Effects of Jumping Techniques on Vertical Jump Performance: Professional Volleyball Players (U15).

Study aim(s): The study aims to determine the effect of arm swing technique and the elastic force stored in tendon during the eccentric phase of jumping on the vertical jump performance of Volleyball Players (U15). Methods: Ten U15 women volleyball players from KV Theranda, averaging 157.0 cm in height and 48.8 kg in weight, participated. Participants performed Countermovement Jumps (CMJ) and Squat Jumps (SJ), recorded at 240 fps on an iPhone 13 Pro using My Jump 3 application. Jump heights were calculated from selected take-off and landing frames. Data analysis using SPSS 26 included normality tests and T-tests to compare CMJ and SJ performance, focusing on arm technique and elastic force. Results: Based on the results, except for strength and power, which showed significant differences (p < 0.05), the analysis revealed a significant advantage for CMJ over SJ in all parameters (p < 0.05). This 70% difference is due to the elastic force in the tendons during the eccentric phase and arm momentum. Conclusions: Countermovement jumps (CMJ) significantly outperform squat jumps (SJ) due to the elastic force stored in tendons and arm momentum during the eccentric phase, resulting in a 70% performance difference. Cheraghi et al. (2017) emphasized peak power's role in higher jumps. Future research should separately analyze CMJ with and without arm movement to understand their impacts. [ABSTRACT FROM AUTHOR]