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Mikko Virmavirta, Juha Kivekäs, and Paavo Komi

The effect of skis on the force–time characteristics of the simulated ski jumping takeoff was examined in a wind tunnel. Takeoff forces were recorded with a force plate installed under the tunnel floor. Signals from the front and rear parts of the force plate were collected separately to examine the anteroposterior balance of the jumpers during the takeoff. Two ski jumpers performed simulated takeoffs, first without skis in nonwind conditions and in various wind conditions. Thereafter, the same experiments were repeated with skis. The jumpers were able to perform very natural takeoff actions (similar to the actual takeoff) with skis in wind tunnel. According to the subjective feeling of the jumpers, the simulated ski jumping takeoff with skis was even easier to perform than the earlier trials without skis. Skis did not much influence the force levels produced during the takeoff but they still changed the force distribution under the feet. Contribution of the forces produced under the rear part of the feet was emphasized probably because the strong dorsiflexion is needed for lifting the skis to the proper flight position. The results presented in this experiment emphasize that research on ski jumping takeoff can be advanced by using wind tunnels.

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Tim L.A. Doyle, AuraLea C. Fain, Jodie A. Wills, Daniel Cooper, Kevin Toonen, and Benjamin Kamphius

) to their squat jump (SJ) performance to calculate an elastic utilization ratio (EUR). 21 , 22 EUR is calculated by dividing CMJ variables by the same SJ variables (eg, jump height, takeoff force, power, or flight time). The CMJ includes an eccentric loading phase, which may allow for the utilization

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Qian Zhang, Liang Zhang, Bing Yan, and Olivier Girard

force platform (Type 9286BA, Kistler) during isometric squatting and all WJS sessions, which allowed vGRF measurement. Dependent variables included maximal takeoff force and peak rate of force development during the concentric phase of the second of the 2 consecutive WJSs. All data were collected at a