Characterization of G6PD_Med− mice. (A) mQTL analysis of samples from 13 091 blood donors highlights correlation of succinate levels with polymorphic G6PD. (B) Locus zoom identifying G6PD as a target of interest. (C) An overview of glucose metabolism in redox homeostasis in RBCs. (D) Total abundance of 6-phosphogluconate (6P-gluconate) from metabolic tracing (sum of labeled and unlabeled) present in genotypes. (E) G6PD activity assay; (F) PPP activation as judged by relative levels of labeled 6P-gluconate to hexose phosphate. (G-H) CS testing of mice (n = 12) showed that G6PD_Med− mice maintained a significantly faster CS (8% increase). Dashed lines indicate CS. (I) G6PD_Med− mice have higher anaerobic work capacity (AWC) as measured by the slope, hG6PD_ND = 1715 and hG6PD_MED- = 945.4 (significance, ∗P < .05, ∗∗P < .01, ∗∗∗∗P < .0001).