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Assessing the efficacy of exercise training in patients with chronic disease

KOUFAKI, PELAGIA; NASH, PATRICK F.; MERCER, THOMAS H.

Medicine & Science in Sports & Exercise: August 2002 - Volume 34 - Issue 8 - p 1234-1241
CLINCIAL SCIENCES: Clinical Investigations

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. V̇O2peak determined via incremental cycle ergometer protocol, and V̇O2 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 V̇O2peak, V̇O2-VT, and V̇O2 kinetics. Post hoc analysis revealed that V̇O2peak and V̇O2 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 V̇O2peak by greater than the standard error of measurement (SEM = 0.07 L·min−1). At 6 months of training, ∼89% of the patients improved by more than the SEM V̇O2 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 V̇O2peak 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.

Centre for Biophysical and Clinical Research into Human Movement, Department of Exercise and Sport Science, Manchester Metropolitan University, Crewe and Alsager Faculty, Alsager, UNITED KINGDOM; and Department of Renal Medicine, North Staffordshire Hospital Trust, Stoke-on-Trent, UNITED KINGDOM

Submitted for publication November 2001.

Accepted for publication March 2002.

©2002The American College of Sports Medicine