Ergogenic aids consist of substances or procedures that improve physical work capacity, physiological function, or athletic performance. Sports foods come in the form of bars, shakers, drinks, and gels and they tend to be more complex and food-like, and often contain one or more kinds of nutrients. Ephedrine is a sympathomimetic agent which is structurally related to catecholamine. Glutamine is a naturally occurring nonessential amino acid and the most abundant amino acid in human muscle and plasma. Glycerol is a component of the triglyceride molecule and an important constituent of the cell membrane. Hydroxy citric acid is a derivative of citric acid found in a variety of tropical plants, including garcinia cambogia and hibiscus subdariffa. Inosine is a nucleoside, a purine base comparable to adenine, which is one of the structural components of ATP. Synephrine, p-synephrine, is an extract from the bitter or sour orange. Both whey and casein are derived from milk proteins as part of the cheese-making process.