Abstract

Ankle injuries are one of the most common injuries in competitive sports and recreational activities. The primary causes of ankle sprains are impaired proprioception, postural control, muscle strength, and prolonged peroneal reaction time. The peak incidence of ankle sprain occurs between 15 and 19 years of age, but there is no significant difference in the incidence of inversion sprain between males and females. Furthermore, inversion sprain occurs in persons less than 50 years old because it is frequently sustained during sports activity. In addition to these epidemiological data, there are no known reports of differences in ankle sprain rates or their risk factors by ethnicity or race. Therefore, the primary aim of this study was to explore the differences in peroneal and tibial muscle latency, which are risk factors for ankle sprains, and secondly the differences in morphology of the peroneus longus and tibialis anterior muscles between black and white races.

Twenty-five healthy recreational male individuals, 12 Africans (mean age, 24.0 ± 3.4 years; mean height, 176.1 ± 5.8 cm; mean body mass, 72.6 ± 12.2 kg; mean body mass index, 23.3 ± 3.3) and 13 Caucasians (mean age, 24.2 ± 2.3 years; mean height, 177.1 ± 5,7 cm; mean body mass, 72.3 ± 8.0 kg; mean body mass index, 23.0 ± 1.7), were enrolled to this study. The leg that the participant uses to naturally kick a ball was defined as the dominant leg. The electromyographic activity parameters (muscle latency, muscle reaction duration and muscle reaction magnitude) of the peroneus longus and tibialis anterior muscles of the dominant leg were measured using an ankle supination tilting platform. There were four different supination conditions: (a) ankle in neutral position and 15° inversion (N15), (b) ankle in neutral position and 30° inversion (N30), (c) ankle in 20° plantarflexion position and 15° inversion (PF15), and (d) ankle in 20° plantarflexion position and 30° inversion (PF30). Besides, the morphology of these muscles was evaluated by ultrasonographic (pennation angle, fascicle length and muscle thickness) measurements.

Only the reaction duration of the tibialis anterior muscle in N15 (66.5 msec in Caucasians and 46.5 msec in Africans, p = 0.030) and N30 (52.2 msec in Caucasians and 35.5 msec in Africans, p = 0.039) condition and reaction magnitude of the peronealis longus (30.4% in Caucasians and 18.8% in Africans, p = 0.046) and tibialis anterior (11.9% in Caucasians and 5.2% in Africans, p = 0.003) muscles in N15 condition were significantly higher in Caucasian subjects. These parameters were not significantly different in PF15 and PF30 supination conditions (p?> 0.05). Besides, no significant differences were found in peroneal or tibial muscle latency between both races in all the four supination conditions (p > 0.05). Similarly, except the different fascicle length values of the tibialis anterior muscle in the contracted state (50.6 mm in Caucasians and 41.9 mm in Africans, p = 0.011), all the other muscle morphological features (muscle thickness and pennation angle) of the peronealis longus and tibialis anterior muscle were similar between the races (p > 0.05).

The results of this study indicates, in general, that there is no race differences between Caucasian and Africans with the evaluation of the electromyographic activity and muscle morphology measures of the peronealis longus and tibialis anterior muscles.