Aging reduces both muscle tissue and muscle tone, according to MedlinePlus. As people age, muscle fibers shrink and muscle is replaced more slowly. These changes begin for men in their 20s and women in their 40s. As people reach middle age and beyond, Gaiam Life explains, the aging-related muscle degeneration process known as sarcopenia continues.
Though sarcopenia occurs naturally as part of aging, physical activity and light resistance or weight training can preserve muscle mass and increase muscle tone, explains Gaiam Life. The age-related degeneration of muscles doesn't occur alone; bones and joints also experience changes, such as osteoporosis, osteoarthritis and rheumatoid arthritis.
Inactivity can become a vicious cycle that weakens the body systematically, influencing strength, flexibility and eventually the gait and balance, allowing falls or injuries to occur. The Better Health Channel explains that inactivity and a sedentary lifestyle contribute more than half of the degenerative changes in muscle, bone, and joints. Many physical activities that preserve and increase muscle tone also improve joint mobility and help maintain bone density. The Better Health Channel recommends weight-bearing exercises, such as walking or weight training, to maintain bone and muscle health and recommends stretching as a way to help maintain joint flexibility.