Abstract
AbstractMuscle 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.
Highlights
In humans, skeletal muscle mass is the major protein molecule deposit which represents about 60% of total body protein
The major concern of this review is related to an appropriate daily requirement of protein intake versus protein degradation induced by regular exercise
Among the amino acids the branched-chain amino acids (BCAA) are of particular interest as 60% of the total distribution of specific enzymes necessary for their oxidation (α-keto acid dehydrogenases) in man are located in skeletal muscle
Summary
Skeletal muscle mass is the major protein molecule deposit which represents about 60% of total body protein. General view of protein metabolism in humans In human beings, the body protein mass provides architectural support, enzymes to catalyze metabolic reactions, signalling intermediates within and between cell tissues, and fuel to assume survival under extreme situations. (b)of near-equilibrium if the maximum activities of both enzymes (E1, E2) are almost identical The importance of those equilibrium and nonequilibrium reactions is leading us the flux-generating steps in a pathway, such as glycolysis to activate the production of energy during intense exercise. The reactions catalyzed at the aminotransferases (using pyridoxal phosphatevitamin B6 as prosthetic group) and by glutamate dehydrogenase (using NAD+ or NADP+ as oxidizing agent) are close to equilibrium so that 2-oxoacids being provided, the overall process can be readily reversed and amino acids can be synthesized as well as degraded.
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