The 3D device Codamotion is easily transportable and could easily reach from the laboratory to the sports grounds. Nevertheless, its use requires very particular light conditions which mean that it can rarely be used outside. This is why, therefore, the second type of optical systems is used: the video which works in 2D like a camcorder. If needs be however, by coupling several 2D cameras, we also succeed in reproducing movement in its three dimensions. “We could say that the optoelectronic systems allow for an almost microscopic approach to movement, while the video cameras allow for a more macroscopic approach”, comments professor Jean-Louis Croisier, president of Motricity Science at the Faculty of Medicine of the University of Liège. He goes on to add: “Everything evidently depends on the information we wish to gather. If it does not need to be very exact, the 2D will often suffice. It also allows the trainer and the athlete to directly visualize the movement studied and its evolution during correction attempts.” Needless to say the 2D and 3D technologies are complementary.

The LAHM has several 2D cameras controlled by a sophisticated software programme called Dartfish. They are capable of supplying 50 images per second. The laboratory is soon to equip itself with a camera that has a capacity greater than 200 images per second.

Synergy

Another indispensable element to the work of biomechanics is the force platform. This makes it possible to measure the ground reaction forces. In the case of a jump for example, it can record how the jumper manages his impetus: speed on the take-off board, time of impetus, analysis of the thrust, etc. The force platforms are generally integrated into the ground, in such a way that the athlete is not affected by their presence. At LAMH, the corridor in which the measurements take place is composed of a succession of interchangeable sections. According to the type of sport or the nature of the planned work, it is therefore possible to place the force platforms at the most appropriate place.

“Very soon, the laboratory will be equipped with a treadmill which will make it possible to study how the movement of a runner evolves when affected by fatigue”, says Jean-Louis Croisier. Moreover, in recording the electrical activity of the muscles, the electromyographic techniques soon to be available to LAMH will serve to identify the motricity strategies put in place for the accomplishment of one or other movement. They will also allow comparison, for a given movement, of patterns of muscular activity depending on the level of expertise of the sportsmen- beginners, confirmed athletes etc. The definition of an index of muscular fatigability will also be possible.

All the techniques available in LAMH are related by being complementary. The modeling of the sports movement is born from the synergy of the information released by each one of them and processed by specialized software. In order to cope with the complexity of procedures and stimulate innovation in the approach to modeling, the ULg laboratory has become multidisciplinary. It has designed a transversal project supported by the Medical Faculty (professors Jean-Louis Croisier and Bénédicte Forthomme) and the Faculty of Aapplied Sciences (professors Olivier Brüls, Serge Cescotto and Vincent Denoël).