These supplements may affect muscle mass or performance in athletic activities. Supplements that affect muscle mass may do so by affecting the rate of muscle protein synthesis and breakdown directly or indirectly — by influencing the amount of resistance exercise people are able to do. Supplements that affect exercise performance may do so by influencing energy production and usage or the fatiguing effects of exercise on muscular and neurological function.
Supplements in this category may be stimulatory, such as caffeine; increase ATP availability, such as creatine; reduce the oxygen requirements of metabolism and increase vasodilation, such as nitrate; increase muscle protein synthesis, such as protein powders; or reduce muscle soreness from exercise, such as certain antioxidants and anti-inflammatory compounds.
