Selecting Metrics that Matter: Countermovement Jump

Introduction

The countermovement jump (CMJ) is one of the most widely utilised performance assessments in strength and conditioning. Its popularity stems from its simplicity, minimal equipment requirements, and the breadth of information it can provide about neuromuscular function (especially if you have access to force platforms). While a wide range of metrics can be derived from the CMJ, previous research has typically investigated these variables within narrow, study-specific aims. As a result, there has been little overarching guidance for practitioners regarding which metrics may be most relevant depending on the intended application of the test.

A recent article sought to address this gap by discussing how the choice of CMJ metrics should differ when the test is used for three distinct purposes: (1) as a proxy for athletic performance, (2) as a tool for monitoring neuromuscular fatigue, and (3) as part of a test battery in the return-to-performance process following injury.

Study Overview

The study did not aim to validate a single metric as superior. Instead, its purpose was to provide practitioners with a framework for selecting the most appropriate CMJ variables depending on the desired outcome of testing. Specifically, the authors highlighted three contexts where CMJ testing is commonly employed:

1. Athletic performance profiling

2. Neuromuscular fatigue monitoring

3. Return-to-performance testing post-injury

Key Insights

1. CMJ as a Proxy for Athletic Performance

When the CMJ is used to infer an athlete’s physical qualities and long-term performance capabilities, metrics such as jump height, peak power, and impulse are most relevant. These variables are closely associated with explosive strength and overall athleticism, making them appropriate indicators of physical development across training cycles.

2. CMJ for Neuromuscular Fatigue Monitoring

For monitoring fatigue, the study suggests focusing on metrics that are sensitive to subtle changes in movement execution rather than absolute performance outcomes. Variables such as flight time, contraction time, and reactive strength indices are more appropriate in this context, as they may detect neuromuscular fatigue before reductions in jump height or power become apparent. This allows practitioners to adjust training loads proactively.

3. CMJ in Return-to-Performance Testing

When the CMJ is integrated into a return-to-play framework, asymmetry measures and force-time characteristics provide the most meaningful information. These metrics allow practitioners to identify limb deficits or neuromuscular imbalances that may persist following injury. As such, the CMJ can form part of a broader test battery to support decision-making in rehabilitation and safe return to competition.

Practical Implications

The findings underscore that the value of CMJ testing lies not in measuring every possible variable, but in selecting metrics that align with the specific purpose of testing. For practitioners, this reinforces the need to adopt a purpose-driven approach to performance monitoring, fatigue management, and rehabilitation.