> ## 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.

# Vertical Displacement (Normalized)

> Vertical 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_vertical`
* **Measurement:** Vertical body displacement between [Apex](/biomechanics/activities/tennis/events/apex) (ball contact) and [Termination](/biomechanics/activities/tennis/events/termination), divided by athlete height

## Description

Vertical displacement (normalized) measures how much the body drops (or rises) 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.

## Use Cases

* Landing mechanics analysis
* Momentum dissipation after contact
* Comparison across players or trials