Prolonged inactivity can lead to muscle mass decline, a condition known as muscle atrophy. This occurs when the muscles are not engaged, leading to a reduction in protein synthesis and overall muscle size. Inactive individuals may experience decreased strength, lower energy levels, and increased risk of injury. This decline in muscle mass adversely affects mobility and can result in a greater likelihood of chronic health issues such as metabolic syndrome or osteoporosis. Regular physical activity is essential to maintain muscle integrity and overall health.