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  • Author: Gregory M. Gutierrez x
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Gregory M. Gutierrez and Thomas Kaminski

Lateral ankle sprains (LAS) are among the most common joint injuries, and although most are resolved with conservative treatment, others develop chronic ankle instability (AI). Considerable attention has been directed toward understanding the underlying causes of this pathology; however, little is known concerning the neuromuscular mechanisms behind AI. A biomechanical analysis of the landing phase of a drop jump onto a device that simulates the mechanism of a LAS may give insight into the dynamic restraint mechanisms of the ankle by individuals with AI. Furthermore, work evaluating subjects who have a history of at least one lateral ankle sprain, yet did not develop AI, may help elucidate compensatory mechanisms following a LAS event. Identifying proper neuromuscular control strategies is crucial in reducing the incidence of AI.

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Gregory M. Gutierrez, Catherine Conte and Kristian Lightbourne

Head impacts are common in contact sports, but only recently has there been a rising awareness of the effects of subconcussive impacts in adolescent athletes. A better understanding of how to attenuate head impacts is needed and therefore, this study investigated the relationship between neck strength, impact, and neurocognitive function in an acute bout of soccer heading in a sample of female high school varsity soccer players. Seventeen participants completed the ImPACT neurocognitive test and had their isometric neck strength tested (flexion, extension, and bilateral flexion) before heading drills. Each participant was outfitted with custom headgear with timing switches and a three-dimensional accelerometer affixed to the back of the head, which allowed for measurement of impact during heading. Participants performed a series of 15 directional headers, including 5 forward, 5 left and 5 right headers in a random order, then completed the ImPACT test again. Neurocognitive tests revealed no significant changes following heading. However, there were statistically significant, moderate, negative correlations (r = −0.500:−0.757, p < .05) between neck strength and resultant header acceleration, indicating that those with weaker necks sustained greater impacts. This suggests neck strengthening may be an important component of any head injury prevention/reduction program.

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Gregory M. Gutierrez, Nicole D. Jackson, Kristin A. Dorr, Sarah E. Margiotta and Thomas W. Kaminski

Context:

Lateral ankle sprains occur more frequently than any other orthopedic injury. Athletes often report sustaining more injuries late in competition when fatigue is present.

Objective:

To evaluate neuromuscular function of the ankle musculature after fatigue. Design: Experimental, pretest-posttest.

Setting:

Research laboratory.

Participants:

Ten female and 9 male college-aged subjects.

Intervention:

Fatigue was induced via continuous concentric and eccentric muscle actions of the ankle: inversion (INV), eversion (EV), plantar flexion (PF), and dorsiflexion (DF).

Main Outcome Measures:

Peak torque (PT), peak EMG, and median frequency (MF) were calculated prefatigue and postfatigue in the tibialis anterior (TA), peroneus longus (PER), and lateral gastrocnemius (GAS) muscles.

Results:

Main effects were noted for test (P < 0.0125) in all statistical tests performed indicating changes in PT, peak EMG, and MF after fatigue.

Conclusions:

A significant decrease in MF of the PER muscle after PF fatigue and corresponding with a decreased firing rate, may be of importance, especially with regard to the role in countering the violent moment seen with inversion ankle sprains.