Assessing the efficacy of exercise training in patients with chronic disease

Abstract

KOUFAKI, P., P. F. NASH, and T. H. MERCER. Assessing the efficacy of exercise training in patients with chronic disease. Med. Sci. Sports Exerc., Vol. 34, No. 8, pp. 1234-1241, 2002.

Purpose: The purpose of this study was to evaluate the meaningfulness of exercise training responses in patients with end stage renal disease (ESRD).

Methods: Eighteen ESRD patients [(mean +/- SD); 54.3 +/- 17.1 yr] completed a training regime progressing to accumulate 40 min of stationary cycling, three times per week for 6 months. [latin capital V with dot above]O2peak determined via incremental cycle ergometer protocol, and [latin capital V with dot above]O2 kinetics determined from a transition from unloaded pedalling to an exercise intensity corresponding to 90% of VT, were assessed at baseline and at 3 and 6 months of training.

Results: Repeated measures analysis of variance revealed significant changes (P < 0.05) on the time factor for [latin capital V with dot above]O2peak, [latin capital V with dot above]O2-VT, and [latin capital V with dot above]O2 kinetics. Post hoc analysis revealed that [latin capital V with dot above]O2peak and [latin capital V with dot above]O2 kinetics significantly (P < 0.05) improved at 3 months of training with no further improvements thereafter. Analysis of individual subject response data revealed that after 3 months of training, 61% of the patients improved [latin capital V with dot above]O2peak by greater than the standard error of measurement (SEM = 0.07 L[middle dot]min-1). At 6 months of training, ~89% of the patients improved by more than the SEM [latin capital V with dot above]O2 kinetics improved by more than the SEM (12.3 s) at 3 months of training in ~55% of the patients, with no increase in the number of patients exhibiting faster time constants after 6 months of training.

Conclusion: Although conventional statistical analyses indicate that exercise training favorably alters [latin capital V with dot above]O2peak and oxygen uptake kinetics of patients with ESRD, it is apparent that considerable interindividual variability exists in the response to training. Consideration of the SEM data underscores the heterogeneity of adaptive response in this patient group and may be valuable in assessing the efficacy of therapeutic exercise rehabilitation.