Variance In VO2peak Research Articles

DETERMINANTS OF VO2 PEAK IN CARDIAC REHABILITATION PATIENTS

14 The purpose of this investigation was to identify factors affecting VO2 peak measured directly during symptom-limited treadmill exercise testing at the conclusion of an early post-hospitalization (Phase II) cardiac rehabilitation program. Subjects consisted of 292 consecutive patients (51 women), age 65 ± 11 years, who completed Phase II cardiac rehabilitation after an index cardiac event (myocardial infarction, coronary angioplasty and/or coronary bypass surgery). Seventy-nine subjects had suffered a previous cardiac event and 38 were diabetic. The majority of subjects (158 of 292) took β-blocking medications and 49 (17 % of subjects) had left ventricular systolic dysfunction (ejection fraction[EF] ≤ 40%). VO2 peak ranged from 12.1 to 43.6 ml/kg/min for men (mean: 24.0 ± 5.8 ml/kg/min) and 9.6 to 35.0 ml/kg/min for women (mean: 19.6 ± 5.3 ml/kg/min). Using multivariate linear regression analysis, eight factors were found to be associated with VO2 peak: age (−0.3 ml/kg/min per year); female gender (−5.7 ml/kg/min); coronary bypass surgery as the index cardiac event (−2.6 ml/kg/min); smoking at the index event (−2.0 ml/kg/min); diabetes mellitus (−1.8 ml/kg/min); left ventricular ejection fraction (+0.07 ml/kg/min per EF unit); body weight (−0.025 ml/kg/min per kg); and peak exercise heart rate (+0.01 ml/kg/min per beat/min). Forty three percent of the variance in VO2 peak was explained by these eight factors (F=21.6, P<0.0001). These data suggest that cardiovascular fitness is poorer, after Phase II cardiac rehabilitation, in certain types of patients. Thus, exercise training may be more critical for these types of patients, and supervised exercise programs may need to be more extensive.

Prediction of Peak Oxygen Uptake from Submaximal Exercise Tests in Older Men and Women

The purpose of this study was to determine the accuracy of two submaximal exercise tests, the Sitting-Chair Step Test (Smith &amp; Gilligan. 1983) and the Modified Step Test (Amundsen, DeVahl, &amp; Ellingham, 1989) to predict peak oxygen uptake (VO2 peak) in 28 adults ages 60 to 85 years. VO2 peak was measured by indirect calorimetry during a treadmill maximal graded exercise test (VO2 peak, range 11.6–31.1 ml · kg −l · min−1). In each of the submaximal tests, VO2 was predicted by plotting stage-by-stage submaximal heart rate (HR) and perceived exertion (RPE) data against VO2 for each stage and extrapolating the data to respective age-predicted maximal HR or RPE values. In the Sitting-Chair Step Test (n = 23), no significant differences were observed between measured and predicted VO2 peak values (p &gt; .05). However, predicted VO2 peak values from the HR were 4.3 ml · kg−1 · min−1 higher than VO2 peak values predicted from the RPE data (p &lt; .05). In the Modified Step Test (n = 22), no significant differences were observed between measured and predicted VO2 peak values (p &gt; .05). Predictive accuracy was modest, explaining 49–78% of the variance in VO2 peak. These data suggest that the Sitting-Chair Step Test and the Modified Step Test have moderate validity in predicting VO2 peak in older men and women.