You don't have to run every day or for an hour or more each time to get heart-healthy exercise that will help you lose weight. Thirty-, 20- and even 10-minute runs can help you achieve healthful workouts, with longer runs and higher speeds burning more calories and building more cardiovascular capacity and muscular endurance.
American Heart Association Guidelines
How long you should run depends on your fitness goals and the speed at which you run. If you aren't ready to try a full run, walk at a brisk pace, or at a moderate intensity, for 150 minutes per week, recommends the American Heart Association. If you can raise that to a jog or run, aim for 75 minutes per week. If you can't sustain a run for more than a few minutes, try alternating walking and running to help you build stamina and endurance. The American Heart Association notes that two or three 10- or 15-minute workouts each day can provide the benefits of a single 30-minute workout.
The speed at which you run is the primary factor in determining how many calories you'll burn. Running a 12-minute mile, or at roughly 5 mph, a 155-pound person will burn almost 300 calories in 30 minutes, according to the Harvard School of Public Health. Raising that to 5.2 mph, or an 11.5 mph speed, she'll burn 335 calories. Running 6-, 7-, 8-, 9- or 10-minute miles for 30 minutes, she'll burn 614, 537, 456, 409 and 372 calories, respectively.
Increasing Your Benefits
Running up hills provides resistance against your muscles, especially your calves, hamstring and buttocks, increasing your calorie burn. Running down hills will work your quads as they try to brake you. Running down steep hills will bring gravity into play, helping you run faster than you can by yourself -- a training benefit if you play sports. If you can hold dumbbells while you run, you can work on upper-body strength and burn more calories. Be careful that you don't fatigue your arms and then get stuck with dumbbells you can't carry after your blocks from your home.
A Safe Workout
Don't start running at full speed with no warmup. Give your heart, lungs and muscles a chance to coordinate their efforts. Start with a light jog for one minute, slowly raising your speed every 30 seconds until you reach the speed you will maintain for the duration of your run. When you're ready to finish your run, slow down for several minutes, letting your breathing get back to normal and your heart gradually reduce its beats per minute. Stretch your muscles by holding them for 20 seconds or longer when you're finished. Don't static stretch before you run because this will temporarily desensitize them and decrease your performance. Running requires you to shorten your muscles, while static stretching lengthens them.