Perhaps one of the most obvious signs of aging is the stooped posture and trembling limbs of the elderly. These signs of aging can often be categorized as senile sarcopenia. It's the result of a loss of muscle mass, which results from the death of motor neurons that control muscle fibers. When a mass of muscle fibers lose the neuron that controls them, they are left inactive, wither and die. In some cases, other neurons will bind themselves to abandoned muscle fibers. The result is an overloaded neuron that controls muscles with lessened precision. Sarcopenia accounts for sagging skin and wrinkles; as we lose muscle fibers beneath our facial skin, the tissue droops.
Luckily, studies have shown that sarcopenia can not only be decreased, its effects can even be reversed through resistance weight training. A 2004 Rutgers University study found that 45 minutes of resistance training three times a week for 12 weeks increased muscle fiber by an average of 32 percent and strength by an average of 30 percent [source: Bliss].