Although skeletal muscle is capable of oxidizing selected amino acids, exercise in the fed and carbohydrate-replete condition results in only a small increase in amino acid utilization. Nevertheless, it may be important to increase the dietary protein requirements of active individuals. There is ongoing debate as to whether the amino acids for oxidation are derived from the free amino acid pool, from net protein breakdown, or a combination of both. There has been interest in the potential ergogenic benefits of amino acid ingestion; however, BCAA ingestion does not appear to affect fatigue during prolonged exercise, there is little support from controlled studies to recommend glutamine ingestion for enhanced immune function, and although glutamine stimulates muscle glycogen synthesis, its addition to carbohydrate supplements provides no additional benefit over ingestion of carbohydrate alone.
Mark Hargreaves and Rodney Snow
Tom R. Eaton, Aaron Potter, François Billaut, Derek Panchuk, David B. Pyne, Christopher J. Gore, Ting-Ting Chen, Leon McQuade and Nigel K. Stepto
Heat and hypoxia exacerbate central nervous system (CNS) fatigue. We therefore investigated whether essential amino acid (EAA) and caffeine ingestion attenuates CNS fatigue in a simulated team sport–specific running protocol in a hot, hypoxic environment. Subelite male team sport athletes (n = 8) performed a repeat sprint running protocol on a nonmotorized treadmill in an extreme environment on 4 separate occasions. Participants ingested one of four supplements: a double placebo, 3 mg.kg-1 body mass of caffeine + placebo, 2 × 7 g EAA (Musashi Create)+placebo, or caffeine + EAA before each exercise session using a randomized, double-blind crossover design. Electromyography (EMG) activity and quadriceps evoked responses to magnetic stimulation were assessed from the dominant leg at preexercise, halftime, and postexercise. Central activation ratio (CAR) was used to quantify completeness of quadriceps activation. Oxygenation of the prefrontal cortex was measured via near-infrared spectroscopy. Mean sprint work was higher (M = 174 J, 95% CI [23, 324], p < .05, d = 0.30; effect size, likely beneficial) in the caffeine + EAA condition versus EAAs alone. The decline in EMG activity was less (M = 13%, 95% CI [0, 26]; p < .01, d = 0.58, likely beneficial) in caffeine + EAA versus EAA alone. Similarly, the pre- to postexercise decrement in CAR was significantly less (M = −2.7%, 95% CI [0.4, 5.4]; p < .05, d = 0.50, likely beneficial) when caffeine + EAA were ingested compared with placebo. Cerebral oxygenation was lower (M = −5.6%, 95% CI [1.0, 10.1]; p < .01, d = 0.60, very likely beneficial) in the caffeine + EAA condition compared with LNAA alone. Coingestion of caffeine and EAA appears to maintain muscle activation and central drive, with a small improvement in running performance.
Christopher Tack, Faye Shorthouse and Lindsy Kass
al., 2001 ). Other supplements, such as olive oil, can reduce oxidative damage during healing ( Rosa et al., 2014 ), whereas the amino acid arginine can improve wound angiogenesis ( Raynaud-Simon et al., 2012 ). The choice of supplement is therefore critical. Additionally, there is evidence of negative
Adam D. Osmond, Dean J. Directo, Marcus L. Elam, Gabriela Juache, Vince C. Kreipke, Desiree E. Saralegui, Robert Wildman, Michael Wong and Edward Jo
, and active rest, have been widely implemented by athletes and exercising individuals. Several prior investigations support the use of supplementary branched-chain amino acids (BCAA) as a nutritional countermeasure to EIMD or related symptoms. When compared with nutritive (eg, carbohydrate) and
Kazunori Nosaka, P.▀ Sacco and K.▀ Mawatari
This study investigated the effect of a supplement containing 9 essential and 3 non-essential amino acids on muscle soreness and damage by comparing two endurance exercise bouts of the elbow fexors with amino acid or placebo supplementation in a double blind crossover design. The supplement was ingested 30 min before (10 h post-fasting) and immediately after exercise (Experiment 1), or 30 min before (2-3 h after breakfast), immediately post, and 8 more occasions over 4-day post-exercise (Experiment 2). Changes in muscle soreness and indicators of muscle damage for 4 days following exercise were compared between supplement conditions using two-way ANOVA. No significant differences between conditions were evident for Experiment 1; however, plasma creatine kinase, aldolase, myoglobin, and muscle soreness were significantly lower for the amino acid versus placebo condition in Experiment 2. These results suggest that amino acid supplementation attenuates DOMS and muscle damage when ingested in recovery days.
