Impact of Plyometric Exercises on the Explosive Strength of Lower Limbs in Junior High School Volleyball Players: A Study at SMP Negeri 3 Palembang

Abstract

Objectives. The objective of this study was to determine the effect of plyometric training on the explosive power of the lower limbs in male volleyball extracurricular students at SMP Negeri 3 Palembang. The research aimed to investigate whether a structured plyometric training program could significantly improve vertical jump height as an indicator of lower limb power.
Materials and Methods. This research employed a quantitative experimental method using a one-group pretest-posttest design. The population consisted of 30 students (20 males and 10 females) enrolled in the volleyball extracurricular program. A purposive sampling technique was applied, resulting in 20 male students as the study sample. The instrument used to collect data was a vertical jump test. The training intervention consisted of plyometric exercises conducted over a defined period. Data were analyzed using the Shapiro-Wilk test for normality and the paired sample t-test to assess the significance of differences between pretest and posttest results.
Results. The findings revealed a statistically significant improvement in lower limb explosive power following the plyometric training intervention. The paired sample t-test showed a t-value of 12.601, which exceeded the critical t-table value of 2.093. The significance level was 0.000 (p < 0.05), indicating a significant difference between pretest and posttest scores. The mean posttest score increased to 31.05, compared to a mean pretest score of 22.50, confirming the positive impact of the training program.
Conclusions. study concludes that plyometric training has a significant effect on enhancing the explosive power of the lower limbs in male students participating in extracurricular volleyball activities at SMP Negeri 3 Palembang. The substantial increase in vertical jump performance after the intervention supports the effectiveness of plyometric exercises in improving athletic performance among adolescent volleyball players.