Am J Physiol Renal Physiol. 2026 Apr 10. doi: 10.1152/ajprenal.00424.2025. Online ahead of print.
ABSTRACT
Peak oxygen consumption (V̇O2peak) is reduced in patients with chronic kidney disease (CKD). Although cardiovascular and skeletal muscle factors are implicated in the declines of VO2peak, few studies have evaluated muscle oxygenation responses during exercise. We hypothesized that lower VO2peak in CKD would be associated with attenuated responses in muscle oxygenation compared to those without CKD. Forty-six male Veterans (CKD stages 3 & 4, n=23; referent controls (REF), n=23) completed the study. Cardiopulmonary exercise testing (CPET) was performed on a treadmill using the Modified Bruce protocol. Peak change in dominant medial gastrocnemius deoxygenated hemoglobin/myoglobin (∆[deoxy(Hb-Mb)]peak), total hemoglobin/myoglobin (∆[total(Hb-Mb)]peak), tissue saturation index (∆TSI), and ∆TSI reoxygenation half-time recovery (∆TSIreoxy1/2time), were assessed via near-infrared spectroscopy (NIRS). V̇O2peak, exercise time, HRpeak, V̇O2 at GET, and exercise time after GET were lower in the CKD group versus the REF group (p=0.002, p<0.001, p=0.020, p=0.044, and p=0.005, respectively). For NIRS outcomes, ∆[total(Hb-Mb)]peak was lower, and ∆TSIreoxy1/2time prolonged, in the CKD group compared to REF group (p=0.032 and p=0.031, respectively). V̇O2peak was positively associated with HRpeak (CKD, r=0.57, p=0.005; REF, r=0.63, p=0.001) and ∆[total(Hb-Mb)]peak (CKD, r=0.63, p=0.001; REF, r=0.52, p=0.012) in both groups. Conversely, V̇O,2peak was positively associated with ∆[deoxy(Hb-Mb)]peak in the CKD group only (r=0.64, p<0.001). These findings suggest that skeletal muscle impairments, in addition to cardiovascular impairments, contribute to reduced V ̇O2peak in patients with CKD.
PMID:41962951 | DOI:10.1152/ajprenal.00424.2025