Flexor mass muscles are found in the forearm. This group of muscles that enable you to grip objects, throw a ball and flex and extend your hand at the wrist. If you've injured your flexor mass muscles, you'll notice a number of signs and symptoms.

A torn gastrocnemius muscle is a severe injury to the back of the calf area of the leg. During a muscle strain, the muscle tissue fibers disengage and separate slightly. An excessive strain can tear this tissue so that any strength imparted by cohesion of the muscle fibers is lost.

Your muscles are strong, tough fibers. However, frequent use, strain and pressure can stretch your muscles too far, resulting in an overuse injury. This injury type is most common in your back and in the muscles in the back of your legs, which are subject to pressure while you exercise.

A calf muscle tear, or strain, can occur when muscle tension is excessive due to too much repetition or high force. A partial tear or complete tear can afflict one or both muscles that make up the calf. Pain, swelling, stiffness and bruising in the belly of the muscle are common signs of a torn calf muscle.

The rectus abdominis is a large muscle in the center of your abdomen that extends from your ribs to the front of your pubic bone. Injuries to this muscle result in varying degrees of abdominal strain.

The sartorius muscle can suffer injury when excessive force causes the upper leg to stretch beyond its capacity. Tissue fibers may partially separate or fully tear, weakening the leg and restricting its motion.

Rhomboid muscles in upper back connect the inner edges of the shoulder blades to the spine.

An abdominal muscle tear, or strain, can occur from overstretching or overusing the muscle and is a common injury among tennis players. A violent, poorly performed movement of the trunk can also strain the abdominal muscles, suggests the Better Health Channel.

The idea of placing electrodes on the skin is a scary thought for many people. This form of treatment, called electrical stimulation, is safe and effective but there are some important facts to know before seeking this treatment.