• J. Flathaut
  • P. Loslever
  • J. Angu'e


INTRODUCTION The approaches usually used to increase knowledge about rock-c1imbing are numeraus and different : psychological, physiological , biomechanical, psychosensorimotor aspects, Though the goal of these different approaches is to compare expert climbers and non expert climbers, none of these tries to compare behaviours of climbers through automate control to show the different strategies for instance -, It is therefore necessary to record the movements of members (hands and feet), and secondly to describe climbers' movement by adequate statistical objects and then to propose statistical methods that allow to compare c1imbers. METHODS The experiment consists in c1imbing an artificial rock-climbing wall at a maximum speed, The scene of the cameras is defined by a threemeters-wide and three-meters-high part of the wall (Dupuy and col). The studied population consists of eight expert climbers and seven non expert climbers. The expert c1imber level reaches more than "7a / 7a+" and a non expert level doesn't overrun " 7a". The ascent of the wall is recorded by two synchronized cameras, both of them connected to a videotape recorder (50 Hz), During the experiment. a set of data is collected in a hyperparallepiped (Loslever 95) aiming at recording the climbers' movements, With this set of data, it is necessary to build, for each subject, a chronology of situations where the extremity of the four members is in contact with the wall, These situations, called "quadricontacts" are defined by a precise position of the four members, each of them occupying a hold, In these conditions, all of the studied statistic units, i.e. 13*3=39 c1imbercondition have to be taken into account. Between two following quadricontacts, generally only one member (RH: right hand, LH : Jett hand, RF : right foot, LF : left foot) has moved, In order to underline the different strategies in the movements, we count the frequency at which a member m' (m'=1 ..4) moves, between the quadricontact i and i+1, Therefore an intersegmental association table is built for each c1imber. The value T(m.m') gives the number of times that a member moves after a member'. RESULTS The number of variations of quadricontacts is about nine to fifty (average=19, ect=8), Globally, we notice that the more frequent associations are first between the two feet t(RF,LF)=15% and t(LF;RF)=14% • second along the two ' diagonals hand -foot" t(LH,RF)=12%, t(RH,LF)=9%, There is practically no "hand-hand" association. The average number of associations between expert and non expert group is nearly the same (13, 14 respectively), that seems to show that differences don't proceed from the number of quadricontacts, The C.FA shows that among the sixteen possible types of associations, the most discriminate ones are respectively LHLF, RHLH, LFLF et RHLF, It seems that the associations LHLF, LFLF, RHLH are more frequent for the non expert (77% against to 23% on the set of this association type), The association RHLF is more frequent for the experts (61% vs to 39%). CONCLUSION It seems that the differences between expert and non expert athletes could be due to the way they alternate the successive positions of hands and feet; experts prefer the association "hand to foot" though non experts would rather the association "hand-hand" or "foot-foot". The expert is thought to try to perform the most efficient and the most economic movement, The expressed hypothesis is that his mental card of the environment is very near to the reality so the expert has a better control of the informational incertainty, REFERENCES Hardy L., Martindale K. 1982. Some physiological parameters in rock-c1imbing.Physical Education Review, 5,1, 41-44 Loslever P., Flahaut J.J. 1995. Biomechanical data characterizing for multifactor and multivariate statistical analysis, I,S,B,S, 1995, Thunder Bay, Dupuy C., Ripoll H., Flahaut J.J. 1992 Organisation spatio-temporelle de la motricite en escalade sportive, ISBN 2-906411-07-8. Recherche en A.P,S. Marseille Luminy, 3 , 233253