Muscle aging

Skeletal muscle is responsible for voluntary movement control of the human body. Aging process leads to a decrease in muscle mass and strength.

In age 20-30, the muscles are in their maximum of physical capacity. In age 30-50 changes in muscle mass, power and strength are small. After age 50, muscle changes with aging process are pronounced which is more than 15% of strength loss per decade. In some research this could start from 40s.

Aging muscles with

Declined muscle fibers

muscle Type II fast twitch fibers appeared smaller and flatter. This results in reduced muscle power

Reduced muscle mass

Muscle mass loss is caused by reduced numbers of muscle fibers. This reduction in muscle cross-sectional area associated with decreases in contractile structures muscle fibers accompanied by increases in non contractile structures such as fat and connective tissue.

Decreased motor units

There were fewer motor unites and muscles are denervated.

Reduced muscle strength

Loss of muscle fibers and innervation reduces strength capacities, decreases muscle metabolism and increase risk of muscle damage. Synthesis rate of muscle protein decreases with aging process. muscle repair capacities are reduced with increased age.

The major cause of strength and muscle mass loss with aging process is endocrine changes, including increased insulin resistant, decreased growth hormone, reduction in oestrogen and testosterone, vitamin D deficiency, increased parathyroid hormone.