That's crap, your knees are not designed to move like that - this is bad technique that has been passed down over decades. You shouldn't push your knees out or in when in side stance, you should just 'sit down' in the stance with your knees in a neutral position. If you try to force your knees out or in, you'll put unnecessary strain on them. It's misinformation like this that results in 'shotokan knee' later in life. Whether you put 'tension' towards the inside or outside of the stance is a different matter altogether, but your knees themselves shouldn't be forced outside their normal range of movement (straight hinge joint). Decide yourself what value you place on your knees. Good: http://www.ozwebart.com.au/kua/kihon/Kiba-Dachi.GIF Bad: http://bushido.karateclub.free.fr/Postures/kiba.jpg See the difference?