Basketball Repeat Rebound Jump Decrement Test: Protocol, Formulas, and Norms

A power forward crashes the offensive glass, tips a miss back in, sprints back to contest a transition three, then boxes out again with 40 seconds left in a tied game. His first jump of that sequence looks like his pre-season vertical. His third one barely leaves the floor. A single countermovement rebound jump the next morning would post a fine number, because that test only asks for one clean rebound effort, rested. It never asks what actually decided the possession: how much height does he lose once he has to do it again, and again, in the same minute?

That's what a repeat rebound jump test answers: a fixed series of maximal rebound jumps back to back, with the percentage drop in height from the first efforts to the last as the score. This guide covers the equipment, a step-by-step protocol built around 10 continuous jumps, the formulas for decrement percentage and fatigue index, benchmark ranges by level, and how the decrement curve maps onto in-game basketball roles.

Why One Rebound Jump Doesn't Show Anaerobic Jump Endurance

A single countermovement rebound jump shows how well an athlete reloads once, right after landing. It says nothing about the sixth or ninth rebound effort of a possession-heavy stretch. A repeat rebound jump test forces that question by stacking several maximal rebound jumps in a row and measuring how far output falls, a direct read on anaerobic jump endurance, a different quality than jump height or single-rep reactive strength.

Čular, Ivančev, Rendulić, and colleagues (2018) built a 30-second continuous jump protocol for this purpose and validated it against the Wingate anaerobic test in young competitive athletes (n=13). Their fatigue index, the percentage drop between the mean height of the first four jumps and the final four, correlated with the Wingate fatigue index at r=0.640 (p=0.014), a moderate-to-large effect. One caveat: jump height was highly reliable session-to-session (ICC=0.884), but the fatigue index was only moderately reliable (ICC=0.657), so a decrement score moves around more than a single jump height, covered in the mistakes section below.

Equipment: Force Plate, Contact Mat, or IMU

A single rebound jump forgives a slightly late stopwatch click. Ten in a row do not; manual timing drift compounds across every rep and can hide or fabricate a decrement that isn't real. Automated timing is close to mandatory past a single-jump protocol.

Video review works for one jump, but 10 reps turns into a frame-counting exercise. A contact mat or IMU logs every rep automatically and hands you a decrement number before the athlete finishes stretching.

Step-by-Step Protocol: The 10-Jump Continuous Rebound Test

Preparation

1. Warm up 8-10 minutes: light cardio, dynamic hip and ankle work, then 3 sub-maximal countermovement jumps.
2. Hands on hips for every rep; a free arm swing changes contact-time patterns as fatigue sets in.
3. Mark one takeoff zone so the athlete rebounds from the same spot each jump rather than drifting forward.

Data Collection

1. From standing, perform a maximal countermovement jump, rebound into a second maximal jump with minimal ground contact, then a third, continuing for 10 total jumps with no pause or visible reset.
2. Record flight time, jump height, and ground contact time for all 10 reps.
3. Run this once per session; a second full attempt just stacks residual fatigue and won't give a clean comparison.
4. If an athlete visibly pauses or stops before rep 10, discard the trial rather than padding the missing reps.

One athlete's actual 10-jump trial, recorded on a contact mat during preseason testing:

Height falls from a 39.0 cm average on reps 1-3 to 33.3 cm on reps 8-10, a decrement of roughly 15%, while contact time climbs from 195 ms to 265 ms. Together the two trends confirm the drop is a real fatigue signal, not noise on one or two reps.

Calculating Decrement %, Fatigue Index, and RSI Per Rep

Three numbers come out of a 10-jump trial, each answering a slightly different question.

In the sample trial, RSI on rep 1 is 0.40 ÷ 0.195 = 2.05, and on rep 10 it's 0.33 ÷ 0.265 = 1.25, a 39% drop, steeper than the 15% height drop, since contact time degrades on top of height, not instead of it. An athlete whose height decrement looks moderate but whose RSI decrement looks severe is staying on the ground longer to produce a comparable jump, a flag worth raising even when height alone looks fine.

Decrement Benchmarks by Training Level

These bands come from field testing with basketball populations, not a single peer-reviewed norms table, so treat them as a starting reference rather than a hard cutoff. An athlete's own baseline across sessions matters more than the general band.

Positions differ inside these bands. Bigs who reload under the rim on nearly every defensive possession tend to sit toward the better end of their group's range even with an unremarkable single jump height, while guards who rarely need a second jump often post a strong CMRJ but a mediocre decrement score, simply because the quality has never been trained.

What the Decrement Curve Says About In-Game Fatigue

The decrement curve maps onto basketball moments more directly than a single jump-height number. A player who drops sharply after rep 4-5 in testing is often the same player whose second and third contest on a broken possession falls short late in a half. A player whose curve stays flat through rep 8-9 is better positioned to survive an extended rebounding battle or a string of weak-side helps late in a close game.

Ghigiarelli, Saldutti, Pottorf, Sell, and Gonzalez (2025) tracked 13 NCAA Division I women's basketball players across a full season, testing them twice weekly on a force plate (3 sets of 2 jumps, 20 sessions). Their central finding: an individualized coefficient-of-variation approach caught real within-athlete fatigue that a population-level reference range would have missed, since normal variation between athletes often exceeds the meaningful change within one athlete week to week. The limitation is real too, a single Division I women's team, n=13, force-plate dependent, not yet replicated in men's basketball, so treat the specific numbers as directional while the individualized-baseline approach travels well to any level.

Mistakes That Inflate or Hide the Decrement

Letting Athletes Pace Themselves

An athlete who knows 10 jumps are coming will sometimes hold back on reps 1-2, flattening the true decrement. Tell athletes before rep 1 that every jump is maximal, and watch the first three reps for restraint.

Changing the Rep Count Between Sessions

A 10-jump decrement isn't comparable to an 8-jump decrement. Pick a count and hold it for the life of the program.

Treating a Single Session's Number as Fixed

Given the moderate reliability of decrement metrics noted above, a 3-4 point swing between sessions is closer to noise than a real change. Build at least 3 baseline sessions before treating one number as a decision point.

Ignoring Contact-Time Drift

A mild height decrement can hide a steeper RSI decrement if contact time is climbing fast. Log both, or you'll miss athletes compensating mechanically before height alone flags a problem.

Building It Into a Testing Calendar

This test fatigues athletes on purpose, so it doesn't belong in a weekly rotation the way a single CMRJ does.

For the programming side, our basketball vertical jump training guide pairs well; this test is the measurement half of that picture.