Fatigue during high intensity sports or activities (~1-10 minutes in length) is caused by several components with strong evidence that muscle acidosis via accumulating hydrogen ions is a key performance inhibitor. To address this issue, skeletal muscle has intra and extracellular buffering mechanisms to attenuate exercise induced acidosis. Carnosine is an intracellular buffer that is key in slowing the decline of muscle Carnosine has a nitrogen containing imidazole side ring which accepts or buffers hydrogen. This buffering can contribute as much as 15% of total buffering capacity. Additionally, carnosine has been shown to be a calcium/hydrogen exchanger, delivering calcium back to the sarcoplasmic reticulum and hydrogen away to the cell membrane. This suggests that carnosine may increase calcium sensitivity and muscle contraction efficiency. Plasma beta-alanine is the rate limiting substrate of carnosine. Approximately 3-6 g/d of beta-alanine supplementation over at least four weeks can elevate muscle carnosine stores by 30-60%. Several meta-analyses have been conducted and has shown 2-3% increased performance in non-elite athletes, followed with just 0.5-1% increased performance in elite athletes.
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