If you're watching CBC, I think you're referring to the comment that Hrudley made about Halak. That burning sensation you get after running super-fast back and forth constantly, stopping and going...that's lactic acid. It's a by-product from the muscles when they've got to produce energy quickly, and sometimes it stays in your limbs (arms, legs, etc...) long after the event. You feel this ache and you feel really tired, I'm sure you know. Usually hockey teams make you ride on a bike after a game (Ottawa started this years ago) to get rid of the lactic acid accumulation, since light aerobic activity actually uses the lactic acid to help make energy. You essentially burn off the lactic acid so you don't get that fatigue and pain.
Hrudley was saying how Halak's performance was affected by this accumulation since it was 48 hours after Game 7 against the Capitals. He keeps moving back and forth in the crease, normally, but in Game 1 against the Penguins, he couldn't be fucked to move so much since he was in a bit of pain/experiencing fatigue. Maybe he didn't ride on a bike or something because they were celebrating? Boh.