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

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Despite what the sweaty fella in the gym tries to tell you, the idea of High Intensity Interval Training (HIIT) is nothing new. It has been around for absolutely ages.

Professional athletes were toying with the notion that bouts of extremely intense exercise, followed by short rest periods, would help condense efforts into shorter, more effective workouts.

The idea comes in all sorts of packages – Tabata, Gibala, Zuniga and Vollaard, to name a few – but they all share one common trait and that is putting in maximum effort for a short period of time, recovering quickly and then repeating.

“Despite the fancy name, HIIT training simply means training at high intensity for short periods of time with rest or low intensity exercise in-between,” explains former championship wrestler and founder of London based personal training company Right Path Fitness, Keith McNiven.

“It’s a great way to exercise because most of us can cope with pretty much any physical activity for 40 seconds or so. Psychologically, it’s much more achievable than, say, pounding a treadmill for 30 minutes or so.

“Results-wise, HIIT is one of the most efficient ways of burning fat and calories, and your body will carry on reaping the rewards for up to 24 hours after the workout ends,” he adds.

  • Why should you try HIIT? Here’s 5 great reasons why

External links: Follow Keith McNiven on Instagram, Twitter and Facebook to receive regular workout tips, nutritional advice and updates from the man himself…

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A word on nutrition

Definitely cook the chicken first

The bottom line is, building muscle is an energy consuming process and your body is going to the need the correct fuel to not only get you through the workout, but to repair and heal the muscle fibres so they can grow.

“If you’re not taking in the right foods, then you can do all the exercises you want but you won’t get bigger muscles,” explains Keith.

“What your body will do is grab onto your carb reserves. The result can be an actual loss of muscle mass and probably the opposite result that you want,” he adds.

Getting nutrition right is key to fuelling your workouts and building muscle, so Keith recommends you should be aiming for around one gram of protein per pound of your body weight and 1.5 to 3 grams of carbohydrate per pound of your body weight per day.

Eating the right foods is one way of achieving this, or you can supplement your diet with all manner of protein shakes, bars and snacks, which make it easier to get the right numbers on-board. You could also try a complete meal replacement system such as Huel.

“With your nutrition right, you have the fuel you need for an intense training programme. Of course, if you’ve never trained before then jumping right into a muscle-building programme might not be for you, so always ensure you’re working at a pace and level that’s right for you and your fitness experience,” he adds.

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How to perform HIIT properly

One of the key benefits of HIIT is that the workouts can be adapted to any kind of exercise. Whether you like to run, cycle, swim, lift weights or do body weight exercises, you can tweak them so that they become a HIIT workout.

But what classifies as high intensity? High intensity means working as hard as you can and giving the exercise everything you’ve got for that short burst of time, say 40 seconds, then taking the intensity down for a shorter amount of time, typically 15-20 seconds.

“If you’re on the indoor spin bike, you’ll be pedalling as fast as you can for 40 seconds and then taking it down to a mild spin,” Keith explains.

“Or, if you’re running, you’ll be sprinting for 40 seconds then jogging for 20. The main aim is to get to between 80-100 per cent of your maximum heart rate, which can simply be calculated as 220 minus your age, ” he adds.

You might want to invest in a fitness tracker, which will allow you to keep an eye on your heart rate during a workout and also helps calculate max heart rate and heart rate zones from a few body metric details.

“It’s really easy to get started with a HIIT workout because you can use the pieces of kit you already have at home, invest in a few pieces or just go for it equipment-free,” Keith says.

“Remember that high intensity doesn’t have to mean high impact, so if your joints can’t handle jumps, you can still work to a high intensity by swapping in lower impact alternatives, like swim sprints or intense cross-trainer work,” he adds.

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Yup, sprinting up a hill can be turned into a HIIT workout

The ultimate HIIT workout

For the following workout, Keith recommends you perform each exercise for 40 seconds as hard, fast and as intensely as possible, making sure form is strong, and then rest for 20 seconds.

