The Treadmill Stepper

Profile: You have a safe, comfortable place to walk, making it easy to fit in workouts — no bad-weather excuses.

Payoff: If you use the machine’s preset programs, incline settings, and a heart-rate monitor, you’re probably pushing yourself to get a good workout. “Unlike walking outdoors, where what goes up must come down, on the treadmill you can walk uphill the whole way,” says Thomas Allison, Ph.D., a heart-disease consultant at the Mayo Clinic in Rochester, Minnesota. “You can’t slow down, because you’ll fall off. It makes you keep up.”

Next Steps: Break up your treadmill routine, since too much consistency can decrease the payoff. Research shows that your body can adapt to the demands of any workout after six to eight weeks, says Fenton, who is also a five-time member of the U.S. race-walking team. Change what you do every two months — mixing in other workouts or varying your program on the machine by, say, going from a steady 3.5-mile-per-hour session to alternating fast and slow intervals, adjusting the incline, ramping up the pace with a minute of jogging for every five minutes of walking, or slowing down the belt and doing some walking lunges.

Try taking a treadmill class at a gym. National chains like Crunch and Equinox offer challenging ones that mix some off-treadmill exercises with walking and jogging.

Tips: Watch your posture. “It’s very common to see people using poor form when walking on treadmills,” says Thompson. Gripping the rails or craning your neck to see the TV will not only slow you down but might also cause an injury. If you tend to grip, you’re probably working too hard. Choose a comfortable setting (start at three miles an hour with no incline) and keep your head up so you can breathe fully. Bend your elbows at right angles so you can pump your arms. Press off the back foot for a full stride and keep your abs firm. Check your form after every mile.