Abstract

We explored the first evidence of a single-session neuromuscular biofeedback ef-fect on motor unit properties, neuromuscular activation, and the Achilles tendon(AT) length 12 days after undergoing AT surgical repair. We hypothesized thatimmediate neuromuscular biofeedback enhances motor unit properties and acti-vation without causing AT lengthening. After 12 days AT surgical repair, MedialGastrocnemius (MG) motor unit decomposition was performed on a 58-year-oldmale before and after a neuromuscular biofeedback intervention (surface electro-myography (sEMG) and ultrasonography), involving unressited plantar flexion.The analysis included motor unit population properties, sEMG amplitude, forceparadigm, and AT length. There were more MG motor unit recruitment, peak andaverage firing rate, coefficient of variation, and sEMG amplitude, and decreasedrecruitment and derecruitment threshold in the repaired AT limb. The non-in-jured increased the motor unit recruitment, and decreased the coefficient of vari-ation, peak and average firing rate, inter-pulse interval, derecruitment thresholdand sEMG amplitude. The AT length experienced −0.4 and 0.3 cm changes in therepaired AT and non-injured limb, respectively. This single-session neuromus-cular biofeedback 12 days after AT surgery shows evidence of enhanced motorunit properties and activation without signs of AT lengthening when unresistedplantar flexion is performed in the repaired AT limb.