The ubiquitous overuse injuries that nag runners may stem from an unlikely culprit: how far you lean forward.
Trunk flexion, the angle at which a runner bends forward from the hip, can range wildly–runners have self-reported angles of approximately -2 degrees to upward of 25. A new study from the University of Colorado Denver (CU Denver) found that greater trunk flexion has significant impact on stride length, joint movements, and ground reaction forces. How you lean may be one of the contributors to your knee pain, medial tibial stress syndrome, or back pain.
“This was a pet peeve turned into a study,” said Anna Warrener, PhD, lead author and assistant professor of anthropology at CU Denver. Warrener worked on the initial research during her postdoc fellowship with Daniel Liberman, PhD, in the Department of Human Evolutionary Biology at Harvard University. “When [Lieberman] was out preparing for his marathons, he noticed other people leaning too far forward as they ran, which had so many implications for their lower limbs. Our study was built to find out what they were.”