Metabolic and performance responses of male runners wearing 3 types of footwear: Nike Vaporfly 4%, Saucony Endorphin racing flats, and their own shoes

Purpose We compared running economy(RE)and 3-km time-trial(TT)variables of runners wearing Nike Vaporfly 4%(VP4),Saucony Endorphin lightweight racing flats(FLAT),and their habitual running(OWN)footwear.Methods Eighteen male recreational runners(age=33.5±11.9 year(mean±SD),peak oxygen uptake(VO_(2peak))=55.8±4.4 mL/kg·min)attended 4 sessions approximately 7 days apart.The first session consisted of a VO_(2peak) test to inform subsequent RE speeds set at 60%,70%,and 80%of the speed eliciting VO2peak.In subsequent sessions,treadmill RE and 3-km TTs were assessed in the 3 footwear conditions in a randomized,counterbalanced crossover design.Results Oxygen consumption(mL/kg·min)was less in VP4(from 4.3%to 4.4%,p≤0.002)and FLAT(from 2.7%to 3.4%,p≤0.092)vs.OWN across intensities,with a non-significant difference between VP4 and FLAT(1.0%-1.7%,p≥0.292).Findings related to energy cost(W/kg)and energetics cost of transport(J/kg·m)were comparable.VP43-km TT performance(11:07.6±0:56.6 mm:ss)was enhanced vs.OWN by 16.6 s(2.4%,p=0.005)and vs.FLAT by 13.0 s(1.8%,p=0.032).The 3-km times between OWN and FLAT(0.5%,p=0.747)were similar.Most runners(n=11,61%)ran their fastest TT in VP4.Conclusion Overall,VP4 improved laboratory-based RE measures in male recreational runners at relative speeds compared to OWN,but the RE improvements in VP4 were not significant vs.FLAT.More runners exhibited better treadmill TT performances in VP4(61%)vs.FLAT(22%)and OWN(17%).The variability in RE(-10.3%to 13.3%)and TT(-4.7%to 9.3%)improvements suggests that responses to different types of shoes are individualized and warrant further investigation.