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, with a high-intensity 20-minute workout geared for each. Your goals: Bust your exercise rut, and your gut, in record time.
The Knee Saver
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 on your joints. So they're a perfect solution if you're a runner who wants to stay in race shape without excessive pounding to your ankles, knees and hips.
Do it right: "Instead of holding on to handles, pump your arms as if you were running," says Kerri O'Brien, C.S.C.S., a trainer in Phoenix. It improves your balance, which will help you whether you're running 2.6 miles or 26.2.
The 20-minute fat-burner: Try this "alternating interval" fat burning exercise workout from Lance Watson, a coach of Canada's Olympic triathlon team. By alternating between levels of high resistance and those of high speed, you'll be able to work at a higher relative intensity for a longer time. Warm up, then increase the machine's resistance level until you're striding at 80 percent of your full effort. After 2 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 full effort. Continue alternating between a high resistance and a fast stride every 2 minutes for a total of 20 minutes.
Rowing Machine
The Total-Body Builder
Burn rate: 11 calories per minute
The benefit: "Rowing machines provide the best total-body workout of any cardio machine," says U.S. Olympic rowing coach Mike Teti. This is because they require equal effort from both your lower and your upper body, which could lead to greater gains in overall cardiovascular fitness.
Do it right: On the back stroke, your knees should be almost completely straight before you squeeze your shoulder blades together and pull the handle to your sternum. Your back should stay in its naturally arched position during the entire movement. Got it? Now sign up with the Million Meter Club at www.conceptII.com. Record your distance online after every rowing session and see how you rank against more than 3,700 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 efficiency of this fat burning exercise routine. 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 full effort. Repeat the cycle until you've rowed for 20 minutes.
Stairclimber
The Health Master
Burn rate: 12 calories per minute
The benefit: Yale researchers found that men with insulin resistance—a risk factor for diabetes and heart disease—who exercised on a stairclimber for 15 minutes 4 days a week improved their sensitivity to insulin by 43 percent in just 6 weeks.
Do it right: The obvious: "Leaning on the handles can cut your caloric expenditure by 20 percent or more," warns Mike Merk, C.S.C.S., director of the YMCA of Greater Cleveland. So, for a better calorie burn, pump your arms as if you were walking or running briskly. Or you can just turn around. A study in the Archives of Physical Medicine and Rehabilitation found that the retrograde version—facing away from the console—burned more calories than the traditional method.
The 20-minute fat-burner: Try this "escalating intensity" workout from Edmund Burke, Ph.D., author of The Complete Home Fitness Handbook. After you warm up, increase the resistance level by one unit while maintaining a pace of 60 to 80 steps per minute for 2 minutes. Then increase the resistance by one unit every 2 minutes until you reach your 20-minute goal. You'll gradually work harder as your workout progresses, so you'll be maxed out at the end of the session—which trains your body to finish hard.
Stationary Bike
The Mood Lifter
Burn rate: 14 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 as they lose the chunks. That's because cycling is not a load-bearing exercise, 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 5 minutes and pedal as if you were climbing a hill for 60 seconds," says Robert Morea, C.S.C.S., a trainer in New York City. "It'll take the pressure off your lower back, force you to use different muscles and break up the monotony of your workout."
The 20-minute fat-burner: Try this workout from Carmichael. 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 4 minutes, then repeat the entire set of intervals.
Treadmill
The Energy Guzzler
Burn rate: 17 calories per minute
The benefit: A 2001 study in Medicine and Science in Sports and Exercise determined that the treadmill burns calories at the highest rate of any exercise machine.
Do it right: If you want to mimic road running, raise the incline of the treadmill to 1 percent before starting your run. Researchers in England found that that's the degree of treadmill elevation that most closely approximates outdoor running.
The 20-minute fat-burner: Try this "up the incline" interval method from Liz Neporent, coauthor of Fitness for Dummies. It'll 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 2 minutes per mile slower than your average outdoor pace. Run at that speed for 2 minutes at an incline of 1 percent. Then raise the incline to 4 percent for another 2 minutes. Continue to raise the elevation of the treadmill by 2 percent every 2 minutes until you reach a 10 percent grade. Then step it back down 1 percent at a time—in 2-minute intervals—until you complete your 20 minutes.
Thanks to Matt Fitzgerald / Men's Health
