Fig. 2.

(A) Skeletal muscle interleukin-6 (IL-6) mRNA expression, (B) FNDC5 mRNA expression, and (C) METRNL mRNA expression assessed by qPCR in response to a single bout of high-intensity interval exercise performed at the same absolute intensity before (pre-training) and after (post-training) 20 days of twice daily high-intensity interval training. Vastus lateralis biopsies (n = 9) were obtained prior to exercise (resting), immediately after (post-exercise), and at 3 h of recovery (3-h recovery). *p < 0.05, compared with resting within condition. ^#p ≤ 0.05, compared with resting in pre-training. ^†p < 0.05, significant main effect of training.