Aerobic Cycling Exercise Training Does Not Improve Impaired Vagal Reactivation in Patients with Chronic Kidney Disease

Abstract

Purpose: Parasympathetic reactivation is essential for the rapid decrease in heart rate following exercise and delayed heart rate recovery (HRR) post-exercise is linked to poor clinical outcomes. Chronic kidney disease (CKD) is associated with autonomic dysfunction including reduced parasympathetic activity. Exercise training may improve parasympathetic reactivation. Therefore, this study aimed to test whether CKD patients experience delayed HRR due to impaired vagal reactivation and if 12 weeks of aerobic exercise can improve HRR.

Methods: Twenty-seven CKD patients (stages III and IV, eGFR 15-59 mL/min/1.73m2) and 18 age-matched controls underwent cardiopulmonary exercise testing (CPET). HRR was assessed through heart rate decay (HRR60s) and heart rate variability (HRV) during the first 60 seconds of recovery. Recovery kinetics were modeled to calculate the time constant (τ). CKD patients were then randomly assigned to aerobic exercise or non-aerobic stretching interventions for 12 weeks (3 days per week) and CPET was repeated post-intervention.

Results: CKD patients exhibited significantly blunted HRR60s (ΔHRR60s: -11 ± 4 bpm vs. -17 ± 6 bpm, P = 0.001) and a longer recovery time constant (τ: 142 ± 33 vs. 116 ± 21 s, P = 0.004) compared to controls. HRV indices increased less post-exercise in CKD patients compared to controls (ΔRMSSD: 0.3 ± 1 ms vs. 1.6 ± 1 ms, P = 0.001). 12 weeks of aerobic exercise did not improve HRR60s (ΔHRR60s: pre -12 ± 4 bpm vs. post -12 ± 7 bpm, P = 0.971) or HRV indices (all P > 0.108).

Conclusions: CKD patients have decreased HRR post-exercise due to impaired cardiac vagal reactivation. 12 weeks of aerobic exercise training did not improve cardiac vagal reactivation. Future studies should explore different exercise modalities and manipulate training variables such as intensity, volume and frequency to assess their potential impact on cardiac vagal reactivation in patients with CKD.

Keywords: CHRONIC KIDNEY DISEASE; EXERCISE TRAINING; HEART RATE; VAGAL REACTIVATION.