Muscles

Why do many of my muscles work in pairs?

                A muscle can only pull in one direction. It needs another muscle to pull in the opposite direction in order to return a bone to its original position.

                When you lift your forearm, the biceps muscle shortens to lift the bone. When you straighten your arm, the triceps muscle pulls it back again and the biceps relaxes. The same action takes place in your legs when you walk and run, and when you move your fingers and toes.

What causes muscle cramp?

                      Cramp is caused by the build-up of a waste substance called lactic acid. When a muscle works harder than usual, it starts to break down stored food without using oxygen. This process is called anaerobic respiration. It produces lactic acid as a waste product. As the lactic acid builds up it interferes with muscle action, making the muscle feel tired, until the acid is flushed away by the blood. If too much lactic acid builds up, it makes the muscle contract very sharply and painfully, causing a cramp.

How does regular exercise help the muscles?

                 Muscles are able to adapt gradually to the amount of work they have to do, so regular exercise can build them up and make them healthier. Exercise strengthens the muscles and improves muscle tone. It can also improve your body shape and posture, as well as strengthening your heart and improving your blood flow. It will generally make you feel much better and help you to sleep soundly.