The literature characterizing force production during skiing, and the associated capacities of skiers, is complicated to synthesize due to aging results or relatively unspecific assessments. The overarching aim of this doctoral thesis was to clarify the importance of force output for skiing and of specific force-production capacities for different ski disciplines. The thesis comprised two themes: 1) characterizing the force output of skiers (N=15) on a giant-slalom course using kinematic and kinetic data from a global positioning system and boot-mounted force-platforms, respectively; and 2) measurement of dynamic and isometric force, the effect of countermovement on force production at different velocities, and specific strength-endurance across disciplines, and performance levels, in national skiers (N=31). The conclusions from Theme 1 were that radial force output applied to turn the skis was linked with performance (r=0.55- 0.72, p<.032) and depended on both total magnitude and the ability to apply the force effectively (ß=0.64-1.00, p<.001). Higher total force was associated with a greater output of the outside limb and a smaller difference between the limbs (ß=0.92-1.00 and -0.65- - 0.92, respectively, p<.001). For Theme 2, athletes from speed and technical disciplines displayed different dynamic and isometric force qualities, with the former showing superior dynamic force at low velocities (Omega2=0.17, p<.001) and in isometric conditions (Omega2=0.16-0.22, p<.003). Overall, performance was linked with a more force-dominant profile (Omega2=0.34; r=0.60-0.67, p<.001) and increased rate of force development characteristics (r=-0.50- -0.82, p<.048). Robust associations existed between maximum isometric force and speed discipline performance (r=-0.88, p<.001), and a trend for higher values in better technical athletes (r=-0.49, p=.052). Force production at moderate velocities did not separate disciplines, nor was it associated with performance. Variability in the shift of mechanical characteristics and inverse correlations between force augmentation at different velocities (rs=-0.74, p<.001) indicated countermovement effect depended on extension velocity. Skiers exhibited a smaller countermovement effect at low velocities (rrb=-0.68, p<.001), with the opposite observation for sprinters (rrb=0.43, p=.008). `Moderate` velocities failed to differentiate groups. Better skiers produced greater force at low speeds with a smaller countermovement effect, which supports velocity-specific strength qualities. The ski-specific strength-endurance assessment yielded some discriminative results, but, due to difficulties selecting and assessing the relevant capacities, the principal value of this section lies in direct future protocol design. This thesis generally supports the assertion that force-production capacities partly limit force output during skiing. On snow, both high force-output capacity and effectiveness of application were associated with performance. Off snow, better-ranked athletes possessed the highest capacity for specific force-production capabilities. High-level skiers appear to display a dominance of force production at low speeds and in isometric conditions compared to other sports, which should be considered in their testing and training.
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