John Taylor, Professor of Economics at Stanford University and developer of the "Taylor Rule" for setting interest rates | Stanford University
John Taylor, Professor of Economics at Stanford University and developer of the "Taylor Rule" for setting interest rates | Stanford University
Hamstring injuries are a common issue for athletes worldwide, making up 10% of all injuries in field-based sports. Despite their prevalence, the mechanisms and prevention strategies remain elusive. Recent studies have provided new insights into hamstring injury prevention.
A study conducted by researchers from the University of Queensland and Stanford University, alongside Stanford Athletics, examined the impact of nine weeks of Nordic hamstring exercises on muscle structure in 12 participants. This research utilized a microendoscopy technique developed at Stanford to measure training effects on human hamstrings with unprecedented detail. The findings were published in the Journal of Sport and Health Science.
"The truly unique part of this study was our ability to examine the microscopic adaptations of the muscle in response to Nordic hamstring exercises. No other studies have been able to explore this in humans," stated Scott Delp, senior author and director of the Wu Tsai Human Performance Alliance at Stanford.
Delp and Mark Schnitzer had previously developed a microscope capable of visualizing sarcomeres within muscle fibers. Using this technology, significant changes were observed in the biceps femoris long head muscle after nine weeks of Nordic exercises. Sarcomeres increased end-to-end with existing ones, potentially reducing overstretching risk.
Max Andrews, first author and graduate student at the University of Queensland, noted that "consistent training is essential to maintain these muscle changes."
The second study explored high-speed running's role in hamstring injuries. Conducted by Delp’s team and published in Medicine and Science in Sports and Exercise, it found that acceleration from lower speeds causes greater stretching than maintaining top speed.
"Running speed alone is insufficient to fully characterize hamstring biomechanics," said Reed Gurchiek, now an assistant professor at Clemson University.
Using OpenCap technology for motion data capture on natural surfaces revealed variability among participants' acceleration techniques. Some minimized injury risk while others struggled with rapid stretching due to poor control over pelvis and torso movements.
Delp highlighted potential applications: "The vision is to screen athletes with OpenCap... This could be a valuable tool across various sports where hamstring injuries are common."
Both studies received support from institutions including Australian Research Council Discovery Project, National Institutes of Health grants, Stanford Graduate Fellowship, The University of Queensland Graduate Scholarship, National Health and Medical Research Council of Australia Fellowship, Wu Tsai Human Performance Alliance at Stanford University, Joe and Clara Tsai Foundation.
For more information or media inquiries: mediarelations@stanford.edu
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