Introduction:
Squat jumps (SJ) and countermovement jumps (CMJ) are commonly used as tests to assess power output of lower extremities.

Aim of the Study:
The aim of this article was to analyze differences between two vertical jumps in order to assess explosive power in elite female volleyball players and identify mechanisms responsible for existence of those differences

Material and Methods:
Participants of this study were 14 elite female volleyball players of the Montenegro U19 national team (age: 18.42 ± 1.34 years; height: 178.15 ± 4.9 cm; weight: 68.1 ± 5.83 kg; body mass index: 21.34 ± 1.10 kg/m2; body fat: 18.89 ± 3.70%). Jump height data for a SJ and a CMJ was obtained using OptoJump device (Optojump, Microgate, Bolzano, Italy).

Results:
The results showed that there is no statistically significant difference (F = 0.093, p < 0.124) between the heights of the SJ (26.64 ± 2.93 cm) and the CMJ (26.65 ± 2.85 cm).

Conclusions:
The findings suggest that elastic energy has very little effect on improving CMJ performance. On the other hand, CMJ training can reduce an ability to effectively create pre-tension and quickly build stimulation, because athletes are not forced to do so, as the CMJ reduces a degree of muscle relaxation and provides more time to create stimulation. Based on the data, the CMJ may be detrimental to high-intensity sports performance if performed over a longer time frame.