Although they might not notice it as it happens, most people lose 20 to 40 percent of their muscle tissue as they get older. Strength exercise can at least partly restore muscle and strength.
Muscle cells contain long strands of protein lying next to each other.
When you want your muscles to move, your brain signals your nerves to stimulate them. A chemical reaction in your muscles follows, causing the long strands of protein to slide toward and over each other, shortening the length of your muscle cells. When you do challenging muscle-building exercises on a regular basis, the bundles of protein strands inside your muscle cells grow bigger. Practice Sitting Straight Sit or stand with your shoulders back, but not pinched, and hold this position while you take slow, deep breaths. You can do this anytime.