The Effect of L-Menthol Application on Maximal Static and Dynamic Resistance Exercise Performance

Introduction. L-Menthol spray application to the skin enhances exercise performance in the heat by improving thermal perception and lowering the rating of perceived exertion (RPE) through evoked sensations of skin cooling. Skin cooling has also been shown to increase the rate of force development during maximal isometric contractions potentially improving performance. Yet the effect of L-Menthol spraying has never been explored on maximal dynamic or isometric exercise performance. We hypothesised an L-Menthol spray would improve lifting performance, reduce RPE and alter muscle electromyography (EMG). Method. Twelve resistance-trained male participants (aged 24 ± 4 years, body mass: 75 ± 8 kg, height: 173 ± 7 cm), volunteered following ethical approval. They completed three laboratory visits: baseline to estimate one repetition maximum (1RM) and two visits during which maximal dynamic lifting (DLT: 75% of 1RM) and isometric maximal lifting (IMLT; 3 x 3-second dynamometer lifts) were performed with either prior spraying of the legs with L-Menthol spray or a control-spray (counter-balanced and double-blind). Key measures were: Weightlifting performance, RPE, EMG and thermal comfort (TC) and sensation (TS). Data were compared using t-test and ANOVA to 0.05 alpha level. Results. L-Menthol spray improved TSlegs in the IMLT (p = .047) and improved TCwb in the IMLT (p = .039) (i.e. participants felt cooler and more comfortable) but felt no less exertion. DLT and IMLT performance were unaffected yet during IMLT, EMG activity of the rectus femoris was greater in the L-Menthol spray condition (grand mean ± SD; 3.49 ± 1.75 v and 4.36 ± 1.96 v; f(1,11) = 5.450, p = .040, ηp2 = .331, control-spray and L-Menthol spray, respectively). Discussion. L-Menthol spraying increased rmsEMG during isometric exercise implying greater muscle motor unit recruitment via the sensory-somatic neural pathway and activation of TRPM8 ion channel. L-Menthol spray may enhance the performance of longer duration static weight-lifting activities.