During what age period do many individuals begin to experience a decline in muscle mass without proper exercise?

While it is recognized that muscle mass can begin to decline as early as the 30s for some individuals, the most significant and noticeable loss typically occurs after the age of 60. This decline is part of a process known as sarcopenia, which is characterized by the loss of skeletal muscle mass, function, and strength.

Around the age of 60, the rate of muscle loss increases, especially if individuals do not engage in regular resistance training or other forms of exercise. Aging leads to hormonal changes, decreased physical activity, and changes in neuromuscular function, all of which contribute to this decline in muscle mass.

Thus, the correct answer reflects the age when a more pronounced decline is commonly seen, emphasizing the importance of exercise in mitigating these effects and maintaining muscle health into older age.