Final answer:
Muscle mass does begin to decline after age 30, which is a change closely associated with a decrease in the body's metabolic rate. The effects of muscle atrophy due to aging, also known as sarcopenia, can be mitigated but not reversed through regular exercise that helps maintain muscle function and strength.
Step-by-step explanation:
The statement that muscle mass begins to decline after age 30 is true. With aging, the human body's metabolic rate decreases, and this is closely tied to a reduction in lean muscle mass or sarcopenia. The rate of muscle mass decline accelerates notably between the ages of 50 and 70, which contributes to a decrease in overall physical strength and can affect the quality of life due to difficulties with movement, balance, and posture. Moreover, sarcopenia leads to fewer powerful muscle contractions, as muscle fibers are replaced by connective and adipose tissues, which cannot produce the force that muscles can.
While muscle atrophy due to disuse can often be reversed with exercise, the type of atrophy associated with aging (sarcopenia) is largely irreversible. Engaging in regular physical activity can, however, delay the onset of muscle loss and mitigate some of its effects by adding structural proteins and causing cellular changes that help preserve muscle function. This is especially crucial considering that an increase in exercise can lead to more cellular mitochondria, greater capillary density, and stronger connective tissue.