10/5 Repeated Jump Test: How to Calculate RSI (Protocol)

You've got a squad session in twenty minutes, no force plate on hand, and a coach asking whether last week's plyo block actually did anything. This is the situation the 10/5 repeated jump test (10/5 RJT) was designed for. Instead of a single drop-and-rebound trial off a box, the athlete performs ten consecutive maximal hops in place, and reactive strength index (RSI) is pulled from the average flight time and ground contact time of the best five of those ten. Harper, Hobbs and Moore first published the protocol in 2011 as a field-friendly alternative to drop jump testing, and Comyns et al. (2019) later confirmed that the best-five scoring convention holds up across male, female, and mixed cohorts rather than being an artifact of one sample. Stratford, Dos'Santos and McMahon (2020) pushed the question further and worked out exactly how many repetitions and trials you actually need before the number in front of you means anything. This guide walks through the setup, execution, scoring, and where the test tends to go wrong in practice.

What Is the 10/5 Repeated Jump Test?

The 10/5 RJT is a continuous multi-rebound protocol: the athlete performs ten consecutive maximal-height hops in place with minimal knee bend, and reactive strength index is calculated from the average flight time and average ground contact time of the best five of those ten repetitions — hence the name 10/5. Unlike a single drop jump, which captures reactive strength across one isolated stretch-shortening cycle action, the 10/5 RJT requires the athlete to hold a fast elastic rhythm across ten straight ground contacts.

That sustained-rhythm demand is the test's main practical advantage. Repeated bounding, cutting, and re-acceleration in field and court sports rarely happen as an isolated action, so a protocol that rewards consistent reactive output across multiple contacts arguably reflects sport demand more closely than a single-trial drop jump. It also requires no box, so it can be administered anywhere an athlete has roughly two meters of flat, firm ground.

Because the first repetitions of a set typically function as a ramp into peak rhythm rather than a true reactive strength ceiling, only the best five of the ten hops are used in the score. This scoring convention, established by Harper and colleagues and validated by Comyns et al. (2019), is what separates the 10/5 RJT from an informal jump-rope-style drill.

Why Repeated Jumps Differ From a Single Drop Jump

A single drop jump tests the stretch-shortening cycle (SSC) once, under a controlled and standardized eccentric load created by stepping off a fixed box height. The 10/5 RJT instead tests whether an athlete can maintain SSC efficiency across repeated, self-generated ground contacts without the benefit of a standardized drop height. Each landing's eccentric load is a direct function of how high the athlete jumped on the previous repetition, which means the test partly measures an athlete's ability to self-regulate leg stiffness from one contact to the next.

Stratford, Dos'Santos and McMahon (2020) found that peak RSI values are not evenly distributed across the ten repetitions: roughly 60% of peak-RSI hops occurred within repetitions seven through ten, with earlier hops serving mainly as a rhythm-establishing ramp. This finding supports discarding the weakest repetitions rather than averaging all ten, since the early contacts genuinely reflect a warm-up-within-the-test effect rather than a true ceiling on reactive capability.

The practical implication for coaches is that the 10/5 RJT is measuring two things at once: peak reactive strength capability (best five hops) and, if the full ten-hop trace is reviewed, the athlete's rate of rhythm acquisition. An athlete who reaches peak RSI by repetition three or four is demonstrating faster neuromuscular readiness than one who needs seven or eight hops to find rhythm, even if their final best-five RSI scores are identical.

Equipment and Test Setup

The 10/5 RJT requires simultaneous, repetition-by-repetition capture of flight time and ground contact time across ten fast contacts, which places higher demands on sampling rate than a single-trial drop jump does. A contact mat or force plate remains the most common lab tool, while a validated IMU sensor is the most practical option for field testing since no box or fixed surface marking is required.

Set-up is simple: mark a small area of flat, firm ground (grass, court, or turf all work), position the mat or plate, and ensure the tester or software can isolate each of the ten individual ground contacts within a trial rather than only reporting a trial average.

10/5 Repeated Jump Test: Step-by-Step Protocol

Pre-Test Preparation

Allow at least 24 hours since the last high-intensity lower-body session. Warm up with 5 minutes of light cycling or jogging, dynamic ankle and hip mobility work, and 3 to 5 submaximal practice hops so the athlete feels the intended rhythm before the scored trial begins.

Starting Position and Technique

1. Athlete stands upright with hands placed firmly on the hips for the entire test (no arm swing).
2. Feet shoulder-width apart, eyes forward, knees soft but not bent into a squat.
3. On the starting cue, the athlete performs ten consecutive maximal-height hops in place with minimal knee and hip flexion at each landing — the movement should resemble a fast jump-rope bounce rather than a series of squat jumps.
4. Each hop should aim to minimize ground contact time while maximizing flight time; coaches should cue jump as high as possible in as little ground time as possible, repeated for all ten hops.
5. The athlete should not pause, travel forward, or bend at the hips between hops.

