Ignore this dumbass >>116139943
It's about pure speed. By unshackling his body from his mind's limitations, his body can act faster than he could have made it go just thinking about it. The pure impulse of speed is what creates that 'heat' they kept talking about, and something going faster also has more energy behind it.
The real problem is, it seems, your body truly going all out is tiring. Go figure.