Reactive Strength Index Norms: RSI by Sport & Level

Reactive strength index (RSI) norms vary by sport, sex, and training level, but general benchmarks are: 0.5–1.5 for beginners, 1.5–2.5 for intermediate athletes, and 2.5–4.0+ for elite jumpers and sprinters. RSI is a ratio of jump height to ground contact time, and it measures how quickly an athlete can absorb and produce force. This article explains what RSI is, how to calculate it, what average values look like across populations, and how to interpret your own score.

Formula

RSI is calculated by dividing jump height (in meters) by ground contact time (in seconds). The standard formula is:

RSI = Jump Height (m) ÷ Contact Time (s)

Where:

• Jump height – the vertical displacement of the center of mass during a rebound jump, measured in meters (or centimeters).
• Contact time – the duration the foot is in contact with the ground during the jump, measured in seconds (or milliseconds).

The result is expressed in meters per second (m/s). A higher value means the athlete can jump higher in less time, indicating better reactive strength.

Worked Example

Using the default values from the calculator: jump height = 40 cm, contact time = 200 ms.

1. Convert height to meters: 40 cm ÷ 100 = 0.40 m
2. Convert contact time to seconds: 200 ms ÷ 1000 = 0.20 s
3. Divide height by time: 0.40 ÷ 0.20 = 2.00 m/s

The calculator returns an RSI of 2.00 m/s, which is a typical score for a well-trained athlete.

What RSI Actually Measures

Reactive strength is the ability to quickly switch from an eccentric (lengthening) contraction to a concentric (shortening) contraction – the stretch-shortening cycle. RSI captures this by combining two variables: how high you jump and how fast you rebound. Unlike a simple vertical jump test, RSI penalizes slow ground contacts, so it rewards explosiveness rather than just raw power.

RSI is often measured using a drop jump (also called depth jump), where the athlete steps off a box and immediately jumps upward. The contact time is the time between landing and takeoff. The jump height is usually calculated from flight time using the formula: height = (g × flight time²) / 8, where g = 9.81 m/s².

Norms by Population

Published norms are scarce and vary widely by testing protocol, but the following ranges are commonly cited for drop jumps (contact time measured from landing to takeoff):

• Recreational adults: 0.5 – 1.5 m/s
• Club-level athletes: 1.5 – 2.0 m/s
• National-level athletes: 2.0 – 3.0 m/s
• Elite jumpers/sprinters: 3.0 – 4.5 m/s

These are approximate. A 2017 study of elite male sprinters reported mean RSI values around 3.0 m/s, while elite female volleyball players often score between 2.0 and 2.5 m/s. Youth athletes (under 16) typically score below 1.5 m/s. Always compare your score to data from the same jump type (drop height, contact mat, calculation method).

How to Choose the Right Drop Height

RSI is highly sensitive to the drop height used. A common protocol uses a 30 cm box for most athletes, but taller or more advanced athletes may use 40–50 cm. The goal is to find the height that produces the highest RSI – this is your optimal drop height. If the box is too low, you don’t get enough stretch; if it’s too high, contact time increases and RSI drops.

Practical approach: start with 20 cm, then increase by 10 cm until RSI decreases. The height with the best RSI is your optimal drop height. For testing norms, always use the same height for all athletes (e.g., 30 cm) to make comparisons valid.

Common Mistakes and Misconceptions

• Mixing units: Height in cm and time in ms will give an RSI in cm/ms unless you convert. Always use meters and seconds.
• Using flight time instead of contact time: RSI uses ground contact time, not flight time. Flight time is used to calculate jump height, not RSI directly.
• Ignoring arm swing: Arm swing can increase jump height by 10–20%. For RSI testing, arms should be fixed on hips to isolate leg strength.
• Comparing different protocols: RSI from a drop jump is not the same as RSI from a countermovement jump. Always note the protocol.

How to Improve Your RSI

Training to improve RSI focuses on plyometrics and strength. Key exercises include:

• Depth jumps (start with low boxes)
• Pogo jumps (small, quick jumps)
• Box jumps with immediate rebound
• Heavy back squats to build maximal strength
• Sprint intervals (short, 10–30 m)

Volume should be low – 3–5 sets of 3–5 reps, with full recovery (2–3 minutes) between sets. Overtraining can increase injury risk, especially in the Achilles tendon and knee.

Limitations of RSI

RSI is a useful metric but has limitations. It doesn’t account for body mass, so a heavier athlete with the same jump height and contact time will have the same RSI as a lighter one, despite different force outputs. It also assumes a perfect rebound – athletes who intentionally pause on landing will get low scores, which may not reflect true ability.

RSI is best used as a monitoring tool over time, not as a single diagnostic. A sudden drop in RSI may indicate fatigue or overreaching, while a gradual increase suggests improved reactive strength.

Frequently Asked Questions

What is a good RSI for a 16-year-old?

For a 16-year-old athlete, an RSI of 1.0–1.5 m/s is typical. Elite youth athletes might reach 2.0 m/s. Focus on technique and strength rather than chasing high numbers at this age.

Can RSI be measured without a force plate?

Yes. You can use a contact mat (or even a smartphone app with slow-motion video) to measure contact time, and a jump mat or video analysis to measure flight time. The accuracy is lower than a force plate but sufficient for tracking trends.

What is the difference between RSI and RSI-mod?

RSI-mod (modified RSI) uses jump height divided by time to takeoff (the time from the start of the countermovement to takeoff) instead of ground contact time. It’s used for countermovement jumps, while RSI is used for rebound jumps. RSI-mod is often larger because the denominator is longer.

Does a higher drop height always give a higher RSI?

No. There is an optimal drop height for each athlete. Beyond that, contact time increases more than jump height, so RSI decreases. Testing multiple heights is the best way to find your optimum.

Is RSI the same as reactive strength?

RSI is a specific measure of reactive strength. Reactive strength itself is a broader quality, but RSI is the most common way to quantify it in a jump test.

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in ht | Jump height | cm | 40 | 0
in ct | Contact time | ms | 200 | 0
out rsi | Reactive strength index | m/s | (ht / 100) / (ct / 1000) | 2
out rsi_au | RSI (arbitrary units) | AU | ht / ct | 2