The benefits of the treadmill

The lowliest of exercise beats skiing, rowing, stair-climbing and cycling machines in a study.

It might be worth the exercise to drag that old treadmill of yours back in from the garage. A study of six popular stationary exercise machines Americans use to torture themselves into shape has reached a startling conclusion: The treadmill, a contraption synonymous with drudgery, burns more calories than a stair-climber, cross-country skiing simulator, rowing machine, and two different cycling machines.

The findings go against much health-club wisdom, which tends to hold that the more elaborate the exercise machine, the more energy it demands. Conducted at the Medical College of Wisconsin in Milwaukee, the study of 13 healthy men and women is the first to compare energy burned by people using those machines under controlled laboratory conditions at set levels of exercise intensity.

For workouts that the researchers described as “some what hard,” people on the treadmill burned about 40 percent more calories per hour (705) than they did on the least-calorie intensive machine, the stationary bicycle (498). In between were the stair-stepping (627) and rowing machines (606), the cross-country simulator (595), and the airdyne cycling machine (509).

The study appears in today’s Journal of the American Medical Association. Manufacturers of exercise machines donated equipment for the study but no money, researchers said. Generally, the treadmill’s supremacy in this study offers some encouragement to those who jog or stroll without the benefit of any machine at all. “It’s fair to think that walking outdoors or on an indoor track is going to be a very good mode of exercise,” said Dr. Martin Hoffman, a physical medicine and rehabilitation specialist who directed the study.

The subjects in the Wisconsin study were eight men, averaging 35 years old, and five women, averaging 27. Their initial fitness levels ranged from virtually inactive to amateur athletes. Twice a week for four weeks the subjects worked out on each machine for 15 minutes, learning to use it at different exertion levels.

The subjects, in effect, taught themselves to exercise at three different intensity levels, on all six machines: “fairly light,” “some what hard,” and “hard”. Those levels corresponded to a standardized scale used by exercise physiologists, the so-called rating of perceived exertion. The “somewhat hard” level fell within the American College of Sports Medicine recommendation that healthy people work out at 60 percent to 90 percent of maximal heart rate to optimize cardiovascular fitness.

Once the subjects were habituated to the different exercises, the researchers tested them as they worked out, measuring the oxygen they consumed, which directly correlates with the calories they burned.

The researchers cannot entirely explain why treadmill workouts burned more energy than the other workouts at the three exercise intensity levels tested. One factor, Hoffman said, is that running involves many large muscles, from shoulder to toe, working through a wide range of motion. In contrast, rowing doesn’t much involve the large leg muscles, while a stationary bicycle does little for the waist up.

The researchers cautioned that the findings don’t necessarily apply to the elderly or to people who are woefully out of shape. And the study wasn’t big enough, they added, to tell if men and women respond differently to the exercise demands.

Moreover, Hoffman cautioned that the calories burned on a given exercise machine depend on a number of variables, including one’s size and fitness. In terms of calorie saving, though, even the seemingly small differences among the various machines can add up.

A half-hour treadmill workout might burn just 40 more calories than a comparable workout on a stair-stepper. But that small edge, multiplied three times a week, could lead to several extra lost pounds over a year, Hoffman said. “It sounds really small but it can really be important,” Hoffman said.

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