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Calculates Reactive Strength Index (RSI) from a drop jump, and optionally RSI-mod from a countermovement jump. This is a coaching aid, not a medical or injury-risk tool.
The default “bands” are coaching-oriented reference points that vary by population and protocol. Edit them to match your team, sport, device, and drop height.
The Incremental Drop Jump RSI Series is a simple way to build a “reactive profile” from drop jumps. Instead of testing one height once, you test several drop heights and repeat multiple trials at each height. The tool calculates RSI for every trial, then summarizes your average RSI at each height and highlights the height where you currently express your best RSI under this protocol.
Use it to standardize monitoring, compare athletes fairly, and make decisions about what kind of plyometric dosage and intensity fits the athlete right now.
A single RSI value can be misleading if the drop height is a poor match for the athlete’s current ability. Some athletes look “bad” at a height that is too low to challenge them, or too high for them to maintain stiffness and contact quality.
Testing across heights helps you answer practical coaching questions:
Which drop height produces the best RSI for this athlete right now?
Do they lose contact quality as height increases?
Are they consistent across repeated trials, or do results swing a lot from jump to jump?
Is the main limiter contact time, jump height, or both?
Keep conditions consistent. This tool is most useful when the test is repeatable.
Suggested setup:
Use the same warm-up each time.
Use the same surface, shoes, box, and measurement device.
Use clear, repeated instructions (same arm use rules, same landing cue, same intent).
Recommended flow:
Enter your drop heights (cm) and set trials per height.
Click “Build inputs” to generate the table.
For each height, complete the specified number of trials.
Enter jump height (or flight time) and ground contact time for each trial.
Click “Calculate series” to generate:
RSI for each trial
Average RSI by height
Best height by average RSI
Actionable focus suggestions
Export results:
Download CSV for logs, athlete profiles, or spreadsheets
Copy summary for notes, practice plans, or reports
Safety note: Use only heights the athlete can land safely and consistently. Stop the test if technique breaks down.
Build a drop-jump RSI profile across multiple drop heights and trials per height. Use this to standardize monitoring and find the height that produces the best RSI under a consistent protocol.
| Height (cm) | Trial | Jump height | Contact time (ms) | RSI |
|---|
Made to Be Shared.
The tool gives you four types of information.
Best height (by average RSI)
This is the drop height where the athlete currently expresses the best mix of jump output and quick ground contact, averaged across trials. Coaches often use this height as:
The athlete’s main monitoring height (for repeatable check-ins)
A “sweet spot” height for reactive work in training blocks
Per-height averages
This shows how the athlete responds as the eccentric demand increases.
Common patterns:
RSI rises with height: athlete may need more eccentric stimulus to express their best output, or they are still learning to coordinate at lower heights.
RSI peaks in the middle: typical “sweet spot,” often a good training and monitoring height.
RSI drops as height increases: athlete may be losing stiffness or contact quality at higher drops, or the heights are beyond current tolerance.
Trial-to-trial consistency
Even without fancy stats, you can see if the athlete repeats similar results or if the numbers jump around.
Consistent trials usually mean stable technique and readiness.
Highly variable trials often mean the athlete is still learning the task, fatiguing quickly, or the test setup is inconsistent.
Actionable focus suggestions
The tool provides coaching suggestions based on the score pattern and the components of RSI. Treat this as decision support, not a diagnosis. Always cross-check with actual sprint times, change-of-direction tests, and jump performance.
Use the outputs to choose the emphasis, not to replace the rest of your testing.
Sprinting: acceleration
If the athlete’s best RSI comes from longer contacts and lower RSI, that can still fit an acceleration-dominant profile. Acceleration allows longer ground contacts than max velocity.
Training implication: keep acceleration work in the program, but build reactive qualities gradually so faster contacts do not collapse mechanics.
Sprinting: maximum velocity
If the athlete maintains strong RSI with short contacts at their best height, it often aligns with qualities that support upright sprinting and fast ground contacts.
Training implication: keep max velocity exposures, protect quality, and use reactive plyometrics that preserve quick contacts.
Change of direction
COD demands braking and re-acceleration. If RSI falls sharply at higher drops, it can be a sign the athlete struggles to maintain stiffness and contact quality when eccentric demand rises.
Training implication: build braking strength and controlled deceleration first, then progress to faster, more reactive COD as contact quality improves.
Jump training
If jump height is the weak link, prioritize strength and concentric power development alongside jump skill.
If contact time is the weak link, prioritize low-amplitude elastic contacts and progressions that improve stiffness and reactivity before higher intensity depth work.
Use the tool the same way every time.
Retest on a consistent schedule (for example, every 2–4 weeks).
Use the same list of heights and the same number of trials.
Track:
Best height
Best average RSI
Whether the profile shifts (peak moves higher or lower)
Whether trial consistency improves
Best height stable and RSI rising: reactive quality improving under the same protocol.
Best height moving lower with the same RSI: athlete may be getting more efficient.
RSI collapsing as height increases: reduce drop intensity, rebuild quality, re-progress.
High variability across trials: improve technique consistency and standardize testing.
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