The following is an excerpt from the 8-week exercise plan featured in the book Tone Every Inch: The Fastest Way to Sculpt Your Belly, Butt and Thighs.
By Natalie Gingerich Mackenzie
Not all cardio is created equal. The cornerstone of the cardio in this plan is all about adding intensity. If you already do some cardio, but the scale isn't budging, intensity may be the missing ingredient. For most of us, if we go out for a walk, or even a run, our bodies naturally find their most efficient pace. Well, let me tell you, efficiency is good for a lot of things — getting work done, cleaning the house, even finishing your workout — but while you're exercising, the last thing you want is for your body to be too efficient. That's because efficiency for your body means conserving calories and fat — hardly the goal if you're trying to lose weight!
Take two workouts: One involves 40 minutes of biking, the other just 20 minutes. Which workout do you think would yield more weight loss? Australian researchers did just that test with two groups of women. To level the playing field, they added a twist: Despite the different workout durations, both groups of women pedaled off the same number of calories (about 200) using stationary bikes.
How is that possible? The 20-minute group had to pick up the intensity in order to burn more calories in less time, so they alternated short 8-second sprints with slightly longer 12-second recovery bouts of slowed pedaling. The 40-minute group of women biked at a steady pace for twice as long. You might be thinking that identical calories burned means they must have lost the same amount of weight. And that alone would be a fairly impressive finding — that you can lose the same amount of weight in half the time just by adding some short sprints.
But the real findings were even more impressive than that. The speedsters didn't just match the weight lost by their peers, they exceeded it by six times. The numbers weren't huge (3 pounds for the sprint group versus ½ pound for the steady cyclists), but they're all the more impressive given the fact that the women in the study were in their twenties and already pretty lean at the start.
But the benefits aren't just for the young and already fit. In another study, this one conducted here in the United States at the University of Virginia in Charlottesville, researchers had two groups of overweight, middle-aged women start walking far enough to burn 400 calories a day, 5 days a week. One group walked at a steady moderate pace (slightly faster than 18 minutes per mile), whereas the second group walked the same 5 days, but on 3 of the days they pushed the pace to about 16 minutes per mile. So they walked off the exact same number of calories but at slightly different walking speeds. How do you think the results stacked up?
Well, the power walkers won again. They lost 66 percent more total weight, including more than twice as much pure fat. One possible explanation is that maintaining speedier paces requires more muscle power, which may help to preserve lean muscle tissue. That means weight loss is focused on fat, not muscle, which you know by now is uber-important to keeping your metabolism buzzing along briskly. Of that fat, the high intensity group lost more than three times as much subcutaneous fat (the kind you can pinch) and more than twice as much dangerous fat (the kind that surrounds the organs and increases your disease risk). And perhaps more impressively, they lost an amazing five times the abdominal fat as the slowgoers did. All from shaving just a couple minutes per mile off their walking pace!
One of the most popular ways to add intensity is with a technique called intervals — the technical term for what the Australian exercisers did in the first study I talk about earlier. The gist: You push yourself harder than you normally would for a brief period, then slow down to catch your breath (and let your muscles at least partially refuel their energy stores) before you go again.
Interval workouts are more challenging than steady-paced moderate workouts, but they give you a lot more bang for your buck. And they work fast. Studies have shown that picking up the intensity for short spurts may improve your fitness (meaning your heart and lungs' ability to pump oxygen and fuel your muscles) in as little as 2 weeks. You could get similar benefits with long, slow endurance training — it would just take you a heck of a lot longer. And improved fitness isn't just good for competitive athletes. It means you feel more energized doing your workouts and in your everyday life, so you're less likely to feel winded carrying groceries in from the car or rushing up a set of stairs.
Another benefit you'll see in as little as 2 weeks: a jump start to your body's fat burning engines. In one study led by Martin Gibala, PhD, chair of the department of kinesiology at McMaster University in Hamilton, Ontario, who specializes in studying the metabolic changes spurred by interval workouts, researchers found that doing interval training increased the body's capacity to spin stored fat into usable energy by 36 percent in just 14 days. That boost is at least in part due to an increase in the number of mitochondria (the fancy term for powerhouses in your muscles that use oxygen to burn calories). In fact, Dr. Gibala's most recent research reveals that this increase in mitochondria action happens after a single interval workout. How's that for instant gratification!
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