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Introduction: In warm conditions topical application of menthol increases cool sensations and influences deep body temperature. The purpose of this experiment was to explore whether different body surface areas (BSA) exposed to menthol influence these responses. It was hypothesized that the forcing function exerted by menthol will be proportionally related to BSA., Method: Using a within-participant design, 13 participants underwent three BSA exposures (Small [S; finger]; Medium [M; arm]; Large [L; upper/lower body]) to 4.13% menthol, and one Placebo exposure. During each exposure participants rested supine in a tent (30 °C, 50%rh) for 30-min before their intervention and 30-min thereafter. Measures included thermal sensation, thermal comfort, irritation, skin blood flow (finger SkBF; laser Doppler flowmetry), rectal temperature (Tre), and skin temperature (chest, forearm, thigh, calf). The Area Under the Curve from minute 30 to 60 was calculated and analyzed using a one-way ANOVA or Friedman's test with post-hoc testing (0.05 alpha level)., Results: There was no significant difference in any measure of thermometry (p > 0.05), while SKBF was significantly lowered in L, M, and S vs. P respectively (p < 0.05). Participants in L felt cooler vs. P and S (p < 0.05). Losses in thermal comfort were noted in L and M vs. P and S (p < 0.05), along with increased irritation in L vs. S (p < 0.05)., Conclusions: Despite similar skin temperatures, larger BSA's exposed to menthol caused cooler sensations, likely due to the activation of a larger pool of menthol-sensitive neurons. This occurred in the absence of thermal discomfort and without perceptions of irritation exceeding 'weak'. Larger BSA's also exhibited greater alterations in Tre, likely driven by a reduction in SkBF, but despite this mean body temperature was regulated suggesting the thermoregulatory system can cope with the range of BSA exposures studied herein., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Introduction: This study assessed the influence of High (H, 4.13%), Medium (M, 2.0%) and Low (L, 0.1%) doses of menthol on temperature perception and regulation, compared to a Placebo Condition (P)., Method: Sixteen participants underwent the aforementioned conditions on four separate days. During each test participants rested supine (Environmental conditions: 30 °C, 50% rh) for 30-min before 40 mL of L, M, H or P gel was applied to the anterior upper body, then rested 30-min thereafter. Primary measures included thermal sensation (TS), thermal comfort (TC), irritation (IRR), rectal temperature (Tre), and skin temperature (chest, forearm, thigh, calf), and EMG (trapezius, pectoralis major, sternocleidomastoid). The area under the curve (AUC) from minute 30 to 60 was compared between conditions using relevant non/parametric tests (alpha level = 0.05)., Results: A cooling trend in Tre was observed following Placebo gel application, but this significantly (p < 0.05) reversed into a heat storage response in M and H. Both TS and TC significantly differed by condition (p < 0.001) in a dose-dependent manner, with L, M, and H doses eliciting significantly cooler sensations and more discomfort than P (p < 0.05). Irritation significantly differed by condition (p < 0.01) in a dose-dependent manner, with L and M eliciting significantly greater irritation than P (p < 0.01). No other differences were observed., Conclusions: Menthol exerts perceptual and thermoregulatory effects independent of skin temperature. A menthol dose-dependent perceptual cooling effect was evident with possible saturation at the moderate dose. A dose-dependent alteration in deep body temperature was also evident., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Unlabelled: This study assessed whether donning a garment saturated with menthol and ethanol (M/E) can improve evaporative cooling and thermal perceptions versus water (W) or nothing (CON) during low intensity exercise and rest in warm, humid conditions often encountered in recreational/occupational settings. It was hypothesised there would be no difference in rectal (Tre) and skin (Tsk) temperature, infra-red thermal imagery of the chest/back, thermal comfort (TC) and rating of perceived exertion (RPE) between M/E, W and CON, but participants would feel cooler in M/E versus W or CON., Methods: Six volunteers (mean [SD] 22 [4] years, 72.4 [7.4] kg and 173.6 [3.7] cm) completed (separate days) three, 60-min tests in 30°C, 70%rh, in a balanced order. After 15-min of seated rest participants donned a dry (CON) or 80mL soaked (M/E, W) long sleeve shirt appropriate to their intervention. They then undertook 30-min of low intensity stepping at a rate of 12steps/min on a 22.5cm box, followed by 15-min of seated rest. Measurements included heart rate (HR), Tre, Tsk (chest/back/forearm), thermal imaging (back/chest), thermal sensation (TS), TC and RPE. Data were reported every fifth minute as they changed from baseline and the area under the curves were compared by condition using one-way repeated measures ANOVA, with an alpha level of 0.05., Results: Tre differed by condition, with the largest heat storage response observed in M/E (p<0.05). Skin temperature at the chest/back/forearm, and thermal imaging of the chest all differed by condition, with the greatest rate of heat loss observed in W and M/E respectively (p<0.01). Thermal sensation differed by condition, with the coolest sensations observed in M/E (p<0.001). No other differences were observed., Conclusions: Both M/E and W enhanced evaporative cooling compared CON, but M/E causes cooler sensations and a heat storage response, both of which are likely mediated by menthol., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

