Spraying with 0.20% L-menthol does not enhance 5 km running performance in the heat in untrained runners.
BACKGROUND
L-Menthol stimulates cutaneous thermoreceptors and induces cool sensations improving thermal comfort but has also been linked to heat storage responses. Therefore, L-Menthol application could lead to a conflict in behavioural and thermoregulatory drivers improving comfort but leading to a higher rate of deep body temperature rise; the present study examined this possibility.


METHODS
Six untrained male participants (age 21 [1] years; height 1.80 [0.07] m; mass 78.9 [6.9] kg; surface area 1.98 [0.13] m2) took part. They completed three trials in hot conditions (34 °C) where their clothing was sprayed (CONTROL-SPRAY or MENTHOL-SPRAY) or not sprayed (CONTROL) after a fixed intensity exercise period (15-minutes), which induced thermal discomfort, before completing a 5 km treadmill time trial (TT). Thermal perception (thermal sensation and comfort; TS, TC), thermal responses (aural temperature [Tau], skin temperature [Tskin]), perceived exertion (RPE), heart rate, pacing (1 km split time) and performance (TT completion time) were measured.


RESULTS
MENTHOL-SPRAY induced improvements in TS (up to 3 km of TT) and TC (up to 1 km) with Tau showing a tendency to be higher than CONTROL-SPRAY (+0.20 [0.29] °C) and CONTROL condition (0.30 [0.34] °C); this was not statistically significant and the rate of rise in Tau was linear. Tau was continuing to rise between the 4th and 5th kilometre of the TT. The other variables were unchanged. TT completion time and pace were not different: CONTROL 27.92 [1.65], CONTROL-SPRAY 28.10 [1.12], MENTHOL-SPRAY 27.53 [2.85] minutes.


CONCLUSIONS
Spraying L-MENTHOL prior to exercise in the heat culminated in improved perception but not altered performance.
Department of Sport and Exercise Science University of Portsmouth, Portsmouth, UK - martin.barwood@northumbria.ac.uk.
M J
MJ
Barwood
J
J
Corbett
D K
DK
White
D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001833:Body Temperature Regulation; D003020:Clothing; D006339:Heart Rate / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008610:Menthol / Q000008:administration & dosage*; D010465:Perception; D005082:Physical Exertion; D012420:Running / Q000502:physiology*; D016037:Single-Blind Method; D012881:Skin Temperature; D013823:Thermoreceptors / Q000187:drug effects; D055815:Young Adult
D008610:Menthol