Biomechanics of Running Research Review

Have you ever wondered whether a certain foot strike is associated with greater injury potential? Or whether foot structure helps some people run faster? This roundup of recent running research may answer those questions.

The first—a retrospective study, published in Medicine & Science in Sports & Exercise (doi:10.1249/MSS.0b013e3182465115)—examined injury rates among 52 collegiate middle- and long-distance runners. The scientists measured the athletes’ strike characteristics and separated the participants into a forefoot group (n = 16) and a rearfoot group (n = 36). They then collected data on incidence of injury and rate and severity of injury, as well as rate of mild, moderate and severe injuries per mile run.

The scientists found that 74% of all the subjects experienced a moderate or severe injury each year. However, rearfoot strikers had twice as many repetitive stress injuries as forefoot runners did.

“One hypothesis, which requires further research, is that the absence of a marked impact peak in the ground reaction force during a forefoot strike compared to a rearfoot strike may contribute to lower rates of injuries in habitual forefoot strikers,” the authors suggested.

The second study—published in the Proceedings of the Royal Society B (doi: 10.1098/rspb.2011.2358)—looked at ankle structure and moment arms (the perpendicular line of force application to the axis of rotation) to highlight the physical characteristics of trained sprinters. According to the study authors, “Recent studies of sprinters and distance runners have suggested that variations in human foot proportions and plantar flexor muscle moment arm correspond to the level of sprint performance or running economy. . . . Less clear, however, is whether differences in muscle moment arm are mediated by altered tendon paths or by variation in the center of ankle joint rotation.”

So, with the help of eight trained sprinters and eight nonsprinters, the researchers used magnetic resonance imaging (MRI) to determine structural differences between the groups. They discovered that the sprinters possessed longer forefoot bones and shorter plantar flexion moment arms than the nonsprinters did.

“The shorter moment arms of sprinters are attributable to differences in the location of the center of rotation rather than to differences in the path of the Achilles tendon,” the authors explained. They concluded that the longer toe bones and shorter moment arms allowed the calf muscles to produce more power during acceleration, making certain individuals mechanically predisposed to greater sprint performance.