Spinal Cord Transcutaneous Stimulation Priming Largely Enhances Lower Limb Performance during a Simulated Power Training Session in Young Active Males

PURPOSE: To investigate the potential efficacy of spinal cord transcutaneous stimulation (scTS) priming to enhance lower limb neuromuscular performance during a subsequent power training session. METHODS: Eleven young active males (age: 21.3 ± 1.6 yr) participated in this randomized crossover, sham-controlled study. The priming protocol consisted of the application of scTS or sham stimulation (Sham) at rest and during warm-up for approximately 25 min. Force, velocity, and power, as well as electromyography (EMG) of lower limbs generated during unilateral half squats on a Smith machine, were assessed over two separate experimental sessions (scTS or Sham) for: 1) four power training sets, each including six unilateral repetitions with 2) the last (fourth) set continuing to failure. RESULTS: Peak and mean power generated during the four power training sets preceded by scTS priming were significantly higher (11%, P < 0.001 and 14%, P = 0.008, respectively) than those generated in the Sham session. Similar trends were also shown by velocity, force, and total impulse of force. Exploratory EMG analysis revealed that scTS priming favored an overall improved activation of the vastus lateralis during the concentric phase. Higher peak and mean power outputs (13%, P = 0.006, and 24%, P = 0.014, respectively), associated with higher EMG amplitude of vastus lateralis, were promoted by scTS priming also for the last set to failure, which resulted in a similar number of repetitions between the scTS (32 ± 17) and Sham priming (32 ± 19) sessions. CONCLUSIONS: scTS priming enhanced neuromuscular outcomes during a simulated lower limb power training session. Further studies should implement scTS priming throughout a longitudinal power training intervention and assess its potential to enhance training-induced neuromuscular adaptations.