You can get in and out of the gym fast and still burn tons of fat. The trick? High-intensity interval training (HIIT). Interspersing short bursts of working at your absolute max effort with brief rest periods can seriously rev your metabolism. How? It's an effect called excess post-exercise oxygen consumption, or EPOC, and triggering it can help keep your metabolic rate up for hours after you exercise.

Essentially, pushing yourself to your physical limits, even for mere seconds, helps create an oxygen 'debt' and while that doesn't sound like a good thing, it most definitely is when it comes to helping you burn fat. What's more, this type of workout triggers fat-incinerating hormones like human growth hormone (you produce a lot of it when you're young, but production peters out as you get older and more sedentary.) Since more and more research is piling in confirming these facts, you need as many HIIT workouts as you can get. So, we decided to add to our 8 amazing fat-burning interval guide to bring you another 8 to add to your fat-fighting arsenal.

Hope you brought an extra t-shirt. These circuits will leave you soaked.

Courtesy of Megan Smith-Hochheimer, owner of Karma Yoga & Fitness Studio, Valrico, FL. Find online training at KarmaFitness or at @karmayogafitness on Instagram

Workout 1: Superset HIIT  

How to do it: Complete the exercises as supersets (do all exercises one after another, then start the set again) for 2-3 sets.

- 5-minute run (for maximum distance)

Circuit 1:
- Pushups x 20
- Bodyweight squats x 50
- Weighted crunches x 50
- Alternating plyometric lunges x 20

* Rest 1 minute *

- Repeat the 5-minute run (for maximum distance)

Circuit 2:
- Plank x 1-minute 
- Jump squats x 20
- Bicycle crunches x 50
- Walking lunges x 1 minute 

* Rest 1 minute *

- Finish with one more 5-minute run (pick up the pace, make this your best run yet!)

Workout 2: AMRAP HIIT

How to do it: Set your timer for 25 minutes and do as many rounds as possible (AMRAP) of the following exercises in the time allotted. Keep track of how many rounds you're able to make it through, and try to beat it next time.

- Squat to overhead press with moderate to heavy weight x 15
- Pushups x 10
- Box jumps x 15
- Burpees x 10
- Plate swings with moderate weight x 15
- V-sits (V-situps) x 10

Workout 3: Plyo + strength HIIT

How to do it: Complete as straight sets. 

Plyometric round:
- Single-arm kettlebell swings x 10 each arm
- Alternating plyometric lunges x 20
- Jump squats (focus on height of the jump as well as a soft landing) x 10
- Crossover pushups on a BOSU x 20
- Burpees with a BOSU x 10
Repeat 2 times, then rest for 2 minutes

Strength round:
- Decline pushups with feet on bench or step x 10
- Triceps bench dips x 20
- Single-arm dumbbell rows (heavy) each arm x 10
- Pullups x 10-20
Repeat 3 times and then rest for 2 minutes

Core round/finisher:
- Weighted crunches x 50
- Weighted Russian twists x 50
- Leg lifts x 50

Workout 4: Sprint HIIT

How to do it: Complete each sprint superset for prescribed number of sets before moving on to the next. 

Complete 3 sets:
- Sprint x 1 minute
- Dumbbell lateral raise x 1 minute (moderate weight)

Complete 3 sets:
- Sprint x 1 minute
- Dumbbell “Arnold” press x 1 minute (moderate weight)

Complete 3 sets:
- Sprint x 1 minute
- Rear delt flyes x 1 minute

Complete 4 sets:
- Sprint x 1 minute
- Plank x 1 minute 

Complete 4 sets:
- Sprint x 1 minute 
- Wall sit holding a (heavy) plate x 1 minute 

Complete 4 sets:
- Sprint x 1 minute
- Walking lunges with dumbbells (moderate to heavy) x 1 minute 

Workout 5

How to do it: Bike as your warmup, then do 5 sets of 20 reps of the following exercises; cool down with biking.  

- Bike 10 minutes for distance

Do 5 sets of 20 reps of the following:
- Bodyweight squats (feet close/narrow stance)
-Mountain climbers
- Burpees
- Plank to pushup (Walk the plank from forearms to hands and back for one rep)
- Hanging knee raises
- Box jumps
- Ab rollouts (with bar or ab wheel)
- Speed skaters (lateral jumps from foot to foot)

- Bike 10 minutes for distance

Workout 6

* Warm up with 10 minute bike or run for distance *

How to do it: Pick the order, but complete the following number of reps:
- Weighted crunches x 100
- Weighted wall sits x 5 minutes   
- Weighted walking lunges x 5 minutes   
- Bodyweight squats x 100 
- Leg press machine with at least one 45pound plate on each side x 100  
- Weighted stepups on bench or box x 100 

- Finish with 5 minute bike or run for distance

Workout 7

How to do it: Complete all sets of each group of exercises before moving on to the next. 

1a. Row or jump rope x 2 minutes
1b. Sprint x 1 minute
1c. Dumbbell military press x 10 sets of 10 reps with 10-second rest between sets

2a. Row or jump rope x 2 minutes
2b. Sprint x 1 minute
2c. Leg extension machine x 10 sets of 10 reps with 10-second rest between sets

3a. Row or jump rope x 2 minutes
3b. Sprint x 1 minute
3c. Hamstring curls x 10 sets of 10 reps with 10-second rest between sets

4a. Row or jump rope x 2 minutes
4b. Sprint x 1 minute
4c. Dumbbell lateral raise x 10 sets of 10 reps with 10-second rest between sets (use moderate weight)

5a. Row or jump rope x 2 minutes
5b. Sprint x 1 minute
5c. Decline pushups x 10 sets of 10 reps with 10-second rest between sets

6a. Row or jump rope x 2 minutes
6b. Sprint x 1 minute
6c. Feet to bar or hanging leg raises x 10 sets of 10 reps with 10-second rest between sets

Workout 8

* Warm up with TRX Squats (get full range of motion) for 1 minute and bodyweight walking lunges for 1 minute *

How to do it: Complete straight sets of the following. Finish all reps before moving on the next exercise.

- Deadlifts (60-80% of max) x 8 sets of 8 reps 
- Plyometric jump squats with TRX x 1 minute 
- Barbell squats (deep squats, full range of motion) (60-80% of max) x 8 sets of 8 reps 
- Plyometric jump squats with TRX x 1 minute 
- Hanging cleans x 8 sets of 8 reps   
- Mountain climbers on TRX x 1 minute 
- Flat Bench Press (60-80% max) x 8 sets of 8 reps   
- Mountain climbers on TRX x 1 minute 
- Smith machine seated overhead press x 8 sets of 8 reps   
- Abdominal pikes on TRX x 1 minute 
- Lat pulldown (60-80% max) x 8 sets of 8 reps 
- Abdominal pikes on TRX x 1 minute