BackgroundAnkle sprains are associated with detrimental long-term sequelae tied to neuromechanical alterations. Neurological adaptations occurring in the initial weeks after injury may be responsible for long-term adaptations resultant in altered movement patterns; however, few studies have quantified neuromechanical and functional adaptations following acute ankle sprains.ObjectiveThis study aims to quantify cortical and reflexive excitability following ankle sprain with concurrent changes in function.DesignPilot cohort study.SettingUniversity laboratory.Participants6 male subjects (age = 20.8 ± 0.8 years, height = 181.2 ± 3.5 cm, body mass = 84.8 ± 9.0 kg) with history of recent ankle sprain volunteered for this investigation.InterventionsParticipants were tested at 1, 2, 4, and 8 weeks from injury. During each session clinical measures of ankle volume, balance (Y-balance test), and dorsiflexion range-of-motion (weight-bearing lunge) were assessed. Electromyography sensors were placed on tibialis anterior (TA), peroneus longus (PL), and soleus (SOL) and cortical and reflexive excitability were assessed bilaterally using transcranial magnetic stimulation (TMS), and Hoffmann reflex, respectively.Main outcome measurementsStimulus- response curves from TMS were used to determine active motor threshold (AMT, %output) and maximal response (MEPmax, %Mmax). Side differences were assessed using descriptive statistics.ResultsDifferences in ankle volume, balance, and dorsiflexion were observed at week 1, and, except dorsiflexion, were no longer present at week 8. Notable side-to-side alterations in cortical excitability were noted for TA AMT and PL and SOL MEPmax. These findings indicated decreased TA excitability, but increased PL and SOL excitability at 1-week (TAINJ = 33.4 ± 15.7%, TANON = 27.7 ± 4.0%; PLINJ = 70.5 ± 35.1%, PLNON = 45.7 ± 34.1%; SOLINJ = 10.6 ± 11.6%, SOLNON = 12.1 ± 5.1%) but the opposite effect 8-weeks after injury (TAINJ = 38.8 ± 2.8%, TANON = 35.6 ± 12.0%; PLINJ = 35.6 ± 9.2%, PLNON = 48.7 ± 9.0%; SOLINJ = 10.5 ± 7.2, SOLNON = 8.1 ± 5.9%). Generally, the H-reflex was slightly elevated for all muscles and time-points on the injured side.ConclusionsChanges in neurological function were observed among this small cohort of participants that reflect both acute and long-term adaptations due to injury. Further analysis is required to determine how these variables might affect functional measures.