Dissimilarities of the demi-plié movement trajectory in its different roles in classical ballet

ABSTRACT

Demi-plié is a coordinated dance movement involving knees bent while keeping hips turned out and heels grounded. It consists of descending and ascending phases, the latter often preparing for the next move. Task goals may influence its trajectory. Ten classical dancers (eight females, two males), aged 20–45 years old performed demi-plié itself and prior to pirouette en dehors, relevé, sauté, and sissonne fermée de côté. Lower limb and hip trajectory data were collected through a motion capture system. Time-series data were aligned across all conditions using a dynamic time warping algorithm. The Euclidean distance measured the hip trajectory between each ballet movement, providing a continuous dissimilarity function over time. Descriptive analysis focused on each participant’s maximum dissimilarity values across conditions. Results showed maximum hip trajectory differences of 40% for demi-plié before sauté, 30% before sissonne, 20% before relevé, and 10% before pirouette. Dissimilarities began in the descending phase of the demi-plié. ANOVAs for repeated measures and Bonferroni’s post-hoc showed that the standard deviation of dissimilarity had the largest effect size for the demi-plié – demi-plié before sauté, and the smallest for the demi-plié – demi-plié before pirouette. Demi-plié prior to jumps demands plyometric forces and has open-loop motor planning, requiring acceleration, whereas demi-plié is closed-loop, relying on proprioceptive updating.

KEYWORDS:

• Demi-plié
• dissimilarity
• dynamic time warping
• Euclidean distance
• movement trajectory
• ballet movement

Acknowledgments

To all the participants that kindly volunteered to participate in this experimental research. To Prof. Dr. Luís Xarez for the inspiration regarding the main research question for this study. To Prof. Dr. João Milho for his help in creating crucial MATLAB routines for data analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data sharing

The data that support the findings of this study are available on request from the corresponding author.

Additional information

Funding

The work was supported by the Fundação para a Ciência e Tecnologia [Provided by PTCRIS: 2021.05182.BD].

Notes on contributors

Virginia Helena Quadrado

Virginia Helena Quadrado is a Doctor of Physical Therapy, Masters in Rehabilitation Sciences, and PhD in Human Kinetics, investigating motor behavior in pediatrics and adult population. She is a former soloist of classical ballet, currently investigating coordination patterns and brain cortical activity in classical ballet dancers. She is also an international clinical physical therapist practitioner, board certified and licensed to practice in the United States, Netherlands, Brazil, and Portugal.

Ana Diniz

Ana Diniz is a professor and a researcher at the Department of Mathematics of the Faculty of Human Kinetics of the University of Lisbon in Portugal. She has a PhD degree in Human Kinetics in the speciality of Mathematical Methods. Her investigation includes mathematical/statistical methods and formal models, e.g. time series models, related to motor control and interpersonal coordination. She regularly publishes papers in high-quality scientific journals, participates in international conferences and supervises doctoral students.

Hugo Alexandre Ferreira

Hugo Alexandre Ferreira is a medical doctor and technological physics engineer, holding a PhD in physics, namely in nanotechnology and biosensors. Associate Professor of the Physics Department of the Faculty of Sciences of the University of Lisbon, teaching Mechanisms of Disease, Histology and Clinical Biochemistry, Medical Devices and Digital Health, Nanotechnology, Robotics, Prosthetics and Regenerative Medicine. Coordinator of the doctoral program in Biomedical Engineering and Biophysics and senior researcher at the Institute of Biophysics and Biomedical Engineering, on the topics of neuroscience, oncology, lung, cardiac and vascular physiology, with a special focus on the development of clinical and non-clinical applications, such as in sport, marketing and arts.

Pedro José Madaleno Passos

Pedro Passos is an Associate Professor at the Faculdade de Motricidade Humana/UL teaching Motor Control and Learning. Director of the Laboratory of Motor Behavior, investigating interpersonal coordination with several papers published in international journals, as well as books and book chapters. His academic path includes a Degree in Physical Education and Sport (1995), a Masters Degree in Sport Psychology (1999) and a PhD in Sport Sciences in 2008, all at FMH/UL. He was a Gymnastics coach (1989-1996) and a Rugby coach (1998-2009). Currently he is the Sport Scientist of the Portuguese Female Futsal National Team. Outside the country, he was an Alpine Ski instructor at Escuela Oficial de Esqui in Sierra Nevada, Spain (1998-2000).