Efeitos do treinamento aeróbico durante as sessões de hemodiálise em parâmetros cardiovasculares na tolerância ao exercício em pacientes com doença renal crônica

Abstract

Introduction: Decreased heart rate variability (HRV) in patients with end stage renal disease (ESRD) undergoing hemodialysis is predictive of cardiac death, especially due to sudden death. These patients have several hemodynamic and peripheral muscle abnormalities which could decrease exercise tolerance and slow the kinetics of oxygen uptake ( O2). Objectives: To evaluate the effects of aerobic training performed during hemodialysis on HRV, left ventricular function, maximal aerobic capacity and O2 kinetics in ESRD patients. Methods: Twenty four patients were randomized into two groups: exercise (n=12, 50.7 ± 10.7 years, 5 men) and control (n=12, 42.2 ± 13 years, 5 men). Patients assigned to the exercise group were submitted to exercise training during hemodialysis, three times weekly, for 12 weeks. At the baseline and after 12 weeks of study, all the participants were submitted to a 24 hours Holter monitoring, an echocardiography, an incremental and two constant work exercises tests (moderate and heavy intensity). Paired Student's t-test or Wilcoxon test were used to assess the change between baseline and the end of the 12 weeks of study. Comparisons between groups were done by unpaired Student's ttest or Mann-Whitney test (p <0.05). Results: After 12 weeks of protocol, no significant differences were observed in ejection fraction and in time and frequency domains measures of HRV. On the other hand, the O2peak (25.8 ± 5.5 ml/Kg/min-1 vs. 29 ± 7 ml/Kg/min-1) and TLIM [232 (59s) vs. 445 (451s)] increased significantly in the exercise group. Training significantly accelerated on-exercise O2 kinetics at both moderate (τ decreased from 62.5 ± 19.6s to 45 ± 12.6s) and heavy (τ decreased from 52.9 ± 17.4s to 40.4 ± 13.8s) exercise intensity domains. Similar beneficial findings of training were observed at the off-exercise O2 kinetics at both exercise intensity domains. Conclusions: Aerobic exercise training performed during hemodialysis sessions increased exercise tolerance and accelerated O2 kinetics, despite no changes in HRV and left ventricular function in ESRD patients.