Effect of sprint training on resting serum irisin concentration - Sprint training once daily vs. twice every other day

Objective. Exercise twice every other day has been shown to lead to increasing peroxisome proliferator receptor gamma coactivator-1 alpha (PGC-1 alpha) expression (up-stream factor of irisin) via lowered muscle glycogen level during second of exercise compared with exercise once daily. This study determined the influence of 4 weeks of sprint training (training once daily vs. twice every other day) on the serum irisin concentration. Materials and methods. Twenty healthy males (20.9 +/- 1.3 years) were assigned randomly to either the SINGLE or REPEATED group (n = 10 per group). The subjects in the SINGLE group participated in a sprint training session once daily (5 days per week), whereas those in the REPEATED group performed two consecutive training sessions on the same day with a 1-h rest between sessions (2-3 days per week). Both groups completed 20 training sessions over 4 weeks. Each training session consisted of three consecutive 30-s maximal pedaling exercises with a 10-min rest between sets. Blood samples were collected before and after training period (48 h after completing the last training session). Results. The serum irisin concentration decreased significantly after training in each group (SINGLE, 338.5 +/- 77.8 to 207.6 +/- 64.6 ng/mL; REPEATED, 329.5 +/- 83.9 to 234.2 +/- 72.8 ng/mL, p < 0.05). The plasma interleukin-6 (IL-6) concentration tended to be lower after training in both groups (main effect for period, p = 0.054). However, there was no significant difference in the serum irisin or plasma IL-6 concentration between groups after training. The serum high-molecular-weight adiponectin concentration did not change significantly after training in either group. Conclusion. Sprint training for 4 weeks significantly decreased the resting serum irisin concentration, despite different training programs (training once daily vs. twice every other day). (C) 2016 Elsevier Inc. All rights reserved.