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 (5×4 minutes at 75% Wmax), SIE (4 × 30 second Wingate sprints), and continuous moderate-intensity exercise work-matched to HIIE (CMIE; 30 minutes at 50% of Wmax), 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-κB p65 phosphorylation immediately after exercise (SIE: ∼40%; HIIE: ∼4%; CMIE; ∼13%; p < 0.05) compared to HIIE and CMIE. AS160Ser588 phosphorylation decreased immediately after HIIE (∼-27%; p < 0.05), and decreased to the greatest extent immediately after SIE (∼-60%; p < 0.05). Skeletal muscle JNK (∼42%; p < 0.05) and p38 MAPK (∼171%; p < 0.05) phosphorylation increased, and skeletal muscle AktSer473 phosphorylation (∼-32%; p < 0.05) decreased, to a similar extent immediately after all exercise protocols. AS160Ser588 phosphorylation was similar to baseline three hours after SIE (∼-12%; p > 0.05), remained lower 3 hours after HIIE (∼-34%; p < 0.05), and decreased 3 hours after CMIE (∼-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 AS160Ser588 phosphorylation decreased in an exercise-intensity and post-exercise time-course dependent manner.