Metabolic alterations detected in the blood before and after exercise. (A) RBC and (B) plasma heat map with hierarchical clustering of the top 25 metabolites significantly different (analysis of variance [ANOVA]) between hG6PD_ND and hG6PD_Med− taken from the before/after exercise fold change. Autoscaled metabolite abundances were compared before and after exercise between hG6PD_ND and hG6PD_Med− genotypes. (C) Glycolysis, PPP, and long-chain FA intermediates before and after CS tests. Metabolite name is color coded according to fraction with plasma (blue) and RBC (red) and genotype is indicated by hG6PD_ND (blue) and hG6PD_Med− (orange). (D) Succinate accumulation after exercise in the plasma and RBCs. (E) Mean corpuscular volumes (MCV) as a function of exercise in RBCs. (F) SEM images of RBC morphology before and after run to exhaustion. (G) Echinocyte-to-discocyte ratios before and after exercise expressed as relative percentages. (H) Before to after changes in markers of hemolysis in plasma (significance ∗P < .05, ∗∗P < .01, ∗∗∗P < .001, ∗∗∗∗P < .0001).