My answer is of course kettlebells. And I agree on the looking up of pavel's work. I just wrote an article on the difference between
kettlebells and traditional weight lifting. I've also previously written articles on the science behind
interval training vs. long slow cardio and about my own
kettlebell workouts which last approx. 12 minutes. You can see my own
personal results (photos) that I've been getting.
Hope that provides some helpful information.
Stephen