Physical Exercise in Patients With Chronic Kidney Disease in Hemodialysis (Pehedal-ESKD)

• Intradialytic aerobic exercise using a cycle ergometer (Behavioral): Participants performed supervised intradialytic aerobic exercise using a cycle ergometer during the first 2 hours of hemodialysis sessions. Exercise was conducted three times weekly for a total of 150 minutes per week at moderate intensity (Borg Rating of Perceived Exertion 12-13). Sessions were supervised by exercise professionals and monitored by dialysis nurses to ensure safety and adherence.
• Intradialytic elastic-band resistance exercise (Behavioral): Participants performed supervised intradialytic resistance exercise using progressive color-coded elastic bands during the first 2 hours of hemodialysis sessions. Training was conducted three times weekly for a total of 150 minutes per week at moderate intensity and targeted both upper and lower limbs. Resistance levels were progressively adjusted according to individual tolerance and proper exercise execution.

Primary outcomes

• Incidence of intradialytic intolerance and hemodynamic instability [Baseline to 6 months]: Exercise tolerability will be evaluated through the incidence of intradialytic intolerance events and the maintenance of hemodynamic stability during hemodialysis sessions. Hemodynamic monitoring will include systolic blood pressure, diastolic blood pressure, mean arterial pressure, and heart rate measured before, during, and after exercise sessions. Clinical signs and symptoms of exercise intolerance, including hypotension, dizziness, muscle cramps, nausea, premature interruption of exercise, or other adverse events occurring during dialysis, will be recorded. Outcomes will be compared among cycle ergometer exercise, elastic-band resistance training, and combined exercise programs to assess the relative tolerability and safety of each intervention.

Secondary outcomes

• Maximal workload during cycle ergometer stress testing [Baseline to 6 months]: Changes in maximal workload achieved during cycle ergometer stress testing.
• Six-minute walk test distance [Baseline and 6 months]: Changes in distance covered during the 6-minute walk test as a measure of functional exercise capacity.
• Step-test performance [Baseline and 6 months]: Changes in step-test performance as an indicator of functional mobility and lower-limb performance.
• Chair-stand test performance [Baseline and 6 months]: Changes in the number of repetitions completed during the chair-stand test as a measure of lower-limb muscle function.
• Handgrip strength [Baseline and 6 months]: Changes in handgrip strength measured using a hand dynamometer.
• Weekly exercise time [Throughout the 6-month intervention period]: Changes in the total amount of exercise completed per week during the intervention period.
• Fat-free mass and fat mass [Baseline to 6 months]: Changes in fat-free mass and fat mass assessed by bioelectrical impedance analysis, both reported as percentage of body weight.
• Bone mineral content [Baseline and 6 months]: Changes in bone mineral content assessed by radiofrequency echographic multi-spectrometry (REMS).
• Bone mineral status (T-score) [Baseline and 6 months]: Changes in T-score as an indicator of bone mineral status.
• Appendicular skeletal muscle mass index (ASMMI) [Baseline and 6 months]: Changes in appendicular skeletal muscle mass index (ASMMI) as a measure of skeletal muscle mass.
• Anthropometric circumferences [Baseline and 6 months]: Changes in upper-limb, lower-limb, and trunk circumferences measured using standardized anthropometric procedures.
• Health-related quality of life [Baseline to 6 months]: Changes in health-related quality of life assessed using the Sarcopenia Quality of Life (SARQoL) questionnaire. The SARQoL questionnaire generates an overall score ranging from 0 to 100, with higher scores indicating better quality of life.
• Medication burden [Baseline to 6 months]: Changes in the number of prescribed medications and antihypertensive drugs between baseline and follow-up.
• Dialysis adequacy [Baseline to 6 months]: Changes in dialysis adequacy expressed as Kt/V.
• Dialysis session duration [Baseline and 6 months]: Changes in the duration of the hemodialysis session (min).
• Blood flow rate [Baseline and 6 months]: Changes in blood flow rate (Qb) during hemodialysis.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Age ≥18 years.
* Receiving maintenance hemodialysis for more than 3 months.
* Clinically stable condition.
* Ability and willingness to provide written informed consent.

Exclusion Criteria:

* Unstable angina.
* Uncontrolled hypertension.
* Any medical condition judged by the treating nephrologist to contraindicate or make intradialytic exercise unsafe