Biomedical subjects

Franck Multon

Publications and source records attributed to Franck Multon.

4 recordsLinked to original sources

PubMed2006

From bone to plausible bipedal locomotion using inverse kinematics.

The purpose of this study is to validate a method based on anatomical data and biomechanical locomotor hypotheses that could be applied in palaeontology to simulate locomotion in fossil hominids. The main problem is to ensure that purely mathematical simulation, based on anatomical descriptions, is enough to test hypotheses on human motion control. A 3D geometric model of the lower limb was therefore processed from anatomical descriptions. From this 3D model, we developed a method to retrieve natural lower-limb motion depending on chosen constraints. We assumed that the role of lower-limb motion is to make the feet move from one footprint to the next by following a trajectory that resembles that of living humans (primary task). This method based on inverse kinematics also allows biomechanical laws of bipedal locomotion to be taken into account (secondary tasks). The laws tested in this study relate to preserving joint limits, minimizing energy and minimizing the distance to a rest posture proposed by anthropologists and viewed as input to our system. A weighted sum of the resulting derivable cost functions enabled us to select a specific solution in the null space of the primary task. In order to validate this approach, we compared simulated and captured motion from ten subjects for whom anthropometrical data were recorded. We concluded that this "anatomically based bipedalism simulation" seems promising as a means of investigating natural locomotion behaviour and might also be used to retrieve natural locomotion in fossil hominids where only little knowledge is available.

Adult↗

PubMed2004

Using virtual reality to analyze links between handball thrower kinematics and goalkeeper's reactions.

This work investigates the design of a new method to evaluate the importance of visual elements taken into account by a handball goalkeeper facing a thrower. Virtual reality was used to design and reproduce standardised situations in a controlled environment. Under such conditions, it was possible to isolate for investigation one visual element in the thrower's gestures. The goalkeeper's movements were recorded in order to compare his reactions to two separate throws where only one visual element was modified. Our systems allowed us to measure and record the effects of small changes in the thrower's movements. With the numerical values we obtained from our results we were able to come up with a scale of significance for each isolated element. These preliminary results look promising for neuroscience, allowing us to better understand the strategies used in duel situations.

Biomechanical Phenomena↗

PubMed2004

Do handball throws always exhibit a proximal-to-distal segmental sequence?

Previous studies on overarm throwing have described a proximal-to-distal segmental sequence. The proximal segments reached their maximal linear velocities before the distal ones. In handball, no study has demonstrated this sequence from the upper torso to the wrist, although a recent study did present a different organization. The aim of this study was to analyse the throwing arm segmental organization during handball throwing. We found that the maximal linear velocity of the shoulder occurred after the maximal linear velocity of the elbow. Moreover, the maximal angular velocity of the upper torso occurred later than that of the elbow. Hence, contrary to other disciplines, the rotation of the upper torso was not suddenly stopped just after the forward arm motion was initiated. These results may apply to handball in general or be specific to the population of handball players studied. It may be advisable in future studies to include international players.

Adolescent↗

PubMed2003

Does training have consequences for the walk-run transition speed?

A number of authors when studying the walk-run transition phenomenon focused either on the mechanical or energy expenditure whilst only a few used both parameters concurrently. Moreover the literature demonstrates that the contribution of these variables changes along with the level and method of training. Consequently the purpose of this study is to find, by analyzing concurrently these two variables, if the walk-run transition speed is linked to the type of training. To this end we calculated two theoretical transition speeds: one based on the metabolic energy expenditure St(1) and the second one based on the internal work St(2). Subjects were divided into three groups (untrained, sprint and endurance-trained men) who were required to walk and run on a treadmill at increasing speeds. Firstly we show that the relationship between St(1) and St(2) differs depending on the groups. Sprinters have a significantly lower St(2) than St(1) whereas the opposite is found for untrained subjects. We also show that the transition speed is linked to the subject's type of training. To conclude it seems that acquiring running techniques through specific training has consequences for the walk-run transition phenomenon.

Acceleration↗