Im going to say one thing and one thing only, the Tabatha Method.
four minutes, does that really count as cardio? Could I do this right after my normal workout?[/quote]
The actual study by Dr. Tabata showed that it improved aerobic capacity by 14% over low/moderate cardio and increased anaerobic capacity by an unprecedented 29%. It also burned 9x more subcutaneous fat. It’s been a while since I read the study, but I think those numbers are accurate.
I do squat/curls, where I squat with two dumbells and on the way up, do a curl. There are endless variations, like the ones that Dan Johns mentioned. My heart rate gets up to 180+ when I am done. I have recently upped the sets to 10, instead of 8. I found that when you can’t go beyond 80-85% of your average, it’s time to stop.