Lung function, maximum and submaximum exercise testing in COPD patients: reproducibility over a long interval

Lung. 1989;167(4):247-57. doi: 10.1007/BF02714953.


This study was designed to investigate the reproducibility and clinical relevance of several lung function and exercise test indices in a sample of patients with stable severe chronic obstructive pulmonary disease (COPD). Twenty subjects (ages 67.8 +/- 2.0 years, forced expiratory volume in 1s, [FEV1] 39.7 +/- 2.8% predicted) receiving conventional medical therapy and pulmonary rehabilitation were tested 4 times at 1 month intervals. Testing procedures included lung function (inspiratory vital capacity [IVC], FEV1, plethysmographic functional residual capacity [FRC], specific conductance of the airways (sGaw), single breath transfer factor divided by the alveolar volume [TL/VA]); incremental, progressive, symptom-limited, cycle exercise (maximum work load [Wmax], maximum heart rate [HRmax], maximum ventilation [VEmax], maximum oxygen uptake [VO2max]); and 2 modes of submaximum exercise (12 min walking test [12 MWD] and endurance cycle test). The mean of the absolute value of the individual patient, session-to-session, variation was found to be 0.131 for FEV1, 102 ml/min for VO2max. The within-subject variability was the smallest for HRmax and IVC (mean intrasubject coefficient of variation, [CV intra] 5.0 and 6.5%) and the greatest for TL/VA, the work performed during the endurance cycle test (EW) and sGaw (CV intra 16.5, 19.4, and 22.7%), while it was reasonably low (8.1-10.2%) for all the other variables studied. Calculation of the F ratio of the intersubject variance to the residual (total minus intersubject) variance, interpreted as a signal-to-noise, ratio, yielded the following, in decreasing order: TL/VA, EW, VEmax, VO2max, IVC, FEV1, HRmax, Wmax, sGaw, 12 MWD, FRC. If we assume that a useful variable should combine a low within-subject variability (CV intra less than or equal to 10%) with a high signal-to-noise ratio, we conclude that, among all the variables studied, IVC, FEV1, VEmax, and VO2max are those with the greatest clinical potential for functional assessment in patients with COPD.

MeSH terms

  • Aged
  • Exercise Test*
  • Female
  • Humans
  • Lung Diseases, Obstructive / diagnosis*
  • Lung Diseases, Obstructive / rehabilitation
  • Male
  • Reproducibility of Results
  • Respiratory Function Tests*
  • Time Factors