00:07:16.770 Your knees are at 90 diploma angles. 00:07:16.770 Your knees are at ninety degree angles. The core is used all through the day, whether or not you're cooking a meal, walking down the Subway stairs, sitting down, standing up, and so forth. It is used in simple, on a regular basis movements. The weaker your core muscles, the extra probably you might be to slouch or hunch when sitting, standing or strolling.