Rig an object hierarchy for KeepOut collision

To rig an object hierarchy for KeepOut

Select the object you want rigged for Keep Out functionality.
The selected object is considered the “animation control” that the animator uses to create poses. Any child objects are reparented under the KeepOut node and can collide with any number of Muscle Objects.
Select Muscle > Self/Multi Collision > Rig selection for KeepOut from the main menu bar.
A new group is inserted as a child of the hierarchy. By default, this KeepOut node attempts to project against its X-axis to stop children from going into Muscle Objects.

The Muscle KeepOut node calculates the required information and has other attributes for the settings of the KeepOut node. A group parented underneath called the “Driven” group, stops or collides with the objects.

You can now connect the KeepOut node to Muscle Objects. See Connect muscles to KeepOut.