Summary:The aim of the study was to examine the effect of plyometric exercises on explosive strength of lower extremities in girls performing of technical and aesthetical sports. Experiment was carried out on three groups; artistic gymnasts (V G , n = 15; age = 12.4 ± 0.7 years), fitness girls (V F , n = 15; age = 13.8 ± 1.9 years) and dancers (V D , n = 15; age = 13.8 ± 2 years). To check, the control group of general population was involved in the study (V K , n = 15; age = 13.9 ± 1.5 years). Following tests on jump ergometer Fitro Jumper were carried out at the beginning and at the end of experimental period: countermovement jump without and with arms swing and 10-second series of repeated vertical jumps.Plyometric program consisted of two plyometric units a week during thirty weeks. The results show that higher improvement in all evaluated tests achieved the group of fitness. In the countermovement jump without arm swing was observed improvement height of the jump 3.4 ± 1.4 cm (p ˂ 0.00001), in the countermovement jump with arm swing 5.7 ± 1.5 cm (p ˂ 0.00001), in difference of height of the jump between countermovement jump with and without arms swing 2.3 ± 1 cm (p ˂ 0.00001), in ten second series of repeated vertical jumps without arms swing in the height of jump 4.2 ± 1.6 cm (p ˂ 0.00001) and in power in active take off phase 8.8 ± 2.2 W.kg -1 (p ˂ 0.00001). Based on finding the study and in coherence with data from literature, we can conclude the effect of plyometric exercises was effective in combination with specific-strength training. Jumping ability is limiting factor of sport performance in technical and aesthetical sports and implementation of plyometric exercises to the training is highly recommend. The high level of jump capabilities can improve the quality and technique of performance complex acrobatic elements and dance leaps thereby increasing overall evaluation of performance in selected sports.

Summary The aim of our study was to determine changes in sport and motor performance of competitors in the category of children’s fitness as a result of conditioning training intervention. We conducted a two-group simultaneous experiment. Experimental group (EG) and control group (CG) consisted of 18 girls competing in the 12 to 15 years old age categories. EG performed supervised conditioning program over a period of 25 weeks with training frequency 3 times per week. Based on the results of physical tests, competitive and expert assessments of sport performance in the children’s fitness category we found significant effect of our conditioning program to increase sport and motor performance in the experimental group. Subsequently, these improvements could lead to success in domestic and international competitions where they occupied the leading positions. Significant relationships (EG = 19; CG = 10) were found between competitive and expert assessments as well as physical tests results, between expert and competitive assessments of physiques and routines. These changes manifested positively not only in the competitive assessment of the physique but also in the expert “blind“ assessment in the competitive discipline of the physique presentation in quarter turns where we observed significant improvements in the EG. Based on the obtained results we recommend to increase the ratio of conditioning training to gymnastic-dance training to 50 %, inclusion of strengthening and plyometric exercises into the training process and monitor regularly the level of general and specific abilities of the competitors in the individual mezocycles of the annual training cycle.