Gabriella A.M. Ten Have, Marielle P.K.J. Engelen, Yvette C. Luiking and Nicolaas E.P. Deutz
The small intestine acts as interface and regulator between the gut lumen and the rest of the body and controls the degree and rate of transport of amino acids coming from dietary protein via the portal vein to the liver and the systemic circulation. To measure protein absorption, kinetics multicatheter animal (pig) models in combination with amino acid tracer technology are available. Dietary factors infuence the absorption rates from the lumen to the gut, metabolism of dietary component in the gut, and the release of amino acids to the portal circulation from digested protein. In a balanced-protein meal, the gut dietary amino acid utilization (30–50%) for gut protein synthesis will result in a labile protein pool in the gut that can be benefcial during the postabsorptive state. To enhance gut retention, amount and quality of protein and the presence of carbohydrate are major factors. Besides this the use of a slowly digestible protein or the presence of fber in the meal can increase retention further. During the absorption of low-quality protein meals, fewer amino acids are utilized by the gut, resulting in higher amounts of amino acid release to the portal circulation. Malnutrition or starvation, protein depletion, defciencies of specifc nutrients, or illness such as sepsis all inhibit the growth and change protein turnover of the intestinal mucosa and therefore affect absorption kinetics. Therefore, the kind of protein meal that has the most optimal absorption kinetics (the most benefcial) for gut and for the rest of the body depends on these (patho)physiological circumstances. Despite the absence of different absorption kinetics between protein, peptides, and amino acids, they could be benefcial in specifc circumstances.
Peter W.R. Lemon
The debate regarding optimal protein/amino acid needs of strength athletes is an old one. Recent evidence indicates that actual requirements are higher than those of more sedentaty individuals, although this is not widely recognized. Some data even suggest that high protein/amino acid diets can enhance the development of muscle mass and strength when combined with heavy resistance exercise training. Novices may have higher needs than experienced strength athletes, and substantial interindividual variability exists. Perhaps the most important single factor determining absolute protein/amino acid need is the adequacy of energy intake. Present data indicate that strength athletes should consume approximately 12-15% of their daily total energy intake as protein, or about 1.5-2.0 g protein/
Peter W. R. Lemon
The current recommended daily allowance (RDA) for protein is based primarily on data derived from subjects whose lifestyles were essentially sedentary. More recent well-designed studies that have employed either the classic nitrogen balance approach or the more technically difficult metabolic tracer technique indicate that overall protein needs (as well as needs for some specific individual amino acids) are probably increased for those who exercise regularly. Although the roles of the additionally required dietary protein and amino acids are likely to be quite different for those who engage in endurance exercise (protein required as an auxiliary fuel source) as opposed to strength exercise (amino acids required as building blocks for muscle development), it appears that both groups likely will benefit from diets containing more protein than the current RDA of 0.8 g · kg−1 ·
Martin J. Gibala
The contribution of amino acid oxidation to total energy expenditure is negligible during short-term intense exercise and accounts for 3–6% of the total adenosine triphosphate supplied during prolonged exercise in humans. While not quantitatively important in terms of energy supply, the intermediary metabolism of several amino acids—notably glutamate, alanine, and the branched-chain amino acids—afreets other metabolites .including the intermediates within the tricarboxylic acid (TCA) cycle. Glutamate appears to be a key substrate for the rapid increase in muscle TCA cycle intermediates (TCAI) that occurs at the onset of moderate to intense exercise, due to a rightward shift of the reaction catalyzed by alanine aminotransferase (glutamate + pyruvate <-> alanine + 2-oxoglutarate). The pool of muscle TCAI declines during prolonged exercise, and this has been attributed to an increase in leucine oxidation that relies on one of the TCAI. However, this mechanism does not appear to be quantitatively important due of the relatively low maximal activity of branched-chain oxoacid dehydrogenase, the key enzyme involved. It has been suggested that an increase in TCAI is necessary to attain high rates of aerobic energy production and that a decline in TCAI may be a causative factor in local muscle fatigue. These topics remain controversial, but recent evidence suggests that changes in TCAI during exercise are unrelated to oxidative energy provision in skeletal muscle.
Dariush Sheikholeslami-Vatani, Slahadin Ahmadi and Hassan Faraji
et al., 2013 ) and ROS production ( Yu et al., 2009 ). By contrast, branched-chain amino acids (BCAA), including isoleucine, leucine, and valine, have unique properties that play important metabolic and physiological roles in all living organisms. It is also found that BCAA might affect gene