The ankle sprain is the most frequently found acute injury in volleyball. Aiming to prevent the occurrence of ankle injuries, prophylactic equipment as the bracing had been developed. This study had the purpose to evaluate the performance of the ankle muscles (tibialis anterior, peroneous longus, and medial and lateral gastrocnemius) by measuring the electrical activity in different volleyball activities (vertical jumping and lateral shuffling) with and without using ankle bracing. Nine young female volleyball athletes with ages ranging from 14 to 17 years (x: 15.8 ± 1.3) were evaluated, all of them without previous injuries in the dominant member. Maximal voluntary isometric contractions (MVIC) of each muscle was collected, and after that, the electromyographic activity in different situations with and without using the bracing, randomly. The bracing used had two lateral supports. The electromyographic signal was quantified by the root mean square (RMS), and normalized by the MVIC. Analysis of the variance with repeated measurement was used to verify the difference of the electric activity of the muscles involved in each activity, with and without using the bracing, with 5% (p < 0.05) significance level. It was identified a statistically significant difference in phase I of the jumping in favor of the tibialis anterior (p < 0.001) and in phase II in favor of the three flexors muscles (p < 0.001; p = 0.01; p = 0.003) in both situations, with and without using the bracing. As to the lateral jump activity, a significant difference was observed in the phase of braked in favor of the tibialis anterior and the lateral gastrocnemius (p = 0.013) in both situations. It was found no statistical difference among muscles of the two groups. Results suggest that using the ankle bracing cannot influence the electrical activity of the muscles studied during the vertical jumping and the lateral shuffling.

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This study analysed the behaviour of the geometric curvature of the spine during sirshasana. The position of dorsal retroreflective markers was computed via stereophotogrammetric analysis in six males and five females (29.4 ± 8.8 years, 63.0 ± 11.4 kg, 1.66 ± 0.08 m [average ± standard deviation]). The spinal points were projected onto the sagittal and frontal planes of the trunk, a polynomial was fitted to the data and the two-dimensional geometric curvature was quantified. The inferior lumbar lordosis decreased compared to the orthostatic position and gait, which may favour the posterior protrusion of the lumbar spinal nucleus pulposus in people with posterior herniation. The lateral deviation at the middle of the thoracic spine increases during sirshasana, which may reflect increased difficulties for postural control and spinal loads. It could be useful for promoting positive spinal structural and functional chronic adaptations for healthy participants, if the yoga programme is carefully planned and the spinal alignment is carefully monitored during a headstand. However, it may aggravate some spinal diseases, especially scoliosis.

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