Effect of Carbon Plated Running Shoes on Half-Hour Treadmill Time Trial Performance

Abstract

Purpose: Performance in distance running events has been substantially impacted by innovative shoe technology using a combination of carbon fiber plates and lighter, more resilient cushioning materials. Times have been getting faster at a rapid rate, and it has been established that these shoes reduce the energetic cost of running. Very limited research has attempted to quantify these savings in terms of speed or pace, which are the most relevant performance outcomes. This study was designed to examine the performance effects of carbon plated racing flats on speed and pace compared to a non-plated racing flat, providing a quantitative estimate of how much faster these shoes make distance runners. Methods: This study used a randomized order, crossover design, with participants blinded to their running speed. Eight trained distance runners (m=5, f=3) completed two 30-min treadmill time trials, approximately one week apart. One time trial was run in a carbon plated shoe (Nike Vaporfly or Asics Metaspeed Sky), and the other was run in a non-plated flat. Average speed, running economy, RPE, RER, and HR were measured during both trials. Results: During the carbon plated time trial, participants covered 0.1188 km (+/- 0.14), ran 0.2373 kph faster (+/- 0.2462), and averaged 3.5 seconds per km faster (p<0.05), and saw no significant change in running economy (RE), RPE, RER, or HR. These improvements indicated a 1.5% (+/- 1.54%) speed improvement in carbon plated shoes. Additionally, a 3.17% improvement in RE was observed during a submaximal warmup period when participants were wearing the carbon plated shoe (d = 0.276), though this difference was not significant (p = 0.184). Conclusion: These data provide a scientific estimate of the performance benefits of carbon plated racing flats. The 3.5 seconds per km identified in this study can provide a basis for coaches, athletes, and distance running regulatory bodies to establish rules, and to contextualize performances between eras and shoes conditions.