Running fast is more likely to damage the shin of the calf than climbing

Science and Technology Daily News (Reporter Zhang Jiaxin) Running and climbing, which sport is more likely to damage the shin of the calf? According to a paper published today on the preprint server arXiv, a team of researchers in Canada and the United States found that you may face a greater risk of tibial fractures during fast running than going uphill or downhill.

When running, repeated movements of the feet hitting the ground can lead to tibial splints or even tibial fractures. Researchers know that these injuries often occur when runners increase the intensity of their training, but it's not too clear which aspects of training are most likely to cause them.

Michael Bagley of the University of Calgary in Canada and his colleagues conducted an experiment to find out. They had 17 volunteers run on a treadmill while wearing 17 different reflective markers on their legs. None of the volunteers were new runners, and no one had been injured in the six months prior to the experiment.

They each completed several runs or climbs at 3 different speeds and 5 different inclines, and the researchers simultaneously measured the force of their feet hitting the treadmill and recorded their leg movements using motion capture technology.

To determine when runners' tibias are most tense and when they are at greatest risk of stress fractures, the researchers combined force, running acceleration, and velocity data from the experiment with a mathematical model to determine how the muscles pull the bones inside the legs. They adjusted the model based on each runner's characteristics, including height and weight, to make the judgment more precise, and also combined computed tomography (CT) scan data from the runner's tibia.

The researchers found that running speed had the greatest impact on shin strains. Uphill or downhill on a treadmill has little to do with the strain associated with stress fractures. But what was clear was that the association increased immediately when volunteers ran faster.

Changes in inclination may have a less pronounced effect, Bagley said, because human legs evolve to adapt to changing terrain, and the strain changes in the shin bone when trying to pick up the pace are difficult to adapt.

Carl Zelik of Vanderbilt University in the United States said that in sports science, the idea that the force of the foot touching the ground is the only determinant of the force on the bones of the leg is a big misunderstanding.