On a treadmill, you can run "uphill" for seconds, minutes or even hours.
Exercising on a treadmill offers many advantages over outdoor workouts. For instance, you're guaranteed good weather and a soft surface, and most treadmills let you track data such as heart rate and caloric expenditure. Perhaps best of all, the machine can calculate and display the incline -- expressed in terms of its percent grade -- of the treadmill belt; because you can set both the incline and your speed exactly, you can fine-tune your "hill" workouts with great precision.
Percent Grade Defined
Percent grade, which is what your treadmill's console displays, is determined by the incline, or the value of the angle between the floor and the treadmill belt. This angle can range from 0 to 90 degrees. The percent grade starts at zero when the belt is flat, is 100 at an incline of 45 degrees, and approaches infinity as the incline approaches 90 degrees. In geometric terms, the percent grade is the tangent of the incline angle.
If you're going to use your treadmill's incline feature, it's handy to know what a given grade translates to in the world of real topographical features, be they human-made or nature's own constructs. U.S. Interstate Highways have a maximum allowable grade of 6 percent, with some exceptions made for roads that cross unusually mountainous terrain. The 7.6-mile Mount Washington Road Race boasts an average grade of almost 12 percent.
Calculating the Slope
Using a tape measure or ruler, you can do manually what the treadmill does via its internal mechanism: measure the "rise," that is, the vertical height of the belt from the horizontal, and the "run," which is is the distance along the floor from the back of the belt to the point directly underneath the front of the inclined belt. To calculate the percent grade, simply divide the rise by the run and multiply by 100. For example, if you raise the belt so that the front is 0.5 feet higher than the back, and the front and the back are separated by 8 feet along the floor, then the percent grade is (0.5/8) * 100 = 6.25 percent.
Unlike most real hills, an inclined treadmill offers a uniform slope of your exact choosing, and furthermore you can make the "hill" as long or as short as you like. Exercise physiologist and Runner's World columnist Greg McMillan suggests doing a workout he calls "Six/Sevens." This includes six to 10 sets of the following: 90 seconds at a 6-percent grade at estimated marathon pace, a 60-second flat recovery jog, 60 seconds at 7-percent grade at estimated marathon pace, and and a two-minute flat recovery jog. You can also do "pyramid" workouts that involve one-minute bursts at a steady pace on grades ranging from 4 percent to 8 percent and interspersed with two- to three-minute recovery jogs. (Ref. 4)