Immediate effect of foot orthoses on plantar force timing during running: A repeated measures study
1Department of Podiatry, Faculty of Health Sciences, La Trobe University, Bundoora, Victoria, Australia. a.mcmillan@latrobe.edu.au
Background:
Despite evidence supporting the use of foot orthoses in the prevention and treatment of several running related conditions, the physical effects of these devices during running is currently unclear. This limitation has clinical consequences in relation to dispensing foot orthoses, as the presumed biomechanical action may not be produced as intended. The aim of this study was therefore to investigate the effect of foot orthoses on plantar force timing during running.
Methods:
A laboratory study with a repeated measures design was conducted with subjects (n = 20) running on a treadmill while wearing an in-shoe force measurement device. The effect of two types of prefabricated foot orthoses (Prothotic™ S and Prothotic™ W) on plantar force timing beneath the rearfoot and forefoot was observed in comparison to a control condition.
Results:
No statistically significant effects between conditions were found for rearfoot variables. In contrast, peak forefoot force occurred earlier and the duration of forefoot off-loading was extended in both orthosis conditions (P < 0.05, d > 0.9) compared with control. The Prothotic™ S was found to have a larger effect on plantar force timing beneath the forefoot, and also decreased the duration of forefoot loading (P = 0.04, d = 0.8).
Conclusion:
The foot orthoses used in this study were observed to have systematic effects on plantar force timing during running. The findings of this study may be used to guide future research in this field, as the clinical importance of these effects remains unclear.