Black silhouette of a sprinter lunging forward in mid-stride with one leg stretched behind, the other knee raised, arms thrust back and wearing athletic shoes.

RSI Interpreter, from number to next step

You know the athlete.

Fast. Springy. Looks like a cheetah on caffeine.

Then they test RSI and the number is… fine. Not scary. Not impressive. Just “fine.”

Here is the problem. RSI is not one thing. It is a ratio. It is jump output divided by time on the ground. That means two athletes can land on the same RSI for totally different reasons, and they need totally different training.

Your RSI Interpreter exists to stop that guessing.

RSI Interpreter

Person performing a drop jump next to an RSI score card (Height 40 cm, RSI 2.75) pointing to an interpretation checklist.

The 15-second refresher: what RSI actually is

Drop Jump RSI is:

Jump height ÷ ground contact time (GCT)

Your tool lets you enter drop-jump RSI using either:

jump height, or
flight time (and it estimates jump height from flight time).

It also supports RSI-mod (jump height ÷ time to takeoff) if you want a CMJ-style option.

Quick Wins

Standardize, or do not compare. Same device, warm-up, drop height, and instructions.
Stop worshiping the score. Read the parts. Your interpretation should start with: “Was height the limiter, or was contact time the limiter?”
Use the fast-SSC flag as a clue, not a trophy. The tool highlights contact time under 0.25 s as “fast SSC range.”

One number can mislead. Build a profile. Use the Incremental Drop Jump RSI Series to find the drop height where the athlete expresses their best average RSI under your protocol.

Checklist titled Standardize RSI testing with five checked items: Device, Warm-up, Drop height, Instructions, Surface/shoes.

Run this test today in under 10 minutes

If you only do one thing this week, do this.

Pick 3 to 5 drop heights you can repeat safely (example format: 20,30,40,50,60 cm).
Do multiple trials per height (same shoes, surface, box, device, warm-up, and rules).
Enter either jump height or flight time plus ground contact time for each trial.
Click Calculate series and look at:
- RSI per trial
- average RSI by height
- best height by average RSI
- trial-to-trial consistency
- focus suggestions
Export it. Download CSV for logs, or Copy summary into your notes.

RSI Interpreter

RSI formula diagram: RSI = jump height ÷ ground contact time, shown with orange dial icons for each.

How to “act on it”, the two-knob playbook

Think of RSI as two knobs you can turn.

Knob 1: Jump height is the weak link

If the athlete is not getting much height even when contacts are not slow, you are missing output.

Training implication (broad, not magical):

prioritize strength and concentric power development
keep jump skill in the mix
do not crank drop height to “force” reactivity before the athlete owns positions

Knob 2: Contact time is the weak link

If the athlete gets decent height but spends too long on the ground, you are missing stiffness and fast elasticity.

Training implication:

prioritize low-amplitude elastic contacts and progressions that build reactivity
earn higher intensity depth work by keeping contacts sharp and consistent first

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theSprint.Club

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