Four muscles on the front of the thigh make up the quadriceps. The vastus medialis, lateralis and intermedius attach to the thighbones and shin bones, and the rectus femoris starts at the pelvis and lies across the hip joint. The muscles play a major role in walking and ambulatory movements.
The primary function of the quadriceps is to move the knee. They become active when you bend and straighten your knee. While the rectus femoris muscle also participates in knee movement, it also is the primary muscle involved in rotating the hips. The quadriceps, also referred to as the quads, are involved in almost every movement of your legs. Your quads work in concert with other leg muscles, such as the hamstrings, to promote effective movement, running, exercise and balance.
When the quads are damaged or overused, they can create difficulty getting around. Quads, like all other major muscle groups, require care and maintenance. Stretching is one of the most effective ways to keep the quadriceps flexible, increase their range of motion and maintain appropriate blood and oxygen circulation in them. Warm up your quads with dynamic stretching -- for example, gentle aerobic exercise such as walking on a treadmill or marching in place -- before you begin working out. For a static stretch after your workout, stand next to a stable object and hold one foot up behind your rear end. Gently pull your foot toward your body and feel the stretch in your quad. Hold for 20 seconds, release and repeat on the other leg.
Any one of the four muscles can be damaged, resulting in a small tear or total rupture. The muscles are particularly vulnerable to strain and tears when you perform strenuous activities without warming up the muscles. The rectus femoris is the most commonly injured muscle and often is injured while kicking, sprinting or jumping. You'll know when you've damaged one of the quadriceps muscles when you feel a twinge or spasm in your thigh or when walking becomes uncomfortable. A more serious tear results in swelling and severe and sudden pain.
Depending on the severity of the damage, you may be out of commission to participate in sports and strenuous exercise for up to 12 weeks, according to the Sports Injury Clinic. Without effective quadriceps, you cannot compete in competitive events and may even require surgery. Sports massage can help relieve the discomfort of strained quads and either electrical stimulation or ultrasound can speed healing. For mild tears, you may be able to use your quads quickly following a period of rest, ice, compression and elevation, which all together are called RICE. Compression bandages may allow you to maintain mobility while the injury heals.