Reliability of a Medicine Ball Explosive Power Test in Young Volleyball Players

Abstract

The purpose of the study was to evaluate the reproducibility of the medicine ball explosive power test to assess explosive power in young volleyball players. Materials and methods. Data were collected using twelve volleyball players (age = 16.5 ± 0.52 years; body mass = 72.05 ± 7.9 kg; height = 182 ± 0.06 cm and body mass index = 21.63 ± 1.85) volunteered for this study. They completed a test and retest of the medicine ball explosive power test on two separate days. The medicine ball explosive power test was conducted using a 3 kg medicine ball. Testing was carried out in two separated testing session preceded by a standardized warming up protocol. The paired-sample t-test was conducted to determine the differences signification observed between the test and the retest of the medicine-ball explosive power test. The intraclass correlation coefficient (ICC1,1) aims to assess relative reliability of the test. The coefficient of variation between test and retest performance was used to check the absolute reproducibility. The Bland and Altman method was used to evaluate the relative and absolute reproducibility of the medicine ball explosive power test. Results and discussion. Explosive power is often considered as one of the main determinants of a successful high-level performance in many team sports including volleyball. It is frequently measured in different occasion during competitive season using field‐based tests. Thus, it is mandatory that strength and conditioning coaches have to use valid and reliable tests to evaluate the power for their athletes. However, contestation regarding test selection still exists grounded upon the particularity of the explosive power evaluation tests in volleyball. There was no significant difference between medicine ball explosive power test (11.08 ± 0.72 meter) and retest (11.27 ± 0.93 meter) performance. The T-paired Sample test did not show any statistically significant difference (t= 1.035; p =0.393), while the intraclass correlation coefficient aimed to assess relative reliability of the test was of 0.83. The coefficient of variation between test and retest performance was of 5.7% which is near to the 5% confidence interval level. The intraclass correlation coefficient was situated between 0.9 and 0.8 (ICC1,1 = 0.83) Thus this study suggests that the medicine ball explosive power test has moderate relative reliability level. Conclusion. The medicine ball explosive power test is reliable regardless to the age. The Bland and Altman method confirmed our finding suggesting the medicine ball explosive power test is a reliable test