Instrumented figure skating blade for measuring on-ice skating forces

Abstract

Competitive figure skaters experience substantial, repeated impact loading during jumps and landings. Although these loads, which are thought to be as high as six times body weight, can lead to overuse injuries, it is not currently possible to measure these forces on-ice. Consequently, efforts to improve safety for skaters are significantly limited. Here we present the development of an instrumented figure skating blade for measuring forces on-ice. The measurement system consists of strain gauges attached to the blade, Wheatstone bridge circuit boards, and a data acquisition device. The system is capable of measuring forces in the vertical and horizontal directions (inferior-superior and anterior-posterior directions, respectively) in each stanchion with a sampling rate of at least 1000 Hz and a resolution of approximately one-tenth of body weight. The entire system weighs 142 g and fits in the space under the boot. Calibration between applied and measured force showed excellent agreement (R > 0.99), and a preliminary validation against a force plate showed good predictive ability overall (R ≥ 0.81 in vertical direction). The system overestimated the magnitude of the first and second impact peaks but detected their timing with high accuracy compared to the force plate.

IceSense Proof of Concept: Calibrating an Instrumented Figure Skating Blade to Measure On-Ice Forces

“…The system used in the present study ( Figure 1 ) is an improved version of the IceSense system described previously [ 13 ] (see Supplementary Material for a description of the improvements).…”

“…Based on the promising preliminary test results presented in our previous paper [ 13 ], the first step for calibrating and validating the system was to use off-ice jumps onto a force plate (called “force plate validation”). The goals of this calibration validation were to determine the number and type of landings to include in calibration for accurate peak force estimation.…”

“…Each skater wore the same pair of skating boots with a 24.8 cm blade (Jackson Ultima, Waterloo, ON, Canada). The blade of the right boot was instrumented as described previously [ 13 ], with the improvements listed. Blade strain data were collected at 1000 Hz.…”

“…Pre-processing: As described previously [ 13 ], horizontal and vertical strain gauges were mounted to both sides of each of the three stanchions. Each strain gauge was mounted so its x- and z axes aligned with those of the other gauges, creating a coordinate system for the blade ( Figure 3 ).…”

“…Accurate on-ice measurements of force have not yet been reported. Previously, we reported on the design of a device that is lightweight, small in size, and water resistant [ 13 ]. This force measurement system consists of strain gauges on the three stanchions that support the skate blade, along with Wheatstone bridge circuit boards and a data acquisition device mounted under the boot.…”