Lower limb joints’ contributions to ballet turnout during unipodal and bipodal jumps in fifth position in pre-professional dancers

Résumé fourni par la source

Turnout, a large external rotation of the lower limb joints, is a key element of jumps and of other postures in classical ballet technique. Correct transverse-plane alignment of body segments in turnout is critical to reduce technical errors and injury risk. Although many studies have examined turnout in static positions, there is a need for a deeper understanding of this element dynamically, particularly during uni- and bipodal jumps with body displacements in fifth position. Such insights could help improve the technique and the training protocols. This study investigated the external rotations of the hip, knee, and ankle in turnout during three phases (preparation, flight, and landing) of two jumps with displacement performed in the fifth position: one unipodal, the Sissone Ouvert, and one bipodal, the Assemblé Dessus. Twenty-eight pre-professional ballet dancers were analyzed with 10.9 ± 3.2 years of ballet practice, 12.4 ± 2.7 hours of weekly training and a passive hip external rotation (static turnout) of 53.9 ± 10.1 deg. The dancers were instrumented with 16 skin-markers according to the Plug-in-Gait protocol and an eight-camera motion analysis system recorded lower limb kinematics in the transverse plane of the self-selected leg. Temporal profiles of joint angles were time normalized and the external rotation peak of hip, ankle, and knee were compared across phases and joints by repeated measures analysis of variance (ANOVAs) and Newman–Keuls post hoc ( p < 0.05). The external rotation peak of the ankle, knee, and hip differed across phases ( p < 0.001) for both jumps. In the Assemblé, hip and knee rotation peaks exhibited a similar behavior between the preparation and flight, while the ankle reached its highest peak at landing ( p = 0.022). In the Sissone’s preparation, knee and ankle peaks showed significantly greater rotation compared to hip ( p < 0.001), whereas in the flight, the hip exhibited the highest rotation compared to the other joints ( p < 0.001). The external rotation peak occurred in different instants in each phase and with respect to normalized jump duration ( p < 0.001). In conclusion, the knee joint has little contribution to external rotations in the turnout; conversely, the ankle and the hip joints appear to be pivotal in maintaining the turnout respectively in the Assemblé and in the Sissone, the latter mainly during the flight phase.

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