Influence of Arch-Support Orthoses with Heel Lift Manipulation on Joint Moments and Forefoot Mechanics in Running

While foot orthosis is suggested to improve rearfoot motion in running, little information is known about forefoot biomechanics. The objective of this study was to examine the effects of arch-support orthoses with various heel lift manipulation on the loading rate, spatiotemporal, and forefoot joint mechanics using a skin marker set model. Fifteen male habitual rearfoot strikers ran at their selected speeds on an instrumented treadmill in four foot orthoses conditions: flat-control, D2 (2 mm heel lift, arch-support), D6 (6 mm heel lift, arch-support), and D10 (10 mm heel lift, arch-support). A repeated measures ANOVA was performed to examine any significant difference in each of the tested variables, with α = 0.05. Wearing D10 led to smaller maximum loading rate than D2 (p < 0.001) and control (p = 0.002). For sagittal plane, D10 had larger rearfoot touchdown dorsiflexion than D2 (p = 0.027) and control (p = 0.007) and larger in D6 than control (p = 0.025). For frontal plane, wearing D10 demonstrated larger rearfoot frontal RoM than D2 (p = 0.018) and peak forefoot eversion than D6 (p = 0.047) and control (p = 0.048). Furthermore, the forefoot frontal range of motion was lowest when wearing D6. For joint moment, wearing control orthosis exhibited larger peak rearfoot eversion moment than D6 (p = 0.035), but smaller peak knee extension moment than D2 (p = 0.025) and D10 (p = 0.010). These findings indicate that the use of arch-support orthoses would alter the running mechanics that are related to injury potential. Lower heel lift orthoses led to alternations to most of the biomechanical variables than higher heel lift orthoses. Further longitudinal study seems necessary to optimize arch-support orthoses design in running.