That's a great post there Ice. I was one of the ones who was doing Tabata intervals on the heavy bag (8 rounds of 20 sec work/10 sec rest). And for some reason I didnt see too much improvement.

A guy who I have alot of respect for at my gym told me not to worry about intervals until I could run 2 miles under 12 minutes. Which I can't. And now I know why!