Preview
Hüseyin Akbulut, MSc (2026). Reactive Strength Index (RSI): Protocol and Application. Sporeus. Retrieved, November 13, 2026. https://sporeus.com/en/egzersiz-testleri-en/reactive-strength-index-rsi/
Measures: Plyometric reactive strength (jump height relative to ground contact time)
Table of Contents
Difficulty: Moderate | Category: Strength
Protocol
The Reactive Strength Index (RSI) is a specific force-speed indicator showing how high a person can jump from a short ground contact. It is calculated from the drop jump test.
Preparation: Contact mat is calibrated. The participant warms up for 10–15 minutes. Box height is selected: typically 30cm, 45cm, or 60cm. Drop jump technique is taught to the participant: drop from the box, make contact with the floor, and jump to maximum height with the shortest possible contact time.
Test Procedure: The participant drops from the designated box, lands on both feet, and immediately jumps maximally. Contact mat or force plate automatically measures contact time (tc) and flight time (tf). 3–5 trials performed; best RSI value used.
Calculation: Jump height = g × tf² / 8.
RSI = jump height / contact time = (g × tf² / 8) / tc.
Alternative ratio: flight time / contact time (unitless; not to be confused with RSI in m/s).
Post-Test: Cool-down and leg stretching. RSI is compared at different box heights to determine optimal drop height.
Formula
RSI (m/s) = jump height / contact time; height = g × tf² / 8; alternative: flight time / contact time
Equipment Required
contact mat or force plate, stopwatch
Interpretation
There is no single widely accepted normative table for this test. Results are best interpreted against the person’s previous measurements with the same protocol and equipment (and, where relevant, left-right comparison).
Practical Applications
RSI is used in plyometric training programming for determining optimal box height, monitoring performance in jumping sports, and evaluating power-endurance balance.
Limitations
Requires a contact mat or force plate. Drop jump technique requires experience; incorrect technique distorts RSI value.
Related Tests: Countermovement Jump, Bosco Continuous Jump Test, Rate of Force Development (RFD)
Sources: Young WB et al., 1995, J Strength Cond Res; Flanagan EP & Comyns TM, 2008, Strength Cond J
Hüseyin Akbulut is the founder of Sporeus and author of THRESHOLD (EŞİK), a 540-page Turkish-language book on endurance science.
- 540pp THRESHOLD Book
- MSc Sport Sciences
- Marmara University
Protocol The Reactive Strength Index (RSI) is a specific force-speed indicator showing how high a person can jump from a short ground contact. It is calculated from the drop jump test. Preparation: Contact mat is calibrated. The participant warms up for 10–15 minutes. Box height is selected: typically 30cm, 45cm, or 60cm. Drop jump technique is taught to the participant: drop from the box, make contact with the floor, and jump to maximum height with the shortest possible contact time. Test Procedure: The participant drops from the designated box, lands on both feet, and immediately jumps maximally. Contact mat or force plate automatically measures contact time (tc) and flight time (tf). 3–5 trials performed; best RSI value used. Calculation: Jump height = g × tf² / 8. RSI = jump height / contact time = (g × tf² / 8) / tc. Alternative ratio: flight time / contact time (unitless; not to be confused with RSI in m/s). Post-Test: Cool-down and leg stretching. RSI is compared at different box heights to determine optimal drop height. Formula
RSI (m/s) = jump height / contact time; height = g × tf² / 8; alternative: flight time / contact time
Equipment Required
contact mat or force plate, stopwatch
Interpretation
There is no single widely accepted normative table for this test. Results are best interpreted against the person's previous measurements with the same protocol and equipment (and, where relevant, left-right comparison).
