Fig. 1

Experimental setup and design for individualized NMES training protocols. A Experimental device allowing for non-invasive longitudinal force measurements and individualized neuromuscular electrical stimulation (NMES) training protocol in response to electrical stimuli applied over the plantar flexor muscle belly. Yellow arrows show the proximal and distal electrodes located below the popliteal fossa and the Achilles tendon, respectively. B Typical mechanical trace obtained in response to a 250-ms 100 Hz tetanic stimulation train allowing for maximal isometric force production measurement. C Typical mechanical trace obtained in response to a 250-ms 50 Hz subtetanic stimulation train allowing for the determination of the training intensity corresponding to 15% of maximal isometric force. D Typical mechanical traces obtained during the first five (top) and last five (bottom) stimulation trains during a typical NMES training session. E Schematic representation of the short-term NMES training protocol. C57BL/6 J mice were submitted to either 6 individualized NMES training sessions or a control intervention over a 8-day period. Maximal force production was recorded at the beginning of each NMES or control interventions as well as at day 8. Then, animals were sacrificed and gastrocnemius muscle was harvested. A cohort of mice was also treated with 5-ethynyl-2'-deoxyuridine (EdU) in drinking water at the indicated timepoints. F Schematic representation of the long-term NMES training protocol. C57BL/6 J mice were submitted to either 12 individualized NMES training sessions or a control intervention over a 3-week period. Maximal force production was recorded at the beginning of each NMES or control interventions as well as at 3 days after the last training session. Then, animals were sacrificed and gastrocnemius muscle was harvested