Muscle mass refers to the amount of muscular tissue present in an individual's body. It is typically measured by body composition analysis, which can be done through various methods such as bioelectrical impedance analysis or dual-energy X-ray absorptiometry (DEXA). Muscle mass plays a crucial role in overall health and fitness, as it contributes to strength, endurance, and metabolic function. Maintaining an adequate amount of muscle mass is important for preventing age-related declines in physical function and reducing the risk of chronic diseases such as diabetes, heart disease, and osteoporosis.