Preliminary MRS/OS findings suggest profoundly altered mitochondrial function in CKD patients. Previous experimental studies suggest that uremia in dialysis patients affects skeletal muscle structure and mitochondrial function. Oxidative damage is highly prevalent in CKD, evidenced by increased biomarkers of oxidative stress and changes in glutathione, an important antioxidant. Prior small studies in non-diabetic CKD patients suggest impairment of ex-vivo mitochondrial function by reductions in mitochondrial enzyme activity. Based on these findings investigators used novel, non-invasive, functional MRS/OS assay to characterize in-vivo mitochondrial function. Preliminary findings in non-diabetic CKD patients indicate markedly reduced ATP to oxygen ratio compared to controls. This finding suggests altered mitochondrial energetics as a candidate central mechanism linking metabolic derangements and impaired physical function in CKD, and motivate the hypothesis that mitochondrial dysfunction is associated with oxidative stress, insulin resistance and impaired physical functioning in CKD.