Sex differences in the physiological and perceptual responses to face masks during exercise

Despite consistent evidence that face masks (FMs) increase dyspnea during exercise, few studies have examined the sex differences in the physiological and perceptual responses to FMs. In a randomized, crossover design, 32 healthy individuals (16 females; 23 ± 3 yr) completed incremental cycling tests on two visits with either no mask or a surgical FM. Dyspnea intensity and unpleasantness were assessed using the 0-10 category-ratio Borg scale. Diaphragmatic electromyography, esophageal pressure (P_eso), and transdiaphragmatic pressure (P_di) were measured using a nasogastric catheter to estimate neural inspiratory drive and respiratory muscle effort. Surface electromyography (EMG) was measured on the sternocleidomastoid and scalene muscles. FMs resulted in a steeper increase in dyspnea unpleasantness in males compared with females across the 0%-100% work rate (estimate = 1.5 CR10, P = 0.0048), with no significant difference in the effect of the FM on dyspnea intensity between sexes (P > 0.05). Males had a greater increase in P_eso and P_di with FMs compared with females across work rate (-3.8 cmH₂O, P = 0.0088; -4.7 cmH₂O, P = 0.011, respectively) and a greater increase in sternocleidomastoid activation from 40%-60% work rate (WR) (all P < 0.05). In addition, moisture accumulation pre- versus postexercise (P = 0.01) was significantly greater in males compared with females. FMs resulted in a similar absolute reduction in exercise time in both sexes although it was only statistically significant in females (P = 0.006). This study highlights that males likely experience greater dyspnea unpleasantness with FMs due to higher flows and ventilations, which increase mask resistance and, combined with greater moisture accumulation, elevate respiratory muscle effort and accessory muscle activation. Nonetheless, the absolute impact on exercise duration appears similar between sexes.NEW & NOTEWORTHY During the coronavirus disease 2019 pandemic, numerous studies evaluated the effects of face masks on the physiological and perceptual responses to exercise. However, the symptoms of breathlessness and associated physiological mechanisms were largely neglected. In addition, our understanding of whether face masks affected males and females differently was particularly limited. We found that sex-specific physiological responses can guide exercise and face mask strategies to improve comfort and performance for individuals engaging in prolonged, intense workouts.