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

Abstract

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.

Comparative Meta-Analysis of the Effect of Concentrated, Hydrolyzed, and Isolated Whey Protein Supplementation on Body Composition of Physical Activity Practitioners

“…For this review, WP supplementation was defined as the voluntary, periodic, and regular consumption of this product, of adjuvant nature to the routine diet, in order to achieve increases in skeletal muscle mass gain by physical activity practitioners, however, uses such as therapeutic, prophylactic, and alternative were not included [15]. As previously established in the PROSPERO protocol, the cutoff point for the implemented dose parameters and the periodicity of WP use was defined according to criteria adopted by each RCT included in this review.…”

“…Although it is a consensus that, compared to the general population, the daily protein recommendation dose for athletes is higher than that estimated by the Dietary Reference Intakes (DRI) [14], its exact values are frequently reviewed. Each year, new predictions for different sports are proposed, based on primary studies conducted with physically active specific population groups [15,16].…”

“…In addition to the type of mechanical effort performed, another determining factor for the improvement of anthropometric markers is the food choice for this population. Criteria such as origin, quality, digestibility, purity, and protein content of the diet, for example, are directly related to the type of supplemented protein [10,11,15,16,17]. Moreover, it has been established that factors such as the content of serum solids, chemical and protein composition, functional properties, and mechanisms of functionality (solubility, gelling, foam stability, hydration, diffusion, adsorption, among others) are sensibly different between WPC and WPI [18].…”

The interaction between physical activity and nutrition is integral to general health and sports performance

“…The eleven papers published in this Nutrition Bulletin Virtual Issue address a range of topics relating to the interaction between nutrition and physical activity/exercise/sports performance. Eight of these articles focus to a greater or lesser extent on sport as distinct from physical activity (Shirreffs ; Leser , ; James ; Reid ; Currell ; Alderton & Chambers ; Egan ); two of the papers focus specifically on the issue of physical activity, appetite and energy balance for general health (Blundell ; Stensel et al . ); and one paper focuses on the role of both diet and exercise in modulating postprandial glucose and triacylglycerol responses, which has relevance for cardiovascular/metabolic health (Edinburgh et al .…”

“…Another paper focusing on protein is by Dr. Brendan Egan () (University College Dublin). Egan stresses that athletes and active adults in general may need more than the reference intake of 0.8 g protein per kg body mass.…”