi: 10.3389/fpsyt.2012.00106. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Caspersen, Powell & Christenson (1985).Caspersen CJ, Powell KE, Christenson GM. Physical activity, exercise, and physical fitness: definitions and distinctions for health-related research. Public Health Reports. 1985;100(2):126–131. [PMC free article] [PubMed] [Google Scholar]
- Costello et al. (2003).Costello EJ, Mustillo S, Erkanli A, Keeler G, Angold A. Prevalence and development of psychiatric disorders in childhood and adolescence. Archives of General Psychiatry. 2003;60(8):837–844. doi: 10.1001/archpsyc.60.8.837. [DOI] [PubMed] [Google Scholar]
- Craig et al. (2003).Craig CL, Marshall AL, Sjöström M, Bauman AE, Booth ML, Ainsworth BE, Pratt M, Ekelund U, Yngve A, Sallis JF, Oja P. International physical activity questionnaire: 12-country reliability and validity. Medicine & Science in Sports & Exercise. 2003;35(8):1381–1395. doi: 10.1249/01.mss.0000078924.61453.fb. [DOI] [PubMed] [Google Scholar]
- Driver & Taylor (2000).Driver HS, Taylor SR. Exercise and sleep. Sleep Medicine Reviews. 2000;4(4):387–402. doi: 10.1053/smrv.2000.0110. [DOI] [PubMed] [Google Scholar]
- Ekeland et al. (2004).Ekeland E, Heian F, Hagen KB, Abbott J, Nordheim L. Exercise to improve self-esteem in children and young people. Cochrane Database of Systematic Reviews. 2004;1:CD003683. doi: 10.1002/14651858.cd003683.pub2. [DOI] [PubMed] [Google Scholar]
- Faulkner & Taylor (2009).Faulkner G, Taylor A. Promoting physical activity for mental health: a complex intervention? Mental Health and Physical Activity. 2009;2(1):1–3. doi: 10.1016/j.mhpa.2009.04.001. [DOI] [Google Scholar]
- Feng et al. (2014).Feng Q, Zhang Q, Du Y, Ye Y, He Q. Associations of physical activity, screen time with depression, anxiety and sleep quality among Chinese college freshmen. PLOS ONE. 2014;9(6):e100914. doi: 10.1371/journal.pone.0100914. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gerber et al. (2010).Gerber M, Brand S, Holsboer-Trachsler E, Puhse U. Fitness and exercise as correlates of sleep complaints: is it all in our minds? Medicine & Science in Sports & Exercise. 2010;42(5):893–901. doi: 10.1249/mss.0b013e3181c0ea8c. [DOI] [PubMed] [Google Scholar]
- Jeoung, Hong & Lee (2013).Jeoung BJ, Hong M-S, Lee YC. The relationship between mental health and health-related physical fitness of university students. Journal of Exercise Rehabilitation. 2013;9(6):544–548. doi: 10.12965/jer.130082. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kessler et al. (2003).Kessler RC, Barker PR, Colpe LJ, Epstein JF, Gfroerer JC, Hiripi E, Howes MJ, Normand SL, Manderscheid RW, Walters EE, Zaslavsky AM. Screening for serious mental illness in the general population. Archives of General Psychiatry. 2003;60(2):184–189. doi: 10.1001/archpsyc.60.2.184. [DOI] [PubMed] [Google Scholar]
- Kessler et al. (2005).Kessler RC, Berglund P, Demler O, Jin R, Merikangas KR, Walters EE. Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the National Comorbidity Survey Replication. Archives of General Psychiatry. 2005;62(6):593–602. doi: 10.1001/archpsyc.62.6.593. [DOI] [PubMed] [Google Scholar]
- Kirkcaldy, Shephard & Siefen (2002).Kirkcaldy BD, Shephard R, Siefen G. The relationship between physical activity and self-image and problem behaviour among adolescents. Social Psychiatry and Psychiatric Epidemiology. 2002;37(11):544–550. doi: 10.1007/s00127-002-0554-7. [DOI] [PubMed] [Google Scholar]
- Kisely, Crowe & Lawrence (2013).Kisely S, Crowe E, Lawrence D. Cancer-related mortality in people with mental illness. JAMA Psychiatry. 2013;70(2):209–217. doi: 10.1001/jamapsychiatry.2013.278. [DOI] [PubMed] [Google Scholar]
- Larun et al. (2006).Larun L, Nordheim LV, Ekeland E, Hagen KB, Heian F. Exercise in prevention and treatment of anxiety and depression among children and young people. Cochrane Database of Systematic Reviews. 2006;3:1–47. doi: 10.1002/14651858.cd004691.pub2. [DOI] [PubMed] [Google Scholar]
- Malhotra et al. (2013).Malhotra R, Ostbye T, Riley CM, Finkelstein E. Young adult weight trajectories through midlife by body mass category. Obesity. 2013;21(9):1923–1934. doi: 10.1002/oby.20318. [DOI] [PubMed] [Google Scholar]
- Mensah & Collins (2015).Mensah GA, Collins PY. Understanding mental health for the prevention and control of cardiovascular diseases. Global Heart. 2015;10(3):221–224. doi: 10.1016/j.gheart.2015.08.003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Meyer et al. (2012).Meyer KA, Wall MM, Larson NI, Laska MN, Neumark-Sztainer D. Sleep duration and BMI in a sample of young adults. Obesity. 2012;20(6):1279–1287. doi: 10.1038/oby.2011.381. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Newcomer (2007).Newcomer JW. Metabolic syndrome and mental illness. American Journal of Managed Care. 2007;13:170–177. [PubMed] [Google Scholar]
