> ## 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.

# Loading Phase Trunk Tilt

> Maximum trunk side-side tilt towards the rear during the loading phase of the serve.

<img src="https://mintcdn.com/upliftlabs/Ku7T6jLWrJyoK7uq/biomechanics/activities/tennis/images/trunk-tilt.png?fit=max&auto=format&n=Ku7T6jLWrJyoK7uq&q=85&s=55120786dc6ac631503926bb6ad2cfdb" alt="Trunk tilt during loading" width="500" height="500" data-path="biomechanics/activities/tennis/images/trunk-tilt.png" />

## Technical Details

* **Variable Type:** Discrete Metric
* **Data Type:** Float
* **Units:** degrees (°)
* **Column Name:** `loading_phase_trunk_tilt`
* **Measurement:** Maximum trunk lateral (side-side) tilt towards the rear during the loading phase ([Ball Release](/biomechanics/activities/tennis/events/ball-release) to [Low Arm](/biomechanics/activities/tennis/events/low-arm))
  * Negative values indicate leaning to the dominant side
  * Positive values indicate leaning to the non-dominant side

## Description

Loading phase trunk tilt is the maximum lateral tilt of the trunk toward the rear (back) side during the loading phase.
It reflects preparatory posture before the upward swing.

## Use Cases

* Loading assessment
* Trunk control during preparation
* Comparison with contact-phase trunk tilt