Studying Force Patterns in an Alpine Ski Boot and Their Relation to Riding Styles and Falling Mechanisms

Abstract

In skiing, performance and safety can depend on small details. Consequently, the measurement of forces within the ski boots, which represent the essential form-fitting and force transmitting interface during skiing, will lead to enhanced performance and more importantly safety. This study presents a methodology to measure force patterns (continuous data acquisition) under laboratory as well as realistic slope conditions. The force measurements will be analyzed to gain insights of the skiing style, skiing technique, specific falling mechanisms (i.e., boot induced anterior drawer, phantom foot, hyperextension of the knee joint, and valgus-external rotation). Furthermore, the locations of force sensors in a overlap designed ski boot are discussed in terms of practicability and applicability. These insights are of particular interest to derive release conditions for predictive binding systems and furthermore provide data to improve the style of skiing (e.g., turn release action or center of gravity behavior). For that purpose, a ski boot was instrumented with seven force (piezoresistive) sensors while the basic structure of the boot and the binding remained unchanged. Three sensors were placed on the insole to measure ground reaction forces as well as the contact forces between the skier's foot and the boot. The other four sensors were positioned at spoiler/shaft and toecap (front sole) regions of the ski boot. The locations of the force sensors within the ski-boot are defined with regard to the main body movement while skiing (body-related planes). In addition, a commercially available ski and body mount measuring system were utilized to correlate speed, inclination and body position with the force patterns occurring during skiing on the slope as well as simulating specific body positions on an inclined ramp under laboratory conditions. The measured force revealed that the toecap (upper) sensors provide insufficient even non-conclusive data to deduce significant patterns. However, the insole sensors (heel and front sole area) as well as the spoiler/shaft (back) sensors are more reliable and show characteristic patterns indicating forward or backward lean. These results will have an important impact to the development of predictiveelectro-mechanical bindings to prevent knee-related injuries, which, from a statistical point of view, concerns largely women and young athletes.

New Technology in Education on Performance Analysis. Wearable Sensors Utility on Alpine Skiing

“…Position, acceleration, and speed are the three variables that must be gathered in the greatest quantity for performance analysis (Fasel et al,2016;Spörri et al, 2016). The repetition of turns, which is the primary element of this sport, has an impact on the competitor's total performance or time (Nimmervoll et al, 2021;Martínez et al, 2019;Ruiz-García et al, 2021). The attention that turns in alpine skiing receive from coaches and athletes clearly demonstrates their significance, as do the numerous publications that cover this subject.…”

Evaluating wrapping alpine ski boots during on-snow carving

“…When advanced skiers are performing carving turns to the right, the peak force occurs under the downhill (or left) foot and vice versa for turning to the left. We then extracted force metrics of the downhill foot during each turn based on previous research on force production during ski carving turns (3,33). Forces from each region were filtered with a bidirectional, 6-Hz, low-pass filter prior to any feature extraction.…”