REF-964 · Zhu et al., 2026 · Frontiers in Nutrition, Vol. 13, article · Paper · PubMed

Effects of different menthol administration routes on endurance performance and physiological responses in the heat: a network meta-analysis

A-fairly strong evidenceMeasured on a mixed groupWritten before October 2026, being re-checked

A network meta-analysis ranking three ways of taking menthol — swallowing it (ingestion, ING), rinsing the mouth (MR) and applying it to the skin (topical, Top) — for exercise performance and physiological responses in hot conditions. Randomized controlled trials run at T≥25 °C were sought in PubMed, Embase, Web of Science and CNKI up to March 2, 2026.

The 15 included trials showed trends that differed by outcome, but most pairwise comparisons were not statistically significant. On SUCRA ranking, ingestion leaned toward a possible improvement in endurance performance (SUCRA = 76.1%) and mouth rinsing toward higher mean power output (SUCRA = 66.9%).

Every route had only a modest effect on core temperature and heart rate, with no statistically significant difference from control; ingestion ranked relatively high for maintaining core temperature (SUCRA = 67.0%), while topical application had the weakest thermoregulatory potential (SUCRA = 6.2%) and may even nudge temperature slightly upward because it physically obstructs heat loss.

Participants

15 randomized controlled trials in hot environments (T≥25 °C). Participant numbers, sex and training level are not given in the abstract.

Protocol

Databases: PubMed, Embase, Web of Science and CNKI; search deadline March 2, 2026.
Included: randomized controlled trials of menthol interventions on exercise performance in hot environments (T≥25 °C).
Two reviewers independently screened, extracted data and assessed risk of bias (Cochrane RoB 2.0).
Network meta-analysis in Stata 18.0; routes ranked by surface under the cumulative ranking curve (SUCRA).

Key Results

OutcomeRoute ranked highest / lowestSUCRA
Endurance performanceIngestion — "potential trend"76.1%
Mean power outputMouth rinsing — "tendency"66.9%
Maintaining core temperatureIngestion — relatively higher67.0%
ThermoregulationTopical application — weakest6.2%
Most pairwise comparisons did not reach statistical significance; the evidence "does not establish definitive superiority among the administration routes".
The impact of all routes on core temperature and heart rate was modest and lacked statistically significant differences compared to control conditions.
The authors suggest topical menthol may even nudge temperature slightly upward, as it physically blocks heat dissipation.
Authors' safety conclusion: menthol may mask true thermal sensation while leaving objective physiological heat strain unrelieved, so in practice its use must go together with objective physiological monitoring to keep exercise safe.

Practical Application

Across 15 randomized trials in the heat (T≥25 °C; network meta-analysis), no menthol route was established as superior — most pairwise comparisons were not significant — but the rankings put ingestion first for endurance performance (SUCRA = 76.1%) and mouth rinsing first for mean power output (SUCRA = 66.9%), and topical application last for thermoregulation (SUCRA = 6.2%), with a possible slight upward trend in temperature. To "drink it, rinse it or put it on the skin?": if menthol is used at all on a hot day, the internal routes rank ahead of the skin, and that ranking is a trend, not a proven difference.
The authors suggest ingestion as an exploratory option for long-duration endurance events and mouth rinsing for tasks focused on instantaneous power output; they call both exploratory.
Safety, from the authors' conclusion: menthol may mask how hot the athlete feels without reducing physiological heat strain, so it must be combined with objective physiological monitoring.
Not from this paper: mouth rinsing alone pooled across temperatures showed no significant effect (REF-962); topical application alone is in REF-963; the cooling methods that do lower heat strain are in REF-111 and REF-112; the base's protocol is in SYNTH-25.

Limitations

Most pairwise comparisons were not significant; SUCRA values rank the routes without showing that any differs from another or from control.
15 trials split across three routes and several outcomes; participant numbers are not in the abstract.
No dose, concentration or timing; the explanation for the topical temperature trend (obstructed heat dissipation) is the authors' interpretation.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

network meta-analysis of 15 randomized trials in which most pairwise comparisons did not reach statistical significance; the rankings are trends, not established differences