something we already know,but never gave it a thought, but when you put it like that, right in the face.. Boy, am I goin` go change my workout, at least for 2 weeks, if there are fine results, I`ll let you know.
tnx for sharing this.

Thanks for those. Just did hill sprints this morning  - certainly not good at them! I'm also looking forward to a holiday over christmas where I will be right next to the beach everyday and can try some sand and water workouts - that's sure to push my limits!

I believe Tony Horton incorporated that principle into the P90X2 workouts by adding an element of balance to classic weight training moves (i.e. preacher curl in warrior 3 stance or pushups on 4 medicine balls)