A single exposure to menthol can, depending on concentration, enhance both cool sensations and encourage body heat storage. This study tested whether there is an habituation in either response after repeated-daily exposures. Twenty-two participants were assigned to one of three spray groups: Control (CON; n=6), 0.05% L-menthol (M(0.05%); n=8), and 0.2% L-menthol (M(0.2%); n=8). On Monday (20°C, 50% rh) participants were sprayed with 100 mL of solution and undertook 40 min of cycling at 45% of their peak power (Ex1), from Tuesday to Thursday (30°C, 50% rh) they were sprayed twice daily whilst resting (R1 to R6), Friday was a repeat of Monday (Ex2). Thermal sensation (TS), thermal comfort, perceived exertion, irritation, rectal and skin temperature (Tsk), skin blood flow (SkBF) and sweat rate were monitored. A two-way ANOVA (alpha=0.05) compared responses from the beginning (Ex1, R1) and end (Ex2, R5) of the testing week. M(0.2%) induced significantly (P<0.05) cooler TS at the beginning of the week (Ex1, R1) compared to the end (Ex2, R5), indicating habituation of TS; this was not observed in M(0.05%). No other perceptual or physiological responses habituated. 0.2% Menthol caused a heat storage response, mediated by vasoconstriction, at the beginning and end of the week, suggesting the habituation of TS occurred in a pathway specific to sensation. In summary, the cooling influence of 0.2% menthol habituates after repeated-daily exposures, but with no habituation in heat storage., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Menthol has recently been added to various cooling products that claim to enhance athletic performance. This study assessed the effect of two such solutions during exercise in warm, humid conditions. Twelve participants (22 ± 2.9 years; VO2peak 47.4 ± 6.2 mL kg(-1) min(-1)) completed a peak power (PO(peak)) test and three separate exercise bouts in 30°C and 70% relative humidity after being sprayed with 100 mL of water containing either 0.05 or 0.2% l-menthol, or a control spray. During each trial, participants underwent 15 min of rest, spraying, 15 min of rest and 45 min of exercise at 45% of PO(peak). The following variables were measured: rectal temperature (T (re)), sweat rate (SR), skin blood flow (SBF), heart rate (HR), thermal comfort (TC) and sensation (TS) votes, irritation (IRR) and rating of perceived exertion (RPE). Mean skin (MST) and body temperatures (Tbody) were calculated. There was no significant difference in MST, Tbody SR, SBF, HR, TC or RPE between conditions. Spraying with 0.2% menthol significantly (P < 0.05) elevated T (re) by 0.2°C compared to the other conditions. Both menthol sprays caused participants to feel significantly cooler than control spraying (P = 0.001), but 0.2% spraying induced significantly cooler sensations (P = 0.01) than 0.05% spraying. Both menthol sprays induced greater irritation (P < 0.001) than control spraying. These findings suggest that 0.05% menthol spraying induced cooler upper body sensations without measurable thermoregulatory impairment. T (re) was significantly elevated with 0.2% spraying. Irritation persisted with both menthol sprays while TC remained unchanged, suggesting a causal relationship. The use in sport of a spray similar to those tested here remains equivocal.

A single exposure to menthol can, depending on concentration, enhance both cool sensations and encourage body heat storage. This study tested whether there is an habituation in either response after repeated-daily exposures. Twenty-two participants were assigned to one of three spray groups: Control (CON; n = 6), 0.05% l -menthol (M 0.05% ; n = 8), and 0.2% l -menthol (M 0.2% ; n = 8). On Monday (20 °C, 50% rh) participants were sprayed with 100 mL of solution and undertook 40 min of cycling at 45% of their peak power (Ex 1 ), from Tuesday to Thursday (30 °C, 50% rh) they were sprayed twice daily whilst resting (R 1 to R 6 ), Friday was a repeat of Monday (Ex 2 ). Thermal sensation (TS), thermal comfort, perceived exertion, irritation, rectal and skin temperature (T sk ), skin blood flow (SkBF) and sweat rate were monitored. A two-way ANOVA (alpha = 0.05) compared responses from the beginning (Ex 1 , R 1 ) and end (Ex 2 , R 5 ) of the testing week. M 0.2% induced significantly ( P < 0.05) cooler TS at the beginning of the week (Ex 1 , R 1 ) compared to the end (Ex 2 , R 5 ), indicating habituation of TS; this was not observed in M 0.05% . No other perceptual or physiological responses habituated. 0.2% Menthol caused a heat storage response, mediated by vasoconstriction, at the beginning and end of the week, suggesting the habituation of TS occurred in a pathway specific to sensation. In summary, the cooling influence of 0.2% menthol habituates after repeated-daily exposures, but with no habituation in heat storage. [ABSTRACT FROM AUTHOR]