Encouraged 6-min walking test indicates maximum sustainable exercise in COPD patients.

Abstract

STUDY OBJECTIVES:

In patients with moderate-to-severe COPD, an encouraged 6-min walking test (6MWT) is a high-intensity submaximal exercise protocol that shows an oxygen uptake (Vo(2)) plateau after the third minute of the test. This last feature prompted the hypothesis that self-paced walking speed is set to achieve "maximal" sustainable Vo(2), namely "critical power" or "critical speed."

PATIENTS AND METHODS:

Eight patients with moderate-to-severe COPD (mean age, 68 +/- 7 years [+/- SD]; FEV(1), 50 +/- 13% predicted; Pao(2), 69 +/- 8 mm Hg) underwent the following tests on different days in order: (1) encouraged 6MWT; (2) standard incremental shuttle test to identify peak walking speed; (3) four different high-intensity, constant walking speed tests to exhaustion to calculate critical walking speed; and (4) timed walking test at critical walking speed (CWS) to examine sustainability of the exercise.

RESULTS:

6MWT and CWS showed similar results (mean of last 3 min): Vo(2) (1,605 +/- 304 mL/min vs 1,584 +/- 319 mL/min), minute ventilation (47 +/- 12 L/min vs 48 +/- 11 L/min), respiratory exchange ratio (0.89 +/- 0.1 vs 0.90 +/- 0.1), heart rate (130 +/- 18 beats/min vs 131 +/- 16 beats/min), Borg dyspnea score (5.4 +/- 1.3 vs 5.5 +/- 2.4), and walking speed (1.49 +/- 0.1 m/s vs 1.44 +/- 0.1 m/s, respectively).

CONCLUSION:

This study supports that 6MWT indicates maximum sustainable exercise that might be related with its predictive value in COPD patients.

• Authors: Alejandro Casas, Jordi Vilaro, Roberto Rabinovich, Anamaria Mayer, Joan Albert Barberà, Robert Rodriguez-Roisin, Josep Roca
• Journal: Chest (Chest) Vol. 128 Issue 1 Pg. 55-61 (Jul 2005) ISSN: 0012-3692 [Print] United States
• PMID: 16002916 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Aged
• Analysis of Variance
• Exercise Test (methods)
• Exercise Tolerance (physiology)
• Humans
• Male
• Middle Aged
• Oxygen Consumption
• Pulmonary Disease, Chronic Obstructive (physiopathology)
• Respiratory Function Tests
• Walking (physiology)