Muscle atrophy, also known as muscle wasting, is the phenomenon in which muscle mass, or the total amount of muscle tissue in the body, decreases. This leads to physical weakness and other problems. Muscular atrophy can happen as a result of diseases and conditions such as peripheral neuropathy, multiple sclerosis, AIDS, herniated spinal disk, kwashiorkor, axillary nerve dysfunction, Lou Gehrig’s disease, stroke, polio, anorexia, osteomalacia, mad cow disease, and type 2 diabetes. However, arguably the most common causes of muscle wasting are simply physical inactivity and aging. Physical inactivity may occur as a result of injury, illness, or living a sedentary lifestyle.
In 1997, a national government survey revealed that 40% of American adults never participate in exercise sports or other physical activities. Sedentary lifestyles are one of the biggest causes of muscle atrophy: Use it or lose it! A Danish study found that being inactive for just 2 weeks is enough for someone to lose up to 30% of their muscle strength. On average, it will take three times the length of time being inactive to regain that muscle mass. So, if you are sedentary for two weeks, it will take three weeks to go back to normal. Those who live sedentary lifestyles most likely will have some degree of muscle atrophy. This atrophy will only worsen with age unless the proper precautions are taken.
However, even those who are physically active experience a decline in muscle mass as they age. Animal studies have shown that old animals have up to 40% less muscle mass than young animals. Their actual strength levels decrease by even more. These changes are not due to the older animals being more sedentary but are actually simply caused by aging.