Reproducibility of onset and recovery oxygen uptake kinetics in moderately impaired patients with chronic heart failure

Oxygen (O2) kinetics reflect the ability to adapt to or recover from exercise that is indicative of daily life. In patients with chronic heart failure (CHF), parameters of O2 kinetics have shown to be useful for clinical purposes like grading of functional impairment and assessment of prognosis. This study compared the goodness of fit and reproducibility of previously described methods to assess O2 kinetics in these patients. Nineteen CHF patients, New York Heart Association class II–III, performed two constant-load tests on a cycle ergometer at 50% of the maximum workload. Time constants of O2 onset- and recovery kinetics (τ) were calculated by mono-exponential modeling with four different sampling intervals (5 and 10 s, 5 and 8 breaths). The goodness of fit was expressed as the coefficient of determination (R2). Onset kinetics were also evaluated by the mean response time (MRT). Considering O2 onset kinetics, τ showed a significant inverse correlation with peak- \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} \ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}}_{2} \end{document} (R = −0.88, using 10 s sampling intervals). The limits of agreement of both τ and MRT, however, were not clinically acceptable. O2 recovery kinetics yielded better reproducibility and goodness of fit. Using the most optimal sampling interval (5 breaths), a change of at least 13 s in τ is needed to exceed normal test-to-test variations. In conclusion, O2 recovery kinetics are more reproducible for clinical purposes than O2 onset kinetics in moderately impaired patients with CHF. It should be recognized that this observation cannot be assumed to be generalizable to more severely impaired CHF patients

Predicting Effects of Exercise Training in Patients With Heart Failure Secondary to Ischemic or Idiopathic Dilated Cardiomyopathy

The purpose of this study was to investigate which patient characteristics may predict training effects on maximal and submaximal exercise performance in patients with heart failure. Together with commonly used clinical and performance-related variables, oxygen uptake kinetics during exercise recovery were included as possible predictors. Fifty patients with heart failure (New York Heart Association class II or III) performed a 12-week training program (cycle interval and resistance training). Training effects were expressed as changes in peak oxygen uptake (Vo2), Vo2 at ventilatory threshold (VT), and the time constant of Vo2 recovery after submaximal exercise (τ-rec). After training, peak Vo2, Vo2 at VT, and τ-rec improved significantly, with a wide variety in training responses. Changes in peak Vo2 were related to changes in VT (r = 0.79, p <0.001), but both changes were not related to changes in τ-rec. Using multivariate regression analyses, post-training changes in peak Vo2 could be predicted by recovery halftime of peak Vo2 (T1/2), peak Vo2 (percentage of predicted), and peak respiratory exchange ratio (R2 = 36%). Post-training changes in VT could be predicted by T1/2 and VT (predicted) (R2 = 29%), whereas changes in τ-rec could be predicted only by τ-rec at baseline (R2 = 34%). In conclusion, oxygen recovery kinetics after maximal and submaximal exercise substantially add to the prediction of training effects in patients with heart failure, presumably because of their relations with, respectively, central and peripheral impairments of exercise capacity. However, the explained variance in training effects is not sufficient to make a definite distinction between training responders and nonresponders

Improved physical fitness of cancer survivors:A randomised controlled trial comparing physical training with physical and cognitive-behavioural training

We compared the effect of a group-based 12-week supervised exercise programme, i.e. aerobic and resistance exercise, and group sports, with that of the same programme combined with cognitive-behavioural training on physical fitness and activity of cancer survivors. One hundred and forty seven cancer survivors (all cancer types, medical treatment 3 months ago) were randomly assigned to physical training (PT, n=71) or PT plus cognitive-behavioural training (PT+CBT, n=76). Maximal aerobic capacity, muscle strength and physical activity were assessed at baseline and post-intervention. Analyses using multilevel linear mixed-effects models showed that cancer survivors' physical fitness increased significantly in PT and PT+CBT from baseline to post-intervention. Changes did not differ between PT and PT+CBT. Physical fitness of cancer survivors was improved following an intensive physical training programme. Adding a structured cognitive-behavioural intervention did not enhance the effect