Whether you’re reading this article sitting down, hovering over your kitchen island, or gliding on the elliptical trainer, your knees are hard at work. As with most parts of your body, you’re unlikely to give them much thought until they start giving you trouble. But experts say considering the well-being of your knees is something you should do every day if you want to stay fit, active, and out of the orthopedist’s office for many years to come.
“Your knees are incredibly important, but also very vulnerable joints,” says Scott Martin, MD, associate professor of orthopedic surgery at Harvard Medical School. “They allow you to walk, run, sit, stand, twist, turn, and do so much more. They’re greatly connected to the rest of your body, so you can’t think of your knees in isolation without considering what your feet, ankles and hips are doing, too.”
One of the reasons your knees suffer injury more so than any other joint in your body is their anatomy. Unlike your hips and shoulders, where the end of one bone fits neatly into a crevice within the other, your knees are hinge joints. “The femur and shin bones come together to form the joint, but don’t actually fit together,” says Christine Pollard, PhD, PT, an associate professor of exercise and sport science at Oregon State University. Instead, they’re connected by ligaments — soft tissues that give the joint lots of mobility, but also increase the likelihood of injury because the joint is inherently unstable, explains Pollard. Capping off the joint is the patella, or kneecap, which floats in the front of the joint and slides within a groove at the front of the femur.
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Living a fit lifestyle has a big impact on the health of your knees. That’s because maintaining a healthy weight reduces your risk of knee pain compared to carrying around excess pounds. A study in the journal BMC Public Health found that obese individuals are three times more likely to suffer knee pain compared to those in a normal weight range. The reason is simple: the heavier you are, the greater the load your knees have to carry. “Each step you take on a flat surface puts about one and a half times your body weight on each knee, and walking up and down stairs puts two to three times your body weight across the knee joint,” says Martin. This means that if you weigh 130 pounds, your knees are loaded with up to 400 pounds of pressure – that’s already asking a lot. But if you weigh 200 pounds, for example, that amount shoots up to 600 pounds, and the stress that is placed on your knees during daily activities can lead to wear and tear much sooner.
But there’s also a downside that comes with being active: exercises like squats and lunges place stress on your knees that is the equivalent of three to five times your body weight, says Martin. “And if you’re adding weights, kettlebells or an incline on the treadmill, the pressure and potential for injury become even greater.”
Fortunately, with the right techniques and training, there’s plenty you can do to reduce your risk of exercise-related injury, so your knees can continue to shine as the unsung heroes of your health.
What’s Your (Q) Angle?
There’s a fact of life that cannot be ignored when it comes to your knees: simply being a woman boosts your risk of injury. According to a 2012 study appearing in The Journal of Bone & Joint Surgery, women are two to five times more likely than men to rupture their ACL, a central stabilizing ligament within the knee. And female athletes are more than twice as likely as their male counterparts to experience patellofemoral pain syndrome (a.k.a. runner’s knee), which causes pain and inflammation in the front of the knee and around the kneecap.
“Ten years ago, we thought the difference in knee injuries between men and women had to do with weakness at the knee, but in the last five years, we’ve found a lot of this is driven by what’s happening at the hip,” explains Pollard. In general, women have a larger Q-angle — the angle that forms between the femur and the tibia, or shinbone — than men because we tend to have wider hips. And the wider your Q-angle, the more your quads tug at the kneecap. This can potentially pull it out of its groove, setting you up for patellofemoral pain syndrome and increased stress along your ACL, says Martin. This also means you’re more likely to be doing certain exercises with a knock-kneed stance, which yanks on the knee joint.
Put Your Best Foot Forward
This doesn’t mean that you need to cut exercises like squats, box jumps and lunges from your routine. But it does mean that your form should always be priority number one. To perform a check-up on your exercise form, do a few reps of single-legged squats while facing a mirror. If your standing knee caves inward, that’s bad news — you’re compromising its integrity with every single rep. If this is the case, Pollard advises to go back to basics and perform your squats and lunges slowly. Pay extra care that your knee tracks directly over your ankle every time you bend your knee while doing these exercises. Decrease your speed and range of motion, and remove any additional resistance until you’re able to perform the move with proper alignment.
Also, remember to pay close attention while performing jumping exercises: be sure to bend at your knees and hips when you land. “Kick your hips back on the landing, and make sure your torso is more upright rather than leaning forward,” instructs Pollard. Not only will you keep yourself safe from injury, performing these exercises with proper form will keep your entire kinetic chain, which supports your knees, strong.
Another reality about being an active woman is that your menstrual cycle may play a role in your risk of knee injuries. Surprising new research suggests that higher estrogen levels during ovulation make your ligaments more flexible, which may put extra stress on your joints and increase your risk of tearing your ACL. What’s more, a 2012 study found that the week before your period, when levels of the hormone progesterone rise, there is less activation in the vastus medialis oblique, a muscle of your quadriceps that controls the movement of your kneecap. “During this phase, you may be less capable of keeping the kneecap from sliding against the femur, which can set you up for injuries,” says study author Matthew Tenan, a PhD student of kinesiology at the University of Texas. “There’s not enough evidence to recommend changing your routine around your menstrual cycle,” he says, but it may be an added incentive to pay extra attention to your form during this time. “It’s also even more reason to focus on exercises that strengthen the muscles around your knee joint, such as lateral step-ups, lateral squats and hip abduction on the cable, in order to keep those muscles strong,” says Tenan. Balance training — such as squats on a BOSU — will also strengthen your hips and core. These stabilizing muscles help your knees track properly in other activities, too, such as biking and running, adds Tenan.
Finally, the footwear you sport outside of the gym may be just as important to your knee health as what you wear during exercise. A 2012 study in the journal Gait & Posture found that women who wore nearly four-inch high heels experienced 39% more stress on the front of their knee than those trekking in 2.5-inch heels. Downsize your heel height as much as you can to protect your knees.
As for your workout kicks? “Everyone has different footwear needs, so it’s important to have someone knowledgeable outfit you with appropriate shoes for exercise,” says Pollard. “Sometimes, knee pain can originate from an injury in your foot or ankle that causes you to change your mechanics during exercise, putting additional stress on your knee.” Pollard also suggests replacing your running shoes about every 500 miles or every six months. As the midsole breaks down, it absorbs less shock, which transfers that pressure to your ankles and knees, putting the health of your joints on the line when wearing your favorite kicks past their prime.
Use Your Head, Protect Your Knees
ldquo;The reality is that many knee problems can be prevented with common sense,” says Martin. “For example, if you have pain in your knee or any joint, stop what you’re doing.” Make an appointment with your doctor to get it checked out so you can treat the condition, or work with a physical therapist to get back to your active life, pain-free.
You also need to play it smart while progressing through your fitness routines. Before increasing the intensity of your workout, take five to 10 minutes to stretch the muscles around your knee joint, including your calves, hamstrings and quads. A study appearing in the journal Dynamic Medicine found that tightness in those muscles may increase the stress on your knees and contribute to injuries. Ease into new exercises, allowing your knees a chance to adapt and get comfortable. For instance, practice exercises using only your body weight, and gradually increase resistance.
Martin also encourages developing a regular cross-training program that combines high- and low-impact activities, often within a single workout. “Your knees can handle high-impact sports like running — as long as you mix it up with lower-impact activities like cycling, using the elliptical trainer and swimming,” he says. “But even 45 to 60 minutes of high-impact activity is too much stress on your knees, and eventually they will let you know.”
Give your knobs the proper care, however, and you will be unstoppable in the gym – and in all aspects of your life. Remember: your fitness hinges on them.