The debate about running and knee health has been raging for decades. It seems one minute, everyone’s saying running will destroy your knees; the next, running is perfectly safe.
So, what do the experts and the research say?
According to registered clinical exercise physiologist Janet Hamilton, MA, certified strength and conditioning specialist, owner of Running Strong in Stockbridge, Georgia, there’s no consistent research to show running is harmful for your knees.
In fact, running may prove to be beneficial for your knees. In one small study, published in the European Journal of Applied Physiology, six recreational runners completed a 30-minute running session and a 30-minute seated session on separate days, while researchers measured levels of inflammation markers in the synovial fluid found in the knee joints. They found a 30-minute running session lowered markers of inflammation, while a 30-minute seated session actually raised inflammation markers.
Meanwhile, a long-term study of more than 70,000 runners suggests running may be linked to a lower risk of osteoarthritis (known as the “wear and tear” kind of arthritis) and hip replacement. Researchers indicate part of this may be thanks to the association between running and a lower body mass index.
And a cross-sectional study of more than 2,600 adults published in Arthritis Care Research found there is no increased risk of osteoarthritis in current and prior runners compared to non-runners.
“My general view is that the typical amount of running people do is safe and potentially protective for preserving joint health or avoiding worsening knee pain,” says study co-author Jeffrey B. Driban, PhD, certified strength and conditioning specialist and, assistant professor in the Division of Rheumatology at Tufts Medical Center.
However, some research is less than favorable: MRI scans of 10 marathon runners revealed biochemical changes in the knee joint that lasted up to three months after their race, according to a study in the American Journal of Sports Medicine. Researchers suggest these changes may place the knee joint at a higher risk for degeneration.
According to Driban, elite marathon runners face a far greater risk of developing osteoarthritis than recreational runners, mainly thanks to the overload that can happen from such high weekly mileage, as well as their tendency to return to training too soon after injury.
Athletes with past injuries in a variety of sports are also at risk of developing osteoarthritis — and at an early age. In fact, according to Driban, roughly half of U.S. adults who are diagnosed with osteoarthritis are under the age of 65. “I’m thinking about the college athlete who tore her ACL and meniscus,” he says. “The data suggests she’s at risk of showing signs of osteoarthritis on X-rays within 10 years.” So, if you have an old meniscus or ACL injury, pay close attention to any aches or pains. And if you currently have osteoarthritis in your knees — or you’re concerned you may develop it — you may want to explore low-impact activities like swimming and cycling.
For the average person, though, running is pretty safe. And when runners do develop knee pain and injury, it’s likely the result of increasing mileage too quickly, running on new terrain, switching shoes or running with muscle weakness and poor biomechanics — not running itself.
“What is bad for your knees is lack of activity leading to muscle weakness or loss of range of motion. The loss of muscle strength or range of motion in the surrounding joints can then contribute to poor biomechanics, which places loads on the joints that are not ideal,” Hamilton explains.
Here are several strategies you can use to keep your knees healthy while running:
Don’t pile on the miles or speed before you’re ready. Instead, gradually increase mileage by no more than 10% per week, and introduce speed training in small increments. Hamilton suggests limiting high-intensity speedwork (5K pace or faster) to no more than 7% of your total weekly mileage. Finally, make sure you alternate training days with recovery days: “It’s during the recovery that your body has the physiological time and space to make cellular changes,” Hamilton says.
Muscular strength is key for keeping your knees healthy and injury-free. Hamilton suggests performing at least two strength-training sessions per week, though you may need to do more if you have any underlying weaknesses. Prioritize multi-joint exercises (i.e., squats, deadlifts, pushups) over single-joint (i.e., knee extensions, leg curls, triceps extensions). “By focusing your efforts on multi-joint exercises, you’ll be more efficient with your time and reap greater rewards overall,” Hamilton says, “since the integrated nature of multi-joint exercises require multiple muscles to coordinate and work synergistically to accomplish the motion.”
If something hurts, don’t shrug it off. Instead, adjust your training: Take a day off completely or cross-train by swapping out your run for lower-impact exercise like swimming or cycling for a few days while the injured tissue heals. “If you ignore the signals from your body, you’ll inevitably be worse off,” Hamilton says.
Try to change your training throughout the week. You could run on different surfaces (e.g., packed dirt, grass, sand, asphalt), do the occasional hill repeats, vary your daily mileage and even try moving in different directions (i.e. backward, sideways, criss-cross). “Strive for variety so you can ensure both overload and recovery,” Hamilton says.
If you’ve had knee issues in the past — or have them now — consider hiring a good coach or physical therapist who can offer specific guidance. “We’re all unique,” Hamilton says, “and you’ll always be better off individualizing your training approach to address your needs.”