Topical application of isolated menthol and combined menthol‐capsaicin creams: Exercise tolerance, thermal perception, pain, attentional focus and thermoregulation in the heat

Abstract

ABSTRACTWe determined the effects of topically applied (i) isolated menthol cream, (ii) menthol and capsaicin co‐application or (iii) placebo cream on exercise tolerance, thermal perception, pain, attentional focus and thermoregulation during exercise in the heat. Ten participants cycled at 70% maximal power output until exhaustion in 35°C and 20% relative humidity after application of (i) 5% isolated menthol, (ii) 5% menthol and 0.025% capsaicin co‐application or (iii) placebo cream. Thermo‐physiological responses were measured during exercise, with attentional focus and pain determined post‐exercise on a 0‐to‐10 scale. Across the three conditions, time to exhaustion was 13.4 ± 4.8 min, mean ± SD infrared tympanic and skin temperature was 37.2 ± 0.6°C and 35.1 ± 1.2°C, respectively, and heart rate was 152 ± 47 bpm, with no changes between conditions (p > 0.05). Perceived exertion was lower in the isolated menthol vs. all other conditions (p < 0.05, ηp2 = 0.44). Thermal sensation was higher in menthol‐capsaicin co‐application vs. isolated menthol (p < 0.05, d = 1.1), while sweat rate was higher for capsaicin and menthol co‐application compared to menthol (p < 0.05, d = 0.85). The median and interquartile range scores for pain were lower (p < 0.05) in the menthol condition (8, 7–8) compared to both menthol and capsaicin (10, 9–10) and placebo (9, 9–10), which was coupled with a greater distraction (p < 0.05) in the menthol condition (9, 7–10) compared to placebo (6, 5–7). Despite no performance effects for any topical cream application condition, these data reiterate the advantageous perceptual and analgesic role of menthol application and demonstrate no advantage of co‐application with capsaicin.