Q: "How many calories do I burn running for 30 minutes at an average grade of three percent? Does 500-600 calories sound realistic?"— Anne D., Eldersburg, Md.
A: That depends on how fast you were running and how hard you were working.
A calorie is a measure of energy and the amount of energy you exert while participating in an activity is measured by the amount of calories burned. Your body is constantly burning calories, but in order to maintain your body weight, you must burn as many calories as you consume. Losing one pound of weight requires burning 3500 calories.
According to popsugar.com, a 130-pound woman would have to run at a pace of six minutes per mile, or 10 miles per hour, to burn 446 calories in 30 minutes while running on a flat surface.
A study in the Journal of Sports Sciences reported that "running on a treadmill at a one percent grade most accurately reflects the energy expenditure experienced from an outdoor run. This means that running outdoors at about 6 mph, or indoors on a treadmill at 6 mph at an incline of 1 percent, will burn about 295 calories in 30 minutes for a 130-pound person."
The more you raise the incline on the treadmill, the harder your workout becomes and the more calories you burn. Same goes for an outdoor run on hills or a steady incline. Livestrong.com notes that hill training "effectively improves your running strength, efficiency, power and aerobic conditioning" and burns more calories than running on a flat surface.
A quick Internet search will turn up multiple websites that allow you to calculate the number of calories burned based on the type of exercise performed in a given amount of time.
For more accurate results, I rely on a GPS watch that calculates distance, pace, time, miles and calories burned based on my personal weight, height and gender.