A and B: fold changes post- versus preexercise training in expression of skeletal muscle transcription coactivators PGC-1α, PPARα, and PPARδ (A) and skeletal muscle gene expression of KAT isoforms 1–4 (B). C: percent change in plasma metabolites KYNA and QUIN post- versus preexercise training. PGC-1α, peroxisome proliferator-activated receptor-γ coactivator 1α; PPAR, peroxisome proliferator-activated receptor; KAT, kynurenine amino transferase; KYNA, kynurenic acid; QUIN, quinolinic acid. Repeated-measures ANOVA; n = 25. Error bars represent SE. **P ≤ 0.01, ***P ≤ 0.001.