Abstract
We determined whether fatigue modifies the effect of custom foot orthoses manufactured from ethyl-vinyl acetate (EVA) and expanded thermoplastic polyurethane (TPU) materials, both compared to standardized footwear (CON), on running mechanics, running economy, and perceived comfort. Eighteen well-trained, males ran on an instrumented treadmill for 6 min at the speed corresponding to their first ventilatory threshold (13.8 ± 1.1 km/h) in three footwear conditions (CON, EVA, and TPU). Immediately after completion of a repeated-sprints exercise (8 × 5 s treadmill sprints, rest = 25 s), these run tests were replicated. Running mechanics, running economy and perceived comfort were determined. Two-way repeated measures ANOVA [condition (CON, EVA, and TPU) × fatigue (fresh and fatigued)] were conducted. Flight time shortened (P = 0.026), peak braking (P = 0.016) and push-off (P = 0.032) forces decreased and vertical stiffness increased (P = 0.014) from before to after the repeated-sprint exercise, independent of footwear condition. There was a global fatigue-induced deterioration in running economy (− 1.6 ± 0.4%; P < 0.001). There was no significant condition × fatigue [except mean loading rate (P = 0.046)] for the large majority of biomechanical, cardio-respiratory [except minute ventilation (P = 0.020) and breathing frequency (P = 0.019)] and perceived comfort variables. Acute intense fatigue does not modify the effect of custom foot orthoses with different resilience characteristics on running mechanics, running economy and perceived comfort.
Highlights
Communicated by Jean -Rene Lacour.University of Western Australia, Perth, WA, AustraliaCustom foot orthoses (CFOs), which refer to shoe inserts built from a three-dimensional representation of the athlete’s feet, have become a contemporary topic in footwear biomechanics literature
This study determined whether acute intense fatigue modifies the effect of CFOs manufactured from ethyl-vinyl acetate (EVA) and expanded thermoplastic polyurethane (TPU) materials, both compared to standardized footwear (CON), on running mechanics, Running economy (RE), and perceived comfort
One strength of our study is that running mechanics during constant submaximal runs were derived from direct ground reaction forces’ recording in both vertical and antero-posterior directions, as opposed to previous studies using tri-axial accelerometers to assess the effects of CFOs before and after an intense run (Lucas-Cuevas et al 2014; Lucas-Cuevas et al 2017)
Summary
Custom foot orthoses (CFOs), which refer to shoe inserts built from a three-dimensional representation of the athlete’s feet, have become a contemporary topic in footwear biomechanics literature. Wearing CFOs is used to provide foot support and shock absorption during ground contact through re-distribution of plantar loading and a better maintenance of foot stability (Crago et al 2019). Prior studies investigating CFOs effects on key biomechanical indicators have reported mixed results with beneficial (Worobets et al 2014; Wilkinson et al 2018) or unchanged (Lewinson et al 2013) adjustments in stride pattern. European Journal of Applied Physiology in running gait (Sinclair et al 2016). Quantifying stride mechanical adjustments in response to CFOs is crucial to better understand how footwear features may eventually influence the energetic cost of running (Moore 2016)
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