Have you had a concussion in the past?

From past posts asking a similar question, it would be extremely rare to get a concussion that way.
As I understand it , there is just not enough force (G forces) when the head does not hit something.

If you had a past concussion and still had some symptoms from it, possibly might trigger a bit of a relapse..
Or if you had any past neck/shoulder issues, it could cause a flare up of that.