Muscular adaptations and insulin-like growth factor-1 responses to resistance training are stretch-mediated

Abstract

Enhanced muscle in vivo (and somewhat IGF-1) adaptations to resistance training are concurrent with muscle stretch, which warrants its inclusion within training.

Triceps Brachii Muscle Strength and Architectural Adaptations with Resistance Training Exercises at Short or Long Fascicle Length

“…It is worth noting that the range of fascicle length used during training was not measured in that previous study [8]. Nevertheless, the apparent discrepancy with the current results might be related to the longer training duration and/or the training experience of the participants.…”

“…In a recent study [8], it was found that training at long fascicle length induced greater increases in strength, distal muscle cross sectional area, and fascicle length of vastus lateralis accompanied by increases in Insulin-Like Growth Factor 1 (IGF-1), as compared to training at short fascicle length. It is worth noting that the range of fascicle length used during training was not measured in that previous study [8].…”

“…Indeed, the small, however non-significant difference in strength increase (44% vs. 40%), muscle thickness (15% vs. 10%), and hypertrophy (16-25% vs. 14-17%) increase in favor of the cable overhead extensions exercise might be an indication for such adaptations, particularly if training was to be continued for a longer duration. Also, in the study of McMahon et al (2014), training was performed for 8 weeks, with three sessions per week, and 4 sets of 8-10 reps for 4-5 exercises per session in moderately trained males, which also suggests a great variance in the training load in favor of the earlier study [8]. Although application of a large training load would be inappropriate in the current study due to the novice nature of the participants, it may not be excluded that the lack of difference in fascicle length increase between the current study and the study of McMahon et al (2014) may be due to the differences in the training volume applied.…”

“…Likewise, isometric training at long muscle length resulted in greater increase in concentric muscle strength whereas training at short muscle lengths induced increases only in isometric strength, which was not related to changes in muscle size [6,7]. In another study, dynamic resistance training using machines and free weights at long muscle length was superior to training at short muscle length [8]. These researchers reported that concentric strength, muscle mass, hypertrophy, and fascicle length of vastus lateralis increased after both training conditions, but more increases were observed after training at long muscle length.…”

“…Recent studies aimed to investigate whether training at different muscle lengths of the knee extensors induces different muscle strength and mass adaptations [5][6][7][8]. Recently, it has been reported that 8 weeks of isometric knee extension training at long muscle length induced greater strength gains compared to training at short muscle length [5].…”