No effect of a commercial carbohydrate-menthol drink on thermal perceptual measures or 15-minute time trial performance compared to commercial carbohydrate drink in hot humid conditions

This study assessed the effect of a commercial carbohydrate menthol drink on cycling time trial (TT) performance in hot and humid conditions compared with a carbohydrate only drink. Ten participants (5 women; V̇O2max: 52.3±8.6mL.kg-1.min-1, Peak Power Output: 286±56W) completed a 40-min cycling preload (50% V̇O2max) followed by a 15-min self-paced TT in hot (~35°C) and humid (~54%) conditions on two occasions (double blind, crossover design). Every 10-min, 85mL of carbohydrate (CHO; SIS GO Energy, 60g.hr-1) or carbohydrate and menthol (CHO+MEN; SIS Turbo+ 60g.h-1, 0.01% menthol) was swilled (~10-sec) and ingested. Rectal temperature (Trec) and heart rate were recorded throughout. Thermal sensation (TS), thermal comfort (TC) and rating of perceived exertion (RPE) were recorded every 5-min. Taste and aftertaste were rated from very pleasant (+5) to very unpleasant (-5). TT performance (total work; kJ) was similar between CHO (153 kJ [95% CI: 129-177 kJ]) and CHO+MEN (151 kJ [128–178 kJ]). During preload exercise, Trec increased by ~0.9°C and was similar at the end of the TT (~38.20°C). Mean preload heart rate was ~140b.min-1 in each condition and reached ~177b.min-1 at the end of the TT. Thermal comfort was rated as ‘much too warm’ and thermal sensation rated as ‘very hot’ in both conditions. Both conditions were ‘extremely hard’ (end point RPE ~19). All participants preferred the taste and aftertaste of the CHO drink. The commercial carbohydrate menthol drink offered no additional ergogenic benefit compared to a carbohydrate only drink during cycling exercise performed in hot and humid conditions. Highlights • The addition of menthol to a carbohydrate drink had no effect on 15-min TT performance. • The addition of menthol to a carbohydrate drink had no effect on thermal perceptual measures or physiological measures. • Taste and aftertaste perceptions were favourable towards the carbohydrate drink compared to the carbohydrate-menthol drink