Stretcher is a kind of sports equipment, mainly for the purpose of exercising arm muscles. The advantage of using a stretcher is that biceps brachii is a muscle with two muscle heads, and its main function is to bend the arm. When you bend your arm, you will also use another muscle-the brachialis muscle. However, only when doing some forearm lifting exercises, such as bending the high-position puller or anti-high-position puller toys, can the brachial muscles be fully exercised. In addition, the flexor brachialis, the main muscle of the upper forearm, also plays a lot of roles in arm flexion, which can be strengthened by lateral bending of the tensioner.