- Novak & Kawacki (2015).Novak D, Kawacki I. Influence of different domains of social capital on psychological distress among Croatian high school students. International Journal of Mental Health Systems. 2015;9(1):18. doi: 10.1186/s13033-015-0010-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Page & Tucker (1994).Page RM, Tucker LA. Psychosocial discomfort and exercise frequency: an epidemiological study of adolescents. Adolescence. 1994;29(113):183–191. [PubMed] [Google Scholar]
- Paluska & Schwenk (2000).Paluska SA, Schwenk TL. Physical activity and mental health. Current concepts. Sports Medicine. 2000;29(3):167–180. doi: 10.1093/med/9780199232482.003.0024. [DOI] [PubMed] [Google Scholar]
- Patten, Williams & Wang (2006).Patten SB, Williams JV, Wang J. Mental disorders in a population sample with musculoskeletal disorders. BMC Musculoskeletal Disorders. 2006;7(1):37. doi: 10.1186/1471-2474-7-37. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peltzer & Pengpid (2016).Peltzer K, Pengpid S. Sleep duration and health correlates among university students in 26 countries. Psychology, Health & Medicine. 2016;21(2):208–220. doi: 10.1080/13548506.2014.998687. [DOI] [PubMed] [Google Scholar]
- Perales, del Pozo-Cruz & del Pozo-Cruz (2014).Perales F, Del Pozo-Cruz J, Del Pozo-Cruz B. Impact of physical activity on psychological distress: a prospective analysis of an Australian national sample. American Journal of Public Health. 2014;104(12):e91–e97. doi: 10.2105/AJPH.2014.302169. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Plante, LeCaptain & McLain (2000).Plante TG, LeCaptain SE, McLain HC. Perceived fitness predicts daily coping better than physical activity. Journal of Applied Biobehavioral Research. 2000;5(1):66–79. doi: 10.1111/j.1751-9861.2000.tb00064.x. [DOI] [Google Scholar]
- Plante, Lantis & Checa (1998).Plante TG, Lantis A, Checa G. The influence of perceived versus aerobic fitness on psychological health and physiological stress responsivity. International Journal of Stress Management. 1998;5(3):141–156. doi: 10.1023/a:1022936930992. [DOI] [Google Scholar]
- Pozuelo-Carrascosa et al. (2017).Pozuelo-Carrascosa DP, Martínez-Vizcaíno V, Sánchez-López M, Bartolomé-Gutierréz R, Rodríguez-Martín B, Notario-Pacheco B. Resilience as a mediator between cardiorespiratory fitness and mental health-related quality of life: a cross-sectional study. Nursing & Health Sciences. 2017;19(3):316–321. doi: 10.1111/nhs.12347. [DOI] [PubMed] [Google Scholar]
- Reichenheim & Coutinho (2010).Reichenheim ME, Coutinho ESF. Measures and models for causal inference in cross-sectional studies: arguments for the appropriateness of the prevalence odds ratio and related logistic regression. BMC Medical Research Methodology. 2010;10:66. doi: 10.1186/1471-2288-10-66. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Richey & Krystal (2011).Richey SM, Krystal AS. Pharmacological advances in the treatment of insomnia. Current Pharmaceutical Design. 2011;17(15):1471–1475. doi: 10.2174/138161211796197052. [DOI] [PubMed] [Google Scholar]
- Rimer et al. (2012).Rimer J, Dwan K, Lawlor DA, Greig CA, McMurdo M, Morley W, Mead GE. Exercise for depression. Cochrane Database of Systematic Reviews. 2012;7:CD004366. doi: 10.1002/14651858.cd004366.pub5. [DOI] [PubMed] [Google Scholar]
- Rudan et al. (2005).Rudan V, Begovac I, Szirovicza L, Filipovic O, Skocic M. The child behavior checklist, teacher report form and youth self report problem scales in a normative sample of Croatian children and adolescents aged 7–18. Collegium Antropologicum. 2005;29(1):17–26. [PubMed] [Google Scholar]
- Sagatun et al. (2007).Sagatun A, Søgaard AJ, Bjertness E, Selmer R, Heyerdahl S. The association between weekly hours of physical activity and mental health: a three-year follow-up study of 15–16-year-old students in the city of Oslo, Norway. BMC Public Health. 2007;7(1):155. doi: 10.1186/1471-2458-7-155. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Štefan et al. (2017).Štefan L, Juranko D, Prosoli R, Barić R, Sporiš G. Self-reported sleep duration and self-rated health in young adults. Journal of Clinical Sleep Medicine. 2017;13(7):899–904. doi: 10.5664/jcsm.6662. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Walker, McGee & Druss (2015).Walker ER, McGee RE, Druss BG. Mortality in mental disorders and global disease burden implications: a systematic review and meta-analysis. JAMA Psychiatry. 2015;72(4):334–341. doi: 10.1001/jamapsychiatry.2014.2502. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Warburton, Nicol & Bredin (2006).Warburton DER, Nicol CW, Bredin SSD. Health benefits of physical activity: the evidence. Canadian Medical Association Journal. 2006;174(6):801–809. doi: 10.1503/cmaj.051351. [DOI] [PMC free article] [PubMed] [Google Scholar]
- World Health Organization (2010).World Health Organization . Global Recommendations on Physical Activity for Health. Geneva: WHO Press; 2010. [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The following information was supplied regarding data availability:
The raw data are provided as a Supplemental File.