Your muscles work in pairs. Bend an arm. A muscle pulls your lower arm bones toward your upper arm bone. Straighten your arm. Another muscle pulls the lower arm bones away from the upper bone.
Now feel the inside of your upper arm while you bend your arm. Straighten your arm. Can you feel your muscles working to move your arm?
Place the palm of one of your hands on the underside of your desk while feeling the bicep of that arm with your other hand. Slightly push up against the desk. Do you feel your bicep pull/contract? Now push down on the desk with the back of one hand. Do you feel the triceps pulling/contracting?
How Can You Help Your Muscles Develop?
You do not build strong muscles in a week or in a few months. You build muscles by using them throughout your life.
Exercise - You should be active for at least 60 minutes a day. The pictures show ways you can enjoy building your muscles and keeping them healthy by playing and exercising.