Comparison of trunk accelerations and knee flexion angle during three types of landing between ballet dancers and non-dancers

Abstract

Purpose: 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. Method: 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: landing, silent landing and raise up landing. 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. Result: In the raise up landing, 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. Conclusion: The impact on the lumbar during raise up landing was less in dancers. In raise up landing, 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.