> ## 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.

# Initiation

> The start of the jump—when the person begins to move downward.

## Technical Details

* **Variable Type:** Event
* **Data Type:** Integer
* **Units:** Frame number
* **Column Name:** `jump_initiation_frame`
* **Required for QA:** False
* **Measurement:** Start of the jump movement

## Description

Initiation represents the very beginning of the jump when the athlete begins the downward movement (e.g., countermovement or drop). This event is used to define the start of the jumping phase and for calculating phase durations.

## Use Cases

* Jump phase timing analysis
* Eccentric phase duration (initiation to bottom)
* Time to takeoff