Trial Structure

Administer 2 to 3 trials with at least 20 seconds of rest between each. Record all ten individual hop values per trial rather than only a trial average, since scoring depends on isolating the best five of ten. Stratford, Dos'Santos and McMahon (2020) reported that a single well-executed trial is generally sufficient to obtain a valid peak RSI score, which makes the 10/5 RJT considerably faster to administer with a squad than a three-trial protocol.

Disqualification Criteria

• Arm swing used at any point (hands must stay on hips throughout).
• Visible squat-style knee bend rather than a stiff, jump-rope-style bounce.
• Forward or lateral travel of more than roughly one foot-length across the ten hops.
• Any pause or double-contact where the athlete stalls between hops instead of maintaining continuous rhythm.

In practice, the failure mode we see most often isn't a dramatic technical breakdown — it's a slow creep. Somewhere around rep seven or eight, a fatiguing athlete starts letting the hips sink a few extra degrees on each landing without noticing it. That extra flexion buys a bit more flight time on the next hop, which quietly inflates the very RSI value the best-five method is designed to capture. Watching hip angle across the full set, not just hand position, catches this before it contaminates the score.

Calculating RSI and Interpreting Norms

The 10/5 RJT conventionally scores RSI as the ratio of flight time to ground contact time, both in seconds, rather than the jump-height-to-contact-time formula common in single-effort drop jump testing: RSI = Flight Time (s) ÷ Ground Contact Time (s).

Example: an athlete's best five hops average a flight time of 0.42 s and a ground contact time of 0.17 s. RSI = 0.42 ÷ 0.17 = 2.47. Because this ratio is unitless and uses flight time rather than calculated jump height, 10/5 RJT scores are not directly interchangeable with drop jump RSI scores expressed in meters per second — the two protocols should be tracked as separate baselines rather than converted into one another.

These ranges are drawn from published 10/5 RJT samples in field and court sport athletes and should be treated as a general reference rather than a fixed cutoff — within-athlete tracking against an individual's own baseline is more actionable than comparison to population norms alone.

Reliability, Trial Number, and Practical Testing Load

Stratford, Dos'Santos and McMahon (2020) reported intraclass correlation coefficients between 0.916 and 0.986 and coefficients of variation at or below 14.5% across 10/5 RJT variables, confirming the test is reliable enough for routine squad monitoring rather than only research use. The same study found that stability in mean peak RSI was typically reached by around the seventh repetition, reinforcing why the best-five-of-ten scoring convention outperforms averaging the full set.

The single-trial finding matters operationally. Testing an entire squad with a three-trial, 20-second-rest protocol per athlete adds meaningfully to session length; if one well-executed trial produces a statistically comparable peak RSI to three trials, as Stratford and colleagues found, teams can screen 20-plus athletes in a fraction of the time a three-trial drop jump battery would require.

Comyns et al. (2019) additionally established that the best-five-of-ten method holds up across male, female, and pooled cohorts, which means normative comparisons and within-athlete tracking do not require separate scoring conventions by sex — though absolute RSI values, as with drop jump testing, still tend to run lower in female athletes at equivalent training levels due to differences in tendon stiffness properties.

Training Applications and Programming Decisions

Because the 10/5 RJT requires no box and can be run in under two minutes per athlete, it is well suited to frequent monitoring — weekly or even pre-session — in ways a full drop jump battery rarely is. A meaningful drop in an athlete's best-five RSI relative to their own rolling baseline, without a corresponding change in flight time, points toward loss of ground contact efficiency and elevated neuromuscular fatigue, similar to the interpretation logic used with drop jump RSI.

Athletes who struggle to establish rhythm within the ten-hop set — showing their best scores clustered in repetitions eight through ten rather than three through six — are demonstrating slower reactive readiness even at an equivalent peak score, and may benefit from more general plyometric preparation (skips, pogo hops, low-amplitude bounding) before progressing to higher-intensity drop jump or depth jump work.

Coaches running both a drop jump and a 10/5 RJT protocol should keep the two as separate tracking lines rather than trying to reconcile them into a single number: the drop jump profile is diagnostic for single-effort SSC quality under a standardized load, while the 10/5 RJT profile is diagnostic for an athlete's capacity to repeat that quality under self-generated, fatiguing conditions — a distinction that matters most for sports involving repeated high-speed changes of direction rather than a single vertical effort.