Fig 1.
Skier equipped with experimental technology.
Pictured is a skier performing a trial, while equipped with boot-mounted force platforms, wired to an acquisition card carried in a small bag around the waist with a GNSS unit secured inside.
Fig 2.
Depicted is a skier (not to scale, for clarity) traversing the course setup. ×, gates; grey line, athlete trajectory through analyzed gates (expanded for clarity); dashed lines represent the separation of the various analysis sections (speed, overspeed, and flat), with the approximate section characteristics (i.e., latitude and altitude) displayed in the corresponding axes (y- and z-axis, respectively). Note: since no course mapping was performed, section characteristics represent the average value between the turn-switches demarcating the beginning and end of each section, across all athletes and trials.
Fig 3.
Pictured are the specialized force-plate devices used to collect the primary SRF data in this study, attached to a pair of standardized boots used during the experiment. The novelty of these devices in contrast to previous designs is that the circular strain gauges are situated at the front and rear of the boots, where they are affixed between two ‘floating’ metal brackets as the only point of connection between the skier and the ski. This shift in the placement of the strain gauges enabled clip-in height to be minimized, and the mass to be reoriented more distally compared to previous iterations. Each force plate could provide force and moments in three axes (medio-lateral = x, antero-posterior = y, normal = z), but only resultant forces were examined in this study.
Fig 4.
Turn-averaged force-outputs for a single high-performing athlete.
Data, in this case, has been normalized as a percentage of turn duration. The solid black line represents total force output (Ftot); the long-dash-dot black line represents the force output of the outside limb (Fin); the long-dash-dot-dot black line represents the force output of the inside limb (Fout); the short dashed black line represents radial force output (Fr); all force data are displayed as a factor of BW.
Fig 5.
Modular outline of approach to data analysis, applied to all sectional datasets.
‘Multiple regression’ models (continuous lines) feature stepwise entry criteria, and ‘Correlation’ models (dashed lines) are Pearson’s product moment correlation coefficient.
Table 1.
Course and sectional descriptive data.
Table 2.
Course performance (T) explained by turn modifiable factors averaged for each section (analysis ‘Level 1’).
Table 3.
Pearson’s product moment correlation coefficients between radial force (Fr) and sectional (Δemech/vin) and course performance (T) (analysis ‘Level 2’).
Table 4.
Multiple regression analysis results assessing the importance of Ftot and RF to predict Fr, specific to the course and each section (analysis ‘Level 3’).
Table 5.
Multiple regression analysis results assessing the importance of Fout and diff to explain Ftot specific to the course and each section (analysis ‘Level 4’).