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Section: New Results

Biomechanics and Motion Analysis

Modeling gesture in sports: tennis serve

Participants : Nicolas Bideau, Guillaume Nicolas, Benoit Bideau, Richard Kulpa.

In the midst of the INSEP project and the PhD of Caroline Martin, the tennis serve has been studied with biomechanical analyses. To this end, we have done kinematic and dynamic analyses based on motion capture, force plate and electromyographic systems. They provided information on how the gesture is performed and how it is related to injuries. Moreover, these analyses have been done on several level of players including top-level ones. A comparison of the kinematic and dynamic data can then be done. Our objective is to use these data in virtual reality to study the interaction between a tennis server and a receiver. We are creating a tool that displays a virtual server in front of a real receiver. The control of the virtual server is then done based on these biomechanical data. The objective is to analyze the reaction of the receiver depending on the movement of the server and its level of expertise.

Motion modeling in clinical applications

Participant : Armel Crétual.

We have developed a new index of gait quantification based on muscular activity called KeR-EGI. After having proved that this index is consistent and complementary with kinematics-based indices, we have shown that it is reproducible in patients even when their impairement level is high. This index is now used in clinical routine in adults. It will be also used in pediatrics in the next few months.

In orthopedics, we have proposed a novel method to quantify shoulder's global mobility called SCSV. It is based on the reachable volume in the whole configuration space of the shoulder, i.e. a 3-dimensional angular space. Clinical evaluations of shoulder's range of motion are quite always based on the analysis of only one axis, and the most usual refers to maximal external rotation from rest posture (ER1). Considering several mono-axial amplitudes, we have shown that ER1 is actually the worst choice to estimate global mobility. Instead of the ER1 procedure, we proposed to use the sum of 3 mono-axial amplitudes: external/internal amplitude at 90° lateral elevation, abduction and flexion/extension.

As shoulder is actually a complex of three articulations (gleno-humeral, scapulo-thoracic and sterno-calvicular), we have evaluated the contribution of each of them on global mobility. This has been done through a cadaveric study where we measured SCSV in any possible blocking conditions of these three articulations (from 0 to 3).