Reduce the risk of knee osteoarthritis by strengthening the quadriceps muscles

You get up out of your car, walk into work and climb your office stairs. After work, you stand in a long line at the grocery store, patiently waiting to check out. Then on the weekend, you climb aboard your bicycle and ride several miles.

All of these activities have one thing in common: They force you to engage your quadriceps muscles, one of the key muscle groups necessary for knee function.

In fact, your quadriceps, or quads, play a vital role in nearly all of your leg movements, so it's important to keep them strong and flexible. Having weak quads not only can diminish your knee's function, but'research'shows it also may put you at risk for knee cartilage loss, the hallmark trait of knee'osteoarthritis.

The quadriceps are the primary muscles that help support the knees. If you have weakness in your quads, that can lead to a degree of instability in your knees.

Improving the strength and flexibility of your quadriceps can go a long way toward boosting your knee function, but it's important to do the right exercises in the right amounts, Bungo cautions. And be sure to focus on other muscle groups that support your knee and help you carry out your activities of daily living.

Why quad strength matters to your knees

The quadriceps are made up of four muscles on the front of your thigh. Their main function is to extend, or straighten, your knee, and they're involved in several important tasks of daily living, such as transitioning from sitting to standing and supporting your knees while you're standing or walking.

In a recent'study, researchers performed isometric strength testing on 163 people, ages 40 to 79, and categorized them as having normal or weak quadriceps. About 12% of the participants had quadriceps weakness when the study began, and they were more likely to report higher levels of knee pain.

Over a mean follow-up period of 3.3 years, 15.5% of the participants experienced loss of knee cartilage, as viewed on magnetic resonance imaging (MRI). This loss of cartilage occurred in 44% of those with quadriceps weakness, compared with 11.7% of those with normal quad strength ' a threefold increased risk of cartilage loss in those with quad weakness ' the study authors reported.

With the quads being the main muscles that support the knee joint, if you don't have good muscle strength there, that can lead to further problems.

Focus on your whole knee

The quadriceps may be the body's natural knee brace,as the study authors referred to them, but they're not the only muscles that are critical for good knee function. Equally important are the hamstrings on the back of your thigh and the gluteal muscles of the buttocks. Like the quadriceps, these muscles not only help you sit and rise from a seated position, but they also enable you to complete other everyday activities. These include climbing stairs, lifting heavy objects and getting into and out of your vehicle.

Unfortunately, many people tend to focus on increasing quad strength and flexibility, at the expense of their hamstrings and gluteal muscles. We see that a lot, and that creates a muscle imbalance, which can predispose you to injury. It's important to have that balance.

Several complications can arise from having weakness or poor flexibility in your quads, hamstrings and gluteal muscles. For instance, you might alter your gait to compensate for these deficiencies, and in doing so, you can put stress on other parts of your body, such as your hips and lower back. Plus, poor leg strength can impair your balance and increase your risk of debilitating falls.

Balance is a combination of lower-body strength and your sense of balance. Knee weakness, and lower-extremity weakness in general, absolutely can increase your fall risk.

How to help your knees

Bungo recommends a four-pronged strategy to promote good knee function and help reduce wear and tear on your knees:

• Choose low-impact aerobic exercises'' biking, cycling,'elliptical training, swimming or walking ' instead of high-impact activities, such as jogging, running or singles tennis.'If you are passionate about running for exercise, consider alternating between running and performing low-impact activities throughout the week.
• Do lower-body strengthening exercises'on at least two nonconsecutive days of the week, targeting the quadriceps, hamstrings, gluteal muscles and calves. Avoid leg-extension exercises at the gym ' leg presses and seated hamstring curls are better options, Bungo advises.
• Perform flexibility activities daily. (See below).
• Minimize high-risk activities, such as repetitive squatting, repetitive heavy lifting, or working for extended periods in a kneeling position (especially without some sort of padding).

We've definitely seen lots of success stories and improvements in function. Folks are able to get back to tolerating a round of golf or being able to play tennis. Building strength to create a more stable joint can reduce pain and improve function. You're probably not going to see yourself get better if you're not doing stretching or strengthening or modification of your activities.

Stretching + strengthening exercises for your knees

Here, Bungo recommends five easy exercises to improve the strength and flexibility of your quadriceps and other muscles that support your knees:

1. Straight Leg Raise:'Lying flat on your back, tighten your quadriceps muscles and lift your leg about a foot off the floor, keeping your knee locked. Hold for a second, and then lower the leg. Aim for two sets of 15 repetitions two to three days a week.
2. Quad Set:'Sit with your legs outstretched and your arms slightly behind you. Push your knees down to the floor, tightening your quadriceps muscles, and hold for five seconds. Do two sets of 15 repetitions two to three days a week.
3. Lying Quad Stretch:'Lying on your back near the edge of a bed, bend your right leg, keeping your right foot flat on the bed. Hang your left leg over the edge, keeping the leg relaxed and your thigh resting against the bed. Hold for 10 to 15 seconds, and then repeat with the opposite leg. You can do this exercise daily. As a more advanced option, bend your knee back while keeping your thigh against the bed.
4. Side-Lying Leg Raise:'Lie on your side, with your hips, knees, and feet stacked in a straight line. Rest your top arm in front of you, and use your hand to maintain your balance. Keeping the top leg straight, lift it up to hip height and hold it there for a count of two to three seconds; then, slowly lower your leg. Aim for two sets of 15 repetitions at least two days a week.
5. Bridging:'While lying on your back, tighten your lower abdominal muscles, squeeze your buttocks, and raise your buttocks off the floor or bed. Hold for five seconds. Aim for two sets of 15 repetitions at least two days a week.