Your body is composed of three types of muscle: skeletal muscle, smooth muscle, and cardiac muscle. Skeletal muscle makes up 40 percent of your total body weight, and smooth muscle and cardiac muscle each make up 5 percent of total body weight.Your muscles must contract in order to facilitate vital bodily functions.our body is composed of three types of muscle: skeletal muscle, smooth muscle, and cardiac muscle. Skeletal muscle makes up 40 percent of your total body weight, and smooth muscle and cardiac muscle each make up 5 percent of total body weight.