If your goal is to burn fat, interval training should be part of your workout program. Interval training is a great way to hammer out a quick workout, and it's extremely effective for transforming your physique.

By incorporating intense periods of work with short recovery segments, interval training helps you give maximum intensity while still maintaining your exercise form. The magic of high intensity interval training (or HIIT, for short) is that it keeps your body burning fat even after you leave the gym. During a HIIT workout, your body can't shuttle enough oxygen to your muscles during periods of hard work. Therefore, your muscles accumulate a “debt” of oxygen that must be repaid post-workout in order to get back to normal. The result: Your metabolism is revved for hours after you leave the gym. Trainers refer to this phenomena as excess post-exercise oxygen consumption, or EPOC. The biggest way to use it to your advantage is to regularly work short, intense bouts of exercise into your workout regimen.

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Intense circuits also stimulate muscle-building hormones like growth hormone and IGF-1. This puts your body in a perfect state to build lean mass. And in addition to the hormone response, interval training also develops the cardiovascular system. By elevating your heart rate during periods of hard work, you’ll increase your cardio ability and strengthen your heart. During the short rest intervals, you also increase your recovery capabilities—meaning you’ll be able to recover faster in future workout sessions.

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When creating interval workouts, focus on including difficult movements that challenge your entire body in a single exercise. Aim to include at least two exercises back to back before allowing your body to recover. Catch your breath in between rounds, but don’t allow yourself to recover fully before attacking the next set.

To jumpstart your routine, we’ve compiled a list of our favorite interval workouts from top trainers. Pick one or two to incorporate in your weekly routine—but be sure to include at least a day of rest between workouts, as these intervals are intense.

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* The following workouts have been approved by the certified training staff of HUMANFITPROJECT.


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Read more: Get the workouts >>>
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WORKOUT ONE >>

Courtesy of Mike Duffy, owner and head trainer at Mike Duffy's Personal Training Studio.

Round One:
> Burpees
> Mountain Climbers
> Jumping Jacks

Three circuits: 10 reps first round, 15 reps second round and 20 reps third round. Non-stop no rests.

> Jump rope 3 minutes

Rest 1 minute

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Round Two:
> Walking Lunges with kettlebell exchange underneath leg
> Pushups
> Lunge Jumps
> Walk-outs (inchworms)

Three circuits: 45 seconds per exercise with a 15 second break between each exercise and circuit.

> Jump rope 3 minutes

Rest 1 minute

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Round Three:
> Traveling Kettlebell Squats
> TRX Pullups
> Box Jumps
> TRX Jack Knives

Three circuits: 45 seconds per exercise with a 15 second break between each exercise and circuit.

> Jump rope 3 minutes

Rest 1 minute

Round Four:
> Traveling Side Lunges
> Dips
> Speed Skaters (lateral jumps)
> Plank to Pushup

Three circuits: 45 seconds per exercise with a 15 second break between each exercise and circuit.

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Read more: Get workout 2 >>>
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WORKOUT TWO >>

Courtesy of Brian Jensen, CPT of Mike Duffy's Personal Training Studio.

> Jump Rope
> Plyo Push-up
> Bodyweight Rows
> Medicine Ball Squat to Overhead Throw
> Burpee
> Medicine Ball Chest Pass
> Renegade Rows
> Jumping Lunges
> Planks
> Treadmill Incline Sprints

Follow a Tabata protocol (20 seconds of work followed by 10 seconds of rest) for each of the above exercises. Go through each exercise once before repeating the entire circuit. Rest two minutes before repeating. Aim to complete three rounds of the circuit.

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Read more: Get workout 3 >>>
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WORKOUT THREE >>

Courtesy of JC Deen of JCDFitness.com

> 30 seconds of this:  25 mark for rope movement
15 second rest
> 30 seconds of sledgehammer to a tire as fast as possible
60 second rest between supersets

Repeat two to three times post workout for conditioning purposes.

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Read more: Get workout 4 >>>
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WORKOUT FOUR >>

Courtesy of JC Deen of JCDFitness.com

> 30 Yard Loaded Sled Push
> 25 Kettlebell Swings 
90 second rest between sets

Repeat two to three times post workout. 

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Read more: Get workout 5 >>>
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WORKOUT FIVE >>

Courtesy of Justin Klein, CSCS with HUMANFITPROJECT

> 1 minute Sprint
90 second Recovery
> 1 minute Sprint at 3% incline
90 second Recovery
> 1 minute Sprint at 6% incline
90 second Recovery
> 1 minute Sprint at 9% incline
90 second Recovery
> 1 minute Sprint at 12% incline
90 second Recovery

Repeat three to six times depending on level of conditioning.

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Read More: Get workout 6 >>>
[pagebreak]

WORKOUT SIX

Courtesy of Justin Klein, CSCS with HUMANFITPROJECT

> 5 minute jogging warm-up

> Increase speed/intensity until heart rate reaches 85% of peak heart rate.

> Lower intensity to a jog/brisk walk until heart rate reaches 65% of peak heart rate

> 5 minute jogging cool-down

Continue these intervals for four to six rounds to start. As conditioning increases set a time limit and attempt to achieve a certain goal of intervals by the end of this time. If you don’t have a heart rate monitor, find your pulse and count for six seconds then multiply that number by 10 to estimate your heart rate.

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Read more: Get workout 7 >>>
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WORKOUT SEVEN  >>

Courtesy of Jeremey DuVall, CPT of JeremeyDuVall.com

> 30 seconds of Tire Flips
> 30 seconds of Medicine Ball Slam
> 30 seconds of Battle Rope Slams
> 100 yards of Loaded Sled Push
> 100 yards of Farmer’s Walk

Repeat for a total of four rounds resting two minutes between each round.

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Read more: Get workout 8 >>>
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WORKOUT EIGHT >>

Courtesy of Jeremey DuVall, CPT of JeremeyDuVall.com

> 30 seconds of Kettlebell Swings
> 30 seconds of Right Arm Kettlebell Snatch
> 30 seconds of Right Arm Kettlebell Push Press
> 30 seconds of Right Arm Overhead Walking Lunges with Kettlebell
> 30 second Sprint

Rest 90 seconds then repeat on left arm. Aim for completing two to three circuits on each arm.

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DOWNLOAD The 21-Day Shred app for iOS to get the full training program, diet, and more. No iOS? No problem. Get a COPY of the PDF.