---
title: "Step 6 - Extract forces and moments"
canonical: "https://help.vicon.com/space/ProCalc16/12648836/Step%206%20-%20Extract%20forces%20and%20moments"
format: markdown
---
Remember that joint reactions already contain the joint forces and moments as part of its components. We now need to transform each into the correct reference coordinate system, and possibly rearrange its order to conform to biomechanical conventions.


    **To extract joint forces:**


1. Create a new variable called **NormalizedLeftAnkleForces**.
2. For the function type, specify **Kinetics** and for the function, select **Extract forces from reaction A in segment B's reference, C normalize**.
3. For the Input Variable type, select **Reaction** for A, **Segment** for B, and **Number** for C.
4. For the Input Variables, choose **Left Ankle Reaction**, **LFO**,and **Bodymass** for A, B, and C, respectively.
5. To the right of the function, select from the **Reorder** list to choose how you would like to output the joint forces. For comparison to Plug-In Gait, leave as **XYZ**.
6. To compare with Plug-In Gait outputs, from the **Negate **list, select  **-** **/+/-**.
7. Copy and mirror.

> ✅ **Tip**  
> ✅ If you do not want to normalize your data, set the **Input Variable** for **C **to 1, and you do not need to follow the above rules.

> Macro (scroll-pagebreak)


    **To extract joint moments:**


1. Create a new variable called **NormalizedLeftAnkleMoments**.
2. For the function type, specify **Kinetics** and for the function, select **Extract moments from reaction A in segment B's reference, C normalize**.
3. For the Input Variable type, select **Reaction** for A, **Segment** for B and **Number** for C.
4. For the Input Variables, choose **Left Ankle Reaction**, **LFO**,and **Bodymass** for A, B, and C, respectively.
5. To the right of the function, select from the **Reorder** list to choose **YZX**. This ensures that the flexion-extension axis (in this case, ankle dorsiflexion) is the first component.
6. To compare with Plug-In Gait outputs, from the **Negate **list, select  **+** **/-/+**.
7. Copy and mirror

> ⚠️ **Note** 
> ⚠️ 
> ⚠️ When normalizing data, to ensure that moments are visualized properly in Nexus 2.14 and later, use at least one of the following naming conventions:
> ⚠️ 
> ⚠️ - Use a default Plug-In Gait output name (eg, `LAnkleMoment`).
> ⚠️ - Use a default Plug-In Gait output name (eg, `LAnkleMoment`) and append an underscore `_` plus any extra characters (eg, `LAnkleMoment_proCalc`).
> ⚠️ - Use the word `Normalized` or `Normalised` in the variable name (eg, `NormalizedLeftAnkleMoments`).