Dyspnea Reduction With L-Menthol Inhalation Improves High-Intensity Endurance Running Performance in Healthy Trained Adults.
Thiago Ribeiro Lopes, Adriano de Almeida Pereira, Felipe Silva Gomes et al.
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In 30 seconds
This randomized, counterbalanced crossover trial tested whether L-menthol inhalation reduces breathlessness and improves high-intensity running performance in 18 trained endurance runners with normal spirometry. Participants completed treadmill time-to-exhaustion tests at 85% of preliminary peak velocity after L-menthol inhalation and strawberry-scent placebo. Compared with placebo, L-menthol reduced dyspnea by approximately 1 AU (p = 0.004) and increased time to exhaustion from 406 ± 94 to 445 ± 106 s (p = 0.009). Most measured cardiorespiratory and metabolic responses did not differ between conditions.
Key findings
- L-menthol reduced dyspnea across the test by approximately 1 AU versus placebo (p = 0.004).
- Time to exhaustion was 406 ± 94 s with placebo and 445 ± 106 s with L-menthol (p = 0.009).
- Pulmonary ventilation, tidal volume, oxygen consumption, carbon dioxide production, oxygen saturation, and heart rate did not differ between conditions.
- Breathing frequency was lower with L-menthol than placebo (p = 0.045).
Why it matters
The findings suggest that perceived breathlessness may constrain high-intensity endurance performance even in trained runners without abnormal spirometry. The improvement in test duration occurred alongside reduced dyspnea, without substantial differences in most measured physiological responses. This highlights the potential contribution of perceptual factors to exercise tolerance, while the results apply to the specific population and treadmill protocol studied.
What to keep in mind
The trial included only 18 trained runners and assessed performance in a treadmill time-to-exhaustion test, limiting generalisability to other populations and exercise settings.