ABSTRACT
Ice climbing has recently been introduced as a competitive practice and involves quadruped locomotion with ice tools in each hand and crampons on each foot. Progression results in contradictory actions: the climber has to determine the best target, followed by a swinging motion to anchor the axe, combining accuracy and strength, so that the climber can pull on the axe to climb up the cliff. Finally, the axe is unanchored by the climber. These successive actions are frequently repeated during progression resulting in fatigue conditions. Analyses of competitions indicates that performance is related to shorter times either for anchor or swing. Low expertise climbers spend more time in static conditions to find the target, using symmetric location of four supports resulting in greater fatigue. Biomechanical data suggests that experts adjust their movement to the kind of ice axe. They are characterized by highly controlled coordination of the upper limb joints. The cocking phase appeared with a proximo-distal coordination associated to lower muscular co-activations, the movement successively involving shoulder, elbow and wrist. The strike phase is characterised by high joint moments with peak coactivations just before the impact, the upper limb stiffening in order to transmit maximal force and velocity to the pick. The distal wrist joint controls the accuracy of the impact. The high co-activations of the digitorum muscles allowed a strong hanging that was very important to transmit force, velocity and accuracy from the upper limb to the axis. Fatigue affects the grasping muscles more than the muscles involved in the ballistic movement.
