The Development of a Menthol Solution for Use during Sport and Exercise

Best, Russell; Spears, Iain R.; Hurst, Philip; Berger, Nicolas

doi:10.3390/beverages4020044

Cited by 21 publications

(33 citation statements)

References 57 publications

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“…The scales were bilateral, i.e., 0 corresponded to neutral, in several studies. For example, TS was assessed with a 9-point scale ranging from very cold (− 4) to neutral (0) to very hot (4). Thus, after extrapolation of the endpoints of the original scales to 0 and 20, in case of TS the middle of the unified scale (10) represented the neutral situation and an increase in TS between 0 (very cold) and 20 (very hot) indicated a weaker cold or stronger warmth sensation.…”

Section: Discussionmentioning

confidence: 99%

Menthol can be safely applied to improve thermal perception during physical exercise: a meta-analysis of randomized controlled trials

Keringer

Farkas

Gede

et al. 2020

Sci Rep

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Menthol is often used as a cold-mimicking substance to allegedly enhance performance during physical activity, however menthol-induced activation of cold-defence responses during exercise can intensify heat accumulation in the body. This meta-analysis aimed at studying the effects of menthol on thermal perception and thermophysiological homeostasis during exercise. pubMed, EMBASE, Cochrane Library, and Google Scholar databases were searched until May 2020. Menthol caused cooler thermal sensation by weighted mean difference (WMD) of − 1.65 (95% CI, − 2.96 to − 0.33) and tended to improve thermal comfort (WMD = 1.42; 95% CI, − 0.13 to 2.96) during physical exercise. However, there was no meaningful difference in sweat production (WMD = − 24.10 ml; 95% CI, − 139.59 to 91.39 ml), deep body temperature (WMD = 0.02 °C; 95% CI, − 0.11 to 0.15 °C), and heart rate (WMD = 2.67 bpm; 95% CI − 0.74 to 6.09 bpm) between the treatment groups. Menthol improved the performance time in certain subgroups, which are discussed. Our findings suggest that different factors, viz., external application, warmer environment, and higher body mass index can improve menthol's effects on endurance performance, however menthol does not compromise warmthdefence responses during exercise, thus it can be safely applied by athletes from the thermoregulation point of view. Menthol (2-isopropyl-5-methylcyclohexanol) is a lipophilic, organic compound which can be extracted from essential oils of aromatic plants or produced synthetically 1,2. The most common naturally occurring form of menthol is the l-isomer, which is used in various products, e.g., candies, beverages, cigarettes, and toothpastes, mainly because of its cooling, analgesic, and anti-inflammatory effects 2,3. It has long been assumed that menthol might improve different aspects of physical performance such as endurance, speed, strength, and joint range of motion, consequently it is often used by athletes in the form of sprays, creams, tapes, beverages, etc. 4,5. Warming-up before an exercise is often used to optimize muscle temperature and, thereby, maximal muscle power production, however, at high ambient temperatures (T a), it increases the thermal and circulatory strain 6. Endurance exercise capacity at a high T a is impaired by heat stress prior to exercise 7 , and hyperthermia induces fatigue during short intense activities and prolonged exercise in the heat 8. On the contrary, physical cooling of the body before and during exercise in the warmth improves exercise endurance and reduces cardiovascular strain 9. A recent meta-analysis of 45 studies also concluded that physical cooling improves aerobic and anaerobic exercise performance in hot conditions 10. From animal experiments it is known that the transient receptor

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Section: Discussionmentioning

confidence: 99%

Menthol can be safely applied to improve thermal perception during physical exercise: a meta-analysis of randomized controlled trials

Keringer

Farkas

Gede

et al. 2020

Sci Rep

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“…The potential risks of oral or topical menthol application in the heat are not yet fully understood. The safety and possible toxicity of menthol containing products must also be considered, independent of mode of application, with factors such as concentration [11], surface area of topical contributors to discuss their justifications, provide clarification, and offer any required caveats to support or reject any remaining statements.…”

