@article{ref1,
title="Cortical hypoexcitability persists beyond the symptomatic phase of a concussion",
journal="Brain injury",
year="2014",
author="Powers, Kaley C. and Cinelli, Michael E. and Kalmar, Jayne M.",
volume="28",
number="4",
pages="465-471",
abstract="Primary objective: The purpose of this research was to assess cortical excitability, voluntary activation of muscle and force sensation beyond the initial highly symptomatic period post-concussion (1-4 weeks post-injury). It was hypothesized that reduced excitability of the motor cortex may impair muscle activation and alter perceptions of force and effort. Research design: Eight concussed varsity football players were age- and position-matched with eight healthy teammates to control for training and body size. Healthy controls had not suffered a concussion in the previous 12 months. <br><br>METHODS and procedures: Paired-pulse transcranial magnetic stimulation was used to assess cortical excitability, voluntary activation was calculated using cortical twitch interpolation technique and sense of force was determined using constant-force sensation contractions. Main outcomes and results: The concussed group had lower intra-cortical facilitation (p = 0.036), lower maximal voluntary muscle activation (p = 0.038) and greater perceptions of force (p < 0.05), likely due to compensatory increases in upstream drive, than their healthy matched teammates. <br><br>CONCLUSIONS: Taken together, these findings suggest a state of hypoexcitability that persists beyond the immediate acute phase of a concussion and may result in neuromuscular impairments that would call to question the athlete's readiness to return to sport.  Keywords: American football; Canadian football; soccer<p /> <p>Language: en</p>",
language="en",
issn="0269-9052",
doi="10.3109/02699052.2014.888759",
url="http://dx.doi.org/10.3109/02699052.2014.888759"
}