Influence of diaphragmatic mobility on exercise tolerance and dyspnea in patients with COPD

Respir Med. 2007 Oct;101(10):2113-8. doi: 10.1016/j.rmed.2007.05.024. Epub 2007 Jul 20.


Background: Patients with chronic obstructive pulmonary disease (COPD) present increased airway resistance, air trapping, pulmonary hyperinflation, and diaphragm muscle alterations, all of which affect pulmonary mechanics.

Purpose: To evaluate the influence diaphragmatic mobility has on exercise tolerance and dyspnea in patients with COPD.

Materials and methods: Fifty-four COPD patients with lung hyperinflation were evaluated to assess pulmonary function, diaphragm mobility, exercise tolerance, and dyspnea (score). Twenty healthy (age- and body mass index-matched) subjects were evaluated as controls.

Results: The COPD patients presented lower diaphragmatic mobility than did the controls (36.27+/-10.96 mm vs. 46.33+/-9.46 mm). Diaphragmatic mobility presented a linear correlation with distance covered on the 6-min walk test (6MWT) (r=0.38; p=0.005) and a negative correlation with dyspnea (r=-0.36; p=0.007). Patients were then divided into two subgroups based on the degree of diaphragmatic mobility: G1 (<or=33.99 mm) and G2 (>or=34 mm). Those in G1 presented poorer 6MWT performance and greater dyspnea upon exertion than did those in G2 (distance covered on the 6MWT: 454.76+/-100.67 m vs. 521.63+/-70.82 m; dyspnea score: 5.22+/-3.06 vs. 3.48+/-2.77). The G1 patients also presented greater residual volume (in liters) and lower maximal voluntary ventilation (in % of predicted values) than did the G2 patients (266.20+/-55.30 vs. 209.74+/-48.49 and 39.00+/-14.94 vs. 58.11+/-20.96).

Conclusion: Diaphragmatic mobility influences dyspnea and exercise tolerance in patients with COPD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Diaphragm / physiopathology*
  • Dyspnea / physiopathology*
  • Exercise Test / methods
  • Exercise Tolerance / physiology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Pulmonary Disease, Chronic Obstructive / physiopathology*
  • Spirometry / methods
  • Walking / physiology