The latter is not an absolute: You'll often find shoulder blades that are «glued» together or stuck in downward rotation in people who bench a lot. (tonygentilcore.com)
In a crash, after the initial downward rotation toward the front of the vehicle, the car seat pops back up toward the rear of the vehicle. (thespruce.com)
This reduces the force of the first downward rotation in a crash. (thespruce.com)