Adolescents who take part in team sports, or who actively commute to school, are less likely to be obese
- Correspondence to
: Dr Catherine B Woods
School of Health and Human Performance, Dublin City University, Dublin D9, Ireland;
Commentary on: 
Implications for practice and research
Prevalence of childhood obesity is a global concern.
Low levels of physical activity (PA) are commonplace; evidence for PA intervention in reducing body mass index (BMI) is inconclusive.
Regular participation in structured sport and frequent walking or cycling to school may decrease the prevalence of overweight children and obesity.
Future research must acknowledge the importance of longitudinal data in order to fully understand the role of PA in the prevention and management of overweight and obesity.
Cross-sectional and longitudinal data suggest PA and fitness markers are associated with enhanced health and cognitive function in adolescents.1 Yet, epidemiological data indicate that, on average, 80% of adolescents do not meet the PA guidelines, and 65% exceed the healthy limit for sedentary behaviour.2 Evidence-based interventions to promote increased PA in adolescents exist.3 Yet, the effectiveness of these interventions for increasing PA and reducing BMI has recently been questioned.4 The conclusions of this paper provide evidence to the contrary; the authors suggest that if adolescents engage in regular participation in sport and/or active school transport (AST), then significant reductions in the prevalence of overweight or obesity in this target group could be realised.
This study relies on a self-report survey methodology and as such is limited. However, its large sample size (N=1718) and longitudinal nature (five waves of data collected over a 7-year period) make it a unique dataset from which to evaluate the relationship between sport, physical education (PE), AST and weight status. The outcomes of interest were adapted from validated measures, and assessed with single items with varying recall timeframes (past 12 months, past 7 days, at different times of the year).
Almost three-quarters of the sample played on sport teams; yet only 10.2% engaged in AST. High proportions of participants reported being overweight/obese (29%) and obese (13%). This study's estimated decreases in overweight/obese (10.6%) and obesity (26.1%) for adolescents who play on at least two sport teams per year, and for adolescents who walk or cycle to school at least 4 days a week (decrease in obesity by 22.1%) are significant and have large potential public health impact. PE was found to have no influence on weight status.
The levels of sport participation were unremarkable, reflecting similar patterns in other countries.5 In contrast, the level of AST reported was very low.5 AST is an achievable behaviour, provided children live within a commutable distance from their school.5 Research on the correlates of AST to establish if unique factors exist within the USA, for example, urban design or school location policies, that hinder AST options for children is needed. PE was found to have no effect on weight status adding further evidence to its educational, rather than energy expenditure, role.
By examining overweight/obesity and obesity as separate functions, the authors identified the real impact of different modes of activity on these variables. Although single-item measures have limitations, when combined with the extensive range of covariates, as in the current study, they provide a useful source of surveillance information for population-based studies.
This study examined the relative effect of different forms of PA on weight status of adolescents. Contrary to other research,4 its findings suggest a large effect and a significant role for regular sport participation and walking or cycling to school. The potential public health impact of these findings is immense. The likelihood of other interventions, such as increasing taxes on sugar-sweetened drinks; obtaining such dramatic results for decreasing prevalence of this chronic disease is questionable.