Exercise intensity for health and sports performance: recent updates

Sport and physical activity prescription guidelines continue to evolve, which helps responding to a global epidemic of obesity, diabetes and several other lifestyle diseases, and addressing sports performance needs. Individualized exercise prescription should consider human physiological and behavioral adaptations and long term adherence. The intensity, duration and mode of exercise all determine the effectiveness and adherence of exercise training in the short and long term. Exercise or physical activity intensity prescription is considered one of the most important determinants for both health and sport related outcomes because of its complex effects on human cardiometabolic, neurological and psychological responses. Exercise training effectiveness can be defined based on several markers or thresholds at maximal and submaximal levels, including oxygen uptake, carbon dioxide production, blood metabolites, and perceived physical exertion, all affected by how intense the exercise is. Unfortunately, blurred definitions of exercise intensity prescription have recently surfaced including high-intensity or supramaximal high-intensity training (HIT or S-HIT). Some suggest HIT as a “novel” method for exercise training based on several findings showing short term-effectiveness in selected populations, which has been swiftly recommended by some as a public health strategy. Inaccurate exercise intensity prescription can be counterproductive, and increases the injury risk of and affect exercise adherence. Perhaps the history of exercise science associated with intensity domains including HIT can be traced back to early physiology work of 1920s. Since then, it had been known that exercise intensity domains are defined as light, moderate, heavy, severe, maximal and supramaximal intensities. Each domain is associated with complex adaptive responses, so HIT is not novel after all. A careful understanding of exercise intensity prescription necessitates an individualized exercise prescription in order to enable exercise scientists and sports medicine professionals to accurately address populations’ health and sporting outcomes.