The CMJ as an Indicator of Neuromuscular Fatigue: How to Use It in Your Training

Updated on 26 de June de 2026 by Adrián Escobar Morales

He countermovement jump (CMJ) It is one of the most used tools in sports science to evaluate neuromuscular performance. But beyond measuring how much an athlete jumps, the CMJ has a practical application that more and more coaches and physical trainers are incorporating into their daily work: detect neuromuscular fatigue before it becomes a problem.

In this article we explain what the CMJ is, why it is a valid indicator of fatigue, what variables to measure beyond jump height, and how to practically integrate it into training planning.

What is CMJ and why is it used to measure fatigue?

He countermovement jump (Countermovement Jump or CMJ) It consists of performing a vertical jump starting from an upright position, first performing a rapid flexion of the knees and hips (eccentric phase) followed immediately by an explosive extension (concentric phase) to take off from the ground.

Its use as a fatigue indicator is based on a simple principle: The neuromuscular system is the first to notice accumulated fatigue, and that loss of performance is directly reflected in the ability to produce force quickly and explosively — exactly what the CMJ measures.

The advantages that make it so useful in practice are clear:

• Is fast: a 3-jump test is performed in less than 2 minutes.
• Is non-invasive and does not generate significant additional fatigue.
• Is reproducible– When measured with validated devices, data is consistent and comparable between sessions.
• It can be done before or after any workout without interfering with the session.
• Provides data goals that complement or replace subjective effort perception scales.

Which CMJ variables are the most useful for detecting fatigue?

Jump height is the best known variable, but not always the most sensitive. A motivated athlete can maintain jump height by compensating with a different technique — for example, increasing the depth of the countermovement — which masks actual fatigue. Therefore, the most advanced professionals combine several metrics:

jump height

It is the most direct and easiest indicator to interpret. A sustained reduction from the athlete’s baseline value — especially if it exceeds 5-10% — is a clear sign of accumulated neuromuscular fatigue. It is recommended not to interpret a single piece of information in isolation, but to always compare it with the athlete’s history.

Flight time

It is directly related to the height reached and reflects the force applied at takeoff. Its advantage is that it is easily measurable with infrared devices such as ADR Jumping, without the need for complex force platforms.

Modified RSI (Reactive Strength Index)

He RSI-mod It is the relationship between flight time and contraction time (from the beginning of movement to takeoff). It is one of the most sensitive indicators of fatigue: when the athlete is tired, contraction time increases — movements become slower — while flight time decreases, producing a pronounced drop in RSI-mod.

Research in Australian football found that values ​​of the flight time / contraction time ratio below 92% of baseline They correctly identified fatigued players up to 96 hours after a match.

Contact time

In repeated jump protocols, the time the foot remains in contact with the ground between jumps reflects the efficiency of the stretch-shortening cycle (SSC). Under fatigue, this time increases — the athlete needs more time to generate the same force.

When is CMJ effective in detecting fatigue and when is it not?

One of the most important contributions of recent research is to clarify that the CMJ is not a universal indicator of fatigue in all contexts. Its limitations are important to know so as not to misinterpret the data:

• Works very well to detect neuromuscular fatigue produced by exercises with high eccentric demand: strength training, sprints, jumping, team sports matches. These types of efforts generate mechanical muscle damage that is clearly reflected in the CMJ.
• It is less sensitive to fatigue of a predominantly metabolic nature without significant muscle damage — for example, after a long session of cycling or swimming at moderate intensity, where the fatigue is more energetic than neuromuscular.

This has a direct practical implication: The CMJ is especially useful for strength, speed, team sports and any modality with a high eccentric component. — precisely the profile of an athlete who works with strength training and VBT.

How to apply the CMJ to monitor fatigue in practice

Set an individual basal value

The first step is to register the reference value (baseline) of each athlete in conditions of optimal rest. It is recommended to perform at least 3-5 measurements on rest days during the first weeks to obtain a reliable average. All subsequent data are interpreted in relation to that individual baseline value, not to general normative tables.

Always measure under the same conditions

For the data to be comparable, the protocol must be consistent: same time of day, same previous warm-up (or directly without warm-up if the objective is to measure the resting state), hands on the hips and self-determined but constant countermovement depth.

Interpret fall thresholds

As a general reference for decision making:

These thresholds are indicative — each athlete has their own variability. Jiménez-Reyes’ research found that CMJ measured during competition week can be a good predictor of performance in speed events such as the 100, 200 or 400 meter dash, which underlines its usefulness for decision making during competition week.

Use pre and post workout for acute fatigue

In addition to chronic week-to-week monitoring, the CMJ can be used within the session itself to quantify the fatigue generated: a test at the beginning and another at the end of training allows the percentage of performance loss for that specific session to be calculated, analogous to the control of intra-set speed loss in VBT.

CMJ and VBT: two tools that complement each other

For a coach who already works with velocity based training (VBT), CMJ is the natural complement. While the encoder measures fatigue inside of each set through intraset speed loss, the CMJ measures fatigue accumulated between sessions through neuromuscular performance at rest.

By combining both tools you get a complete picture of the athlete’s status:

• He ADR Encoder tells you how the athlete is performing within the session.
• He ADR Jumping It tells you how the athlete arrives at that session — if he is recovered or if he is carrying fatigue from previous days.

Together, they allow you to make informed load decisions at all times: if the CMJ shows a 12% drop from baseline, it may not be the day for a high-intensity block with high velocity losses; If the CMJ is at normal values ​​or higher than baseline, it may be a good sign to take advantage and increase the training load.

Conclusion

The CMJ is a simple, non-invasive neuromuscular fatigue monitoring tool supported by extensive scientific evidence. Its greatest value is not in a specific piece of information, but in the longitudinal follow-up of each athlete compared to their own baseline.

To get the most out of it you need three things: a validated measurement device, a consistent protocol, and a historical record of data. With the ADR Jumping and the app ADR System You can have all three from day one: the device measures flight time, contact time and RSI in real time, and the app stores the history in the cloud so you can compare the evolution of each athlete session by session.

Literature

Los siguientes estudios respaldan los datos y conclusiones de este artículo sobre el CMJ como indicador de fatiga neuromuscular:

1. Claudino, J.G. et al. (2017). The countermovement jump to monitor neuromuscular status: A meta-analysis. Journal of Science and Medicine in Sport, 20(4), 397–402. See in PubMed →
2. Jiménez-Reyes, P. & González-Badillo, J.J. (2011). Monitoring training load through the CMJ in sprints and jump events for optimizing performance in athletics. New Studies in Athletics, 26(1–2), 35–45.
3. Gathercole, R., Sporer, B., Stellingwerff, T. & Sleivert, G. (2015). Alternative countermovement-jump analysis to quantify acute neuromuscular fatigue. International Journal of Sports Physiology and Performance, 10(1), 84–92. See in PubMed →
4. Malone, S. et al. (2015). The positional match running performance of elite Gaelic football. Journal of Strength and Conditioning Research.

Adrián Escobar Morales