Hi, has anyone had weird reactions when riding their bike?

I know it can cause AD. Has anyone had problems with their bp going too low while riding?

One time when I was riding I started feeling really anxious and was shivering/shaking a bit. I think a lot was me not being use to my heart beating like that and in my throat so I had a mini panic attack. Plus the stims may have been too high to start out. The first time I rode I was about 9 yrs post so my legs hadn't worked like that in years!