Inactivity has a significant impact on muscle mass, leading to muscle atrophy and strength loss. When muscles are not regularly used, they can begin to shrink and weaken due to the lack of stimulus to maintain their size and strength. This decline can occur quickly; within a few weeks, noticeable reductions in muscle mass may be observed. Additionally, inactivity contributes to poorer metabolic health and can increase the risk of chronic conditions. Thus, maintaining a consistent exercise regime is essential to preserve muscle mass and overall health.