Keep Your Indoors Workouts Interesting

Exercise machines weren't created to punish people who eat too much. That's what diets are for. But men and women spend hours, day after day, churning their arms and legs and waiting for the StairMaster or treadmill to make their bellies vanish. The result: They make it about as far as the average rat.

But your machine workout doesn't have to be a road-or row-to nowhere. "By decreasing the duration and varying the intensity of your exercise sessions, you'll get better results in less time," says Chris Carmichael, founder of Carmichael Training Systems, and coach to Lance Armstrong.

Try our guide to the five most popular exercise machines—the elliptical trainer, the rower, the stair climber, the stationary bike and the treadmill—with a high-intensity 20-minute workout geared for each. Your goals: Bust your exercise rut, and your gut, in record time. And to really turbocharge your results, follow these five steps to chisel your abs.

The knee saver (aka elliptical trainer)

Burn rate: 13 calories per minute

The benefit: Researchers at the University of Mississippi found that elliptical trainers provide the same cardiovascular benefits as treadmill running, without the impact to your joints.

So it's a perfect solution if you're a runner who wants to stay in race shape while avoiding excessive pounding to your ankles, knees and hips.

Do it right: Instead of holding onto handles, pump your arms as if you were running. It improves your balance, which will help you whether you're running 2.6 miles or 26.2. For an even greater challenge, transfer weight from heel to toe throughout the workout. And on your noncardio days, try one of these body-transforming workouts.

The 20-minute fat-burner: Try this "alternating-interval" workout. By alternating between levels of high resistance and high speed, you'll be able to work at a higher relative intensity for a longer period of time. Warm up, and then increase the machine's resistance level until you're striding at 80 percent of your full effort. After two minutes, lower the resistance to the level you used during your warmup, but increase your stride rate so that you're still exercising at 80 percent of your maximum effort. Continue alternating between a high resistance and a fast stride every two minutes until you reach a total of 20 minutes.

The total-body builder (aka rowing machine)

Burn rate:12 calories per minute

The benefit: "Rowing machines provide the best total-body workout of any cardio machine," says former U.S. Olympic rowing coach Mike Teti. That's because they require equal effort from both your lower and your upper body. A study in the European Journal of Applied Physiology found that the amount of blood your heart pumps with each beat—known as stroke volume—is greater when you're rowing than when you use a treadmill at the same intensity. Rowing uses more muscle groups, and the seated position improves your heart's efficiency, which could lead to greater gains in overall cardiovascular fitness. Discover more ways to improve your health and reinvent your body into a sleeker, fitter version of its younger self.

Do it right: On the back stroke, your knees should be almost completely straight before you bend your elbows and squeeze your shoulder blades to pull the handle to your sternum. Your back should stay in its naturally arched position during the entire movement. Got it? Now join the Million Meter Club at www.conceptII.com. Record your distance online after every rowing session and see how you rank against thousands of other club members. (Stay motivated by finishing your second million in less time.)

The 20-minute fat-burner: Try Teti's routine. It's designed to max out your muscles during each interval, while the recovery periods help increase the rate at which you burn fat. Set the rowing machine at a resistance of four. Then perform sets of 10, 15 and 20 power strokes—pulling the handle to your torso as fast and as hard as you can. Separate the power strokes with 60 seconds of easy rowing at about 50 percent of your maximum effort. Repeat the cycle until you've rowed for 20 minutes.

The mood lifter (aka stationary bike)

Burn rate: 15 calories per minute

The benefit: Researchers at the University of Northern Arizona found that cycling on a stationary bike for as little as 10 minutes reduced fatigue and negative moods, while improving energy levels. The stationary bike is also the perfect vehicle to prevent chunky guys from hurting themselves while they lose the chunks. "Since it's not a load-bearing exercise, it's easier on the knees and ankles for men who have a hard time running on a treadmill," says Kate Heelan, Ph.D., an exercise researcher at the University of Nebraska at Kearney.

Do it right: Many cyclists develop lower-back pain because of their semifetal posture. "Stand up every five minutes and pedal as if you were climbing a hill for 60 seconds," says personal trainer Robert Morea, C.S.C.S. "It'll take the pressure off your lower back, force you to use different muscles, and help break up the monotony of your workout." Another way to break up the boredom: Listen to music. Researchers at Springfield College in Massachusetts found that men rode 29 percent longer when they listened to music than when they had the headphones off. (The music's not to distract you, it's to motivate you.) Check out 20 other ways to keep your workout exciting so you stick to it.

The 20-minute fat-burner: Try this workout from Chris Carmichael, who coaxed you-know-who to four (out of his seven) Tour de France victories. It varies your sprints to challenge your cardiovascular system and muscles in different ways. Following your warmup, start cycling at an intensity that's about 95 percent of your full effort for 90 seconds, followed by a 90-second recovery interval at about 40 percent of your full effort. Then, using the same intensities, perform 60-second and 30-second intervals. After the final 30-second recovery period, cycle at 70 percent of your full effort for four minutes, then repeat the entire set of intervals.

The energy guzzler (aka treadmill)

Burn rate: 18 calories per minute

The benefit: A study in Medicine and Science in Sports and Exercise found that the treadmill burns calories at the highest rate of any exercise machine.

Do it right: If you want to better mimic road running, raise the incline of the treadmill to 1 percent before starting. Researchers in England found that that's the degree of treadmill elevation that most closely approximates outdoor running. Just be sure you're using proper running form to maximize your fat burn.

The 20-minute fat-burner: Try this "up-the-incline" interval method. The ever-increasing incline will build your leg strength and prepare you for the toughest road courses around, while helping you shed fat fast. Pick a speed that's about two minutes per mile slower than your average outdoor pace. Run at that speed for two minutes at an incline of 1 percent. Then raise the incline to 4 percent for another two minutes. Continue to raise the elevation of the treadmill by 2 percent every two minutes until you reach a 10 percent grade. Then step it back down 1 percent at a time until you complete your 20 minutes.

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