One researcher believes pounding the pavement may not put your knees at risk like previously thought
Ever been told that all those miles running will mess up your knees when you’re older? Running is no more likely to cause knee problems than walking, reports new research out of Canada.
In the study, researchers had adults walk or run on a moving platform that captured data on the amount of force, or load, each step had with the ground over a set distance. Results showed that the force exerted on the knees while running was as much as 3 times higher than while walking, but this was offset by the time runners spent in the air and the length of their stride.
While the extra load caused by running has long been a concern, especially for bigger guys who are pounding the pavement, it has never been shown to increase the risk of knee osteoarthritis—the irreversible wearing away of the knee cartilage—for runners, says Ross Miller, Ph.D. and study author.
In fact, for healthy, in-shape runners, knee cartiliage will actually strengthen under high forces, explains Bill Hartman, C.S.C.S., P.T., co-owner of Indianpolis Fitness and Sports Training. However, that doesn’t mean there’s no risk if you’re overweight. Extra pounds can cause mobility issues and throw your joints out of alignment, he warns. When you add high impact to an out-of-whack joint over and over again—like you can do when running—you’re setting yourself up for knee pain or an injury, he says. Before you start logging miles, shed the weight first with low-impact methods like swimming.
If weight isn’t an issue for you, the load on your joints from running may be mitigated by other factors, according to Miller’s research. Every step you take walking exerts a load on the knee 2 to 3 times your body weight, he says. The force exerted from running increases that load to anywhere between 5 to 12 times your weight, depending largely on running speed or form.
“While walking, your foot is on the ground about 60 percent of the time, but in running that’s reduced to about 30 percent of the time,” says Miller. “Even though the load is higher, you don’t experience it for a very long time.” Additionally, because running has a longer stride length than walking, it means fewer steps are required to travel the same distance.
“When we calculated the load you accumulate over a set distance, the load your knee experienced was the same while walking as it was while running,” says Miller. Running can still lead to other injuries in the lower body, but the single-largest risk factor for knee osteoarthritis is obesity.