Yoshifumi Tsuchiya

Resistance exercise induces a greater irisin response than endurance exercise

OBJECTIVE We determined detailed time-course changes in the irisin response to acute exercise using different exercise modes. METHODS In experiment 1, seven healthy males rested for 12h (8:00-20:00) to determine the diurnal variation in plasma irisin concentration. In experiment 2, 10 healthy males conducted three exercises to clarify time-course changes in plasma irisin concentration over 6h, using a randomized crossover design. The resistance exercise (R) trial consisted of eight exercises of 12 repetitions with 3-4 sets at 65% of one repetition maximum (1RM). The endurance exercise (E) trial consisted of 60 min of pedaling at 65% of maximal oxygen uptake (VO2max). In the combined mode (R+E) trial, 30 min of endurance exercise was preceded by 30 min of resistance exercise. RESULTS In experiment 1, no significant changes in plasma irisin concentration were observed over 12h. In experiment 2, the R trial showed a marked increase in plasma irisin concentration 1h after exercise (P<0.05), but not in the E or R+E trials. The area under the curve (AUC) for irisin concentrations for 6h after exercise was significantly higher in the R trial than in the R+E trial (P<0.05). The AUC for irisin concentrations was significantly correlated with AUC values for blood glucose, lactate, and serum glycerol (r=0.37, 0.45, 0.45, respectively. P<0.05). CONCLUSIONS Resistance exercise resulted in significantly greater irisin responses compared with endurance exercise alone, and resistance and endurance exercises combined.

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 γ coactivator-1α (PGC-1α) 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 4weeks of sprint training (training once daily vs. twice every other day) on the serum irisin concentration. MATERIALS AND METHODS Twenty healthy males (20.9±1.3years) 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 (5days per week), whereas those in the REPEATED group performed two consecutive training sessions on the same day with a 1-h rest between sessions (2-3days per week). Both groups completed 20 training sessions over 4weeks. 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 (48h 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±64.6ng/mL; REPEATED, 329.5±83.9 to 234.2±72.8ng/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 4weeks significantly decreased the resting serum irisin concentration, despite different training programs (training once daily vs. twice every other day).

Wearing Compression Garment after Endurance Exercise Promotes Recovery of Exercise Performance

The present study examined the effects of wearing a lower-body compression garment (CG) after endurance exercise on recovery of physiological function. 18 males were divided into 2 experiments, the downhill running (n=10, DHR) experiments and the level running (n=8, LR) experiments. Subjects performed 30 min of DHR (gradient: - 10%) or LR (gradient: 0%) at 70% of  ˙VO2max with either wearing a CG (CG trial) or normal garment (CON trial) for 24 h after running. Changes in jump performance (counter movement jump; CMJ, rebound jump; RJ, drop jump; DJ), subjective feelings, circumferences of leg, and blood variables (creatine kinase, myoglobin, interleukin-6, high-sensitivity C-reactive protein) were evaluated before exercise, immediately after exercise, 1, 3 and 24 h following exercise. Running economy was evaluated at 24 h following exercise. CMJ height and RJ index were significantly higher in the CG trial than in the CON trial 24 h after running (P<0.05). Although changes in muscle soreness and blood variables were significantly greater in the DHR experiment than in the LR experiment, there was no significant difference between the trials in either experiment. Wearing a CG following endurance exercise facilitated recovery of jump performance under situations with severe exercise-induced muscle damage.

Irisin response to downhill running exercise in humans

[Purpose] To determine the effects of exercise-induced muscle damage, we examined irisin responses during level running (LR), with less muscle damage, and downhill running (DHR), with greater muscle damage under equivalent exercise duration and oxygen consumption (⩒O2) conditions. [Methods] Fifteen healthy men (age: 21.6 ± 2.0 y, height: 170 ± 1.3 cm, weight: 64.8 ± 2.7 kg) were randomly assigned to either the LR group (n = 8) or the DHR group (n = 7). Subjects in the LR group performed treadmill running at 70% of maximum oxygen uptake (⩒O2max) for 30 min on a 0% gradient. In contrast, subjects in the DHR group performed the same exercise on a –10% gradient. Blood samples were collected before exercise, immediately after exercise, and 1, 3, and 24 h after exercise. [Results] No significant interaction (group × time) or main effect of group or time was observed for changes in plasma irisin concentrations over time (P > 0.05). However, the area under the curve of plasma irisin concentrations during a 3-h post-exercise period was significantly greater in the DHR (239,197 ± 8,166 ng/mL) group than in the LR (92,293 ± 8,755 ng/ml) group (P < 0.05). The blood lactate, serum cortisol, myoglobin, and plasma interleukin-6 concentrations were significantly higher in the DHR group than in the LR group after exercise (P < 0.05 for all variables). [Conclusion] DHR associated with marked muscle damage promoted a greater increase in exercise-induced irisin did LR after the same duration under identical VO2 conditions.