Has anyone ever heard of these contraptions??? They are called Kangoos, they are "shoes" you can run in (I've seen youtube videos of actual cardio classes that use these too) but they are suppose to add resistance to your running, even though there is an extra spring in your step. I hear it's quite the workout, and I really do actually want to try these guys...but I must say I am a little shy to go out in these guys in public lol. I also want to know if they are worth the investment...they are kind of a pretty penny but I am definately all for trying something new. I wish I was a bit more of a free spirit and didn't care...but I could see myself thinking "wtf" if someone ran by me with these babies on lol. Anyone ever tried them? I would like to hear your input if you have or even your thougths on them.