PT Journal AU Lehnert, M Lamrova, I Elfmark, M TI Changes in speed and strength in female volleyball players during and after a plyometric training program SO Acta Universitatis Palackianae Olomucensis. Gymnica PY 2009 BP 59 EP 66 VL 39 IS 1 DE Explosive power; speed; youth; training AB The goal of this article was the validation of a plyometric training program and the evaluation of the changes in monitored speed and explosive power predispositions during and after the end of the training program. The program was applied to a group of female youth volleyball players (n = 11) twice a week during an eight week period. Their actual level of explosive power and locomotor speed was evaluated before, during and after the intervention was completed. The levels were determined with the following tests: the standing vertical jump, the vertical jump with an approach and the shuttle run for 6 x 6 m. There were positive changes in the average values of test scores during the period of testing, but the dynamics of the changes in the explosive power and the speed were different. Other increases in all the characteristics were noticeable when the final measurements were made six weeks after the completion of the training program. Examination of the differences in the test scores by the follow up group, before the beginning and six weeks after finishing the intervention, was centred on objectively and statistically important changes in the volleyball players' motor predispositions (p < .05). The results of the program support the opinion that plyometric exercises are effective tools in the development of explosive power and speed in young athletes. ER