Comparison of different models of Wʹ balance in high-level road cycling races

This study aimed to compare different models of Wʹ balance (Wʹbal) during road cycling races. These models allow tracking of the depletion and reconstitution of energy reserves during intermittent exercises. Fifteen high-level cyclists shared a year of data, including the power output and GPS records. They then selected a race during which they were in very good condition, and where they reached a maximum level of exhaustion in the final phase. Based on their seasonal data, their critical power and Wʹ were calculated and incorporated into the integral and differential models of Skiba and Bartram model. Wʹbal was calculated throughout the races and normalised to Wʹ. The integral, differential, and Bartram models predicted a mean Wʹbal of 41 ± 27%, 67 ± 17%, and 82 ± 9%, a minimum Wʹbal of −21 ± 28%, −3 ± 22%, and 22 ± 24%, and a Wʹbal at the identified point of exhaustion of 0 ± 30%, 21 ± 28%, and 42 ± 23% (all significantly different, p < 0.01). Given the large differences between the models and the high inter-individual variability of Wʹbal at the participant-identified point of exhaustion, this study shows that the models are not interchangeable and that the values of Wʹbal should be considered with caution when analysing races.