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

This study aimed to investigate whether Chronic Kidney Disease (CKD) influences O-2 supply including O-2 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 (VO2peak). Throughout the exercise, near-infrared spectroscopy allowed the investigation of changes in oxyhemoglobin (triangle O(2)Hb), deoxyhemoglobin (triangle HHb), and total hemoglobin (triangle THb) in the vastus lateralis muscle. VO2peak was significantly lower in HD group. In addition, HD patients had impaired changes in muscular oxygenation (triangle HHb and triangle O(2)Hb) and blood volume (triangle THb) during the exercise (p < 0.05). Moreover, a positive correlation was observed between VO2peak and muscle blood volume (triangle THb) in both groups (p < 0.05). This study provides the first evidence that HD patients displayed lower VO2peak 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.