Maintaining Muscle Strength as You Get Older From the age of 30, our bodies gradually begin to lose muscle. On average, people lose about 3 to 5% of their muscle mass every decade. You may not feel the difference at first, but over time, this decline can lead to noticeable weakness. Eventually, the loss may result in a condition known as sarcopenia. “As people get older, they often experience a decrease in muscle size and power, which can limit their ability to perform everyday activities,”