The Quadriceps & Muscle Atrophy

The quadriceps are a large group of muscles located on the front of the thighs. They are a powerful knee extensor used in climbing, jumping and rising from a seated position. Well-functioning quadriceps plays an important role in strengthening the knee joint. When these muscles begin to atrophy, or decrease in size, problems in the knee joint may arise.

Muscle atrophy is defined as the wasting, or loss, of muscle mass. A decrease in muscle strength accompanies this decrease in muscle size. Muscle atrophy results in decreased muscle tone, which describes your muscle's ability to contract in response to stimulation. Adequate quadriceps muscle tone is extremely important in reinforcing the knee joints.

​Read more​: Quad Exercises for Knee Injuries

Atrophy of the quadriceps muscles can occur for a variety of reasons, one of which is lack of activity or exercise of the muscles. Individuals who work at sedentary jobs, wear a leg cast or brace that prevents movement in the knee joint or are bedridden are at very high risk for atrophy of the quadriceps. Those with medical conditions such as stroke and arthritis and have limited mobility may also experience muscle wasting.

Injury or disease of the femoral nerve, the nerve that innervates the quadriceps, results in a more severe type of atrophy. Lastly, sarcopenia, the loss of muscle mass associated with aging, is another common cause of quadriceps muscle atrophy.

The consequences of muscle atrophy in the quadriceps goes far beyond a decrease in muscle strength. Decreased muscle tone and strength of your quadriceps could increase your risk for developing arthritis or intensify the severity of already existing arthritis in your knee.

Strong quads support your knee while absorbing some of the impact your joint must endure. Weakness of the quadriceps muscles is the most often cited area of concern when dealing with patellofemoral pain syndrome, a common disorder characterized by pain in the front of the knee.

Functional quad muscles keep your knee cap tracking in its proper position and reduce wear of the patellar cartilage; when they're atrophied, the connective tissue in the knee degrades quickly. The worst consequence of quadriceps muscle atrophy would be complete disability of your leg.

Although it is never too late to begin a quadriceps-strengthening program, work to prevent any muscle atrophy before it begins. If you work a sedentary job, make sure to get up and move around several times a day. Take the stairs instead of the elevator, or walk for 30 minutes daily at lunch, to really get a quad workout it.

For those who are incapacitated due to injury, you may have to endure some level of atrophy. In this case, rehabilitation is crucial -- begin with gentle stretching and strengthening exercises and progress as instructed by your doctor or physical therapist.

The best way to prevent muscle atrophy is to build and maintain strong quadriceps. This can be accomplished through regular aerobic and strength-training exercises. Some quad-targeting exercises include running, stair-climbing, squats, step-ups and lunges.

​Read more:​ Quadriceps Exercises at Home