The Effect of 6-Week in-Season NASM-OPT Model Applications on Reactive Strength in Professional Level Female Volleyball Players

Abstract

The aim of this study is to investigate the effects of NASM-OPT model applications implemented over a period of six weeks during the season on the Reactive Strength Index in professional female volleyball players.

In this study, a group of 15 training participants (age: 24 ± 4.6), 15 control group (age: 24.5 ± 4.5), a total of 30 female volleyball athletes participated voluntarily. The athletes performed 6-week NASM-OPT model training programs planned for the in-season period. Reactive Strength Index (RSI) tests of the athletes were measured with ENODE brand Vmaxpro (Blaumann & Meyer-Sports Technology UG, Magdeburg, Germany) sensor.

The normality of the data was assessed using the Shapiro-Wilk test, and Skewness and Kurtosis were evaluated using symmetric distributions. Categorical variables were reported as percentages and numbers, while continuous variables were reported as means and standard deviations. The independent samples t-test (Student's t-test) was employed to analyse the comparisons between RSI measurements in the training and control groups. All statistical analyses were performed using SPSS (v30.0, Statistical Package for the Social Sciences, Armonk, NY) and JAMOVI (v2.5.2) software packages. The statistical significance was set at the two-tailed p <0.05 level.

The six-week distribution of RSI averages in the training and control groups was evaluated. Accordingly, in the training group, a steady increase in the mean RSI was observed from week 1 to week 6 (week 1: 1.82 ± 0.40; week 6: 2.32 ± 0.39). In contrast, RSI values remained relatively constant in the control group (week 1: 1.75 ± 0.25; week 6: 1.96 ± 0.27).

It was determined that 6-week NASM-OPT model practices applied in-season contributed to the development of reactive strength index values of professional level volleyball players compared to traditional training methods.