> ## Documentation Index
> Fetch the complete documentation index at: https://docs.uplift.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Forward Displacement (Normalized)

> Forward body displacement between ball contact and finish, expressed as a multiple of athlete height.

## Technical Details

* **Variable Type:** Discrete Metric
* **Data Type:** Float
* **Units:** × height (ratio to athlete height)
* **Column Name:** `displacement_forward`
* **Measurement:** Forward body displacement between [Apex](/biomechanics/activities/tennis/events/apex) (ball contact) and [Termination](/biomechanics/activities/tennis/events/termination), divided by athlete height

## Description

Forward displacement (normalized) measures how far the body moves forward, toward the net, between ball contact and the finish of the serve, expressed as a multiple of the athlete's height so it is comparable across athletes of different sizes. It provides the underlying continuous measurement behind the [Landing Phase Excessive Forward Drift](/biomechanics/activities/tennis/flags/landing-phase-excessive-forward-drift) movement flag, which flags forward displacement greater than 0.50x height.

## Use Cases

* Momentum and follow-through analysis
* Related to Landing Phase Excessive Forward Drift flag
* Court positioning after the serve