On-Slope Testing of an Instrumented Alpine Ski Boot

Abstract

In recent years, alpine ski boots have increased in height and in lateral and medial stiffness. As a result of these changes, the forces experienced by the lower leg, and the resulting injury pattern, have changed. Fractures and sprains of the ankle and spiral fractures of the tibia have declined significantly. In order to understand more fully the nature of these forces, a normal ski boot was modified by the inclusion of twelve transducers. These transducers measured forces in various areas on the lower leg, as well as under the forward part of the foot and the heel. The knee angle and the ankle flexion angle in the sagittal plane were also recorded. The instrumentation required was completely portable and weighed approximately 6 kg. A test skier made a number of runs with the equipment in place. The results show that, as the skier drove his knee forward, the forces on the frontal area of the tibia increased. The forces on the heel and forward part of the foot also increased. In going through a turn, the heel thrust took place first, followed by an increase in force in the forward part of the foot. The slalom turns show a more inconsistent, or rapidly changing, pattern of force application than the giant slalom turns.

Materials, Designs and Standards Used in Ski-Boots for Alpine Skiing

“…The torsion moment showed minimum values in correspondence with the maximum roll values, therefore suggesting that the boot-board stiffening effect is not requested when the ski is in full carving conditions. Instrumented boot-boards and pressure devices have been extensively used for the determination of the loads that are present during skiing [24][25][26][27][28] with the aim to understand the causes of injuries, and design more efficient and safe ski-boots. For example, Schaff et al [29] have studied the effect of foot pressure patterns in ski-boots with different designs and dimensions.…”

Control of Subtalar Motion with the Use of Ski Boot Footbeds

“…Because of the locking effect of the buckled ski boot there is no true heel strike or toe-off experienced (Macintyre and Matheson, 1988). Using transducers located in the footbed and tongue of a ski boot, Medoff et al (1985a) found the foot to go through a repetitive pattern of motion beginning with a heel thrust, followed by an even distribution of forces on the heel and forefoot, and finally a push-off on the forward part of the foot. In addition it was observed that short radius slalom type turns showed a more rapid, inconsistent pattern than that observed during long radius turns (Medoff et al, 1985a).…”

“…The forces involved in causing the ski to arc during a turn are transferred from the skier through the ski boots to the ski (Medoff et al, 1985a). At the same time forces are being transferred from the snow through the boot and back up to the skier (Medoff et al, 1985a).…”

“…The forces involved in causing the ski to arc during a turn are transferred from the skier through the ski boots to the ski (Medoff et al, 1985a). At the same time forces are being transferred from the snow through the boot and back up to the skier (Medoff et al, 1985a). The boot is the main link in this system of action and reaction, and as such it is of vital importance that the foot to boot fit be as close as possible (Medoff et al, 1985a).…”

“…At the same time forces are being transferred from the snow through the boot and back up to the skier (Medoff et al, 1985a). The boot is the main link in this system of action and reaction, and as such it is of vital importance that the foot to boot fit be as close as possible (Medoff et al, 1985a). For example, the ankle eversion required to initiate a ski turn is a subtle motion.…”