Protein intake for athletes and active adults: Current concepts and controversies

The demands of physical exertion mean that protein requirements for athletes and active adults are now accepted as being greater than sedentary populations and those described by population reference intakes of ~0.8 g protein per kg of body mass per day (g/kg/day). Recent scholarly reviews and the latest guidelines for nutrition and athletic performance from the American College of Sports Medicine suggest intakes ranging from 1.2‐2.0 g/kg/day whether performing aerobic or resistance exercise, with the higher range of intakes appropriate for the latter. Specific situations of hypoenergetic diet or injury likely require greater protein intakes in order to preserve lean body mass (LBM), which is often paramount in athletes. The optimal dose of protein per meal is 0.25–0.40 g/kg when aiming to maximally stimulate muscle protein synthesis, a marker of repair, growth and adaptation, but multifactorial interactions between protein source, meal timing and pattern of distribution, and macronutrient co‐ingestion around exercise influence recommendations on a meal‐by‐meal basis. Longer term studies are required to confirm the efficacy of these recommendations, which are primarily inferred from data from acute (<24 hours) studies. Notwithstanding the positive effects on LBM of higher protein intakes combined with exercise, it would be remiss not to consider potential adverse effects of long‐term high‐protein intakes, although these concerns are rather preliminary at present. Therefore, within the broad framework of recommended ranges and being cognisant of overall energy and other macronutrient intakes, a personalised and periodised approach to nutrition is required depending on an individual's sport, training volume, phase and goals.