Multidimensional assessment of exertional dyspnea in young healthy males and females who select unsatisfied inspiration at peak exercise

Historically, it was thought that healthy humans predominantly described their breathing as a sense of increased work or effort (W/E) during maximal exercise. However, emerging data show that many healthy adults select unpleasant dyspnea descriptors such as "unsatisfied inspiration" (UI), with relatively more females selecting UI than males. We hypothesized that males and females who select UI would report higher dyspnea intensity ratings during exercise, select more distressing dyspnea qualities post exercise, and have greater inspiratory constraints than those who do not. Sixty-four healthy, nonsmokers (32 males:32 females; 23 ± 5 yr) completed questionnaires, pulmonary function tests, and maximal incremental cycling with detailed dyspnea evaluation. Males in UI and non-UI subgroups reported similar Borg 0-10 dyspnea intensity ratings of W/E, UI, and unsatisfied expiration (UE) (all P > 0.05). Females in the UI subgroup reported significantly higher UI and UE ratings than females in the non-UI subgroup (both P < 0.01). Both UI subgroups reported greater air hunger, chest tightness, and mental breathing effort than non-UI participants (all P < 0.05). In males only, masculine gender was negatively correlated (ρ = -0.402, P = 0.02) and anxiety positively correlated (ρ = 0.363, P = 0.04) with submaximal UI ratings. Females with UI had smaller peak tidal volume (Vt) [1.74 (0.32) vs. 2.06 (0.33) L, P = 0.03] than non-UI females; and Vt was negatively correlated with submaximal (ρ = -0.496, P = 0.004) and peak (ρ = -0.495, P = 0.004) UI ratings in all females. There were no differences in Vt or correlations between Vt and dyspnea in male subgroups. Absolute lung volumes and psychosocial factors appear important in understanding sex differences in the perception of UI during exercise.NEW & NOTEWORTHY The mechanisms of sex-based differences in the sensation of unsatisfied inspiration (UI) in healthy humans during exercise are poorly understood. We found that females who selected UI at peak exercise had worse dyspnea intensity ratings throughout exercise. Both sexes who selected UI at peak exercise also reported more distressing dyspnea qualities post exercise. Psychosocial factors appeared to influence male dyspnea perception, whereas smaller absolute lung volumes correlated with worse UI ratings in females.