Fiber Optic-Based Wearable Sensing Device for Foot Curvature Monitoring in Classic Ballet Dancing

Monitoring the execution of exercises during classic ballet training is crucial, as incorrect preparation and accomplishment of these latter can both lead to artistic errors and increase the risk of injuries. Among the various exercises, the battement tendu represents a standard, and is used by both academy students and professionals as a warm-up to improve the dancer's muscular control. In this work, we analyze the foot curvature of two volunteer dancers with different levels of training (professional and amateur) during the repeated execution of the lateral battement tendu movement. The monitoring system consists of a wearable anklet, realized by 3D printing, and equipped with an optical fiber with five fiber Bragg gratings (FBGs) sensors, capable of detecting foot strain and curvature during the exercise. The maximum curvature reached by professional dancer is 24.7 ± 1.1 μm-1, instead is 54.3 ± 1.6 μm-1 for the amateur. In addition to the higher maximum values achieved, the amateur dancer has a greater range of variation in terms of mean curvature along the measurement axis, also pointed out by the higher standard deviation. Thanks to these results, it is finally possible to detect incorrect exercise execution and to evaluate improvement solutions to readjust preparation and prevent injuries.