Participants will receive diaphragmatic biofeedback combined with respiratory muscle training three times per day for 6 weeks

Placebo intervention based on conscious breathing three times per day for 6 weeks

This intervention is novel because it integrates diaphragmatic biofeedback into a structured respiratory muscle training program specifically designed for patients with chronic kidney disease, a population in which respiratory dysfunction is prevalent yet under-addressed. By providing real-time feedback on diaphragmatic activity, the intervention aims to enhance motor learning, improve activation of the diaphragm, and optimize training efficiency beyond conventional breathing or respiratory muscle training approaches.

Adverse events and discomfort related to the intervention will also be recorded to evaluate overall number of adverse events registered during intervention period.

Respiratory symptoms will be assessed using the validated symptom questionnaire and clinical reporting, focusing on perceived dyspnea and fatigue , and other respiratory-related complaints during daily activities. The Edmonton Symptom Assessment Scale (ESAS) is a validated instrument that assesses symptom severity, with each symptom rated on a numeric scale ranging from 0 (no symptom) to 10 (worst possible severity). Thus, higher scores indicate a worse outcome and greater symptom burden.

The occurrence of respiratory complications during the intervention period will be monitored and recorded, including any clinically relevant respiratory events reported by participants or identified during follow-up assessments.

Health-related quality of life will be assessed using a validated questionnaire to evaluate perceived physical, emotional, and functional well-being in participants undergoing the intervention. The EuroQol 5-Dimension (EQ-5D) questionnaire is a standardized measure of health-related quality of life comprising five dimensions (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression). Health states are converted into a utility index score, typically ranging from values below 0 (worse than death) to 1 (full health), where higher scores indicate better health status; additionally, the EQ-5D includes a visual analogue scale (EQ-VAS) from 0 to 100, with higher scores reflecting better perceived health.

Changes in cardiorespiratory capacity will be evaluated using standardized functional or physiological assessments appropriate for patients with chronic kidney disease, aiming to determine whether the intervention improves respiratory and exercise-related capacity. The Six-Minute Walk Test (6MWT) measures functional exercise capacity by recording the total distance walked in six minutes, expressed in meters, with higher distances indicating better functional performance. There is no fixed minimum or maximum value, as results depend on the individual's physical capacity and clinical condition.