D-Aspartic acid is an amino acid that regulates testosterone synthesis. While it occurs naturally in the testes, the amount in the body can differ due to diet and age. D-Aspartic acid effectively enhances testosterone levels, aiding muscle mass. Furthermore, it can increase athletic performance. Testosterone has an impact on speeding up recovery time of muscle soreness, as well as increasing libido. Aspartic acid is important in building protein in the body, therefore, consuming a healthy dose of D-Aspartic acid will be extremely beneficial for muscle gain and energy.