• Health promotion

The impact of (in)sufficient levels of physical activity (PA) have been well described and without argument, the promotion of PA—defined as moderate to vigorous physical activities, including sports and exercise—is now a cornerstone of contemporary public health.1 In our global effort to decrease the individual and public burden of chronic and lifestyle-related diseases, PA is being promoted as a medicine or drug, with the implication that it is a treatment and a preventive measure. Although the pharmacological benefits of PA have been well described,2 the analogy between PA as medicine is not drawn in full, because any substance that is capable of producing a therapeutic effect can also produce unwanted or adverse effects.3 The potential for adverse effects of PA, and the need to mitigate them, are mostly ignored in PA research and PA interventions alike.

An adverse drug reaction is defined by the WHO as “a response to a drug that is noxious and unintended and occurs at doses normally used in man for the prophylaxis, diagnosis or therapy of disease, or for modification of physiological function.”3 An injury resulting from the recommended daily dose of 30 min of moderate to vigorous PA certainly fits this definition. However, truth be …