The Comparison of Muscle Timing between Athletes with and without Chronic Ankle Instability during Lateral Jump Landing

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Most studies have investigated peroneal reaction time in relevant conditions of unexpected inversion perturbation occurring. The need to conduct more functional and dynamic testing that closely mimics athletic performances has been emerged.The aim of present study was to compare premotor time and motor time of leg muscles between athletes with and without chronic ankle instability during landing phase of a lateral jump condition.Twelve athletes with self-reported unilateral chronic ankle instability and 12 matched controls participated in the study. Participants performed lateral jump landing test during a relatively simple dynamic choice reaction task.An electromyography device synchronized with a force plate collected data during the landing phase of lateral jump. Premotor time, motor time and reaction time of leg muscles were recorded and group differences were assessed.

Mean premotor time values for peroneus longus and tibialis anterior muscles were significantly (P=0.000, P= 0.035 respectively) greater in chronic ankle instability patients compared to controls. There was astatistically significant (p=0 .001, P= 0.014 respectively) decrease in motor time measures for peroneus longus and brevis muscles in chronic ankle instability group compared to control group. There was no statistically significant difference in reaction time between the 2 groups.This study found muscle timing deficits in injured ankles of athletes with chronic ankle instability compared to healthy ones. The greater premotor time delay of peroneus longus and tibialis anterior muscles demonstrated in subjects with ankle instability in compared to healthy athletes should be taken in to consideration during assessment and rehabilitation programs.

Ankle sprains are one of the most common injuries affecting athletes. Many ankle injuries are found in sports that require jumping and landing such as basketball, volleyball and soccer. Ankle sprains account for up to 25% of all lost time from participation in sport competitions. People who experience an ankle sprain are at risk of developing Chronic Ankle Instability (CAI) which is characterized by subjective, repeated episodes of giving way after an initial ankle sprain. It has been estimated that up to 80% of athletes experience a recurrent sprain. Symptoms of residual instability represent in 20-40% of patients and this can lead to osteoarthritis in long term. Proprioception, muscle strength, muscle reaction time, and postural control are the factors contributing to impaired neuromuscular control that is believed to be the main cause of ankle instability development.