Satellite cell activation and mTOR signaling pathway response to resistance and combined exercise in elite weight lifters

Purpose Our aim was to compare the effects of a single exercise training mode (resistance exercise) with a combined exercise training (resistance and plyometric exercise) mode on satellite cell activity and anabolic signaling at the molecular level. Methods Eighteen male weight lifters (20 ± 4 years, BMI 27 ± 6 kg/m 2 ) were randomly assigned to either a series of resistance exercise or a series of combined exercise group. The intensity of the exercise was set at 60% of their 1 RM weight and subjects completed three sets each of six repetitions. The combined exercise group performed three different types of resistance exercise alternating with three different types of plyometric exercise, whereas the resistance exercise group performed only the three different types of resistance exercise which was repeated twice. Muscle biopsies were obtained the vastus lateralis muscle immediately before and 3 h after one bout of exercise. Results Exercise induced increases in satellite cell activation and myofibrillar protein synthesis following both exercise modes, but the resistance exercise group was superior compared to the combined exercise group in satellite cell activity expressed by Ki67/CD56 (165 vs 232%) and PI3K/Akt protein expression (121 vs 157%), mTOR protein expression (117 vs 288%), p70S6K protein expression (253 vs 809%), and 4E-BP1 protein expression (70 vs 139%) of anabolic signaling pathway. Conclusions These results suggest that the previous findings showing a greater effect of combined as opposed to a single exercise mode could be the effect of a greater training volume rather than a true-training effect of a combined exercise program.