> ## 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.

# Pelvis Coil

> Maximum amount of pelvis twist rotation away from the serve direction (preloading the twist before the serve).

## Technical Details

* **Variable Type:** Discrete Metric
* **Data Type:** Float
* **Units:** degrees (°)
* **Column Name:** `pelvis_coil`
* **Measurement:** Maximum pelvis twist rotation away from the serve direction during the preparation/loading phase
  * reflects how much the pelvis is "coiled up" before uncoiling toward contact

## Description

Pelvis coil is the maximum twist rotation of the pelvis away from the serve direction during the early phases of the serve.
It reflects lower-body preloading before the acceleration phase and contributes to [Pelvis Stretch](/biomechanics/activities/tennis/metrics/pelvis-stretch) (twist range of motion).

## Use Cases

* Lower-body coiling and loading assessment
* Pelvis contribution to kinetic chain
* Comparison with trunk coil and stretch metrics