Muscle oxygen supply impairment during maximal exercise in patients undergoing dialysis therapy

Abstract

This study aimed to investigate whether Chronic Kidney Disease (CKD) influences O₂ supply including O₂ delivery and release to the active muscles during maximal physical exercise. Twelve CKD patients undergoing dialysis therapy (HD group) and twelve healthy adults (CTR group) performed an incremental exercise test to determine maximal oxygen uptake (VO_2peak). Throughout the exercise, near-infrared spectroscopy allowed the investigation of changes in oxyhemoglobin (∆O₂Hb), deoxyhemoglobin (∆HHb), and total hemoglobin (∆THb) in the vastus lateralis muscle. VO_2peak was significantly lower in HD group. In addition, HD patients had impaired changes in muscular oxygenation (∆HHb and ∆O₂Hb) and blood volume (∆THb) during the exercise (p < 0.05). Moreover, a positive correlation was observed between VO_2peak and muscle blood volume (∆THb) in both groups (p < 0.05). This study provides the first evidence that HD patients displayed lower VO_2peak and blunted muscular deoxyhemoglobin increase during exercise. This result supports the hypothesis of an increase in oxygen affinity and/or mitochondrial dysfunction in this population.

Keywords: Chronic kidney disease; Exercise; Hemodynamic; NIRS; VO2peak.