Introduction
What is Frontal Plane Torque?
Frontal Plane Torque (FPT) measures the rotational force your body generates around the frontal plane axis during a golf swing. Think of it as measuring how effectively you're using ground reaction forces to create rotational power.
When you swing a golf club, your feet push against the ground, and the ground pushes back. This interaction between your body's center of mass and the forces at your feet creates torque - a rotational force that helps power your swing.
Feature Components
The FPT feature includes two main components:
- FPT Graph (DataBox) - A time-series graph showing torque values throughout your swing with key metrics
- 3D Visualization - Real-time moment arm and force decomposition overlays on the motion capture skeleton view
Why Does This Matter?
Understanding your frontal plane torque can help you:
- Identify power generation patterns - See how efficiently you transfer ground forces into rotational energy
- Visualize biomechanical leverage - See the moment arm relationship between your center of mass and ground forces in 3D
- Analyze timing - Understand when peak torque occurs relative to ball impact
- Break down force components - See how your ground reaction force distributes across different directions
- Compare swings - Track changes in your force generation over time
Prerequisites
To use Frontal Plane Torque analysis, you need:
- Required: Force plate recording with ground reaction force data
- Required: Motion capture data for center of mass tracking
- Required: Calibrated camera setup
- Required: Body weight measurement (for normalized values)
Getting Started
Adding the FPT DataBox to Your Layout
- Open a recorded swing in the analysis view
- Click the DataBox menu or layout editor
- Find Frontal Plane Torque in the available DataBox list
- Add it to your analysis layout
- The DataBox will automatically populate with data from your recording
Enabling 3D Visualization
The moment arm and force decomposition visuals appear in the 3D video viewport alongside the skeleton. To enable them:
- Open a recording with motion capture and force plate data
- Locate the Force Vector Settings panel in the video view
- Enable the visualization options you want to see
Required Data
For FPT analysis to work properly, your recording must include:
| Data Type | Required | Purpose |
|---|---|---|
| Force plate data | Yes | Provides ground reaction forces (Fx, Fz) and center of pressure |
| Motion capture | Yes | Provides center of mass position for torque calculation and 3D visualization |
| Body weight | Yes | Used to normalize torque values for comparison |
| Camera calibration | Yes | Required for proper 3D alignment |
| Impact bookmark | Recommended | Enables timing metrics relative to ball contact |
Understanding the Display
The Graph
The main graph shows torque values over time:
- X-axis (horizontal): Time from the start of your swing to finish
- Y-axis (vertical): Torque values (can show percentage and/or absolute)
- Zero line: The horizontal line at zero - values above and below indicate opposite rotational directions
Dual-Axis System
The graph can display two different scales simultaneously:
- Left axis (Percentage): Shows torque normalized by body weight (Nm/kg, displayed as Force Factor)
- Right axis (Absolute): Shows actual torque in Newton-meters (Nm)
Key Metrics
Three key metrics are displayed alongside the graph:
1. Max Torque (Force Factor)
- What it shows: The peak torque magnitude, normalized by body weight
- Units: Nm/kg (shown as Force Factor)
- Example: A value of 0.85 means your peak torque was 0.85 Newton-meters per kilogram of body weight
2. Max Torque Timing
- What it shows: When peak torque occurs relative to ball impact
- Units: Milliseconds (ms)
- Note: Only displayed when an impact bookmark is set
- Example: -50ms means peak torque occurred 50ms before impact; +20ms means 20ms after impact; 0ms means at impact
3. Force Factor (Raw)
- What it shows: The raw normalized torque value including direction (positive or negative)
- Units: Nm/kg
- Example: +0.85 and -0.85 have the same magnitude but opposite rotational directions
Phase Highlighting
When enabled, colored bands overlay the graph to show different phases of your swing:
- Backswing, Downswing, Impact, Follow-through
3D Visualization
Moment Arm Visualization
The moment arm visualization shows the biomechanical leverage relationship between your center of mass (COM) and the ground reaction force.
| Element | Appearance | What It Shows |
|---|---|---|
| Moment Arm Line | Orange solid line | The perpendicular distance from your COM to the line of action |
| Line of Action | Orange dashed line | The extended line along which the force acts |
| Distance Label | White text on dark background | The moment arm distance in centimeters (±X.X cm) |
Force Vector Decomposition
The force decomposition visualization breaks down the total ground reaction force into three perpendicular components. The colors always represent the same physical force direction regardless of camera view:
| Component | Color | Physical Direction | What It Shows |
|---|---|---|---|
| X Component | Pink | Side-to-side (mediolateral) | Lateral force distribution |
| Y Component | Teal | Up-down (vertical) | Vertical force distribution |
| Z Component | Green | Front-back (anteroposterior) | Forward/backward force distribution |
Each component arrow also displays a percentage label showing what portion of the total force is in that direction.
Camera View Behavior
The force vectors are displayed relative to your camera view. Components that would appear as depth (going into/out of the screen) are hidden for clarity:
| Camera View | Visible Components | Hidden Component |
|---|---|---|
| Face-On | X (Pink, horizontal), Y (Teal, vertical) | Z (Green, depth) |
| Down-the-Line | Z (Green, horizontal), Y (Teal, vertical) | X (Pink, depth) |
Note: The colors always represent the same physical direction - Pink is always mediolateral force, Teal is always vertical force, and Green is always anteroposterior force. Only the screen position changes based on camera angle.
3D Visualization Settings
Moment Arm Settings
| Setting | Default | Description |
|---|---|---|
| Show Moment Arm | Off | Toggles the orange solid line from COM to the force line |
| Show Line of Action | Off | Toggles the orange dashed line showing the force direction extension |
| Show Distance Label | Off | Toggles the distance value label (±X.X cm) |
Force Decomposition Settings
| Setting | Default | Description |
|---|---|---|
| Show X/Y/Z Components | Off | Toggles all three component arrows and percentage labels |
Configuration Options (Graph)
- Show % (Percentage Axis): Default On - Toggles normalized torque (Nm/kg)
- Show Newton (Absolute Axis): Default Off - Toggles absolute torque (Nm)
- Highlight Phases: Default Off - Shows colored bands indicating swing phases
- Show Gridlines: Default On - Displays horizontal gridlines
- Chart Type: Mountain Chart (default) or Line Chart
Troubleshooting
"No Person on Plate" Message
- Ensure the athlete was standing on the force plate at the start of recording
- Check that body weight has been entered in the athlete profile
- Verify force plate calibration is complete
Empty or Missing Graph Data
- Confirm the force plate was active during recording
- Verify motion capture data was recorded (required for FPT calculations)
- Check that the recording includes the full swing duration
Timing Metrics Not Displayed
- Set the impact bookmark in your recording