Menthol as an Ergogenic Aid for the Tokyo 2021 Olympic Games: An Expert-Led Consensus Statement Using the Modified Delphi Method.

INTRODUCTION: Menthol topical application and mouth rinsing are ergogenic in hot environments, improving performance and perception, with differing effects on body temperature regulation. Consequently, athletes and federations are beginning to explore the possible benefits to elite sport performance for the Tokyo 2021 Olympics, which will take place in hot (~ 31 °C), humid (70% RH) conditions. There is no clear consensus on safe and effective menthol use for athletes, practitioners, or researchers. The present study addressed this shortfall by producing expert-led consensus recommendations. METHOD: Fourteen contributors were recruited following ethical approval. A three-step modified Delphi method was used for voting on 96 statements generated following literature consultation; 192 statements total (96/96 topical application/mouth rinsing). Round 1 contributors voted to "agree" or "disagree" with statements; 80% agreement was required to accept statements. In round 2, contributors voted to "support" or "change" their round 1 unaccepted statements, with knowledge of the extant voting from round 1. Round 3 contributors met to discuss voting against key remaining statements. RESULTS: Forty-seven statements reached consensus in round 1 (30/17 topical application/rinsing); 14 proved redundant. Six statements reached consensus in round 2 (2/4 topical application/rinsing); 116 statements proved redundant. Nine further statements were agreed in round 3 (6/3 topical application/rinsing) with caveats. DISCUSSION: Consensus was reached on 62 statements in total (38/24 topical application/rinsing), enabling the development of guidance on safe menthol administration, with a view to enhancing performance and perception in the heat without impairing body temperature regulation.

Precooling does not Enhance the Effect on Performance of Midcooling with Ice-Slush/Menthol.

This study investigated whether the combination of internal precooling (PC) and internal midcooling (MC cooling during exercise) would enhance performance more than MC alone. 9 trained males completed two 30-km cycling trials in a hot and humid environment (WBGT: 29±0.7°C, 80±0.02% relative humidity). For 30 min before exercise, the subjects sat quietly and drank water at 23°C (MC) or 3°C (PC+MC). During the MC and PC+MC time trials, they drank an ice-slush/menthol beverage (i. e., 0.025% menthol). Trial time, gastrointestinal temperature (Tco ), heart rate (HR), rating of perceived exertion (RPE), thermal sensation (TS), and thermal comfort (TC) were assessed. Trial time was not significantly different (P>0.05) between MC and PC+MC (3 737±552 s and 3 815±455 s). Before exercise, Tco was lower with precooling (37.0±0.3°C; P<0.02). During exercise, no between-trial differences were noted for Tco, HR, RPE, TC or TS, but RPE was significantly lower with PC+MC in the latter stages (P<0.05). (1) Cold beverage intake before exercise did not improve the subsequent exercise performance with ice-slush/menthol beverage intake, and (2) despite no improvement in performance, RPE declined in the latter stages of exercise in the condition of PC+MC, suggesting that this combination might be beneficial for longer exercise.