Effect of exercise training on muscle function in dialysis patients

To participate in the study, patients were qualified by a nephrologist and a cardiologist. The nephrologist’s permission to participate in the study was based on the patient’s recent health status and biochemistry results. Each patient was informed of the voluntary nature of the study and of the option to withdraw from the exercise training. To carry out the study, approval from the Bioethics Committee of the University of Physical Education in Wroclaw was obtained. All patients gave their informed written consent to participate in the study. The research was conducted at the dialysis center of the Department of Nephrology and Transplantation Medicine at the Medical University in Wroclaw (group I and group II) and in a gymnasium in the Department of Physiotherapy of the University of Physical Education in Wroclaw (group III). Research procedures Respondents will be divided into 3 groups. Studies with each of the 3 groups will be conducted over a period of 6 months, 3 times a week for 60 minutes (group I and group II) and 2 times a week for 60 minutes (group III). In group I and group II all intervention activities were undertaken whilst undergoing dialysis. In group III on the non-dialysis days. Group I- patients with ESRD undergoing supervised endurance training during hemodialysis on the MOTOmed letto unit. Group II- patients with ESRD undergoing supervised resistance training during hemodialysis. Group III - patients with ESRD participating in training Tai Chi on the non-dialysis days. Physical Exercise Training Trainings in group I and group II took place in the first 2 hours of hemodialysis on the seat the patient used for dialysis. Trainings were constantly supervised by a nephrologist and a physiotherapist. Each training was divided into three parts: 1) Introductory part, a short warm-up lasting 5 minutes. It included active exercises of the lower limbs in recumbent position (simple exercises: flexion, extension in ankles and knee joint without load) 2) Main part, 10-50 min. In this part, depending on the training allocated: Group I performed endurance training on a MOTOmed letto2cycle ergometer (RECK, Germany) which is a motorized exercise therapy device that has a CE 0124, EMV, ISO Qualitätsmanagement safety certificate which enables a patient to ride in a recumbent or reclined position. Training on ergometer concentrates on lower limbs, the position was chosen by the patient according to their comfort and, just as important, to the fluency of dialysis. Training intensity was selected on the basis of subjective feelings of the patient and steadily increased from low to moderate levels based on a 10-point fatigue assessment (Borg scale). This is a reliable indicator for evaluating the intensity of physical exercise, among dialysis patients. In the first week of training the length of the cycle ergometer ride was 10 minutes. The objective was to reach exercise intensity level 3 according to the RPE scale. The time was steadily increased while maintaining a moderate level of intensity for a minimum of 2 to 3 weeks. The final stage of rehabilitation was the accomplishment of a 35–50-minute ride on the cycle ergometer at a moderate level of intensity. The exercise was carried out until reaching subjective feeling of fatigue (5-6 on the 10 –point Borg scale). The number of evolutions and load were constant, individually tailored to the patient depending on the tolerance of a given exercise. They were as follows: speed regulation from 10 to 60 [RPM], regulation of motor power from 1 to 10 [Nm], and preset therapy duration from 0 to 120 minutes. The parameters were selected in such way that the number of revolutions and the workload made it an endurance type of training. It should be added that the course of training shown on the ergometer screen in the form of a power level achieved [W] for both lower limbs was a motivating factor for the patient to continue with the exercise. Group II performed resistance training with weights, balls and Thera Bands. Mostly the lower limbs and one upper limb free of the arteriovenous fistula were engaged. Exercises of the lower limbs included: straightening / bending of the knee, straightening / bending at the hip, adduction / abduction at the hip. Exercises of the upper limbs included: "rowing" single-handedly (limb adduction to the body in the sagittal plane); "squeezing" with one hand (bending limbs in the shoulder joint in the transverse plane, limb in 90° abduction in the coronal plane), bending the forearm at the elbow joint; straightening the forearm in the elbow joint). One exercise in each exercise referral scheme was performed, the workout consisted of 4 - 5 sets; 1 lightweight 20 repetitions, 2-5 main of 10 - 20 reps; until exhaustion. The intensity was determined according to subjective feelings, matching color-coded bands or weights adequately. The intensity was increased by raising the number of sets or repetitions while maintaining the load. In the case when a patient reported tolerance, training load was increased and maintained at a constant level for at least 3 trainings (1 week) in order to adapt to a new load. If the patient showed some progress, the load was increased also in the following week. Only in the case of indisposition was the load reduced, however, at the next training the previous load was restored. Exercise was performed until onset of subjective feelings of exhaustion (at the beginning 5-6 in the 10-point Borg scale), however, not until “muscle failure” (in order to avoid the risk of injuries in and around tendons, muscle attachments, etc.). Weights used for the lower limbs were: 1.1 kg – 3.7 kg; for upper limbs: 1-3 kg. The duration of the main part was increased gradually from 10 minutes in the initial period of training up to 50 minutes. Resistance training was completed in a seated position. 3) Final part, relaxation, lasted about 5min. and included free active exercises of the lower limbs in recumbent position as well as breathing exercises. Stopping exercises during the training session was allowed in cases where a participant was feeling unwell or fatigued, experienced the onset of muscular, joint or coronary pain, nausea, dizziness or shortness of breath, obtained a heart rate above 80% of maximum (HRmax), exceeded blood pressure values above 200/110 mmHg or below 110/50 mmHg, and in the case of incapacity to maintain the recommended exercise pace. For safety reasons, heart rate, blood pressure and the degree of subjective fatigue levels according to the 10-point Borg scale were monitored before, during and after exercise. Group III had Tai Chi training under constant supervision of a certified Tai Chi specialist and an attending practitioner. The Tai Chi 24-form Yang (24 forms of Beijing) was used in the training. The form 24 Tai Chi Chuan of the Yang style was the most common form of Tai Chi training, defined as a standardised form from Beijing. The intensity of classes increased gradually. For patients’ safety, a team of therapists were monitoring the limits permissible in cardiac rehabilitation concerning heart rate and blood pressure, as defined by international standards. In addition, the basic parameter determining the maximum safe level of physical activity was the heart rate limit (HRmax), which was determined individually for each patient during the exercise stress test. An increase in the heart rate of up to 50% HRmax of in weeks 1–4, up to 60% of the rate in weeks 4–8, up to 70% in weeks 8–16, and up to 80% in weeks 16–24 was deemed safe. An allowable subjective submaximal fatigue during training, not exceeding 7-8 points on a simplified 10-point Borg scale, was also considered. Physical therapist was administering the intervention.