The surprising reason your knees hurt—and what to do about it
Your “bad knees” could actually be caused by weakness elsewhere in your body. (Willie Dalton/Stocksy)
Get hip to this: If your knees ache when you run or engage in other types of exercise, weak hip muscles may be to blame. A new study reports that people with stronger hips are less likely to have knee pain — a finding that comes at no surprise to leading experts.
“When the hips are weak, the knees have a tendency to fall inward, which places unnecessary stress on the front part of the knee,” certified corrective exercise specialist Ryan Krane tells Yahoo Health. Strong hip muscles, on the other hand, help control the motion of the legs and knees as you run, reducing pressure on the knee joint.
Related: This Simple Trick Will Improve Your Next Run
In the study, which was published online in the Journal of Orthopaedic & Sports Physical Therapy, approximately 630 beginner runners were tracked for one year. The Danish researchers tested the participants’ hip abduction strength — that is, how powerful the hips are when you’re extending your legs out to the side — and used GPS data to track their mileage.
The results: Subjects with a high level of hip strength, as determined by the study authors, were significantly less likely to report pain around or underneath the kneecap. What’s the connection? “A runner’s musculoskeletal system is faced with a high demand of maintaining stability and alignment across several joints,” says study author Daniel Ramskov Jorgensen, PT, MHSc, a PhD student at Aarhus University in Denmark. If the hip muscles can’t handle this demand, he tells Yahoo Health, the femur (top leg bone) will rotate inward.
The problem: Your kneecap rests in a groove at the bottom of the femur, and moves along the groove any time you bend your leg. But when the femur turns inward, Ramskov Jorgensen says, the kneecap tracks on the groove improperly. This triggers inflammation and pain, Krane says, and over time can contribute to injuries.
The recent Denmark study is one of the largest experiments to date on the connection between hip and knee health, and previous research supports the new findings. An older study in the Journal of Orthopaedic & Sports Physical Therapy, for example, compared 15 young women with patellofemoral pain syndrome (discomfort around the kneecap during activity) to 15 pain-free young women. Those with knee pain had 26 percent less hip abduction strength compared to controls.
Related: 4 Exercises That Improve Your Posture
Knee problems are the most common type of pain or injury among recreational runners, according to a research review of 17 published studies in the British Journal of Sports Medicine. The review also found that people who jogged more than 40 miles per week or ran regularly for an entire year without taking a break from training were more susceptible to lower-body injuries and aches. Women are more than twice as likely as men to have knee pain during activity, according to a study of 1,525 people in the U.S. Naval Academy.
The Exercise To Help Achy Knees
Several small studies have shown that working out your hips can help relieve sore knees. In one experiment from the University of Wisconsin-Milwaukee, 19 women with patellofemoral pain syndrome followed a hip and core strength-training program for eight weeks. When the researchers observed the subjects as they ran, the experts noticed less knee movement at the end of the study. The subjects also reported experiencing significantly less knee pain after the training program.
"Running requires strength, and if you are a novice, preparing the muscles involved in hip abduction for the strength demands of running is of value," Ramskov Jorgensen says. "It may be especially beneficial for getting you past the early stages of accumulating to training," he adds.
To develop hip strength, Krane recommends an exercise called lateral tube walking. To do it, grab an elastic resistance band with handles on each end. (A large loop resistance band works, too.) Step on the middle of the band with feet about a foot apart, and hold the handles at hip-height. Take a controlled step to the side with your right foot, then follow with your left. Perform 10 to 15 shuffle steps to the right, then repeat to the left side. Keep your feet facing forward and your torso upright during the move. Do the exercise two to three times a week for the best results.
(Disclaimer: If your knee pain is severe or came on suddenly, see a doctor or physical therapist.)
