I have been experimenting exhale dive for a few months. I usually run into a strange condition when pushing it. I started with doing FRC dnf pool swimming. Every dive on my recovery breath, I feel ranging from light tingling on my fingers to light hands/legs shaking for 1-2 sec if I push it a bit. My head was still clear so at first I thought it must be the strong dive response, so I kept on doing for about 20 dive for a session. I can only do about 45m though as im not sure what would happen if I push further. Also i also feel a little numb on my tongue which may stay for an hour after dive
I tried partial exhale on free immersion to sub 30m I can feel a small version of the symptom. On full lung I ran into it on deeper dive but noticeably milder.
So I thought, great, this must be a strong dive response. I also pee quite often while diving, like 8 times in 1.5 hour.
Today was interesting, I did a dry full lung breath up in the morning, not pack, but just compress my chest and lift it up to fill the shoulder part, then i standed up with my eyes closed I felt the thing on my finger. I was like WOW dry dive response. I tried to pack and stand up, nothing happened, so I tried without pack and stand up eyes closed listening to music for one more time, the next thing I remember was I was on the ground with my hands shaking for a couple secs just like the FRC swimming but with losing a brief of conscious . I carefully tried it a few more times with eyes open and focus, it did not come.
I guess I might be a low blood pressure kinda guy. Sometimes I have light headed when standing up from long sit on a hot day.
So is this dive response or samba? I experienced a BO while diving once. It wasn't like this, as my buddy told me i surfaced, took one breath, rolled eyed and fell asleep.