RUNNING WITH a slight forward lean of the trunk results in less stress on the patellofemoral joint, and might therefore relieve knee pain, according to research published in the Journal of Orthopaedic & Sports Physical Therapy.
Twenty-four runners with no history of knee pain ran at just faster than 5 minutes per kilometre with three variations of trunk posture: self-selected, flexed (forward lean) and extended (erect trunk). Researchers measured the movement of the runners’ trunk and knees, ground reaction forces, and activity in some lower-leg muscles. The researchers combined these measurements for an overall barometer of stress to the knee joint.
The average trunk flexion angle in the self-selected running style was 7.3 degrees. The significant finding from that condition was that the runners with the least amount of flexion experienced the greatest knee stress, and vice versa.
When the runners were asked to consciously alter their trunk position, the difference in knee stress became even more pronounced.
“On average, a 6.8-degree increase in the mean trunk flexion angle resulted in a 6.0 percent decrease in peak [patellofemoral joint] stress, whereas a 3.3-degree decrease in mean trunk flexion angle led to a 7.4 percent increase in peak [patellofemoral joint] stress,” the researchers report.
As noted above, the runners weren’t experiencing knee pain at the time of the study. The research measured the stress on the runners’ knee joints, not the runners’ reports of how running with the various degrees of forward lean made their knees feel.
Still, the study’s findings are in line with a growing consensus that some common areas of discomfort while running can be addressed with form alterations.
For example, because heel striking is associated with more loading forces on the knee than midfoot striking is, some sports medicine professionals recommend that people with chronic knee pain experiment with a midfoot strike. Conversely, midfoot and forefoot striking is associated with a greater load on the Achilles tendons, so people with chronic Achilles pain are sometimes advised to use a heel strike. (Both recommendations come with this caveat: The landing forces have to go somewhere. These form changes are an attempt to lessen the forces on a troublesome area, not a way to lessen overall landing forces.)
As this study’s authors write, adopting a slight forward lean could be an alternative to switching to a midfoot strike for runners seeking to lessen chronic knee pain. Like the majority of runners, the runners in this study were heel strikers. Changing one’s natural foot strike might be more difficult than running with a bit more of a forward lean.
These methods of potentially relieving chronic pain should be seen as short-term measures while you address the root cause of the problem. In the case of runner’s knee and other causes of knee pain, many experts recommend strengthening the hips and glutes.
