> ## 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.

# SFMA Back Bend

> Biomechanical analysis of SFMA back bend movement assessment, including shoulder flexion and hip extension range of motion.

## Overview

The SFMA back bend is a standardized movement assessment used in the Selective Functional Movement Assessment (SFMA) protocol to evaluate spinal extension and identify potential sources of pain or limitation. This assessment provides valuable information about thoracic and lumbar spine mobility.

## Instructions

From a standing position, raise both arms forward and above you and reach upwards and behind you as far as possible.
Allow your hips to come forward and your shoulders and head to move back. Hold max extended position for \~1 second
then return to standing.

## Example Videos

<Frame>
  <video controls src="https://uplift-docs-assets.s3.amazonaws.com/stability/stability-sfma_back_bend_combined.mp4" />
</Frame>

## Dimensions

Required inputs for processing:

* **None**

## Movement Grading as Functional

Classification as "Functional" requires:

* Shoulder flexion ROM ≥ 165°
* Hips pass in front of toes
* Shoulders pass behind heels
* No shoulder compensation (a 10° reduction in shoulder flexion when nearing peak extension)

## Generic Outputs

Every capture includes session metadata, standard joint angle/velocity time series, and 3D keypoint positions common to all movements. See [Generic Outputs](/biomechanics/activities/generic_outputs) for the full list.

## Discrete Metrics

| Metric                      | Units   | Description                                                                                                                                             | Column Name                            |
| --------------------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------- |
| Max Shoulder Flexion        | degrees | Maximum shoulder flexion angle (average of left & right)                                                                                                | `max_shoulder_flexion`                 |
| Shoulder Flexion ROM        | degrees | Range of shoulder flexion motion (average of left & right)                                                                                              | \`\`                                   |
| Max Hip Extension           | degrees | Maximum hip extension angle (average of left & right)                                                                                                   | \`\`                                   |
| Hips Pass Toes              | bool    | Whether hips move forward past toes                                                                                                                     | `sfma_back_bend_hips_pass_toes`        |
| Shoulders Pass Heels        | bool    | Whether shoulders move backward past heels                                                                                                              | `sfma_back_bend_shoulders_pass_heels`  |
| Hips To Toes Distance       | meters  | Horizontal distance from hips to toes at maximum reach. Positive value indicates reaching past mark, negative value indicates insufficient reach.       | \`\`                                   |
| Shoulders To Heels Distance | meters  | Horizontal distance from shoulders to heels at maximum reach. Positive value indicates reaching past mark, negative value indicates insufficient reach. | \`\`                                   |
| Shoulder Compensation       | bool    | Whether shoulder compensation occurred (> 10° reduction in shoulder flexion)                                                                            | `sfma_back_bend_shoulder_compensation` |
| Functional                  | bool    | Whether movement is functional (see above)                                                                                                              | `sfma_back_bend_functional`            |

## Notes

* Kinematic data typically captured at 60Hz for stability activities