Spinal Cord Transcutaneous Stimulation Priming and Lower Limb Neuromuscular Performance in Individuals with Anterior Cruciate Ligament Reconstruction After Their Return to Sport: A Case Series

Background: Neuromuscular deficits may persist following anterior cruciate ligament reconstruction (ACLR), even after returning to sport. In this exploratory case series, we investigated the effects of non-invasive spinal cord transcutaneous stimulation (scTS), applied during warm-up for approximately 25 min to prime the nervous system, on neuromuscular performance of the ACLR limb during a simulated half-squat power training session. Methods: Four young, non-professional athletes with time since ACLR between 9.0 and 14.5 months, who were already returned to sport, participated in this study. Force, velocity, power, and electromyography of representative thigh muscles generated by the ACLR and intact limbs during unilateral half-squats on a Smith machine, were assessed over two separate experimental sessions (scTS or sham stimulation priming). Results: Three of the four participants showed power deficit in the ACLR limb during the concentric phase. scTS priming promoted higher power output generated by the ACLR limb in these three participants. Oscillatory-like force pattern during the downward phase was more prominent in the ACLR limb for one subject, and scTS priming attenuated it. Conclusions: These findings support future controlled trials to assess the efficacy of scTS priming as an aid to enhance rehabilitation and physical training after ACLR.