Last updated: Apr 01, 2008
Your to-do list may expand during the holidays, but your butt and thighs dont have to, thanks to these 20-minute interval workouts. Created by top coaches, our quickie sessions will burn major calories and shave minutes off the time youd spend on a moderately-paced routine.


And get this: A recent study found that women boosted their fat burn in an hour of cycling by nearly 40 percent after just two weeks of interval training. Plus, new guidelines from the American College of Sports Medicine say three weekly 20-minute bouts of vigorous exercise (like intervals) provide all the cardio you need to keep your heart healthy.