Protein metabolism and physical training: any need for amino acid supplementation?

Abstract

Muscle mass is the major deposit of protein molecules with dynamic turnover between net protein synthesis and degradation. In human subjects, invasive and non-invasive techniques have been applied to determine their skeletal muscle catabolism of amino acids at rest, during and after different forms of physical exercise and training. The aim of this review is to analyse the turnover flux and the relative oxidation rate of different types of muscle proteins after one bout of exercise as well as after resistance and endurance condition of training. Protein feeding in athletes appears to be a crucial nutrition necessity to promote the maintenance of muscle mass and its adaptation to the need imposed by the imposed technical requirements. In resting human individuals, the recommended protein daily allowance is about 0.8 g (dry weight) kg −1 body weight per 24 h knowing that humans are unable to accumulate protein stores in muscle tissues. Nevertheless, practical feeding recommendations related to regular exercise practice are proposed to athletes by different bodies in order to foster their skills and performance. This review will examine the results obtained under endurance and resistance type of exercise while consuming single or repeated doses of various ingestions of protein products (full meat, essential amino acids, specific amino acids and derivatives, vegetarian food). From the scientific literature, it appears that healthy athletes (and heavy workers) should have a common diet of 1.25 g kg −1 24 h to compensate the exercise training muscle protein degradation and their resynthesis within the following hours. A nitrogen-balance assay would be recommended to avoid any excessive intake of protein. Eventually, a daily equilibrated food intake would be of primer importance versus inadequate absorption of some specific by-products.

12th IFDC 2017 Special Issue – High protein sports supplements: Protein quality and label compliance

“…The only product showing non-amino acid nitrogen content in excess of 5% was Product O, with the main product ingredient listed on the label as "beef protein". This product possibly contains large quantities of collagen (containing hydroxyproline), which has little value for muscle recovery and gain (Poortmans & Carpentier, 2016). In some products the sum of all amino-acids exceeded crude protein content.…”

“…Various multinational, regional and national companies are operating within the fast growing South African market. The Vitamins and Supplements market in South Africa experienced an annual growth rate of 13.5% between and 2016(B2B Market Research, 2017. However, the South African market has not had as strong growth as compared to other developing markets around the globe due to current developments within the national regulatory environment (B2B Market Research, 2017).…”

Molecular Differences in Skeletal Muscle After 1 Week of Active vs. Passive Recovery From High-Volume Resistance Training

“…Rest between each compound set was standardized to 2 minutes; however—if the subject felt prepared to execute the next compound set—they were allowed to do so. Importantly, the standardization of intensity at 60% of estimated 1RM was made in concert with data collected during a pilot of the study design ( n = 2) and a review published by Poortmans and Carpentier (24), suggesting a robust increase in myofibrillar protein synthesis when training is completed at ∼60% of 1RM.…”

A Novel Dietary Intervention Reduces Circulatory Branched-Chain Amino Acids by 50%: A Pilot Study of Relevance for Obesity and Diabetes

“…Although BCAA-restricted diet studies have been successfully undertaken in animal models to investigate the pathogenic mechanisms of BCAA in regulating glucose homeostasis and weight [ 8 , 19 ], allied dietary intervention studies in human subjects have been lacking [ 9 , 20 ]. In designing our BCAA-restricted diet, we considered the potential impact BCAA restriction would have upon skeletal muscle mass, which represents the largest storage pool of amino acids in the body [ 21 ]. Indeed, EAAs including BCAAs are crucial in maintaining muscle mass [ 22 ].…”