The effect of exercise-intensity on skeletal muscle stress kinase and insulin protein signaling

Background Stress and mitogen activated protein kinase (SAPK) signaling play an important role in glucose homeostasis and the physiological adaptation to exercise. However, the effects of acute high-intensity interval exercise (HIIE) and sprint interval exercise (SIE) on activation of these signaling pathways are unclear. Methods Eight young and recreationally active adults performed a single cycling session of HIIE (5 x 4 minutes at 75% W-max), SIE (4 x 30 second Wingate sprints), and continuous moderate- intensity exercise work-matched to HIIE (CMIE; 30 minutes at 50% of W-max), separated by a minimum of 1 week. Skeletal muscle SAPK and insulin protein signaling were measured immediately, and 3 hours after exercise. Results SIE elicited greater skeletal muscle NF-kappa B p65 phosphorylation immediately after exercise (SIE: similar to 40%; HIIE: similar to 4%; CMIE; similar to 13%; p < 0.05) compared to HIIE and CMIE. AS160(Ser588) phosphorylation decreased immediately after HIIE (similar to-27%; p < 0.05), and decreased to the greatest extent immediately after SIE (similar to-60%; p < 0.05). Skeletal muscle JNK (similar to 42%; p < 0.05) and p38 MAPK (similar to 171%; p < 0.05) phosphorylation increased, and skeletal muscle Akt(Ser473) phosphorylation (similar to-32%; p < 0.05) decreased, to a similar extent immediately after all exercise protocols. AS160(Ser588) phosphorylation was similar to baseline three hours after SIE (similar to-12%; p > 0.05), remained lower 3 hours after HIIE (similar to-34%; p < 0.05), and decreased 3 hours after CMIE (similar to-33%; p < 0.05). Conclusion Despite consisting of less total work than CMIE and HIIE, SIE proved to be an effective stimulus for the activation of stress protein kinase signaling pathways linked to exercise-mediated adaptation of skeletal muscle. Furthermore, post-exercise AS160(Ser588) phosphorylation decreased in an exercise-intensity and post-exercise time-course dependent manner.