Running can relieve stress, improve your overall athletic performance, promote good health and, of course, burn calories to help you lose weight. Pinning down an average number of calories burned in 20 minutes of running really isn't as simple as it seems. Your calorie burn depends on the intensity of your run -- which translates into how many miles you cover, as well as the terrain -- along with your size and age.
A General Rule: 100 Calories per Mile
A very rough rule of thumb is that, if you have an average healthy body weight, you'll burn roughly 100 calories for every mile you cover. So, if you cover 1 1/2 miles in 20 minutes, you'll burn about 150 calories. If you're a faster runner and cover 3 miles, you'll burn roughly 300 calories in the same amount of time. Of course, if you weigh more than average, you'll burn more calories. If you weigh less, you'll burn fewer calories.
More Specific Calorie Burn Rates
The larger you are and the faster you go, the more calories you burn. For example, a person who weighs 130 pounds burns 157 calories in 20 minutes of running at a 5-mile-per-hour pace; 226 calories running at a 7-mph pace; and 295 calories at a 9-mph pace. A 205-pound person going the same paces burns 248, 357 and 465 calories in 20 minutes, respectively.
A trail run burns about 177 calories in 20 minutes for a 130-pound person and 279 calories for a 205-pound person. If you're pushing a jogging stroller or a wheelchair as you run, expect to burn 157 to 248 calories in 20 minutes.
Post-Run Calorie Burn
The faster you run for the 20 minutes dictates not only how many calories you burn during the session but also how many you burn afterward. When you run at an extremely challenging pace for 20 minutes, your heart rate and breath rate remain elevated afterward -- more so than they do when you run at an easy pace. Because it takes longer for you to recover, you burn slightly more calories immediately afterward.
Use the 20 minutes of running to perform high-intensity intervals to better induce fat loss and post-exercise calorie expenditure. For example, you could warm up for five minutes and then alternate hard one-minute runs with easy one-minute runs five times for 10 minutes and then cool down. This is known as high-intensity interval training, and how many calories it burns depends on your personal profile. As pointed out in a paper published in a 2011 issue of the Journal of Obesity, it better induces fat loss because of how it affects muscle fat oxidation and blood sugar levels.
Walking Vs. Running
Running requires your feet to leave the ground with each step. Walking uses far less energy because both feet never lose contact with the ground at the same time. Calorie burn rates reflect this difference in effort. Covering a mile burned about 105 calories per mile when running at a 6.3-mph pace for the average man, but only 52 calories when covering a mile at a 3-mph pace, according to research published in a 2004 issue of Medicine and Science in Sports and Medicine.
Running's intensity increases the impact it puts on your body. Taking on too much too soon, or running when you have joint problems or a lot of weight to lose, might cause problems. As long as you follow an appropriate program, however, running is perfectly safe. Talk to your doctor if you have concerns, and consult a professional for help with a starter running schedule.