If you are prone to knee pain, going fast for short distances (versus going slow for long distances) may keep you healthy.
Fast running seems to boost the odds of many types of overuse injuries, including those in the foot and Achilles tendon. But a new Danish study suggests some people prone to knee pain might benefit from picking up the pace.
In runners who land on their heels, the total load on the front of the knee actually increases with slower running, according to findings published in the Journal of Orthopaedic & Sports Physical Therapy. This could cause or aggravate patellofemoral pain syndrome, commonly known as runner’s knee.
At first, the results seems counterintuitive. After all, the faster you run, the harder you hit the ground—potentially increasing the strain on all your muscles and joints, including your knees.
“But when you run, you don’t take one step—you take many steps, many strides,” says senior author Rasmus Nielsen of Aarhus University in Denmark.
His research team recruited 16 heel-strikers with personal best 5K times of 17 minutes or slower. Each ran 1,000 metres on a track with a force plate at three speeds: 8 kilometres per hour, 11.79 kilometres per hour, and 15.78 kilometres per hour.
The runners’ knees took more abuse with each stride during faster running. However, the slower they went, the more strides they required to cover the same distance. As a result, runners accumulated 80 percent more load on the front of their knees at a slow pace than at a fast pace.
The results help explain why running more mileage is linked to the development of runner’s knee, Nielsen says. Most runners naturally slow down to cover longer distances—so they’re increasing the load on their knees in two ways, both by covering more distance and by taking more steps per kilometre.
Cumulative load is “a small piece of the puzzle” when determining the underlying cause of running injuries, Nielsen says. But based on the findings and his clinical experience, he says heel-strikers coping with knee pain might want to consider running shorter distances at faster paces as they recover, especially if other treatment options haven’t helped. (The results wouldn’t apply to runners who hit the ground with the middle or front of their feet, since that changes the loading equation, Nielsen notes.)
On the flip side—based on past research—fast running increases the strain on the Achilles tendon and hamstrings. Runners with injuries to these body parts will likely benefit more from running slowly, he says.
What counts as fast and slow depends on many factors, including your regular pace. In general, though, slow running means being able to talk with others as you stride, while fast running should leave you a bit breathless, Nielsen says.
