Reliability of two methods for identifying the timing of medium latency responses in subjects with and without chronic ankle instability

This study aims to: (1) to compare 2 methods of assessing the timing of medium latency responses (MLR), in regard to intrasession reliability and mean values, in subjects with and without chronic ankle instability (CAI), and (2) to analyze the influence of CAI in timing of MLR and in its reliability. Thirty six athletes with (16) and without (20) CAI participated. Bilateral electromyography of peroneus longus (PL), peroneus brevis (PB), tibialis anterior (TA) and soleus (SOL) muscles was collected during a unilateral sudden inversion perturbation to assess the timing of MLR onset, in both standing and perturbed positions, through a baseline-based method and a peak-response-based method. The group without CAI presented higher relative reliability of SOL and peroneal muscles MLR with the peak response-based method than with the baseline-based method. Compared with the group without CAI and in both methods, the group with CAI presented a delayed and less reliable TA MLR, as well decreased coefficient variation of PL MLR in the uninjured limb. In conclusion, regardless of the method subjects with CAI present delayed and less reliable TA MLR while in subjects without CAI the peak response-based method provides higher reliability.