I have problems with my muscles so less effort is required if I'm kneeling than crouching but it's just something I've always done and find it more comfortable. I have a tendancy to fall over when I'm crouching lol and that's before a drink tee hee hee!
------------- If you have a problem stressing you, sort it. If you can't, there's no point worrying about it coz it won't make a blind bit of difference!!!! Jules