Did you know your knees are the strongest joints in your body? They have to be. They’re designed to support your body weight and keep you erect and stable when you’re standing and walking. With healthy knees, you’re able to run and jump without pain. Knee pain can greatly reduce the quality of life. When your knees are stiff and sore going up and down stairs, rising from a chair or even walking can be painful.
Your knees are made up of ligaments, tendons, and cartilage that help maintain the integrity and stability of the knee joint. Unfortunately, these structures can be damaged or torn as a result of injury or become inflamed due to overuse. One of the most common causes of knee stiffness and discomfort, not due to injury, is knee osteoarthritis.
What is Osteoarthritis and How Common Is It?
Knee osteoarthritis is degeneration of the cartilage that lines the bones in your knees, the femur, tibia, and fibula, and helps absorb shock when you walk, squat or bend your knees. With osteoarthritis, the cartilage wears away, leaving the bones exposed. As the cartilage layer erodes and becomes thinner the tip of the femur and tibia rub up against one another when you bend your knees or walk. As a result, you can experience knee pain, swelling, and stiffness. The friction of bone touching bone can also produce bone spurs.
Osteoarthritis is common and the knees are the most frequently involved joints. In fact, most people will develop some degree of osteoarthritis as they age, although not everyone has symptoms that greatly reduce their quality of life. Knee osteoarthritis is more common after the age of 45, but if you have certain risk factors, you can develop this problem earlier.
Are You at High Risk for Osteoarthritis?
According to new research from the Arthritis Research Primary Care Center at Keele University in England, one out of four cases of knee arthritis is related to being overweight or obese. Being overweight almost doubles your risk for experiencing osteoarthritis of the knees whereas being obese more than doubles it. Some studies show people at the highest quintile of body weight have ten times the risk of knee arthritis compared to those in the lowest quintile. No wonder! Every extra pound you carry on your frame places an additional force of 3 to 4 pounds on your knees. That takes its toll on your poor knee joints over time. Staying lean is the most important thing you can do to lower your risk.
Other Risk Factors for Knee Osteoarthritis
Being overweight isn’t the only risk factor for knee osteoarthritis. Simply being female raises your risk. Men have a 45% lower likelihood of developing arthritis of the knees relative to women. The risk goes up in women around the time of menopause. The link between menopause and knee osteoarthritis has led researchers to question whether estrogen could be protective. Cartilage has estrogen receptors on its surface, suggesting it responds to this hormone, and one study linked osteoarthritis of the knee with low estrogen levels. Another reason is women have less knee cartilage than men to begin with and they lose it faster.
If you’ve had a knee injury in the past, your risk for developing osteoarthritis in that knee is higher. Also, if you have osteoarthritis in other joints like your hips or hands, you’re more likely to develop it in your knees. Genetics play a role too. If you have family members with arthritis, your risk may be higher for experiencing osteoarthritis in general.
Is Exercise Protective?
People with a predisposition to knee arthritis sometimes avoid exercising for fear of “damaging” their knees. Doctors sometimes perpetuate this idea by encouraging patients with knee osteoarthritis not to do any weight-bearing exercise with the exception of water aerobics. According to some studies, physical activity may LOWER the risk for knee osteoarthritis. A study published in the journal Rheumatology showed men and women who exercised moderately were less likely to develop severe arthritis of the knees.
A number of studies support the benefits of aerobic exercise and resistance training for people with knee osteoarthritis. Resistance training builds strength in the muscles that support the knee joint and give it greater stability. Plus, resistance training and aerobic exercise loosens up stiff joints and improves overall physical functioning. Not to mention, exercise helps with weight control, which is vital when you consider the additional force excess body weight places on the knees. Some research even shows strength training slows the progression of osteoarthritis.
Tips for Keeping Your Knees Healthy
Strengthen the muscles in your thighs and calves to give your knees more support and resistance to injury. Use good form and modify exercises that cause knee discomfort.
Wear the proper shoes when you do lower body exercises like squats. Don’t wear running shoes or shoes that have an elevated heel. The safest shoes for squats and deadlifts are flat and offer good foot support.
Always warm up with five minutes of light cardio to warm up your muscles and lower your risk for injury.
Lose weight if you’re overweight to reduce the force on your knees.
Do gentle stretching exercises after a workout to keep your knee joints flexible.
If you have knee osteoarthritis, give yourself adequate recovery time between workouts. Don’t train every day. Give your knees a day of rest in between. Limit the amount of high-impact exercise you do, especially exercise that involves running or jumping.
The Bottom Line?
The worst thing you can do for your knees is to add more force on your knees by gaining weight. Exercise can help you avoid knee problems strengthening the muscles that surround the joint and by helping with weight control. Osteoarthritis doesn’t have to limit your activities as you get older. Take care of your knees by staying active and maintaining a healthy body weight.
OrthoInfo. “Arthritis of the Knee”
Med Page Today. “Weight Still Top Risk Factor for Knee Arthritis, Pain” 12/29/14.
WebMD. “Osteoarthritis of the Knee”
John Hopkins Arthritis Center. “Role of Body Weight in Osteoarthritis”
Arthritis Foundation. “Role of Body Weight in Osteoarthritis”
Rheumatology (2001) 40 (4): 432-437. doi: 10.1093/rheumatology/40.4.432.
“Training Clients with Arthritis” Johndavid Maes, M.S., and Len Kravitz, Ph.D.
Ther Adv Musculoskelet Dis. Oct 2010; 2(5): 279-290.doi: 10.1177/1759720X10378374.
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