Cumulative pre-cooling methods do not enhance cycling performance in tropical climate

failed to show the effectiveness of these mixed pre-cooling strategies on the change in Tgi. Moreover, some authors have highlighted the positive impact of a long rest between pre-cool- ing and exercise on the time to exhaustion and the core temperature [18, 21]. In our study, the cyclists had only a 5-min transition between the warm-up on the cycle trainer and the starting line in the velodrome. This transition was probably too short to allow the pre-cooling strategies to lower the core temperature sufficiently before the cycling performance began, and thus it could not enhance the total distance traveled over 20 min. Also, evaporation is hindered in a hot and wet environment [4], and a humid layer added to an already tropical condition, even if it was cooled (i.e., the regularly refreshed cooling vest in ICE-VEST and MEN-VEST condi- tions), may have impacted the evaporation process, limiting the dissipation of the heat load and leading to no improvement in the cooling rate. The main strength of this study was to have considered methods of precooling during a demanding warm-up, which has not often been tested in the literature. Having considered this reinforces the ecological aspect of this study. The counterpart is that a small number of subjects could be recruited due to the demanding selection criteria in a small area (i.e., heat-acclima- tized well-trained male road cyclists competing regularly in elite road races). Another impor- tant limitation of this study is to have presented physiological parameters in the form of a

cooling rate, thus limiting the possible appearance of variations and their interpretation. Given all these, future investigations, which will have to consider wind speed in addition, are needed to recruit a very large number of subjects in order to clarify the effectiveness of these mixed techniques (an internal pre-cooling method with menthol associated with external pre-cooling with or without menthol during warm-up) and to discriminate the added value of menthol −on−skin pre-cooling during a performance longer than 20 min. This would be particularly useful when the warm-up is performed on a cycle trainer before a long−duration cycling race. Conclusion Results of this study failed to show improvements in performance (total distance), physiologi- cal parameters (cooling rate, HR) and perceptions (RPE and thermal perceptions) according the precooling conditions. Nevertheless, an increase of the thermal sensation was observed during the performance only in NO-VEST condition. The absence of a modification of the thermal sensation at the end of the cycling test under the mixed conditions (ICE-VEST and MEN-VEST) could suggest a beneficial effect of wearing a cooling vest on thermal sensation although it had no effect on performance. Therefore, other methods to improve performance of well-trained male cyclists in a velodrome during a short distance time trials in hot and humid conditions should be considered. Thus, further data are needed to develop this, but also to test the impact of the mixed techniques using regions of high alliesthesial thermosensitivity

(neck, head, face) and during longer performances. Supporting information S1 Data. (XLSX) Acknowledgments The authors wish to thank all the participants for their involvement. Author Contributions Conceptualization: Aure´lie Collado, Ke´vin Rinaldi, Eric Hermand, Olivier Hue. PLOS ONE Tropical cycling performance and cumulative pre-cooling PLOS ONE | https://doi.org/10.1371/journal.pone.0291951 October 12, 2023 12 / 15