Sex differences in exertional dyspnea in patients with mild COPD: physiological mechanisms

Respir Physiol Neurobiol. 2011 Aug 15;177(3):218-27. doi: 10.1016/j.resp.2011.04.011. Epub 2011 Apr 16.


The purpose of this study was to evaluate the physiological basis for sex-differences in exercise-induced dyspnea in patients with mild COPD. We compared operating lung volumes, breathing pattern and dyspnea during incremental cycling in 32 men (FEV(1)=86±10% predicted) and women (FEV(1)=86±12% predicted) with mild COPD and 32 age-matched controls. There were no sex differences in dyspnea in the control group at any work-rate or ventilation (V(E)). Women with COPD had significantly greater dyspnea than men at 60 and 80 W. At 80 W, dyspnea ratings were 5.7±2.3 and 3.3±2.5 Borg units (P<0.05) and the V(E) to maximal ventilatory capacity ratio was 72% and 55% in women and men, respectively (P<0.05). Comparable increases in dynamic hyperinflation were seen in both male and female COPD groups at symptom limitation but women reached tidal volume constraints at a lower work rate and V(E) than men. Superimposing mild COPD on the normal aging effects had greater sensory consequences in women because of their naturally reduced ventilatory reserve.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Analysis of Variance
  • Carbon Dioxide / metabolism
  • Case-Control Studies
  • Dyspnea / etiology*
  • Exercise Test / adverse effects*
  • Exercise*
  • Female
  • Forced Expiratory Volume / physiology
  • Heart Rate / physiology
  • Humans
  • Male
  • Middle Aged
  • Oxygen Consumption
  • Predictive Value of Tests
  • Pulmonary Disease, Chronic Obstructive / physiopathology*
  • Respiratory Function Tests
  • Severity of Illness Index
  • Tidal Volume / physiology


  • Carbon Dioxide