The muscular strengthening process used by the skiers of the French Federation is generally inspired by weight lifting and athletics schools. Mostly aimed at reinforcing the inferior limbs, this activity is added up to a systematic strengthening of the trunk muscles in order to improve the skier's capacity to keep his posture under acceleration strain. The basic movements used are squat and exercises of pliometric rebound. These movements are proved to improve the strength of the extension muscles in the trunk as well as in inferior limbs. However, numerous studies have shown the specificity of strength acquisition, and therefore its limitation to the training situation (THORSTENSSON et al., 1977, SALE, 1988, THÉPAUTMATHIEU et al., 1997). On an empirical level, we know the conditions of squat practice are far different from the actual alpine ski practice. For instance, during practice, the chain of extensor muscles of each inferior limb is put under a variable snow/ski strain which is rarely perpendicular to the snow slope; so many conditions which are not present in classic squat practice, where the normal ground/foot interaction occur on a horizontal surface. We can therefore question the accuracy and efficiency of such exercises in the alpine skier's preparation. Our complementary couple, composed of a researcher for didactics and a physical trainer in charge of a European Cup Federal group, works in the perspective of overcoming the above mentioned contradiction. They co-elaborate a muscle strengthening method specifically targeted at alpine skiers. For this purpose, we have to rely on kinematics models of the ski-skier system, which were created by the researcher thanks to the data collected directly during competition practices (ROUX, 2000). Our research methodology for didactics was conceived in order, on the one hand, to generate technical knowledge (BOUTHIER, DUREY, 1994) which are indispensable to our knowledge objectives as well as to the conceptions provided by the performance actors, and, on the other hand, to provide guidelines for the elaboration of an experimental process of movement analysis. This processing system is an induction-deduction process (ASTOLFI, DEVELAY, 1989) aiming at producing kinematics data (DIETRICH, 1996-2002) which reveal the characteristic features of body techniques, specific to the "Giant" specialists within the World Cup Federal groups whose actions and regularities were analysed for our study purposes. Our aim is to assemble technical knowledge, which the practitioners themselves validated, depending on their efficiency, for training, for being trained, for building skis… In this perspective, we created a technological model, stemming from the mechanical model of referential social practice (MARTINAND, 1989). This model is constituted by an ensemble of univocal observable parameters which represent each body technique considered as significant in regard to the performance; each observable parameter being the symbolic signifier of that particular technique (WALLON, 1970). This conception is outlined by a spotted image and by words (VYGOTSKI, 1985, CLOT, 1979, BACHELARD, 1971). Our methodology is distinguished by the creation of muscle strengthening situations which we inferred from body techniques turned into objectives through movement analysis. For instance, the concept of rotation of the "leg plane", or that of lateral and longitudinal hip inclination, enable us to conceive exercises during which the muscular chain solicitation occur on a pelvis hold or in the course of open/closed feet squat (convergent, parallel or divergent), ensuing from internal or external rotations of the "leg plane" combined with lateral and longitudinal pelvis displacement (adductionabduction and hip flexion with thighbone rotation on its great axis), on a horizontal, tilted (squat with ski boots), or unstable (squat on stirrups) foothold. Another example, the move explaining the dissociation between inferior limbs' actions at the occasion of a turn. We conceived series of ensuing squat exercises with feet out of line on a vertical surface with backward and forward move starting from a single foothold on unstable or stable, tilted or horizontal, supporting surfaces. Displacement exercises complete these previous tasks, such as the "Cossack" starting from dissociated foothold positions. Last example, the notions of screwing down and rolling around the hips' and shoulders' axis enable us to create so-called " dynamic-postural " exercises, with or without displacement, targeting more specifically at the trunk muscles. Therefore we shall suggest exercises which respect the rotations and rolling related to hips' and shoulders' axis revealed by the movement analysis, with a proximal hold positioned at pelvis level or a distal hold situated at foot level. In addition, a global work integrating the muscular chains which belong altogether to the inferior limbs, to the trunk, and to the superior limbs, will be exposed - so-called exercise "on wood duty".
© Copyright 2002 Expertise in Elite sport. 2nd International Days of Sport Sciences, 12.-15. November 2002, INSEP, Paris (France). Veröffentlicht von INSEP. Alle Rechte vorbehalten.