Repeat this four times for each exercise, and you’ll have completed four minutes of that exercise. Then move onto the next.

This routine should only take you around 30 minutes to complete, so is great for those time-strapped individuals who want to squeeze a quick and effective session in at lunchtime or after work.

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1. Jumping Jacks

After a quick dynamic warm up to stretch out your muscles (running on the spot or butt-kickers work well), start off with jumping jacks, keeping the knees slightly bent and putting the full range of motion into each movement of the arms and legs.

If you like, you can also add some light dumbbells to the jacks for added pain.

Burpees hurt but they burn fat fast

2. Burpees

These are a killer but get the heart rate soaring. To perform a proper burpee, start from standing and then squat down so the palms of your hands are on the floor and your knees are tucked into your chest.

Kick the legs back in an explosive fashion until you’re in a push up position, then pull the legs back in towards the hands and jump as high as you can with arms raised.

You could also add in some heavy weights (hexagonal dumbbells are best, as they don’t roll) or special push up bars here for when you get to the push up position.

Keep them on the floor (making sure not to trip over them) and use them for the push up segment of the burpee to add an extra level of intensity.

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Grab a plyo box for home and light up a HIIT session

3. Step-ups

Most gyms will have aerobics-style steps or soft plyo boxes you can use for this – the latter is basically a giant cube that you step or jump onto.

They come in different sizes, or can be positioned to offer multiple platform heights, so you can choose the intensity of the jump or step.

A step or a plyo box is an affordable but useful piece of kit that you might want to invest in for home use, or you could improvise with your stairs, a sturdy chair or even your bed.

Start by standing straight with the step or box in front of you and step up using your right foot and back down on the same right foot. Repeat this, but let the left foot lead next time, swapping each time.

Keep the intensity high for this move and ensure you are squeezing as many steps as possible into the 40 seconds without letting the form drop.

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4. Mountain Climbers

Start in the plank position, resting on your palms and toes with elbows tucked in close to your body.

Bring your right knee in as close as you can towards your chest and return it to the starting position. Do the same with your left knee, then up the pace as soon as you get in the rhythm. Make this even harder by adding ankle weights.

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The Tuck Jump: leaping from a rock optional

5. Tuck Jump

For this simple move, you’re going to get into a leaping position with arms out straight in front of you. Your aim is to jump high enough to allow your knees to hit the palms of your hands.

Jump in an explosive manner to keep the intensity high and try to keep the time between leaps as short a possible. It is best to land on the balls of your feet and explode back up again for maximum effect.

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6. Skipping

A skipping rope is a great piece of kit to have at home, as it is cheap and easy to store. Keep the knees bent and legs together as you jump.

For a greater challenge, look for weighted ropes that allow you to increase the weight as your fitness improves.

7. Push-up

To finish off, it’s the move that is as old as time but one that’s excellent for building muscle and stamina.

Start in full push-up position, with arms fully extended, and then lower your body until your chest reaches the floor. Return to the starting position by pushing back up with maximum force.

Perform these relatively quickly but don’t compromise on form and remember to inhale on the way down and exhale on the way up.

To make this move harder, you could use a weighted plate on your back (the kind that you put on either end of a barbell in the gym) or add in a clap, which really gets the pulse racing.

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5 Best 20 Minute HIIT Cardio Workouts For Rapid Fat Loss

Are you pumped, excited, and downright jumping out of your skin to saddle up to the treadmill for another 45-minute walk?

I didn’t think so.

Mundane, mind-numbing, and boring are just some of the words that come to mind. But you’ve read all of the mainstream noise about how you need to slog away on the treadmill, bike, or elliptical for hours every week if you want to burn body fat and finally get lean, right?

Related: 6 Intense Treadmill Workouts That Are Anything but Boring

There has to be a better way. A more effective and efficient way to scorch the fat and let your physique show. And there is.

You may have run across the term HIIT before (or high-intensity interval training). What is it?

