Aim: 

Transcutaneous neuromuscular electrical stimulation (NMES) exerts significant effects on the skeletal muscle phenotype and function through increase of muscle mass, force and exercise capacity. Whereas the impact of NMES on skeletal muscle mass and function has been described in detail, no information are available on the molecular mechanisms underlying such adaptations. In the present study we aimed to analyse proteome changes following NMES in the skeletal muscle of young humans.

Methods: 

In this study, ten, young (18–35 years of age), healthy, male subjects were subjected to 24, 18-min sessions of isometric (bilateral) NMES of the quadriceps muscle over a period of 8 weeks with 3 sessions per week. Needles biopsies were taken from the vastus lateralis muscles pre- and post-training. SDS page and real time PCR were performed to analyze the pattern of myosin heavy chain (MHC) expression. 2D gel electrophoresis was used to examine the overall protein pattern before and after NMES.

Results: 

Maximum voluntary contraction (MVC) and neural activation were found to be significantly higher post-training (+20% and +9% respectively). MHC isoform distribution showed a significant shift from MHC-2X towards MHC-2A and MHC-1, i.e. a fast to slow transition. Real-time PCR analysis of changes in MHC expression showed the same pattern. Interestingly, a-cardiac, embrional and perinatal MyHC isoforms, considered as transitional isoforms, were expressed at the levels of mRNA but not at the level of protein. Fluorescently stained proteome maps showing ~600 spots were obtained pre- and post-training and differentially expressed proteins were identified and subdivided in different categories.

Conclusion: 

NMES exerts a profound change in muscle protein expression pattern and shows peculiar features in comparison with voluntary training.