Effect of addition of menthol to a drink on voluntary fluid and carbohydrate intake during exercise in humans.

Abstract

The purpose of this study was to investigate if the cold sense of menthol facilitates voluntary fluid and carbohydrate (CHO) intake during exercise in humans. Eighteen women's hockey player performed a routine training session were given 3 beverages : water (W), 5% CHO drink (C; 5% CHO, 0.1% citric acid, 0.1% NaCl) and 5% CHOwith menthol drink (MC; 5% CHO, 0.1% citric acid, 0.1% NaCl, 0.1% menthol). The subjects chose these drinks freely during the training and the intake of each drink was measured after the training. The subjects were asked to answer a visual‐analog‐scale (VAS) questionnaire on the feelings on each drink. Although the intake of each drink did not differ significantly, the intake of C and MC tended to be greater than W. The subjects fell into three groups according to their most favorite drink; W (PW, n=3), C (PC, n=7), MC (PMC, n=8). Fluid and CHO intake of PC and PMC was calculated as the sum of the most favorite drink and water. The ratio of water intake was higher in PC than PMC (43.0% (SD 34.9) vs 8.7 (6.1), P < 0.05). Consequently, C was diluted more compared to MC. As a result CHO concentration was PMC > PC (4.6% (SD 0.3) vs 3.6 (0.9) , P < 0.05). VAS data showed that sweetness was stronger in MC and C than W (P < 0.05), and tended to be lower in MC than C. These results suggest that the cold sense of menthol reduces sweetness which would avoid diluting a drink so that larger amount of CHO could be supplied during exercise, which would be beneficial to improve physical performance.