Introduction:
Ultra-cycling is a complex sport and a variation of individual characteristics.

Aim of the study:
This study aimed to analyze the mechanical power, energy cost, and performance (estimated time of arrival – ETA) between the old (OWR) and new (NWR) 24-hour road cycling world record.

Material and methods:
An experienced ultra-cyclist broke the world record (WR) for the second time in 24-hour road cycling. Split times (intervals of 6 h) were used to evaluate the racing performance (0-6 h; >6-12 h; >12-18 h; >18-24 h), to compare the performance between OWR and NWR regarding power to overcome the drag (Pd), power for rolling resistance (PRR), total mechanical power (PTOT), energy cost (Ec) and ETA. One-way ANOVA was used to compare OWR and NWR. Effect size was presented using Cohen’s d.

Results:
The 6-hour split times allowed to compare the WRs and statistically significant changes (p < 0.05) were found for all the assessed variables [Pd (W), PRR (W), PTOT (W), Ec (J/m), Ec (J/Lap), Ec (Kcal/Lap), and ETA (s)]. The comparisons for the variations intra-WR showed significant differences (p < 0.05) for all variables between split times. For the OWR, no statistically significant differences were noted between 6-12 h and 12-18 h for PRR, Ec (J/Lap and Kcal/Lap) and ETA. For the NWR, no statistically significant differences were found for the split time between 6-12 h and 12-18 h for Pd, PRR, PTOT, Ec and ETA.

Conclusions:
The cyclist’s ability to deliver more mechanical power and energy cost in setting the NWR allowed him to break the 1000 km in 24 h record and establish an NWR. The variable with higher effect was Pd in both WRs and the lower effect was observed in Ec for the OWR and PRR for the NWR.