It is a form of cardiovascular exercise that has you performing high levels of intensity for short durations coupled with rest periods. Each of these intervals is repeated for predetermined amounts of times in specified workouts. They are designed to be short to moderate in total workout duration increasing excess post-exercise oxygen consumption (EPOC for short) enabling you to burn calories long after your session is over.

So, you get the benefits of:

  • More intense workouts
  • A workout that actually holds your interest
  • Shorter cardio sessions
  • An increased post-exercise calorie burn

Here are 5 unique and different 20-minute HIIT cardio workouts for rapid fat-loss. You’ll crank up the intensity and finish in record time!

1. The Kettlebell Conditioner

Use this circuit utilizing only one kettlebell. Both the imbalance of the kettlebell and the fact that you will be fighting the weight on one side of the body will have your stabilizers, core, and other dormant muscles working in overdrive. This, in turn, will crank up your cardiovascular system all the while conditioning your muscles.

Perform 4 to 5 rounds of 10 to 15 reps each resting 1 minute after each round.

Exercise Reps
One-Arm Clean 10-15
Double Arm Front Swing 10-15
Goblet Squat 10-15
One-Arm Overhead Press 10-15
Reverse Lunge 10-15
Floor Crunch 10-15

Notes: For each single-limbed exercise, perform 10 to 15 reps for each limb. For the reverse lunge carry the kettlebell in the opposite arm as your stepping leg. The floor crunch can be performed with the kettlebell on your chest or as a standard non-weighted crunch.

2. The Outdoor Blazer

Nothing beats training outside. Fresh air, no waiting on equipment, and the ability to perform cardio anywhere. Enter sprint interval training. Saying no to the treadmill and its other boring and confining friends will enable you to take advantage of real running drills with no push of a button required.

Related: Power Hour Cardio Routine for Gym Rats

Perform one of the following sprint interval workouts each workout alternating if needed:

  • Sprint 10 yards walk back to start, then sprint 20 yards and walk back to start. Sprint to each 10 yard marker up to 50. Shoot for 5 rounds.
  • Perform ten 30-yard sprints alternating going back to start with backwards running and side shuffles.
  • 10 rounds of a predetermined bleacher run, walking down to start each interval.

3. The Nontraditional Burner

Fat-burning cardio doesn’t have to be relegated to running, biking or rowing. Some nontraditional ways to get leaner are becoming the norm. Sled pulls/pushes, kettlebell circuits, and plyometric work not only are effective but can break the boredom that usually accompanies the traditional modes of cardio.

Perform 3 to 4 rounds of the following circuit. Rest 2 minutes between each round.

Exercise Reps
Sled Push 10yds
Kettlebell Front Swing 10-15
Sled Pull 10yds
Burpee 10-15
Box Jump 10-15
Push Up 10-15
Hanging Leg Raise 10-15

Notes: If your gym doesn’t have a sled, substitute with farmer’s walks and/or suitcase carries. If you are unable to perform box jumps substitute with jump squats and/or jump lunges.

4. The At-Home Fat Scorcher

If equipment is a factor or you don’t belong to a gym, then an at-home circuit may be your best bet for a fat-loss workout. The fact is you don’t really need anything fancy to get in a great workout – your bodyweight is more than enough.

Additionally, bodyweight training builds real-world strength and muscle allowing you to manipulate your body in such a way that weights and machines can’t.

Perform 3 to 5 rounds of 10 to 15 reps of the following circuit. Rest 2 minutes between rounds.

Exercise Reps
Burpee 10-15
Push Up 10-15
Floor Crunch 10-15
Squat Jump 10-15
Bicycle Crunch 10-15
Mountain Climber 10-15
Reverse or Walking Lunge 10-15
Short Distance Sprint 20yds

Notes: For bicycle crunches, mountain climbers, and lunges, reps are counted per limb. For sprints choose a predetermined distance such as 20 yards. If you don’t have access to an area for sprinting (due to space or weather) perform jumping jacks for 10 to 15 reps.

