The impact of fatigue accumulation on performance during stage races in professional road cyclists

Cumulative fatigue influences performance in professional road cyclists during stage races. This study examined the interaction between internal and external factors on performance parameters using race data from seven male professional cyclists collected over three seasons. Maximal rolling means for power output (PO) and heart rate (HR) were calculated across durations from 1 to 3600 s, and PO– and HR–duration curves were generated for grouped race days (Days 1–3 to 19–21). Mean PO and HR for 5-, 10-, and 20-min efforts were also analysed. For each effort duration, average PO, relative performance (% best), mean HR, PO/HR ratio, cumulative energy expenditure, and consecutive race days were computed. Data was analysed with mixed-effects linear models (REML). Both HR (p<0.0001) and PO (p<0.01) were altered between the first and later race days group, confirming performance declines across stages. Maintaining a higher PO/HR ratio was associated with superior 5-min (Z-score=0.5915), 10-min (Z-score=0.6524), and 20-min (Z-score=0.7299) efforts (all p<0.0001). Accordingly, cyclists with higher PO/HR ratios maintained better 10- and 20-min performance considering prior mechanical work and successive race days accumulated. Despite overall reductions in PO and HR across stages, riders able to preserve a higher PO/HR ratio under accumulated fatigue produced superior short- to mid-duration efforts, highlighting cardiovascular efficiency as a key determinant of performance during multi-stage competitions.