Giandolini M., Arnal P., Millet G., et al (2012). Impact reduction during running: efficiency of simple acute interventions in recreational runners. European Journal of Applied Physiology, 113(3):599-609 Details
Customer study highlights
Running can be difficult, painful even – to many this presents a legitimate reason for not doing it. For others, however, running is an enjoyable social activity that can fit into the busiest lifestyles. Yet it may become a source of injury. Some 20% of sports injuries are due to stress fractures, with a significant proportion involving the bones in the lower leg and the feet.
Why are some runners more prone to stress fractures than others? The outcome of a joint French and Canadian research project demonstrates that foot-strike technique is a key factor.
Gandolini et al tested whether specific interventions could reduce vertical ground reaction force (VGRF), which is a risk factor for stress fracture injuries. Nine young, fit adults who exhibited a ‘rear foot-strike’ pattern were asked to run on an instrumented treadmill at an initial pace of 2.5 m/s for a total of 5 minutes per trial, while EMG data and VGRF measurements were sampled into LabChart.
In one of the interventions subjects were asked to adopt a mid-foot as opposed to a rear-foot strike pattern. On average this resulted in a 57% decrease in the vertical ground loading rate (LR; i.e., the mean time-derivative of VGRF signal during the first 50 ms of the support phase). Since subjects were normally rear-foot strikers this also altered EMG patterns throughout the stride cycle, with a 208% increase in gastrocnemius lateralis preactivation and a 56% decrease in tibialis anterior muscle activity. Other interventions, including wearing racing shoes and increasing step frequency by 10%, had no significant effect on LR.
Followers of the old adage “Run like hell and get the agony over with” (Clarence DeMar) may see benefit in modifying their technique. However, whether the mid-foot reduction in LR represents benefits for long-distance running has yet to be tested.