Effects Of Minimal, Traditional, And Highly Cushioned Shoes On Injury-related Biomechanics In Rear And Non-rearfoot Strike Runners

Abstract

Running barefoot, in minimal shoes, or traditional shoes alters certain injury-related biomechanical variables and these footwear effects can be influenced by foot strike pattern. It is unclear however how highly cushioned shoes might alter this interaction. PURPOSE: Given the increasing popularity in highly cushioned footwear in runners, this study assessed the interaction of footwear and foot strike pattern on injury-related biomechanical variables in experienced runners. METHODS: Six rear (RFS) and seven non-rearfoot strike (NRFS) experienced runners completed five running trials at 3.5m/s (±5%) in minimal (MSH), standard (SH) and high cushioned (HC) shoes. A mixed-design repeated measures ANOVA was used to test interaction effects for all injury-related variables. Paired t-tests were used to decipher any interaction effect and Cohen’s d effect sizes were computed to assess mean difference magnitudes. Given the preliminary nature of this work and the small sample size, alpha level was set to 0.1. RESULTS: Strike index confirmed the different strike patterns while running in SH between RFS (15.2±3.1%) and NRFS (102.8±11.8%) groups (p<0.001). Interaction effects were not observed for any of the variables except for peak eversion velocity (p=0.1) and instantaneous vertical loading rate (IVLR; p=0.1) (Figure 1). Main footwear effects were observed for IVLR (p=0.004) and peak eversion velocity (p=0.01). Main foot strike effects were observed for step length (p=0.041), strike index (p=0.00), and IVLR (p=0.00). CONCLUSION: Similar to prior research, these current preliminary findings suggest there might be an interaction between foot strike and footwear in experienced runners for peak eversion velocity and IVLR. Thus, if these biomechanical variables are of interest to scientists or clinicians, these findings suggest that footwear type and strike pattern should both be considered in research or return to running programs.Figure 1:: Instantaneous vertical loading rate (A; IVLR) and peak eversion velocity (B) in the three footwear conditions in rare (RFS; black) and non-rearfoot strike (NRFS; red) runners. *: foot strike group difference within footwear; #: footwear difference within foot strike group (p < 0.1).