Predicting Eccentric Strength from a Loaded CMJ

Most strength testing batteries tell you how much force an athlete can produce concentrically or isometrically. They tell you very little about eccentric strength, which is arguably the capacity most relevant to deceleration, direction change, and injury resilience. Here is how to close that gap using data you are likely already collecting.

The Strength Quality Most Practitioners Are Missing

Maximal strength is a cornerstone of high-performance sport. It underpins sprinting, skating, jumping, and the ability to absorb and redirect force. Yet most testing batteries are built around concentric output such as 1RM testing, or isometric output such as the isometric mid-thigh pull. Both are valuable. Neither captures eccentric strength.

This is not a minor gap. Eccentric strength governs braking mechanics, deceleration, change of direction, and the force absorption phase of stretch-shortening cycle tasks. An athlete can display impressive concentric 1RM values while carrying a meaningful deficit in eccentric capacity. That deficit may not surface until a high-demand deceleration scenario exposes it.

The reason eccentric strength is so rarely tested directly is straightforward. True maximal eccentric assessment requires supramaximal loading, which means loading an athlete beyond their concentric 1RM. This introduces safety considerations, specialized equipment, and logistical barriers that most applied environments cannot support. So the default has been to skip it entirely.

There is now a better option.

Why Eccentric Strength Is Physiologically Distinct

Before getting into the practical method, it is worth understanding why eccentric strength deserves its own attention rather than being treated as a simple extension of general strength.

The force-velocity relationship is a foundational principle in exercise physiology. It defines that force production declines as movement velocity increases during concentric contractions. The same relationship also tells us that during eccentric contractions, muscles are capable of producing approximately 1.3 times more force than during concentric actions at equivalent velocities.

This difference reflects distinct underlying mechanisms. At the single-fiber level, passive structural elements, particularly titin, contribute significantly to force during active lengthening. Titin is a large elastic protein within the sarcomere that behaves like a spring inside the muscle fiber, storing and releasing energy during eccentric loading in a way that does not occur during concentric contractions.

At the whole-body level, neural activation strategies during eccentric tasks also differ from concentric tasks. Motor unit recruitment patterns, inter-muscular coordination, and the specific skill of resisting lengthening under load are trainable qualities that respond to eccentric-specific training methods. Those methods look meaningfully different from traditional maximal or explosive strength training.

This is why the blind spot matters. If you are not assessing eccentric strength, you cannot track it, you cannot systematically develop it, and you cannot identify deficits before they become problems.

Predicting Maximal Eccentric Strength from Loaded CMJ Mechanics

Countermovement jump testing is already embedded in most high-performance monitoring systems. Loaded CMJ protocols, typically performed with a trap bar or barbell, are widely used for force-velocity profiling. If you are running these assessments, you are already collecting the inputs needed to estimate maximal eccentric strength.

The CMJ contains a distinct eccentric deceleration phase in which the athlete resists the downward displacement of the centre of mass before transitioning into the propulsive phase. Under additional load equal to 60% of body mass, the mechanical demands of that eccentric phase become substantial enough that its outputs are meaningfully predictive of maximal eccentric strength capacity.

Using data from the BW + 60% loaded CMJ trial, maximal single-leg multijoint eccentric strength can be estimated using the following model (McClean et al., 2024):

Predicted Eccentric Strength =
(BW+60% max downward velocity × −306)+
(BW+60% eccentric deceleration impulse × 1.2) +
(Sex [M=1, F=0] × 368) +
955 (constant)

This approach carries an approximate 14-15% prediction error in collegiate athletes, consistent with error ranges reported for other indirect strength prediction methods. It will not replace a supramaximal eccentric testing protocol where one exists. For the vast majority of applied environments, however, it provides a level of insight that was previously inaccessible without a significant change to the testing battery.

The inputs required, specifically peak downward velocity and eccentric deceleration impulse from the BW + 60% trial, are standard outputs from most modern force plate systems.

How to Use This in Practice

Generating a predicted eccentric strength value is straightforward. Using it well requires some additional context.

1. Track it longitudinally, not as a single data point
The predictive error associated with this method means that a single value should be interpreted with appropriate caution. The real value emerges over time. Tracking predicted eccentric strength across training blocks, rehabilitation phases, or competitive seasons allows you to identify directional trends, including whether eccentric capacity is increasing in response to training, declining under accumulated load, or recovering following injury. The metric’s sensitivity to real change is greater than its absolute precision at any single time point.

2. Compare it against concentric and isometric estimates
Evaluating eccentric strength in isolation misses one of its most informative applications, which is understanding the balance across contraction types. An athlete demonstrating high concentric and isometric output with disproportionately low eccentric capacity may be at elevated risk in high-deceleration scenarios. The ratio between eccentric and concentric strength is a more informative data point than either in isolation.

3. Situate it within a broader performance profile
Maximal eccentric strength is one component within a broader neuromuscular performance profile. When combined with measures of explosive power, plyometric function, and stiffness, it contributes to a more complete picture of an athlete’s current capacity and the specific qualities that may require development. Questions like how does this athlete’s eccentric-to-concentric ratio compare to their sport-matched peers become answerable when eccentric strength is included alongside other monitoring outputs.

Practical Takeaway

If you are already running loaded CMJ testing, the data required to estimate maximal eccentric strength is likely sitting in your monitoring system unused. Adding this calculation requires no additional equipment, no change to your testing battery, and no supramaximal loading.

The result is a more complete picture of your athlete’s strength profile, one that includes the capacity most relevant to the mechanical demands of deceleration, direction change, and dynamic sport performance.

For a deeper breakdown of how this approach integrates into a full neuromuscular performance profiling system, including comparisons of eccentric, isometric, and concentric capacity against sport-specific normative data, the strength prediction tool is available free through the member portal.

Reference: McClean et al. (2024). Predicting Multijoint Maximal Eccentric and Concentric Strength With Force-Velocity Jump Mechanics in Collegiate Athletes. International Journal of Sports Physiology and Performance. Read the paper →