Effect of Menthol on Dyspnea During Exercise in Individuals With COPD.

OBJECTIVE

To investigate the effects of olfactory stimulation with menthol on exertional dyspnea and physiological data during cycling exercise in patients with chronic obstructive pulmonary disease (COPD).

DESIGN

Controlled trial. Patients with COPD hospitalized for pulmonary rehabilitation performed endurance exercise training using a cycle ergometer and resistance training with and without menthol to decrease respiratory sensations.

SETTING

Three exercise sessions on a cycle ergometer.

PARTICIPANTS

Twenty-one adult patients (N=21; women; mean age ± SD, 64±8y; Global Initiative for Chronic Obstructive Lung Disease (GOLD) score IV) referred for pulmonary rehabilitation with functional chronic dyspnea (rated ≥2 on the modified Medical Research Council scale) were included.

INTERVENTIONS: Session 1 without menthol, session 2 with menthol, and session 3 without menthol.

MAIN OUTCOME MEASURES: The primary evaluation criterion was the maximum dyspnea experienced during the sessions on a cycle ergometer. Several parameters were recorded and analyzed, including oxygen saturation, heart rate, muscle fatigue (assessed using the modified Borg scale), and dyspnea, as well as the duration of exercise, power output, and distance covered on the cycle ergometer. After completing the sessions, patients were asked about their preference regarding the use of menthol (with or without).

RESULTS

Three types of patients were identified based on dyspnea during exercise: responders (n=7; 33%), partial responders (n=7; 33%), and nonresponders (n=7; 33%). The comparison between responders and nonresponders showed a significant difference regarding the oxygen flow rate during effort (2.5 [0.0-3.0] vs 0.0 [0.0-0.8] l/min; P=.04). No significant differences were found in the other parameters, even with the MDP questionnaire.

CONCLUSIONS

Menthol could be an adjuvant to exercise rehabilitation, improving exercise-induced dyspnea in patients with chronic dyspnea, particularly in patients with high oxygen flow during exercise.