Well, sticking feathers up your butt won't make you a chicken, probably won't help your posture either.
Isometrics, and those shoes are awesome, all bitches need to wear them all the fucking time.
http://www.planetshoes.com/mmplanet/...rs/shapeup.jpg
I ran around in a pair of these in a store once:
http://www.strength-shoes.com/images...-shoes%202.jpg
You feel that shit FAST, the shape ups are a lot lower impact, but the same concept. Makes you tense up all the little core muscle groups, keeps you aware of the major groups, it's kinda like walking up stairs/up hill all day.