In addition to electrolytes, sweat also contains certain amino acids. Some of these are present in sweat at higher levels than they are found in plasma, indicating an active secretion mechanism. Because the circulating pool of free amino acids in plasma is quite small, these sweat losses may significantly deplete the pool available for repair of muscle proteins immediately following exercise.
When specific amino acids are in short supply, muscle tissue will be broken down to provide them, prolonging the recovery and repair processes. The specific amino acids found at highest proportion in equine sweat are Serine, Glutamine, Histidine, Aspartic Acid, Leucine and Lysine. These have been formulated into a supplement designed to replace sweat losses and aid in muscle recovery following exercise, Horsepower BoostAA.