> ## 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.

# Linear Stretch

> Distance between the lead ankle and center of both wrists along the pitch direction at foot contact. This measures the linear stretch of the body during the swing.

## Technical Details

* **Variable Type:** Discrete Metric
* **Data Type:** Float
* **Units:** raw: m, display: in
* **Column Name:** `linear_stretch`
* **Aggregation:** mean
* **Precision:** 1
* **Measurement:** Distance from lead ankle to center of wrists
* **Direction:** Along pitch direction
* **Timing:** At foot contact event
* **Typical Range:** 12.4 – 25.4 in
* **Optimal Direction:** Middle — moderate values are optimal

## Description

Linear stretch measures the distance between the lead ankle and the center of both wrists along the pitch direction at foot contact, indicating the body's linear extension during the swing.

## Normative Ranges

Percentile distributions by competition level from the 2026 Q1 dataset; the optimal range spans the 25th–75th percentiles.

| Population         | Optimal Range (25th–75th) | 10th | 25th | 50th | 75th | 90th |
| ------------------ | ------------------------- | :--: | :--: | :--: | :--: | :--: |
| Youth              | 10.3 – 14.7 in            |  9.1 | 10.3 | 12.4 | 14.7 | 17.4 |
| High School        | 12.0 – 16.3 in            | 10.4 | 12.0 | 13.7 | 16.3 | 26.3 |
| College            | 17.6 – 26.3 in            | 13.8 | 17.6 | 21.7 | 26.3 | 31.0 |
| Professional       | 23.0 – 29.6 in            | 19.3 | 23.0 | 27.0 | 29.6 | 33.4 |
| Broad (All Levels) | 12.4 – 25.4 in            | 10.0 | 12.4 | 16.3 | 25.4 | 29.6 |

## Use Cases

* Body extension analysis
* Stretch assessment
* Linear mechanics evaluation