Assessment of physical performance and muscle function in hemodialysis patients participating in an exercise regimen: A cluster-randomized, single-center study.

Background: Many studies reported positive effects of physical exercise on the condition of dialysis patients. The insufficient value of those changes makes it difficult to interpret their clinical relevance.

Objective: This study aimed to assess the influence of selected training (endurance, resistance, tai chi) on cardiopulmonary fitness and muscle function, as well as to analyze the factors having the most significant effect on cardiopulmonary fitness in a group of dialysis patients.

Methods: Ninety-eight patients agreed to participate in the study. Selection of the type of training was done by cluster randomization. Group 1 were patients in a cluster with an endurance exercise program, and group 2 in a cluster with resistance exercises. Group 3 consisted of patients who took part in a tai chi program (non-cluster randomization). Exercise programs with each of the 3 groups were conducted for a period of 6 months, 3 times a week (groups 1 and 2) and twice a week (group 3), up to 60 min for 1 session.

Results: The full exercises was completed by 45 patients: group 1 - 16; group 2 - 15; group 3 - 14. The significance of the observed difference in the cardiopulmonary function was confirmed only in endurance group for absolute oxygen concumption (VO2) and heart rate (HR). Measurements of peak torque (PTQ) and total work (TW) performed at a speed of 60°/s showed a significant increase in the measured values only in the resistance training group. Measurements of PTQ and TW performed at 180°/s showed a significant increase in the measured values in the endurance and resistance group.

Conclusions: The 6 months of training resulted in a slight improvement in cardiopulmonary parameters only in the endurance group. The above results seem to confirm the observed limited potential for improving aerobic capacity in dialysis patients. The results of strength and speed parameters shows the specificity of each training, expressed by selective improvements in isometric and both isokinetic tests.