BACKGROUND Patients with CKD suffer from impaired physical performance. Exercise has been shown to improve physical performance in CKD, but its impact on immune cell mitochondrial function is unknown. We tested the impact of exercise on peripheral blood mononuclear cell (PBMC) mitochondrial function and their link with inflammatory biomarkers. METHODS We performed an interim analysis of pilot randomized trial of 12 weeks of home-based, video supervised exercise intervention in CKD. Intact PBMC bioenergetics were measured using the high resolution respirometry (Oroboros O2k). We estimated basal, maximal respiration (MR) and reserve capacity (RC). Plasma IL-10 concentrations were measured using ELISA. Two-way ANOVA was used to evaluate the impact of exercise on PBMC bioenergetics. Spearman correlation was calculated for changes in log-transformed MR and IL-10 concentrations in exercise responders defined with >5% improvement in total work measured by cycle ergometry testing. RESULTS Twelve participants (60.6+/-11.1 yrs) were randomized to the exercise (EX) group and 5 (64.5+/- 8.1 yrs) were randomized to the non-exercise control (CTL) group. The mean EX eGFR was 33.3+/-14.1 compared to eGFR of 37+/-3.1 of CTL. The mean MR was 10.9 (3.8) and mean RC was 8.57 (2.8). EX was associated with a marked reduction in MR and RC compared to CTL (p=0.03 and p=0.02, respectively) (Figure 1A). The change in PBMC MR inversely correlated with changes in plasma IL-10 concentration among EX responders (n=9, r=-0.83, p=0.008) (Figure 1B). CONCLUSION A decrease in PBMC MR is associated with an increase in anti-inflammatory IL-10 levels which suggest that exercise alters PBMC mitochondrial energetics in CKD. Future studies will focus on the impact of exercise on immune cell metabolic health and its immunomodulatory effects in CKD