COMPARISON OF TRUNK ACCELERATIONS AND KNEE FLEXION ANGLE DURING THREE TYPES OF LANDING BETWEEN BALLET DANCERS AND NON-DANCERS / 体力科学

<b>Purpose:</b> The purpose of this study was to determine whether the impact on the body during landing in dancers is less than in non-dancers by using accelerometers and motion analyzer.<b>Method:</b> Eleven ballet dancers and 11 non-dancers participated in this study. Each subject was instructed to perform 3 types of landing from a height of 30cm: <i>landing, silent landing</i> and <i>raise up landing.</i> Markers were put on the iliac crest, greater trochanter, knee joint, lateral malleolus. The peak vertical and horizontal accelerations of the lumbar, peak vertical acceleration of the greater trochanter and the peak flexion angles of the hip and knee joints were measured after the trials.<b>Result:</b> In the <i>raise up landing,</i> the peak vertical acceleration of the lumbar region in dancers was less than that in non-dancers (p < 0.01), and the peak knee-flexion angle in dancers was greater than that in non-dancers (p < 0.01). There were no differences between the peak hipflexion angles of dancers and non-dancers.<b>Conclusion:</b> The impact on the lumbar during <i>raise up landing</i> was less in dancers. In <i>raise up landing,</i> the trunk tends to be fixed when the dancer stands upright. Moreover, dancers attenuated the shock to the lumbar region by increasing the knee-flexion angle to a greater extent than the non-dancers did. This result may indicate the importance of the knee joint flexion in attenuating the shock during landing and show that dancers excel in using their knees flexibly.

Posterior Impingement Syndrome of the Ankle Joint in Classical Ballet Dancer / 대한정형외과학회잡지

In the classical ballet dancers, ankle joints are frequently overused. Especially the Pointe and the Releve are the two basic steps of ballet dance which cause the narrowing of the posterior aspect of the ankle joint. Posterior impingement syndrome of the ankle joint is defined as impingement occuring at the anatomical interval between the posterior tibial articular surface and os calcis. The purpose of this study is to describe the anatomy and etiology of this injury and to review the non-operative and operative treatments. Sixteen cases of posterior impingment syndrome had been treated between March 1994 and March 1995. Ten dancers were professional and six were students. The patients was divided 3groups by etiologic factor. Group 1 is anatomical problem factor, Group 2 is overuse factor and Group 3 is ankle sprain factor. Thirteen dancers (81.2%) improved with conservative treatment including local steroid injection. Among the other three dancers, operation was performed in one case. The other two cases stopped dancing. The result was good in one dancer after operation. In the classic ballet dancers, posrerior impingement syndrome was frequent disorder and major etiologic factors are anatomical problem and overuse. Operation was necessary in only group l. It is good result in conservative treatment and operation.