Menthol Mouth Rinsing Maintains Relative Power Production during Three-Minute Maximal Cycling Performance in the Heat Compared to Cold Water and Placebo Rinsing

Abstract

Previous menthol studies have demonstrated ergogenic effects in endurance-based activity. However, there is a need for research in sports whose physiological requirements exceed maximal aerobic capacity. This study assessed the effects of 0.1% menthol mouth-rinsing upon a modified three-minute maximal test in the heat (33.0 ± 3.0 °C; RH 46.0 ± 5.0%). In a randomised crossover single blind placebo-controlled study, 11 participants completed three modified maximal tests, where each trial included a different mouth rinse: either menthol (MEN), cold water (WAT) or placebo (PLA). Participants were asked to rate their thermal comfort (TC), thermal sensation (TS) and rating of perceived exertion (RPE) throughout the test. Heart rate, core temperature, oxygen uptake (V̇O2), ventilation (V̇E) and respiratory exchange ratio (RER) were monitored continuously throughout the test, alongside cycling power variables (W; W/kg). A blood lactate (BLa) level was taken pre- and post- test. Small to moderate effects (Cohen’s d and accompanying 90% confidence intervals) between solutions MEN, WAT and PLA were observed towards the end of the test in relation to relative power. Specifically, from 75–105 s between solutions MEN and WAT (ES: 0.795; 90% CI: 0.204 to 1.352) and MEN and PLA (ES: 1.059; 90% CI: 0.412 to 1.666), this continued between MEN and WAT (ES: 0.729; 90% CI: 0.152 to 1.276) and MEN and PLA (ES: 0.791; 90% CI: 0.202 to 1.348) from 105–135 s. Between 135–165 s there was a moderate difference between solutions MEN and WAT (ES: 1.058; 90% CI: 0.411 to 1.665). This indicates participants produced higher relative power for longer durations with the addition of the menthol mouth rinse, compared to cold water or placebo. The use of menthol (0.1%) as a mouth rinse showed small performance benefits for short duration high intensity exercise in the heat.

Performance effects of internal pre- and per-cooling across different exercise and environmental conditions: A systematic review

“…And int the other study (99), the intermittent exercise protocol used was less affected by cooling strategies. Similarly, mouth rinse 10.3389/fnut.2022.959516 of cold water 1 min before the start of exercise (25 mL at 4 • C) did not show effect on relative power output in both male and female subjects (105). Though, it is important to refer that applying a thermal cooling technique only 1 min before a 3-min exercise may not be enough time to notice the benefits of these methods, neither for men nor for women.…”

“…The average VO 2 max of the participants was 56.0 mL⋅kg –1 ⋅min –1 (ranging from 46.2 ( 103 ) to 67.2 mL⋅kg –1 ⋅min –1 ( 109 )). Seventeen studies included physically active participants ( 93 , 94 , 97 , 101 , 104 , 105 , 107 , 110 – 118 ), twenty-one included recreational athletes ( 95 , 96 , 98 – 100 , 106 , 108 , 119 – 131 ), and five involved professional athletes ( 102 , 109 , 132 – 135 ).…”

“…Overall, 472 subjects (408 male and 64 female) from 43 studies were included in the qualitative analysis, with the number of participants ranging from 7 (93-96) to 52 (97). Thirty-four studies assessed only male participants, three only females (98)(99)(100), and six included a mixed-sex sample (101)(102)(103)(104)(105)(106). The average age of the participants was 27.1 years (ranging between 18 (107) and 42 years (108)).…”

“…•min −1 (109)). Seventeen studies included physically active participants (93,94,97,101,104,105,107,(110)(111)(112)(113)(114)(115)(116)(117)(118), twenty-one included recreational athletes (95, 96, 98-100, 106, 108, 119-131), and five involved professional athletes (102,109,(132)(133)(134)(135).…”

“…sufficient to orally rinse and expectorate (100,101,105,110,111,116,128,129). Menthol activates thermoreceptors located in the oral cavity, one of the most densely innervated parts of the body with several peripheral receptors (149), that my trigger an ergogenic effect (108).…”