Abstract
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.
Highlights
For ground reaction force (GRF) variable (Table 1), wearing D10 orthosis led to smaller maximum loading rate than D2 (p < 0.001, d = 0.50) and control orthoses (p = 0.002, d = 0.46)
This study examined the changes in loading rate and spatiotemporal, sagittal, and frontal joint kinematics and moment variables across arch-support orthosis conditions
Our results found that orthoses with higher heel lift were associated with smaller maximum loading rate, which is not in line with another study which found higher loading rate in higher heel lift condition instead [47]
Summary
Improper running mechanics and footwear contribute to the risk of developing running-related injuries [2,3,4]. Foot orthoses, which refer to shoe inserts that contour plantar foot surface, are frequently used in footwear in attempts to re-distribute the plantar loading, maintain stability, and minimize the localized plantar pressure, reducing injuries [5,6] and improving comfort for better running performance [7]. The use of arch-support orthoses with arch-support aims to increase the foot-insole contact area and pressure at medial longitudinal arch of a foot, enhancing somatosensory inputs over the plantar foot [8] to provide foot support and shock absorption during contact on the ground [9]
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