5. The Dueling Partner Punisher

Training with another similar goal-oriented person has so many advantages. It obligates you to adhere to a program, you have to show up for accountability reasons, you are more inclined to be pushed during the workout, and you instill a little fun and competition between each other. If you have a dedicated training partner then you are that much better-suited for success.

Perform the following workout as a pair. You will start with the first exercise while your partner will perform the second exercise. Each of you will alternate between the two exercises without rest for 3 to 5 rounds before moving on to the next pair. Either take no break between pairs or take 30 seconds – depending on your level of experience. Shoot for 10 to 15 reps for each exercise.

Notes: Box jumps can be substituted with jump squats, any kettlebell exercise can be substituted with dumbbells, sled pushes and pulls can be substituted with farmer’s walks or suitcase carries, and sprints can be substituted with jumping jacks.

What is High Intensity Interval Training (HIIT) and what are the benefits?

High Intensity Interval Training (HIIT) is a system of organizing cardiorespiratory training which calls for repeated bouts of short duration, high-intensity exercise intervals intermingled with periods of lower intensity intervals of active recovery. On a 1-10 scale of perceived exertion, high intensity can be considered anything over an effort level of 7. When using max heart rate (MHR) as a guide, high intensity can be considered exercising above 80% of MHR. Modes of HIIT can include outdoor activities such as running or cycling, or using equipment such as treadmills, elliptical runners, stair-climbers or stationary bikes. HIIT training calls for challenging work-rates such as sprints (whether on a bicycle or running) for short time frames lasting from thirty seconds to two minutes.

What is a typical HIIT session like?

A typical HIIT session would call for a warm-up of 5-10 minutes where the intensity gradually increases from a RPE of 3 to a RPE of 5. Once the body is warmed up, it is then time to begin the work intervals. The appropriate work to recovery ratio for HIIT is 1 minute of work to every 2 to 3 minutes of active recovery. Staying active during the recovery period allows the muscles to remove the metabolic waste and produce more energy for the next bout of high intensity exercise. Start with a lower number of work intervals and work up to doing 10-12 high intensity work intervals.

An example of outdoor HIIT training would be running at the fastest pace possible on a track for 200 meters, then jogging at a slower pace for 400m (or twice the length of time required to run the 200 meters). An example of indoor HIIT training would be an indoor cycling class where the instructor has the class do hill climbs for two minutes working at a RPE of 7 or 8, followed by four minute flat road intervals working at an RPE of 4 or 5.

What are the benefits of this kind of training?

One of the major benefits of HIIT fitness is that using the appropriate work-to-recovery intervals can train the body how to become efficient at producing and using energy from the anaerobic energy system. This type of session can also train the body to effectively remove metabolic waste from the muscles between the work intervals. In addition, HIIT also serves as an effective way to increase VO2 max without having to run for long distances or periods of time. Due to the high level of intensity and the amount of time necessary to appropriately recover from the exercise session, it is recommended to do no more than two days of HIIT per week, allowing at least one full day of recovery between training sessions.

Don’t Have Time to Exercise? Do This for 10 Minutes

In the fitness world, the word “miracle” gets thrown around like a two-pound dumbbell. But when it comes to high-intensity interval training (HIIT), a very short workout, the benefits you’ve heard about are both legitimate and—we’ll say it—miraculous.

HIIT is a combination of brief, very-high intensity bursts of cardio exercise followed by equal or longer periods of rest. Think 30 seconds to a minute of sprinting, followed by a minute or two of walking or slow jogging. Repeat this cycle for just 10 minutes, and you’ll complete a HIIT workout.

“We now have more than 10 years of data showing HIIT yields pretty much the exact same health and fitness benefits as long-term aerobic exercise, and in some groups or populations, it works better than traditional aerobic exercise,” says Todd Astorino, a professor of kinesiology at California State University, San Marcos, who has published more than a dozen study papers on HIIT.

