Effects of Aerobic and Resistance Training on Accumulation of Old, Modified Proteins in Young and Older Adults

Muscle proteins accumulate damage during aging and leads to the loss of muscle mass and function in older people. Exercise can increase the making of new proteins and removal of older proteins, but it is not known if the effect changes with aging or type of exercise. The investigators will determine the ability for endurance, resistance, or a combination of exercise training to remove older-damaged proteins and make newer-functional muscle proteins in groups of younger and older people. The investigators will particularly study protein that are involved with energy production (mitochondrial proteins) and force production (contractile proteins). Hypothesis 1: Older people will have greater accumulation of damaged proteins than younger people. Hypothesis 2: Aerobic exercise will decrease the accumulation of damaged forms of contractile and mitochondrial proteins in younger and older people. Hypothesis 3: Resistance exercise will decrease the accumulation of damaged forms of contractile proteins in younger and older people.