D. Cooper, A. Grebe, F. Roe, S. Teno, W.M. Silvers

Whitworth University, Spokane, WA

There is little empirical support for the notion that menthol can improve respiratory function and breathing quality, despite popular beliefs to the contrary. PURPOSE: The purpose of this study was to investigate the effects of a menthol lozenge on spirometry parameters and perceived breathing quality. METHODS: Fifty-six, college-aged, male and female students (nm = 26, nf= 30), with no previous chronic respiratory diseases, completed a repeated measures spirometry test to obtain forced vital capacity (FVC) and forced expiratory volume (FEV1.0) under the influence of a menthol lozenge for one session and a control with no lozenge for the repeated measure. Participants evaluated their quality of breathing via visual analogue scale (VAS) after five-min of rest. Participants were given either a menthol lozenge (M), which contained 15 mg of menthol or were told to wait for six-min in place (C) of the time taken to consume the lozenge for the control session. Prior to the spirometry test, participants evaluated their breathing again via VAS. Then, the participants performed three spirometry tests. After each test, the participants evaluated their breathing quality with the VAS. Wilcoxon signed-rank tests (significance level p< 0.05) were utilized to inferentially compare experimental conditions for all dependent variables. RESULTS: There were no significant differences between C and M conditions for pre-resting VAS, FVC, and FEV1.0(p = 0.760 - 0.913). Nevertheless, there were significant differences observed between conditions for both post-resting VAS scores (C 70.99±16.49%, M 78.74±14.21%; p= 0.00) and forced VAS scores (C 68.67 ± 16.61%, M 72.80 ± 17.99%; p = 0.002). CONCLUSION: Menthol lozenges did not improve scores for spirometry tests under the examined research conditions. However, the menthol lozenges appeared to improve the participants’ perceived breathing quality. The primary explanation for the observed results was that menthol lozenges induced a possible placebo effect. Further research should include a larger sample size, sample populations with obstructive respiratory disease, larger dosage of menthol, administration techniques, or the underlying physiological function that contributed to better perceived breathing.

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