"Hypoxic vs. Aerobic Training in Chronic Kidney Disease (IHT-CKD)

Pharos University in Alexandria

Status: Not yet enrolling

Conditions: Chronic Kidney Disease (CKD), Stages 3-4 Exercise Tolerance / Functional Capacity Vascular Health / Arterial Stiffness Fatigue in CKD

Treatments: Behavioral: hypoventilation group

Study type: Interventional

Funder types: Other

Identifiers

NCT07180875

OlaElgohary-IHT-CKD-01

Details and patient eligibility

About

Chronic kidney disease (CKD) leads to poor exercise tolerance, vascular dysfunction, and reduced quality of life. This randomized controlled trial will compare intermittent hypoxic training (IHT) with traditional aerobic training in patients with CKD stages 3-4.

A total of 60 participants aged 40-65 years will be recruited and randomized into three groups. Interventions will last 12 weeks, with three 30-minute supervised sessions per week. Outcome measures include exercise tolerance (6-Minute Walk Test), cardiovascular parameters (blood pressure, heart rate recovery), kidney function (serum creatinine, eGFR), fatigue (Fatigue Severity Scale), and quality of life (KDQOL-36)

Full description

Chronic kidney disease (CKD) stage 3 is characterized by reduced exercise capacity, muscle weakness, and increased cardiovascular risk, which negatively impact quality of life. Exercise interventions have shown benefits in improving functional outcomes, but traditional aerobic training may be limited due to comorbidities and reduced physiological reserve. Intermittent hypoxic training (IHT) improves oxygen utilization, cardiovascular adaptation, and mitochondrial function. Specialized hypoxicator devices are costly and not widely available, so practical alternatives such as hypoventilation training and breathing restriction masks may provide comparable benefits.

Study Objective:

To evaluate the effects of hypoventilation training and breathing restriction mask training on exercise tolerance, cardiovascular function, kidney function, fatigue, and quality of life in CKD stage 3 patients.

Study Design:

Randomized controlled trial including 60 patients with CKD stage 3, aged 40-65 years, recruited from outpatient clinics at Aboker Hospital and Pharos University. Participants will be screened for eligibility through medical history, vital signs, and laboratory tests (serum creatinine, eGFR, hemoglobin, electrolytes).

Interventions:

Group A - Hypoventilation Training:

Moderate-intensity aerobic exercise on a cycle ergometer (40-60% HR reserve)

Intermittent breath-holding: 5-10 seconds every 1-2 minutes

Continuous monitoring of SpO₂, heart rate, and blood pressure

Group B - Breathing Restriction Mask Training:

Same aerobic protocol as Group A

Participants wear an adjustable resistance mask to simulate hypoxia

Mask set to induce mild hypoxemia (SpO₂ ≥85%)

Continuous monitoring of SpO₂, heart rate, and blood pressure

Group C - Control Group:

Same aerobic exercise protocol under normal breathing conditions

Moderate intensity (40-60% HR reserve)

Periodic monitoring of vital signs for safety

Intervention Duration:

12 weeks, 3 supervised sessions per week, 30 minutes per session

Outcome Measures:

Primary Outcome:

Exercise tolerance assessed via 6-Minute Walk Test (6MWT) at baseline and post-intervention

Secondary Outcomes:

Fatigue: Fatigue Severity Scale (FSS), self-reported, 9 items, 7-point Likert scale

Quality of Life: KDQOL-36, disease-specific questionnaire covering physical/mental health, symptoms, effects, and burden of CKD

Cardiovascular Assessment: Blood pressure (SBP, DBP) and Heart Rate Recovery (HRR = HR_peak - HR_1min)

Kidney Function: Serum creatinine and eGFR (CKD-EPI/MDRD

Enrollment: 60 estimated patients

Sex: All

Ages: 40 to 65 years old

Volunteers: Accepts Healthy Volunteers

Inclusion and exclusion criteria

Inclusion Criteria:Adults (40-65 years) diagnosed with CKD stages 3a,b

• Medically stable and cleared for exercise

Exclusion Criteria:

• Uncontrolled hypertension
• Severe cardiac arrhythmias
• Recent hospitalization (<3 months)

cardiovascular disese unstable

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Single Blind

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60 participants in 3 patient groups

Hypoventilation Training group

Experimental group

Description:

* Mode: Stationary cycling (ergometer). * Intensity: Moderate (40-60% VO₂max or Borg RPE 11-13). * Duration: 30 minutes per session. * Frequency: 3 sessions per week, for 12 weeks. * Technique: * Patients instructed to hold their breath (hypoventilation) for 5-10 seconds every 2-3 minutes during cycling. * Breathing then resumes normally until recovery. * Cycle repeated throughout the session

Treatment:

Behavioral: hypoventilation group

Breathing Restriction Mask Training

Experimental group

Description:

* Mode: Stationary cycling (ergometer). * Intensity: Moderate (same as Group A: 40-60% VO₂max). * Duration: 30 minutes per session. * Frequency: 3 sessions per week, for 12 weeks. * Equipment: Commercially available breathing restriction mask (e.g., altitude simulation mask). * Technique: * Mask settings adjusted to provide increasing resistance over time, simulating hypoxic breathing (FiO₂ \~14-16%). * Patients cycle continuously with mask worn throughout the session. * Monitoring: * SpO₂, HR, BP monitored continuously. * Mask removed immediately if SpO₂ \< 88% or severe dyspnea occurs.

Treatment:

Behavioral: hypoventilation group

Control Group (Conventional Aerobic Training)

Active Comparator group

Description:

* Mode: Stationary cycling (ergometer). * Intensity: Moderate (40-60% VO₂max or Borg RPE 11-13). * Duration: 30 minutes per session. * Frequency: 3 sessions per week, for 12 weeks. * Technique: * Continuous cycling at steady pace. * No hypoventilation or mask used. * Monitoring: o HR, BP, and SpO₂ checked pre- and post-session. * Progression: * Workload (watts) increased every 2-3 weeks to maintain moderate intensity

Treatment:

Behavioral: hypoventilation group