Key factors influencing cycling performance and overall race time in the Ironman 70.3 for amateur athletes

Previous study has shown that cycling is the most predictive modality in the Ironman 70.3 triathlon distance. As a result, understanding the physiological and anthropometric variables that are mostly closely related to cycling performance can help coaches and athletes to direct their training programs. This study aimed to investigate the physiological, anthropometric, and general training characteristics influencing overall race time and cycling split time in Ironman 70.3. The present study also investigated the significance of body composition as a performance-related variable.

A questionnaire was used to assess training characteristics in 12 athletes (six men and six women), body composition in dual X-ray absorptiometry, and physiological variables in an incremental cardiopulmonary test. Ironman 70.3 São Paulo–Brazil 2023 was completed by all participants. The relationship between performance and the variables measured were investigated, and a multiple regression model for cycling split time and overall race time was developed.

Functional threshold power (FTP) can predict cycling split time in Ironman 70.3 (r² = 0.638, p = 0.002). Maximal oxygen uptake ( \(\dot{\text{V}}\) $\dot{\text{V}}$ O₂max) (r² = 0.667, p = 0.001) can predict overall race time. FTP and \(\dot{\text{V}}\) $\dot{\text{V}}$ O₂max are also strongly related to lean mass and fat mass percentage.

While FTP is the most important predictor of cycling split time, \(\dot{\text{V}}\) $\dot{\text{V}}$ O₂max is the most important predictor of overall race time in an Ironman 70.3. Furthermore, because body composition (fat mass %) and muscle mass (kg) are variables strongly related to FTP and \(\dot{\text{V}}\) $\dot{\text{V}}$ O₂max, we recommend that coaches and athletes consider to conduct a body composition assessment.