Neuromuscular electrostimulation (EST) is normally used in rehabilitation of patients with neural deficits or to treat muscle atrophy (due to disuse) in healthy people. EST is known to increase force in maximal voluntary contraction (MVC) and voluntary muscle activation, even before muscle hypertrophy occurs.

This study aimed to analyse at muscle fibre level the effect of EST training in one elderly subject to validate the use of EST as tool to counteract sarcopenia. A 64 years old, healthy, volunteer underwent to electrostimulation training consisting in 24 sessions during 8 weeks to 18 min per session (40 contractions 6.25 seconds each) Parameters were: frequency 75 hz; pulse duration 400 msec; intensity variable set at 60% maximal isometric voluntary contraction. Needle biopsies (4–10 mg) were taken on Vastus lateralis muscle before and after the training. We analysed in single muscle fibres: (i) cross sectional area (CSA), isometric tension, i.e. isometric force/CSA during maximal activations (Po), and MHC isoforms composition of single fibers and (ii) the number of satellite cells and the nuclear domain size. The results obtained showed that CSA and isometric tension (Po) were significantly increased, and that the number of satellite cells was reduced in post-training. In conclusion, our results suggest that the training protocol used is able to increase of muscle size and strength and to stimulate a specific signaling resulting in changes in number of satellite cells.