The main objective of the study was to determine to what degree higher muscular activity, achieved by increasedload in the extension phase (eccentric muscle action) of the vertical jump, affects the efficiency of the vertical jump.Sixteen elite biathletes participated in this investigation. The biathletes performed tests that consisted of five, single“maximal” vertical jumps (counter movement jump - CMJ) and five, single vertical jumps, in which the task was totouch a bar placed over the jumping biathletes (specific task counter movement jump - SCMJ). Then, they performedfive, single drop jumps from an elevation of 0.4m (DJ). Ground reaction forces were registered using the KISTLER9182C force platform. MVJ software was used for signal processing (Król, 1999) and enabling calculations forkinematic and kinetic parameters of the subject’s jump movements (on-line system). The results indicate that onlyheight of the jump (h) and mean power (Pmean) during the takeoff are statistically significant. Both h and Pmean arehigher in the DJ. The results of this study may indicate that elite biathletes are well adapted to eccentric work of thelower limbs, thus reaching greater values of power during the drop jump. These neuromuscular adaptive changes mayallow for a more dynamic and efficient running technique.