- Jan 1
- 4 min read

Eccentric Utilisation Ratio (EUR).

"Physics is mathematical not because we know so much about the physical world, but because we know so little; it is only its mathematical properties that we can discover." —Bertrand Russell.

The concept of the Eccentric Utilisation Ratio (EUR) appears to be one of the simplest parts of the performance puzzle, as it uncovers the proportion of the two most widely used slow stretch‐shortening cycle (SSC) jumps in sports science: the squat jump (SJ) and the countermovement jump (CMJ).

The calculation of EUR displays the relationship between SJ and CMJ performance and is believed to be a precise indicator of lower-extremity slow stretch-shortening cycle (>0.25 s) performance, serving as a guidepost for plyometric programming choices, as well as for further clinical and/or developmental reasoning.

Let's take a closer look at this idea and consider whether it is really as useful as it sounds or just constitutes a quantification delusion.

Methodology.

EUR is typically calculated using force plates. It investigates the relationship between lower body power movements in the squat jump (SJ) and the countermovement jump (CMJ). The first (SJ), being purely concentric and thus a 'non-counter movement' jump, is compared with the second (CMJ), which represents an archetype of all 'counter movement' (CM) jumps used widely by sports science professionals around the world.

This comparison is consistent with the general observation that CM–based jumps are usually higher in value, which may be attributed to the ability to utilise the SSC in these kind of movements. The most frequently used subject of comparison is the results of jump height [cm], as determined by the second, JH–based part of the following equation:

The simplicity of this approach speaks for itself.

Performing a series of jumps takes a small amount of time (5 minutes is enough in my experience), which can easily be integrated within a jumping block without detracting from the planned work or excessively shifting focus from the athlete to technology. Estimates such as these appear to be highly replicable and may contain some value in terms of observing how trends change over time or how they correspond to the ideal norm.

Norms and Values.

The 'norm' is assumed when the CMJ score is 1.1 times (10%) higher than that of the SJ, or when the EUR value falls within a ratio ranging from 1.10 to 1.25. These ranges reveal the logic underpinning the rather straightforward decision-making emerging from this model.

If the value is less than 1.10, it is generally advisable to design a training cycle focused on elastic abilities through plyometric modalities. Conversely, if the result falls within the normative range, the undergoing cycle should concentrate on non–SSC maximal strength–based and force output methods.

EUR in Rehabilitation.

Considering that jumping from squat positions mainly involves dynamic loading of the hip and knee joints, sports science technology companies and their educators sometimes propose that EUR might be appropriate for managing lower limb injuries impacting these joints, for instance in post-ACLR or hamstring injury rehabilitation scenarios.

Consequently, JH-based EUR metrics are sometimes used in clinical settings to guide practitioners in determining if the treatment direction is appropriate. Similarly, they are considered to be another key reference point, offering insights on more individualised treatment selection based on a quantifiable, thus 'scientific' digit. Actually, deviations from assumed norms can tell clinicians something about typical injury–specific disorders in eccentric, transitional and/or concentric muscle function under dynamic load.

It's hypothesised that athletes with a low EUR (<1.10) may be more prone to injuries and/or re–injuries, such as muscle strains and ligament tears, due to ineffective force absorption during eccentric actions. However, given the complex nature of sport injuries, confirming this hypothesis conclusively is challenging, and it is not advisable to consider it a universal law of athletics.

Some researchers even recommend using joint-oriented EUR measurements to facilitate more precise rehabilitation, but none of the aforementioned approaches are considered the gold standard in sports medicine.

Uncertain Efficacy.

If there's one thing common in simple observational concepts, it's the tremendous ease of falsification.

This is no different for the numerals based on the Eccentric Utilisation Ratio (EUR). To begin with, it merely indicates the relationship between CMJ and SJ variables. What may seem like a tempting benchmark for many coaches (≥1.10) could simply result from poor SJ performance, potentially linked to poor rapid force development and increased muscle slack. Since performance is correlated with a lower rate of force development and greater muscle slack, it's worth rethinking the usefulness of EUR as an objective measure of SSC ability.

Furthermore, giving that CMJ is a relatively slow SSC action, the utilisation of stored elastic energy may contribute minimally to its execution, except when performed with small amplitude. Another issue is that more valuable indicators of SCC ability, such as the reactive strength index and others, are time-dependent which is not takien into account in EUR–driven results.

These findings are consistent with studies indicating that while plyometric and weight lifting training can enhance jumping ability, they do not significantly alter EUR. This revealing pattern calls for a reassessment of EUR's effectiveness in clinical and high-performance contexts.

Personal Perspective.

The resulting conclusions drawn solely based on EUR are – in my humble opinion – overly simplistic, sometimes even naive. They represents a shortcut, providing comfort and ease when addressing the delicate complexities of exercise, health, and athletic performance.

If I were to use the EUR despite its conceptual limitations, I would utilise it during the mid-phase of rehabilitation to assess the relationship between CMJ and SJ. Nevertheless, I would avoid using it to dictate training types in the later stages or the return-to-performance phase, particularly when dealing with robust, dynamic, agile, competing, and successful athletes.

To understand the state of SSC–type movements that need to be performed rapidly, I would recommend more reliable profiling based on the time-dependent parameter of reactive strength index and rate of force development, along with its modified, unilateral, single–leg applications.

To obtain these, focusing on countermovement and drop jumps is sufficient.