Reliability of isokinetic strength and aerobic power testing for patients with chronic heart failure
Selig, S and Carey, MF and Menzies, DG and Patterson, J and Geerling, RH and Williams, AD and Bamroongsuk, V and Toia, D and Krum, H and Hare, DL, Reliability of isokinetic strength and aerobic power testing for patients with chronic heart failure, Journal of Cardiopulmonary Rehabilitation, 22, (4) pp. 282-289. ISSN 0883-9212 (2002) [Refereed Article]
PURPOSE: The objective of this study was to assess the reliability of testing skeletal muscle strength and peak aerobic power in a clinical population of patients with chronic heart failure (CHF). METHODS: Thirty-three patients with CHF (New York Heart Association (NYHA) Functional Class 2.3 ± 0.5; left ventricular ejection fraction 27% ± 7%; age 65 ± 9 years; 28:5 male-female ratio) underwent two identical series of tests (T1 and T2), 1 week apart, for strength and endurance of the muscle groups responsible for knee extension/flexion and elbow extension/flexion. The patients also underwent two graded exercise tests on a bicycle ergometer to measure peak oxygen consumption (VO 2peak ). Three months later, 18 of the patients underwent a third test (T3) for each of the measures. Means were compared using MANOVA with repeated measures for strength and endurance, and ANOVA with repeated measures for VO 2peak . RESULTS: Combining data for all four movement patterns, the expression of strength increased from T1 to T2 by 12% ± 25% (P < .001; intraclass correlation coefficient [ICC] = 0.89). Correspondingly, endurance increased by 13% ± 23% (P = .004; ICC = 0.87). Peak oxygen consumption was not significantly different (16.2 ± 0.8 and 16.1 ± 0.8 mL·kg -1 ·min -1 for T1 and T2, respectively; P = .686; ICC = 0.91). There were no significant differences between T2 and T3 for strength (2% ± 17%; P = .736; ICC = 0.92) or muscle endurance (-1% ± 15%; P = .812; ICC = 0.96), but VO 2peak decreased from 16.7 ± 1.2 to 14.9 ± 0.9 mL·kg -1 ·min -1 (-10% ± 18%; P = .021; ICC = 0.89). CONCLUSIONS: These data suggest that in a population of patients with CHF, a familiarization trial for skeletal muscle strength testing is necessary. Although familiarization is not required for assessing oxygen consumption as a single measurement, VO 2peak declined markedly in the 3-month period for which these patients were followed. Internal consistency within patients was high for the second and third strength trials and the first and second tests of VO 2peak .