Countermovement jump (CMJ) test: how to do it and what it tells you

The countermovement jump is the single most widely used test in athlete assessment. The reason is simple: it takes two minutes, leaves no fatigue and tells you about lower-body explosive power and nervous system freshness at the same time. In this article we take a detailed look at how to administer the CMJ correctly, what the numbers mean and how it's used for weekly fatigue monitoring.

What is CMJ and what does it measure?

The athlete stands, quickly squats down (the countermovement) and immediately jumps as high as possible. This squat-to-jump transition engages the stretch-shortening cycle: elastic energy stored in muscles and tendons is returned during the concentric phase.

The test reflects three things at once:

• Lower-body explosive power: Force that can be produced in a short time.
• Elastic qualities: Efficiency of the eccentric-to-concentric transition.
• Neuromuscular freshness: A fatigued athlete's CMJ value drops, and even their jump strategy changes.

Correct testing protocol

Warm-up

A standard RAMP warm-up: 5 minutes of light jogging or cycling, dynamic mobility, 2–3 submaximal jumps. The warm-up must be identical for every test; a different warm-up produces a different result.

Technical rules

• Hands on hips: Eliminating the arm swing standardizes the measurement. A jump with arm swing can be taken as a separate test, but the two should not be mixed.
• Self-selected squat depth: The athlete is told, “choose the depth that lets you jump highest.” Fixing the depth disrupts the natural strategy.
• No pause in the transition: There should be no pause between the squat and the jump; if there is, the test turns into a squat jump.
• Landing: Controlled landing on the takeoff spot, knees slightly bent.
• Number of attempts: 3 valid attempts, 30–45 seconds apart. The best is recorded; the average is noted too.

Measurement methods

Which method you use doesn't matter as long as you're tracking the athlete's own changes over time. But you shouldn't compare across methods: 42 cm on a contact mat and 42 cm on a Vertec are not the same thing.

What do the values mean?

Absolute values vary widely by sport, sex and training age. The ranges below are a rough reference:

But the real value of CMJ isn't in comparison — it's in the same athlete's own curve. Going from 38 cm to 42 cm is far more meaningful information than another athlete sitting at 45 cm.

CMJ for fatigue monitoring

This is the most practical use of CMJ. The athlete's rested average is established (from at least 5–7 measurements). Then, in weekly measurements:

• A drop of more than 5% from the average: A signal of neuromuscular fatigue. That day's high-intensity content is reduced.
• A drop two weeks in a row: Weekly load is reviewed; sleep and nutrition are questioned.
• Same height but a changed flight/contact ratio: The athlete is reaching the same result with a different strategy, which is a sign of hidden fatigue (visible only with a force plate).

This monitoring is especially valuable in seasons with a heavy match load; an athlete saying “I'm fine” doesn't always match the true state of their nervous system.

What to look at alongside CMJ

CMJ on its own is an incomplete picture. It gains meaning when combined with the following:

• Squat jump: A jump without a countermovement. The difference from CMJ (eccentric utilization ratio) shows elastic qualities. If the difference is below 10%, the athlete isn't using the stretch-shortening cycle efficiently.
• Drop jump / RSI: Short-contact reactive capacity.
• IMTP or estimated 1RM: The maximal strength side. If CMJ is high but strength is low, the program shifts toward heavy strength.
• Single-leg CMJ: Detecting asymmetry. A difference above 10% needs monitoring.

Common mistakes

1. Changing the warm-up: A 3 cm difference in the same athlete can come from the warm-up alone.
2. Testing at different times of day: There's a meaningful difference between morning and evening values.
3. Testing while fatigued: A CMJ done after a heavy session measures fatigue, not performance; the two shouldn't be confused.
4. Taking a single attempt: The first attempt is often the lowest; at least three attempts are needed.
5. Switching devices: The device must stay the same for serial monitoring.

How we use CMJ at Skyland

In the assessment session, CMJ, squat jump and single-leg CMJ are taken together and repeated at the end of each block. For athletes with in-season performance goals, a quick weekly CMJ check is done and the result feeds into that week's load plan. For the detailed protocol, see our performance testing guide, and for ways to improve your jump, our vertical jump article .

Frequently asked questions