At first I was really tired. I had the kyBoot shoes on for 2–3 hours and then felt tired. My legs grew heavy. I don't have that feeling any more. You have to get used to it. You're using different muscles than in normal shoes, that's my interpretation, anyway.
It definitely gives you a more upright posture and it makes you more flexible too. You stand on a soft sole. I like the fact that when I stand, I’m not rigid and motionless, I am moving around.