Effects of Aerobic Versus Resistance Training on Bone Metabolism in Stage 3-4 Chronic Kidney Disease

Sinai University60 enrolled

Overview

This randomized controlled trial investigates the comparative effects of aerobic versus resistance training on bone mineral density (BMD) and bone metabolism markers in patients with stage 3 or 4 chronic kidney disease (CKD). The primary aim is to evaluate the impact of two distinct exercise modalities on serum osteoprotegerin (OPG), receptor activator of nuclear factor kappa-B ligand (RANKL), and the OPG/RANKL ratio, as well as densitometric changes at key skeletal sites.

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a common complication in non-dialysis CKD patients, driven by disrupted calcium-phosphate metabolism, secondary hyperparathyroidism, and altered bone remodeling pathways, such as the OPG-RANKL axis. Exercise is an emerging non-pharmacological strategy to mitigate skeletal deterioration in CKD, yet the differential effects of aerobic and resistance training on bone health remain poorly understood in this population. This study recruited 60 CKD patients (stage 3-4, aged 30-50 years) and randomly allocated them into two groups (n=30 each): a resistance training group and an aerobic exercise group. Both groups underwent supervised exercise 3 times per week for six months. Bone mineral density was assessed using dual-energy X-ray absorptiometry (DEXA) at the lumbar spine (L2-L4), femoral neck, and distal radius. Serum concentrations of OPG and RANKL were measured via ELISA at baseline and post-intervention.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Enrollment

Conditions

Osteopenia

Interventions

Resistance ExerciseBEHAVIORAL

Structured machine-based resistance exercise protocol performed under supervision, targeting osteogenic loading to improve bone mineral density and alter bone metabolism markers in CKD stage 3-4 patients.

Aerobic TrainingBEHAVIORAL

Participants in this arm performed supervised aerobic exercise (treadmill walking) three times per week for six months. Each session included: 5-minute warm-up 30-minute treadmill walking at 60%-80% of age-predicted maximum heart rate (HRmax = 220 - age) 10-minute cool-down Exercise sessions were supervised by trained exercise professionals and tailored to maintain target heart rate zones.

Eligibility

Sex: ALLMin age: 30 YearsMax age: 50 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Adults aged 30 to 50 years * Diagnosed with stage 3 or 4 chronic kidney disease (non-dialysis dependent) * BMI between 20 and 24 kg/m² * Not currently taking medications that affect bone density (e.g., corticosteroids, bisphosphonates) * Non-smokers and abstinent from alcohol * Not receiving hormone replacement therapy * Willing and able to participate in supervised exercise sessions for 6 months Exclusion Criteria: * Diagnosis of type 1 diabetes mellitus * Uncontrolled hypertension * History of cardiovascular, musculoskeletal, endocrine, or metabolic bone disease * Pregnant or planning pregnancy during the study period * Participation in a structured exercise program within the last 3 months * Contraindications to exercise as determined by medical evaluation * Use of investigational drugs or enrollment in another clinical trial during the study period

Outcomes

Primary Outcomes

Change in Serum Osteoprotegerin (OPG) and RANKL Concentrations

To determine biochemical changes in bone metabolism markers. Both OPG (pg/mL) and RANKL (ng/mL) are measured using validated ELISA kits.

Time frame: Baseline to 6 months post-intervention

Change in Bone Mineral Density (BMD)

To assess densitometric changes in skeletal structure due to exercise. BMD is measured in g/cm² using ISCD-certified DEXA equipment.

Time frame: Baseline to 6 months post-intervention

Change in OPG/RANKL Ratio

Baseline to 6 months post-intervention

Time frame: To assess the regulatory balance of bone remodeling. A higher OPG/RANKL ratio reflects reduced osteoclastic activity and improved bone metabolic status.

Secondary Outcomes

Change in eGFR (estimated Glomerular Filtration Rate)

To explore the potential renal benefits of structured exercise in CKD patients. Measured in mL/min/1.73 m².

Time frame: Baseline to 6 months

Change in Serum Albumin and Hemoglobin Levels

These indicators provide information about overall nutritional and hematologic status. Albumin (g/dL) and Hemoglobin (g/dL) are assessed via standard lab procedures.