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.

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.

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.

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


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Workout 1

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

Round 1:
1. Burpees
2. Mountain climbers
3. Jumping jacks

How to do it: Complete 3 circuits of Round 1, performing 10 reps in the first round, 15 reps in the second round, and 20 reps in the third round. Take no rest.

* Jump rope for 3 minutes *

Rest 1 minute

Round 2:
1. Walking lunges with kettlebell exchange under your legs
2. Pushups
3. Lunge jumps
4. Walk-outs (inchworms)

How to do it: Complete 3 circuits of Round 2, performing each exercise for 45 seconds, taking a 15-second break between each exercise and circuit.

* Jump rope 3 minutes *

Rest 1 minute

Round 3:
1. Traveling kettlebell squats
2. TRX pullups
3. Box jumps
4. TRX jack knives

How to do it: Complete 3 circuits of Round 3, performing each exercise for 45 seconds, taking a 15-second break between each exercise and circuit.

* Jump rope 3 minutes *

Rest 1 minute

Round 4:
1. Traveling side lunges
2. Dips
3. Speed skaters (lateral jumps)
4. Plank to pushup

How to do it: Complete 3 circuits of Round 4, performing each exercise for 45 seconds, taking a 15-second break between each exercise and circuit.


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Workout 2

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

- Jump rope
- Plyo pushup
- Bodyweight rows
- Medicine ball squat to overhead throw
- Burpee
- Medicine ball chest pass
- Renegade rows
- Jumping lunges
- Planks
- Treadmill incline sprints

How to do it: 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 2 minutes before repeating. Aim to complete 3 rounds of the circuit.


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Workout 3

Courtesy of JC Deen of JCDFitness.com

1. 25 Mark for rope movements x 30 seconds (watch the video how-to here)
* 15 second rest *
2. Sledgehammer tire hits x 30 seconds as fast as possible
* 60 second rest between supersets *

How to do it: Repeat 2 to 3 times post workout for conditioning purposes.


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Workout 4

Courtesy of JC Deen of JCDFitness.com

1. 30-yard loaded sled push
2. 25 kettlebell swings 
* 90 second rest between sets *

How to do it: Repeat this finisher 2 to 3 times post workout. 


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Workout 5

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

How to do it: Repeat 3 to 6 times depending on your level of conditioning.


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Workout 6

Courtesy of Justin Klein, CSCS with HUMANFITPROJECT

1. 5 minute jogging warmup
2. Increase speed/intensity until heart rate reaches 85% of peak heart rate
3. Lower intensity to a jog/brisk walk until heart rate reaches 65% of peak heart rate
4. 5 minute jogging cool down

How to do it: Continue these intervals for 4 to 6 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 6 seconds, then multiply that number by 10 to estimate your heart rate.


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Workout 7

Courtesy of Jeremey DuVall, CPT of JeremeyDuVall.com

1. Tire flips x 30 seconds
2. Medicine ball slam x 30 seconds  
3. Battle rope slams x 30 seconds 
4. Loaded sled push x 100 yards  
5. Farmer’s walk x 100 yards   

How to do it: Repeat for a total of 4 rounds, resting 2 minutes between each round.


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Workout 8

Courtesy of Jeremey DuVall, CPT of JeremeyDuVall.com

> Kettlebell swings x 30 seconds 
> Right-arm kettlebell snatch x 30 seconds 
> Right-arm kettlebell push press x 30 seconds 
> Right-arm overhead walking lunges with kettlebell x 30 seconds 
> Sprint x 30 seconds

How to do it: Rest 90 seconds then repeat on your left arm. Aim to complete 2 to 3 circuits on each arm.


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.