There are effectively 3 types to Falls in Parkinson’s Disease.
Type 1. Where a muscle or muscle group fail to energize to cause a topple.
Type 2. Where muscle or group of muscle fail to relax or de-energize, to cause a topple.
Type 3. Where Type 1 & Type 2 combine working against each other, resulting in a tripping up like fall.
Determining the Fall type is essential to assist in any relevant prescription in medication and or physio therapy and exercise routine.
I hope this helps, especially for those who find themselves hitting the ground on a daily basis.
Kind Regards
Andy