> ## 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.

# Contact Phase Shoulder Abduction

> Amount of shoulder abduction at apex (ball contact).

<img src="https://mintcdn.com/upliftlabs/Ku7T6jLWrJyoK7uq/biomechanics/activities/tennis/images/shoulder-abduction.png?fit=max&auto=format&n=Ku7T6jLWrJyoK7uq&q=85&s=438123bcff4920daf129a5cc5b659d13" alt="Shoulder abduction at contact" width="500" height="500" data-path="biomechanics/activities/tennis/images/shoulder-abduction.png" />

## Technical Details

* **Variable Type:** Discrete Metric
* **Data Type:** Float
* **Units:** degrees (°)
* **Column Name:** `contact_phase_shoulder_abduction`
* **Measurement:** Shoulder abduction angle (dominant arm) at [Apex](/biomechanics/activities/tennis/events/apex)

## Description

Contact phase shoulder abduction is the sideways lift angle of the dominant arm at ball contact.
It reflects the height and position of the arm at the moment of impact.

## Use Cases

* Shoulder position at contact
* Technique and consistency