I created an account just so I can comment on this. I have been able to do this same thing for as long as I can remember. I'm 24 now.
It is a peculiar sensation that I can summon throughout my entire body on command. The other people in this thread seem to have described the same sensation. Many comments on here seem very legitimate. This has to be something that some people have the ability to do, and some don't. Like being able to wiggle your ears haha. I wonder if there's any benefit to it.
Note: I can usually only make this feeling happen when I am sitting, laying down, or standing still. It takes a lot more focus to be able to do it when I'm moving.
To me, it feels like this: There is an immediate tingling sensation that rushes through my body. It usually starts in my legs, then works it's way up to my diaphram. All within a fraction of a second. It's very quick. After about 1 second of holding it (yes, I can hold it), my muscles begin to feel like they are flexing/being activated, but none of my muscles are ever flexing or contorting in any way. After about 2-3 seconds, I experience muscle jerks/twitches in my legs and diaphragm. When I do it repeatedly over and over, the muscular jolts/jerks happen for frequently. After I stop, there is a feeling of exhaustion in my legs and core, as if I had just been flexing them. But NONE of my muscles ever flex when I do this. It's strange. It may increase my heart rate at some times. I can hold the sensation for around 4-6 seconds at a time until I release it. The more I do it, the more exhausted I feel. The exhaustion is most common in my legs and chest.
I'm a car nerd, so let me phrase it like this: It feels like I am revving up my nervous system like a car that is in park or neutral. I can make the feeling happen in short "revs", and I can also 'rev up' this tingling sensation and HOLD it there. It's exactly like flooring the gas pedal in a neutral/parked car, until the tachometer bounces back and forth off the redline with the engine screaming at it's highest RPM. That's what it feels like. Like my nervous system is screaming at the redline. But again, I can only hold it for like 4-5 seconds.
