Running is a great form of exercise enjoyed by millions of people daily, but it can be one of the harder physical activities to perform without injury. The nature of running is high-impact on the joints, and many have had to cut a session short because of runners’ knee, among other overuse strains and pains. By simply adjusting your posture, running may become less impactful on your joints and help you enjoy the sport longer.
Research brought to us from the University of Colorado Denver finds that good running shoes, while helpful, are only part of the equation for a more comfortable run. The last thing you think of when it comes to running posture is probably the angle of your head or how far forward you lean, but it’s contributing to the stress on all the joints from the neck, back, and knees.
Healthy adult runners practiced running with a measured degree of trunk flexion (the angle of how far forward the top half of the body is angled), and it resulted in noticeable changes in the ground reaction forces placed (GRF) on the legs. Altering the degree of flexion in groups of participants from 10, 20, and 30 degrees was accomplished by hanging a light weight from the ceiling while they ran to position them at precise angles.
Since the top half of the body accounts for almost 70% of the body’s mass, these slight changes were significant. When the front half of the body leans forward, it translates to more flexion in the hip and the knee that’s picked up off the ground in mid-stride, as well as changing the foot position itself. Leaning froward increased ground reaction force impact by up to 20% the more the trunk was angled forward.
To reduce the impact of running, researchers suggest remembering that the whole body is affected by running, and to avoid leaning forward when running to help keep those pesky overuse and impact-related joint injuries at bay.
Anna Warrener, Robert Tamai, Daniel E. Lieberman. The effect of trunk flexion angle on lower limb mechanics during running. Human Movement Science, 2021; 78: 102817