The primary objective of the study is to investigate the effect of shoe cushioning on the time, magnitude and frequency characteristics of impact forces using frequency-domain analyses. The secondary objective is to explore which of these impact force characteristics are associated with the risk of running-related injury.
The relationship between impact forces and running injury risk remains inconclusive and speculative. Nevertheless, it has been suggested that paradigms (e.g. shoe conditions or running technique modifications) leading to a decrease or elimination of impact forces would reduce injury risk. Accordingly, the use of cushioning systems in running shoes is based on the assumptions that impact forces relate to injury risk and that cushioning material can reduce these impact forces. In a recent randomised trial, the shoe version with lesser cushioning (i.e. Hard shoe) was associated with greater injury risk. However, vertical impact peak force was lower in participants with the Hard shoe version, while time to vertical impact peak force was shorter and the proportion of steps with detectable vertical impact peak force was higher. This impact peak anomaly has previously been explained and suggests that time-domain analyses of the vertical ground reaction force component may not be an appropriate approach to identify modifications of impact peak characteristics in runners.
"Our study is the first worldwide to investigate both running technique and injury risk
in such a large cohort and over such a long period of time.",
says Laurent Malisoux, PhD, Group Leader of PASH research group.