A symptom-limited incremental step test determines maximum physiological responses in patients with chronic obstructive pulmonary disease

Respir Med. 2013 Dec;107(12):1993-9. doi: 10.1016/j.rmed.2013.06.013. Epub 2013 Jul 14.


Background: Step tests have been used to evaluate exercise tolerance and effort-related hypoxemia in different diseases. A symptom-limited incremental step test (IST) has never been tested in COPD patients.

Aim: To compare maximal physiological responses between an IST and cardiopulmonary exercise testing (CPET), to test the reproducibility of the IST on different days, and to provide a predict equation to estimate VO2 from the IST in patients with COPD.

Material and methods: At the same day, thirty-four patients (VEF1 46 ± 14% of pred) underwent a CPET on cycle ergometer and the first IST (IST-1) (1 h apart). After 2-5 days, patients repeated the IST (IST-2). Pulmonary gas exchange was measured during all tests.

Results: Peak VO2 was significantly higher in IST-1 and IST-2 than in CEPT (Mean ± SD: 1.19 ± 0.39 L, 1.20 ± 0.40 L, 1.07 ± 0.35 L) with no difference for ventilation (VE), heart rate (HR), and perception of effort. ISTs were highly reproducible, with significant intraclass correlation coefficient (CCI [95% confidence interval]) for number of steps (0.98[0.95-0.99]), VO2 (0.99 [0.98-0.99]), VE (0.97[0.93-0.99]), HR (0.92[0.81-0.97]), and SpO2 (0.96[0.90-0.98]). Desaturation was significantly higher for IST-1 and IST-2 compared with cycling (Mean ± SD: -6 ± 5%, -6 ± 4%, -3 ± 3%). Number of steps and patient weight explained 81% of the variance in peak VO2 (p < 0.001).

Conclusion: A symptom-limited incremental step test, externally paced, elicits maximal cardiopulmonary and metabolic responses, and is well tolerated and reproducible in patients with COPD.

Keywords: COPD; Cardiopulmonary exercise test; Exercise tolerance; Field test; Oxygen uptake; Step test.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Exercise Test / methods
  • Exercise Tolerance / physiology*
  • Forced Expiratory Volume / physiology
  • Humans
  • Male
  • Oxygen Consumption / physiology
  • Prospective Studies
  • Pulmonary Disease, Chronic Obstructive / physiopathology*
  • Pulmonary Gas Exchange / physiology
  • Vital Capacity / physiology
  • Walking / physiology