The Women's Health Big Book of 15-Minute Workouts: A Leaner, Sexier, Healthier You--In 15 Minutes a Day! Read Free

training is also the ticket for better health. Researchers in Norway reported that interval training was far more effective for reducing blood pressure, controlling blood sugar, and improving cholesterol than traditional one-speed workouts.
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    Percent more calories you burn after doing back-to-back sets of two different exercises (supersets) compared with sets that let you rest between moves, according to the Journal of Strength and Conditioning Research .
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    When you stop and think about how your body works, all of this seemingly counterintuitive science suddenly makes a lot of sense. Our bodies are built to adapt to the work we demand of them. When you get up and go out the door for a leisurely jog, you’re asking your slow-twitch (endurance) muscle fibers to wake up and get to work, but all those fast-twitch (speed and power) muscle fibers go largely untapped. Over time, many of the neurons that once served fast-twitch fibers will get rewired to serve their slower counterparts. Others will die off. Turning up the intensity of your workouts not only gives you firmer, more shapely muscles by tapping in to all those unused fibers (think Dara Torres), but also fast-tracks your fitness gains, says HIIT training researcher Martin Gibala, PhD, professor of kinesiology at McMaster University. “High-intensity exercise kind of shocks your system. Your body thinks, ‘She’s making me do some really hard work,’ so it increases your total exercise capacity—your ability to use oxygen and burn fat—in a fraction of the time than if you’d exercised less intensely,” he says. In fact, according to neuromuscular researcher Christopher Knight, PhD, of the University of Delaware, there’s an almost immediate effect when you tap into your fast-twitch fibers with strength training and/or high-speed intervals. “We’ve found that you can increase your fast-twitch firing rates after just 1 week of training,” he says.
    That’s the genius of the Superfast Workout Plan. You combine 15-minute resistance-training workouts with 15-minute HIIT workouts to lose the most weight. Scientists already know that combining cardio and resistance training works faster and better than either alone. When Pennsylvania State University researchers put three groups of overweight people on a diet and then had them do cardio, resistance training and cardio, or no exercise at all, they found that though each group lost roughly 21 pounds, the lifters dropped 6 more pounds, or 40 percent more, of fat (which, remember, takes up more room than muscle and doesn’t look nearly as nice). That’s right, nearly every ounce they lost was in the form of fat, while the other two groups dropped precious metabolism-revving muscle as well. Now you get to reap all these rewards in a fraction of the time you ever thought possible.
    But the 15-minute secret doesn’t just give you the shortest, most effective workout on the planet. You’ll also:
    1. Trade Fat for Muscle
    Whether you want to be bikini ready or are just looking to boost a sagging bottom, 15 minutes is all it takes. Premiere strength-training researcher Wayne Westcott, PhD, CSCS, instructor in the exercise science department at Quincy College in Massachusetts, confirms that when you choose your exercises wisely, a handful of moves—just four in some cases—is all you need to change your body composition. “Navy research shows you can get tremendous overall improvement—losing 4 pounds of fat and adding 2 pounds of muscle in 8 weeks—by doing just four exercises that work every major muscle,” he says. The four moves are the squat, chest press, row, and abs curl. Do them during several rounds of a 15-minute workout for total body transformation.
    2. Burn More Calories
    Even better, the calorie-burning benefits of even the shortest strength-training bout keep coming long after you’ve left the gym. In a study from Southern Illinois University, researchers found that when