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.
Tom R. Eaton, Aaron Potter, François Billaut, Derek Panchuk, David B. Pyne, Christopher J. Gore, Ting-Ting Chen, Leon McQuade, and Nigel K. Stepto
Mark Hargreaves and Rodney Snow
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.
Ricardo J.S. Costa, Kayla Henningsen, Stephanie K. Gaskell, Rebekah Alcock, Alice Mika, Christopher Rauch, Samuel N. Cheuvront, Phil Blazy, and Robert Kenefick
with whey protein hydrolysate promoting a greater gastric load ( Snipe et al., 2017 ). Whether these beneficial effects were due to the whole protein energy content or the presenting amino acid mixture affecting villi microvascular perfusion, cell stability, and/or function is unclear. The acute intake
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
Daniel L. Plotkin, Kenneth Delcastillo, Derrick W. Van Every, Kevin D. Tipton, Alan A. Aragon, and Brad J. Schoenfeld
Of the 20 amino acids recognized to compose the building blocks of human protein, only three possess a branched side chain: leucine, isoleucine, and valine. Numerous supplements are sold consisting of these three amino acids, collectively known as the branched-chain amino acids (BCAA), with claims
Sarah R. Jackman, Gareth A. Wallis, Jinglei Yu, Andrew Philp, Keith Baar, Kevin D. Tipton, and Oliver C. Witard
Nutritional modulation of the muscle anabolic response to exercise is underpinned by changes in muscle protein turnover at the metabolic level ( Tipton & Wolfe, 2001 ). Ingesting an amino acid source following resistance exercise stimulates muscle protein synthesis (MPS), leading to a positive net
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/