Background Carbon ‘super shoes’ improve running economy and running performance compared with traditional running shoes. However, the influence of carbon shoes on running economy and performance after prolonged cycling for triathletes remains to be investigated.

Purpose To 1) compare the running economy and muscle oxygenation before and after a 2-hour cycling session wearing carbon ‘super shoes’ vs standard neutral running shoes, and 2) compare the post-cycle running performance in a self-paced 10-km time-trial wearing carbon ‘super shoes vs standard neutral running shoes, in male long-distance triathletes.

Methods Eight active trained male triathletes participated in the study. Participants visited the laboratory on three separate occasions to perform a variety of assessments and trials while wearing either a neutral or carbon shoe during the running assessments. The first visit was a baseline anthropometric measurement that included an incremental bike test for V̇O2peak. Visits two and three were prolonged trials that aimed to replicate triathlon demands. This included a fresh (pre) treadmill running economy assessment, a 2-hour fatiguing cycle on a stationary bike, and a post-cycle running economy assessment, followed by a self-paced 10-km treadmill time-trial wearing either neutral or carbon shoes.

Results There was no shoe*time interaction (p > 0.05). However, a significant main effect of shoe on both mean running economy relative to body mass (mL.kg-1.min-1; p = 0.05, ηp2=0.49), and running speed (mL.kg-1.km-1; p < 0.05, np2=0.55), indicating a lower running economy for carbon shoes compared to neutral shoes during running, was observed. There was a significant difference between the gastrocnemius muscle oxygenation during the 5-min running economy assessment before and after the fatiguing cycle (F=8.206, p < 0.05, np2=0.58). However, for quadriceps muscle oxygenation, there were no significant differences between the two shoe conditions (F=0.931, p > 0.05), in an unfatigued or fatigued state (F=3.781, p > 0.05), and no linear relationship between the two different shoe conditions in an unfatigued or fatigued state (F = 0,099, p > 0.05). The mean post-cycling 10km running performance time when wearing carbon shoes was significantly faster than neutral shoes (49.0 ± 5.0 for carbon vs 51.6 ± 5.6 min for neutral shoes; 5.0%, p=0.02, Cohen’s d=1.06).

Discussion and Conclusion In summary, carbon shoes, when compared to neutral shoes, elicited a main effect indicating enhanced running economy. However, there were no differences in running economy between shoes over time in the unfatigued and fatigued state (pre- and post-prolonged cycling respectively). Despite this, the majority of participants improved their running performance wearing carbon shoes compared to neutral shoes indicating their beneficial effect in recreational and trained triathletes.