Dysanapsis and the resistive work of breathing during exercise in healthy men and women

• Published in: Journal of applied physiology (1985) Vol. 119; no. 10; pp. 1105 - 1113
• Main Authors: Dominelli, Paolo B., Molgat-Seon, Yannick, Bingham, Derek, Swartz, Philippa M., Road, Jeremy D., Foster, Glen E., Sheel, A. William
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 15.11.2015
• Subjects: Adult; Biological effects; Exercise; Exercise - physiology; Expiratory Reserve Volume - physiology; Female; Gender differences; Humans; Male; Middle Aged; Organ Size - physiology; Pulmonary Ventilation - physiology; Respiration; Respiratory Mechanics - physiology; Sex Characteristics; Statistical models; Viscoelasticity; Work of Breathing - physiology; Young Adult; airways; mechanical ventilatory constraints; sex differences; expiratory flow limitation
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00409.2015

We asked if the higher work of breathing (W b ) during exercise in women compared with men is explained by biological sex. We created a statistical model that accounts for both the viscoelastic and the resistive components of the total W b and independently compares the effects of biological sex. We applied the model to esophageal pressure-derived W b values obtained during an incremental cycle test to exhaustion. Subjects were healthy men ( n = 17) and women ( n = 18) with a range of maximal aerobic capacities (V̇o 2 max range: men = 40-68 and women = 39–60 ml·kg −1 ·min −1 ). We also calculated the dysanapsis ratio using measures of lung recoil and forced expiratory flow as index of airway caliber. By applying the model we found that the differences in the total W b during exercise in women are due to a higher resistive W b rather than viscoelastic W b . We also found that the higher resistive W b is independently explained by biological sex. To account for the known effect of lung volumes on the dysanapsis ratio we compared the sexes with an analysis of covariance procedures and found that when vital capacity was accounted for the adjusted mean dysanapsis ratio is statistically lower in women (0.17 vs. 0.25 arbitrary units; P < 0.05). Our collective findings suggest that innate sex-based differences may exist in human airways, which result in significant male-female differences in the W b during exercise in healthy subjects.