Slightly tremor when meditating heavily?

[black1ce94]

Whenever I meditate heavily and am really concentrated I slightly tremor (almost always my head), a sort of shake but not really a shake, it's like I can't help it.
I'm not aware of having opened any chakra so it's strange.
I'm usually good at manipulating energy.
When I meditate easily and clean my aura, absorb energy, it does not necessarily happen.
I also get a feeling like i'm being lifted inside, something not physically from the exterior.
I've read the page on JOS about how the Vatican Assassins cand hover or float when meditating.
I don't have that effect no matter how concentrated I am.
Can anyone explain?

 

[black1ce94]

Alright, those are interesting and logical point of views.
Thanks