Myokine gene expression in the vastus lateralis before and after the endurance exercise bout. A, Myostatin gene expression decreased on average 20% with endurance exercise. B, IL-6 increased eightfold with endurance exercise. C, IL-8 increased 25-fold with endurance exercise. D, LIF mRNA increased approximately 8.5-fold from preexercise levels. E, CTGF increased 10-fold over preexercise expression levels. F, IL-15 did not significantly change with a single endurance exercise bout. Data represent mean ± SEM. *P < 0.05 and ***P < 0.001.