Athlete perceptions of flavored, menthol-enhanced energy gels ingested prior to endurance exercise in the heat

ABSTRACT

Background

L-menthol evokes a cooling sensation by activating cold sensing cation channels. Menthol-enhanced fluids can be ergogenic during exercise in the heat by improving thermal perception; hence, the addition of menthol to energy gels may benefit athletes. Previously, unflavored menthol gels were deemed acceptable at 0.1% concentration, but no research has been undertaken on menthol gels with additional flavoring. Therefore, we determined athlete perceptions of flavored energy gels with different menthol concentrations.

Methods

With a randomized, crossover, double-blind, placebo-controlled design, 27 athletes (34.8 ± 6.7 y, 9 females) ingested an energy gel with either 0.1%, 0.3%, 0.5%, or 0.7% menthol concentration, or a non-menthol, flavor-matched placebo (CON), on separate occasions before outdoor exercise. Gels were rated for cooling sensation, irritation, flavor, and overall experience on 100-point sensory and hedonic labeled magnitude scales. The duration of any cooling sensation was also reported.

Results

All menthol gels delivered a greater cooling sensation compared to CON (7.4 ± 8.1 AU) with a significantly greater response for 0.7% (59.9 ± 20.5 AU) and 0.5% (57.7 ± 21.8 AU), compared to all others. Irritation was higher for all menthol gels compared to CON (3.4 ± 7.2 AU) and for 0.7% compared to 0.1% (31.1 ± 31.0 vs. 16.3 ± 21.0 AU, p = 0.041), with none rated above a ‘mild-moderate’ intensity. The menthol gels delivered a significantly longer cooling sensation duration (12.3-19.6 min) versus CON (2.2 ± 4.8 min) with no difference between menthol gels.

Conclusion

A flavored menthol energy gel at 0.1–0.7% concentration provides a cooling sensation for athletes when ingested before exercise. The 0.5% concentration is recommended to maximize the cooling sensation whilst minimizing irritation.

KEYWORDS:

• Endurance
• cooling
• thermal perception
• supplement
• mint

Acknowledgments

The authors gratefully acknowledge the participants, as well as Brandon Kirchmeyer and GU Energy Labs for producing the energy gels used in this study.

Authorship

Conceptualization, R.M.V., C.J.S., and M.L.R.; Methodology, R.M.V., C.J.S., and M.L.R.; Investigation, R.M.V., J.E.R., and C.J.S.; Writing—Original draft, R.M.V.; Writing—Review & editing, R.M.V., C.J.S., C.S., J.E.R., and M.L.R. Visualization, R.M.V.; Supervision, C.J.S., C.S., and M.L.R. All authors approved the final version of this paper.

Disclosure statement

R.M.V. is an employee of GU Energy Labs.