Section: Methodsmentioning

confidence: 99%

“…However, some studies have sought to address the effectiveness of menthol topical application during advanced thermal stress, showing some potency to extend performance [6,37]. Whilst tests conducted on elite athletes may be desirable due to their improved consistency [67], advantageous performance outcomes may be within the typical error of the test and so may be discredited, although these effects may be of practical importance [11]. Overall, further research is needed to test menthol's effectiveness in elite populations particularly in the build-up to Tokyo 2021 and beyond.…”

Section: Populationmentioning

confidence: 99%

“…As with any intervention, the use of menthol should be trialled extensively in training to determine both the ergogenic efficacy and safe implementation using verified, food-grade products [66]. It is noteworthy within rinsing protocols that a clear dose-response has yet to be identified, and thus, individual approaches are warranted above pursuing a 'more is better' approach [11]. As with thermal cooling strategies, the influence of perceptual cooling on pacing and subsequent thermoregulatory responses, i.e., increased self-selected work rate, and concurrent increases in heat production should also be examined [27].…”

Section: Health Effectsmentioning

confidence: 99%

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

et al. 2020

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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.

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“…The suggested preparation involves the addition of 0.1-0.5 g of crushed menthol crystals (dissolved in alcohol) to 1 L of water or the use of a commercial premixed menthol/alcohol solution (Stevens & Best, 2016). Light green or blue menthol solutions appear to illicit the most positive response, potentially due to their subjective qualities and association with coolness (Best et al, 2018). Extreme caution should be taken if preparing menthol solutions from basic ingredients for oral ingestion.…”

Section: Other Nutritional Strategies To Enhance Thermal Comfortmentioning

confidence: 99%

Sports Dietitians Australia Position Statement: Nutrition for Exercise in Hot Environments

McCubbin

Allanson²,

Caldwell

et al. 2020

International Journal of Sport Nutrition and Exercise Metabolism

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It is the position of Sports Dietitians Australia (SDA) that exercise in hot and/or humid environments, or with significant clothing and/or equipment that prevents body heat loss (i.e., exertional heat stress), provides significant challenges to an athlete’s nutritional status, health, and performance. Exertional heat stress, especially when prolonged, can perturb thermoregulatory, cardiovascular, and gastrointestinal systems. Heat acclimation or acclimatization provides beneficial adaptations and should be undertaken where possible. Athletes should aim to begin exercise euhydrated. Furthermore, preexercise hyperhydration may be desirable in some scenarios and can be achieved through acute sodium or glycerol loading protocols. The assessment of fluid balance during exercise, together with gastrointestinal tolerance to fluid intake, and the appropriateness of thirst responses provide valuable information to inform fluid replacement strategies that should be integrated with event fuel requirements. Such strategies should also consider fluid availability and opportunities to drink, to prevent significant under- or overconsumption during exercise. Postexercise beverage choices can be influenced by the required timeframe for return to euhydration and co-ingestion of meals and snacks. Ingested beverage temperature can influence core temperature, with cold/icy beverages of potential use before and during exertional heat stress, while use of menthol can alter thermal sensation. Practical challenges in supporting athletes in teams and traveling for competition require careful planning. Finally, specific athletic population groups have unique nutritional needs in the context of exertional heat stress (i.e., youth, endurance/ultra-endurance athletes, and para-sport athletes), and specific adjustments to nutrition strategies should be made for these population groups.

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The Development of a Menthol Solution for Use during Sport and Exercise

Cited by 21 publications

References 57 publications

Menthol can be safely applied to improve thermal perception during physical exercise: a meta-analysis of randomized controlled trials

Menthol can be safely applied to improve thermal perception during physical exercise: a meta-analysis of randomized controlled trials

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

Sports Dietitians Australia Position Statement: Nutrition for Exercise in Hot Environments

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