Setting your treadmill to an incline or running a hilly route definitely burns more calories than doing the same workout on a flat road. Any climb you can do may boost your total burn by as much as 50 percent. Whether you're walking or running, you'll feel the effects of a more intense workout and build greater leg strength.
Why Hills are Harder
When you run or walk uphill, your body weight acts a resistance. Your muscles, in turn, must work harder to propel you forward. All of your leg muscles, from the calves to the glutes, recruit a greater number of fibers to do the extra work. More muscle fibers working mean more calories burned.
The degree of incline you're traveling up and the speed you're going determine your calorie burn. Note that larger people burn a greater total number of calories than smaller people; these calculations are based on a 150-pound person.
If you walk on a road with no incline at a pace of 4 mph, you'll burn about 8.5 calories per minute. An incline of 5 percent raises the burn to 10.2 calories per minute. If you go up a 10 percent incline at 4 mph, you burn about 11.8 calories per minute. Increase your speed to a pace of 6 mph and burn 12.2 calories per minute on a flat surface; 14.7 calories per minute on a 5 percent incline; and 17.2 calories per minute at 10 percent incline. Raise your speed to 8.5 mph -- roughly equivalent to a 7-minute mile -- and your calorie burn accelerates even more. With no incline, you burn about 17 calories per minute; at 5 percent, 20.5 calories per minute; and at 10 percent, 24 calories per minute.
Hills do more for your body than burn a greater number of calories. Because your leg muscles have to work harder to get you uphill, you build greater running or walking strength. A flat or downhill route aggravates some running weaknesses, including shin splints and sore knees; running uphill isn't as stressful on these areas. Running uphill helps you build better running economy, too. Hills train you to keep your stride short and quick and to use your arms in a pumping manner to help you move forward.
Adding Hills to Your Workout
Gradually work up to hiking or running hills. Start with modest inclines of 2 to 4 percent and increase the incline from there. Hills also offer an opportunity for interval training. Warm up at an easy pace for about 5 minutes and then add in 30- to 90-second bursts of speed walking or running uphill. Between the intervals, work easily on a level surface or downhill for at least as long as the hard interval took to complete. Do between 5 and 10 total intervals for a solid workout that burns significant calories.