Most people turn to treadmill workouts to torch calories. You jump on, raise the speed and zone out for somewhere between 20 and 40 minutes. There are a few ways to annihilate calories on the treadmill in less time. Try each of these workouts on alternate days, and you'll see results in no time. Speed changes and incline increases will make you tired quicker -- a sure sign that you're working harder, and not just burning calories, increasing your fat burn as well.
With these (and all other) workouts, spend 5 minutes on your warm up at a low intensity. This will get your blood pumping to all of your muscles. Complete your warm-up and all "resting" levels at an incline of 1.0. Treadmills often naturally slope downward, so running at a flat incline of 0.0 is actually downhill -- and easier. All workouts use the manual or quickstart setting
This challenging workout maintains a steady speed for the duration, but ups the intensity by incorporating 1 minute incline bursts to really target glutes and hamstrings. Warm up, then begin your run at a speed that you can sustain for the duration of your workout. Aim for about a 6.0 speed if you are just starting, or shoot for 6.5-6.8 if you use the treadmill often. Run for 1 and 1/2 minutes at this pace, then bring on the hills! Raise the incline to 5.0 for the first hill, and run for 1 minute. Drop the incline back to 1.0 and run at your regular pace for 1 and 1/2 minutes. Repeat the high and low intervals for the remainder of your workout, but raise the incline by 1 entire percent each time. You will likely want to top out at a 7.0 or 8.0 incline, so continue to raise your incline to that percent and repeat until your cool down.
Complete your workout like as you did with the hill workout, but instead of raising the incline, raise the speed for 1 minute after your 1 and 1/2 minute low interval. Your sprint section at a fast speed, say 7.2 - 8.5, depending on your ability, for each interval.
3. Pyramid Sprints
This sprint incorporates both of the above workouts, but drops to a brisk walking speed for the low interval. Build both elements for 1 minute per interval, beginning at 6.0 for both speed and incline. Lower the duration of your low interval by dropping it to 1 minute at a walking pace. On the second (and subsequent) intervals, raise the speed and incline by 0.5% each time until you reach 8.5. Then, bring down the speed and incline, decreasing it by .5 each time for the remainder of your workout.
4. Big Burner
Cover up the time log for this workout and hunker down for a tough one! This is probably the most difficult sprint workout that there is, so, spend a few weeks on the other sprint workouts, and make this your goal for week four. Warm up, then raise the speed and the incline to at least 8.0 at every interval, though you could likely start at a higher level. This should be an all out sprint, and should last for about 1 minute. However, don't pay attention to the clock-- listen to your body and push on for as long as you can. You should feel your thighs burning before you consider stopping! Toward the end, your sprint may be shorter than the beginning sprints were. Then, drop the speed and incline and walk as long as it takes you to mostly recover, where you could maintain a conversation. Then, repeat the sprint and recovery as many times as you can.
You may only be able to complete 10 minutes at first, but eventually, you'll work up to 20 minutes as your endurance builds and you get stronger.