Understanding adolescents’ mental health and academic achievement: Does physical fitness matter?

This review aims to summarize the latest developments with regard to physical fitness and several health outcomes in young people. The literature reviewed suggests that (1) cardiorespiratory fitness levels are associated with total and abdominal adiposity; (2) both cardiorespiratory and muscular fitness are shown to be associated with established and emerging cardiovascular disease risk factors; (3) improvements in muscular fitness and speed/agility, rather than cardiorespiratory fitness, seem to have a positive effect on skeletal health; (4) both cardiorespiratory and muscular fitness enhancements are recommended in pediatric cancer patients/survivors in order to attenuate fatigue and improve their quality of life; and (5) improvements in cardiorespiratory fitness have positive effects on depression, anxiety, mood status and self-esteem, and seem also to be associated with a higher academic performance. In conclusion, health promotion policies and physical activity programs should be designed to improve cardiorespiratory fitness, but also two other physical fitness components such us muscular fitness and speed/agility. Schools may play an important role by identifying children with low physical fitness and by promoting positive health behaviors such as encouraging children to be active, with special emphasis on the intensity of the activity.

The objective of the present systematic review was to investigate whether physical fitness in childhood and adolescence is a predictor of cardiovascular disease (CVD) risk factors, events and syndromes, quality of life and low back pain later in life. Physical fitness-related components were: cardiorespiratory fitness, musculoskeletal fitness, motor fitness and body composition. Adiposity was considered as both exposure and outcome. The results of 42 studies reporting the predictive validity of health-related physical fitness for CVD risk factors, events and syndromes as well as the results of five studies reporting the predictive validity of physical fitness for low back pain in children and adolescents were summarised. Strong evidence was found indicating that higher levels of cardiorespiratory fitness in childhood and adolescence are associated with a healthier cardiovascular profile later in life. Muscular strength improvements from childhood to adolescence are negatively associated with changes in overall adiposity. A healthier body composition in childhood and adolescence is associated with a healthier cardiovascular profile later in life and with a lower risk of death. The evidence was moderate for the association between changes in cardiorespiratory fitness and CVD risk factors, and between cardiorespiratory fitness and the risk of developing the metabolic syndrome and arterial stiffness. Moderate evidence on the lack of a relationship between body composition and low back pain was found. Due to a limited number of studies, inconclusive evidence emerged for a relationship between muscular strength or motor fitness and CVD risk factors, and between flexibility and low back pain.

We addressed three questions: 1) Is there a dose-response relation between physical activity and health? 2) Is there a dose-response relation between cardiorespiratory fitness and health? 3) If both activity and fitness have a dose-response relation to health, is it possible to determine which exposure is more important? We identified articles by PubMed search (restricted from 1/1/90 to 8/25/00) using keywords related to physical activity, physical fitness, and health. An author scanned titles and abstracts of 9831 identified articles. We included for thorough review articles that included three or more categories of activity or fitness and a health outcome and excluded articles on clinical trials, review papers, comments, letters, case reports, and nonhuman studies. We used an evidence-based approach to evaluate the quality of the published data. We summarized results from 67 articles meeting final selection criteria. There is good consensus across studies with most showing an inverse dose-response gradient across both activity and fitness categories for morbidity from coronary heart disease (CHD), stroke, cardiovascular disease (CVD), or cancer; and for CVD, cancer, or all-cause mortality. All studies reviewed were prospective observational investigations; thus, conclusions are based on Evidence Category C. 1) There is a consistent gradient across activity groups indicating greater longevity and reduced risk of CHD, CVD, stroke, and colon cancer in more active individuals. 2) Studies are compelling in the consistency and steepness of the gradient across fitness groups. Most show a curvilinear gradient, with a steep slope at low levels of fitness and an asymptote in the upper part of the fitness distribution. 3) It is not possible to conclude whether activity or fitness is more important for health. Future studies should define more precisely the shape of the dose-response gradient across activity or fitness groups, evaluate the role of musculoskeletal fitness, and investigate additional health outcomes.