Abstract:

BACKGROUND:Whether high-or-low intensity exercise coupled with neuromuscular electrostimulation (NMES) affect IGF-1 and IGFBP-1 is unknown. The scope of this study was to test whether 8-week High-Intensity Interval Training (HIIT) and Continuous Aerobic Training (CA) combined with/without NMES performed at 65% and 120% of VO2max on a cycle ergometer induce different metabolic adaptations. METHODS:A randomized controlled trial with a parallel groups study design was used. Thirty healthy untrained male participants (age:21.33±1.24years, height:177.80±5.97cm, weight:73.74±7.90kg, lean body mass:64.29±5.11kg, percent body fat:12.43±5.34%) voluntarily participated in this study. Six participants were allocated to Control, 6 to HIIT, 6 to HIIT+NMES, 6 to CA, and 6 to CA+NMES. RESULTS:Pre- to post-test IVO2max, blood lactate concentrations, O2 kinetics, peak torques at 60o/s and 180o/s were found statistically significant (p<0.05, p<0.001). IGF-1 pre 15 min in CA and IGF-1 post 30 min in HIIT group was found significantly higher compared to control group (16.93±8.40 vs 6.05±4.25, p=0.024; 10.80±3.94 vs 6.15±2.56, p=0.037), respectively. Additionally, IGFBP-1 were found significantly higher in CA+NMES group than HIIT group (0.95±0.67 vs. 1.23±0.56). Eight week post IGF-1/IGFBP-1 ratios were found higher in pre 15 min, post 30 min and post 24 h compared to baseline pre 15 min, post 30 min and post 24 h measurements in all groups (8.92±4.72 vs 3.93±3.14; 9.41±3.72 vs 3.99±1.76; 8.63±3.01 vs 5.89±3.01), respectively. Also, IGFBP-1 post 30min was significantly lower in HIIT+NMES while CA group showed significantly lower baseline and 24h post IGFBP-1 compared to pre- test measurements (Z= -3.20, p=0.001; Z= -3.72, p=0.000; Z= -2.93, p=0.000). CONCLUSIONS:HIIT and CA training induce different stimuli on IGF-1 and IGFBP-1 and NMES application combined with high-and-low intensity exercise is highly effective in improving athletic performance.