Benefits of exercise on cognitive performance in schoolchildren

There have been various changes in schools over the last decade or so which have contributed to reducing the amount of time that children engage in physical activity. These include increased time children spend in preparing for and undertaking formal assessments, reduction in recess ⁄ playtime, and the erosion of school sport facilities. Schools should be concerned about these changes, not only for the physical health and well-being of their students but also in relation to the capacity for classroom learning. For a long time there has been a belief that exercise is linked to enhanced cognitive performance. However, it is only relatively recently that this has been systematically investigated in school-aged children and there are two approaches that have been taken in this area. One has been to examine the extent to which chronic exercise (e.g. regular sport participation) benefits intelligence and academic achievement. The second approach has been to examine the short-term effects of acute bouts of exercise on cognitive performance. Limitations in the sampling, measurement, and design of studies in this area have rendered interpretation of the varied findings difficult. However, the latter approach does lend itself to greater control over the length and intensity of exercise and examination of more specific aspects of cognitive performance. This is demonstrated in the study by Hill et al., which also incorporates a careful crossover design and counterbalancing of groups in a large sample of 8to 12-year-old children. Given the methodological rigour of this study, one can have confidence in the findings that show a clear benefit of acute exercise on cognitive performance in this age group. Moreover, the nature of the exercise sessions employed suggests that these could easily be devised and implemented within any school setting, without the need for specialist equipment or personnel. Although the exact dose of exercise needed to produce a significant effect on cognitive performance has not been scrutinized, the short sessions of moderately intensive exercise used by Hill et al. were found to be effective. This represents only a short investment of time that would seem to be manageable within the busy school curriculum. Future work in this field should also gather information on child and teacher perceptions of classroom exercise of this type. This might provide useful information to optimize the implementation of and compliance with such exercise programmes. The mechanisms underlying the beneficial effects of exercise on cognitive performance have yet to be clearly understood. However, animal and human studies have demonstrated that aerobic exercise increases the production and release of various molecules (including brain-derived neurotrophic factor), which seem to play an important role. It has been shown that exercise exerts specific, rather than global effects on cognitive function in children. These relate to executive functioning processes such as those tapped by the ‘mental tracking’ tasks employed by Hill et al. However, much is still to be learned about the underlying processes at the molecular, cellular, and behavioural level and the effect of factors such as age and exercise intensity.