Author(s): VECBERZA, L., PLAKANE, L., Institution: UNIVERSITY OF LATVIA, Country: LATVIA, Abstract-ID: 690

INTRODUCTION:
The reactive strength index (RSI) is a key assessment of lower limb neuromuscular efficiency, whereas kinetic variables provide in-depth information into an individuals jumping performance [1]. High-intensity movements impose a significant mechanical load on the ankle joint [2]; therefore, unilateral RSI can more accurately reflect an athletes single-limb readiness for plyometric activities and the potential risk of ankle-complex injury. This study aimed to indicate floorball players unilateral RSI as a readiness indicator for plyometric activities and compare metrics across age groups, playing positions, and levels.
METHODS:
Seventy-six male floorball players (age: 18.9 ± 3.9 years; height: 180.0 ± 7.1 cm; body mass: 76.1 ± 9.9 kg; body mass index: 23.4 ± 2.5) from the three highest and first league teams (grouped as follows: U17: n = 29, U20: n = 23, 20+ years: n = 24) performed a unilateral foot-ankle 10/5 rebound jump test on an infrared contact grid (MuscleLab, Norway). Jumping strategy-based metrics, including jump height (JH), contact time (CT), flight time (FT), vertical stiffness (Kvert), average power (AP), and RSI, were determined and used for correlational analysis. For the jump strategy, standardised z-scores were calculated; however, for the readiness, t-scores as RSI benchmarks were used. However, a one-way ANOVA test was used to compare age groups and eta squared (η²) to determine effect size, but an independent t-test and Cohen’s d for playing position and level. All test results were statistically significant if p < .05.
RESULTS:
Significant differences in RSI, JH, and FT were indicated among age groups (p < .05, η² = .111 to .133), but no differences in CT. RSI is significantly higher in U20 than U17 (p = .014), but U17 showed shorter CT than U20 and the 20+ group (p < .05). Higher-league athletes had higher RSI, JH, FT, and AP compared to the first league (p < .001), but no differences by playing position. Unilateral RSI was negatively associated with Kvert (r = - .49, p < .05) in the U20 group. Twelve athletes had good RSI, while twelve showed poor RSI, indicating unpreparedness for plyometric activities. Twenty-seven athletes showed short CT with low JH jumping strategy, mostly from U17, while longer CT with higher JH was mostly utilised in the U20 group (n = 10).
CONCLUSION:
Athletes with poor RSI have low reactive strength capabilities and are unprepared for moderate to high-intensity plyometric activities, where low AP and JH indicate a need for strength development. These findings indicate that unilateral RSI from rebound jumps is a key dynamic performance indicator and a useful data-driven tool to assess an athlete’s readiness, providing coaches with athlete-centred monitoring and appropriate training decision-making.
1. Suchomel et al. (2016) 2. Radtke et al. (2021)