Using the reactive strength index modified to evaluate plyometric performance.

Area of Science:

• Sports Science
• Biomechanics
• Exercise Physiology

Background:

• Quick force development is crucial for athletic performance.
• The reactive strength index (RSI) measures explosive strength using jump height and ground contact time, primarily for depth jumps (DJ).
• Current RSI limitations restrict its application to exercises with identifiable ground contact times.

Purpose of the Study:

• Introduce a modified RSI (RSImod) applicable to any vertical plyometric exercise.
• Assess the reliability of the RSImod.
• Evaluate RSImod across diverse plyometric exercises and examine gender differences.

Main Methods:

• Twenty-six men and 23 women performed five plyometric exercises: countermovement jump (CMJ), tuck jump, single-leg jump, squat jump, and dumbbell CMJ.
• Data were analyzed using a two-way ANOVA to assess RSImod differences across exercise types and genders.
• Intraclass correlation coefficients were used to determine reliability.

Main Results:

• Significant differences in RSImod were found across all tested plyometric exercises (p
• No significant interaction was observed between plyometric exercise type and gender (p > 0.05).
• The RSImod demonstrated high reliability for all exercises studied.

Conclusions:

• The modified reactive strength index (RSImod) is a reliable and versatile tool for assessing explosive power in various plyometric exercises.
• RSImod provides a standardized method to evaluate explosive strength beyond traditional depth jumps.
• This metric can be applied across different plyometric movements without gender-specific considerations.