Sport: how much is too much?

Numerous research studies have shown that physical activity has a positive effect on physical and mental health. More particularly, regular aerobic exercise and resistance training are associated with a reduced risk for cardiovascular morbidity and mortality. In 2020, the updated World Health Organization (WHO) recommendations highlighted that adults aged over 65 years should engage in at least 150 min/week of moderate intensity aerobic activities or 75 min/week of vigorous intensity aerobic activities or an equivalent combination. In addition, complementary muscle- strengthening activities should be performed involving major muscle groups on two or more days a week. However, the WHO provides no recommendations for upper limits in terms of intensity and volume of physical activity. Yet, the health effects of exercise volumes beyond the “optimal dose” are currently under debate. Some observational studies have reported an increased risk of disease and/or mortality at the highest exercise volumes. Excessive exercising can indeed have harmful effects on physical (e.g. injury) and mental health (e.g. addiction-like behaviour, relative energy deficiency in sport (RED-S)). Regarding the musculoskeletal field, data on how much sport is too much are scarce, especially in the older adult. In this Meet-the-Expert session, we will first discuss the adverse effects observed in randomised controlled trials that have evaluated the impact of physical activity programmes in the older population. Then, we will discuss available data having assessed the impact of different exercise load (i.e. volume, intensity) on the risk of musculoskeletal disorders (e.g. osteoarthritis, tendinopathy, stress fracture, muscle tear, overuse injuries). Finally, we will discuss the advantages and disadvantages of the "weekend warrior" behaviour, i.e. a person who only exercises at the weekend. We will end the session with some practical recommendations to prescribe the optimal dose of sport.