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J Appl Physiol (1985). 2018 Apr 1;124(4):1092-1106. doi: 10.1152/japplphysiol.00608.2017. Epub 2017 Dec 14.

The effects of age and sex on mechanical ventilatory constraint and dyspnea during exercise in healthy humans.

Author information

1
School of Kinesiology, University of British Columbia , Vancouver , Canada.
2
Centre for Heart and Lung Innovation, St. Paul's Hospital , Vancouver , Canada.
3
Division of Family Medicine, Faculty of Medicine, University of British Columbia , Vancouver , Canada.
4
Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia , Kelowna , Canada.
5
Centre for Human Performance, Exercise and Rehabilitation, College of Health and Life Sciences, Brunel University London , Uxbridge , United Kingdom.
6
Division of Respiratory Medicine, Faculty of Medicine, University of British Columbia , Vancouver , Canada.

Abstract

We examined the effects of age, sex, and their interaction on mechanical ventilatory constraint and dyspnea during exercise in 22 older (age = 68 ± 1 yr; n = 12 women) and 22 younger (age = 25 ± 1 y, n = 11 women) subjects. During submaximal exercise, older subjects had higher end-inspiratory (EILV) and end-expiratory (EELV) lung volumes than younger subjects (both P < 0.05). During maximal exercise, older subjects had similar EILV ( P > 0.05) but higher EELV than younger subjects ( P < 0.05). No sex differences in EILV or EELV were observed. We noted that women had a higher work of breathing (Wb) for a given minute ventilation (V̇e) ≥65 l/min than men ( P < 0.05) and older subjects had a higher Wb for a given V̇e ≥60 l/min ( P < 0.05). No sex or age differences in Wb were present at any submaximal relative V̇e. At absolute exercise intensities, older women experienced expiratory flow limitation (EFL) more frequently than older men ( P < 0.05), and older subjects were more likely to experience EFL than younger subjects ( P < 0.05). At relative exercise intensities, women and older individuals experienced EFL more frequently than men and younger individuals, respectively (both P < 0.05). There were significant effects of age, sex, and their interaction on dyspnea intensity during exercise at absolute, but not relative, intensities (all P < 0.05). Across subjects, dyspnea at 80 W was significantly correlated with indexes of mechanical ventilatory constraint (all P < 0.05). Collectively, our findings suggest age and sex have significant impacts on Wb, operating lung volumes, EFL, and dyspnea during exercise. Moreover, it appears that mechanical ventilatory constraint may partially explain sex differences in exertional dyspnea in older individuals. NEW & NOTEWORTHY We found that age and sex have a significant effect on mechanical ventilatory constraint and the perception of dyspnea during exercise. We also observed that the perception of exertional dyspnea is associated with indexes of mechanical ventilatory constraint. Collectively, our results suggest that the combined influences of age and biological sex on mechanical ventilatory constraint during exercise contributes, in part, to the increased perception of dyspnea during exercise in older women.

KEYWORDS:

aging; dyspnea; exercise; expiratory flow limitation; operating lung volumes; respiratory mechanics; sex differences; work of breathing

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