Whether your goal is to improve your fitness, lower your risk for cardiovascular disease, lose weight, strengthen skeletal muscle or help get your blood sugar under control, a few minutes of HIIT seem to be as effective as much longer periods of moderate-paced running, cycling, swimming or other forms of traditional cardio. For well-trained athletes, HIIT may be the best way to elevate your physical performance.

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One small study of healthy but sedentary people found just one minute total of HIIT performed three days a week for six weeks was enough to significantly improve blood sugar scores and aerobic capacity, a measure of physical fitness. The study participants completed 10- to 20-second bouts of “all-out” cycling on a stationary bike, each broken up by a couple minutes of rest. The total workout time, start to finish, was 10 minutes.

Other research finds that HIIT may outperform traditional cardio when it comes to fat loss. A HIIT-induced surge in your body’s levels of growth hormones and other organic compounds “can increase fat burning and energy expenditure for hours after exercise,” says study author Stephen Boutcher, an associate professor of medical sciences at the University of New South Wales in Australia.

It doesn’t just work for the young, fit and healthy. Among people with heart disease, HIIT improves cardiorespiratory fitness nearly twice as much as longer stretches of moderate-intensity running, cycling or other aerobic exercises, one review study concluded.

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How can HIIT do so much good in so little time? During very intense exercise, “the heart cannot pump enough blood to satisfy all the muscles,” says Ulrik Wisløff, a HIIT researcher and head of the cardiac exercise research group at the Norwegian School of Science and Technology. This lacking oxygen delivery to the muscles starts a “cascade of molecular responses in most organs of the body” that produces a greater training response than more leisurely bouts of exercise, he says.

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Exercise of any intensity switches on genes that increase the growth of mitochondria—the power generators of the cells—and triggers all of the other beneficial biological changes linked with physical fitness, says Astorino. “But to activate these genes with traditional cardiovascular exercises, you have to do fairly large or long bouts,” he says. With HIIT, it appears that even very short bouts of training can switch on those genes, so it’s an efficient workout.

HIIT can work for a wide range of people. But how you should practice it depends on your fitness level.

The key to HIIT is pushing your heart rate up above 80% of its maximum, Astorino says. “Subtract your age from 220 to estimate your maximal heart rate,” he says. (A heart rate monitor can provide an accurate assessment. But if you’re really sucking wind after pushing yourself, you’ve probably hit your target, Astorino says.)

MORE: 7 Surprising Benefits Of Exercise

If you’re fit, try sprint interval training. After walking or slow jogging for a few minutes to warm up, sprint as hard as you can for 30 seconds, then recover for four minutes by walking or jogging slowly. Complete four to six sets of this sprinting-recovery program. (For an even faster version, keep the warmup, then complete three sets of 20-second sprints, each separated by two minutes of recovery, Astorino says.)

If you’re overweight or obese and you haven’t exercised in months, sprinting isn’t necessary (or safe for your joints). Instead, 30 seconds to four minutes of brisk walking on an inclined treadmill or hill should be enough to push your heart rate up into the HIIT zone, Astorino says.

You can also practice these programs with a stationary bike, rowing machine or in the pool. Any form of cardio can push your heart into the HIIT zone, Wisløff says. (This fact sheet from the American College of Sports Medicine offers more in-depth details on how to design a HIIT program.)

And yes, HIIT is safe. Wisløff and colleagues analyzed nearly 50,000 hours of HIIT data collected from cardiovascular disease patients in Norway. In seven years of data, he turned up just two instances of (non-fatal) cardiac arrest.

He says people with unstable angina or serious heart issues should speak with their doctor first. But, in general, “it’s much more dangerous not to perform HIIT than to perform it,” he says.

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It’s time to HIIT it! Rising slowing in popularity for a while, HIIT workouts first made the American College of Sports Medicine’s list of fitness trends back in 2014, and they are still going strong. If you haven’t jumped on the HIIT bandwagon yet, here’s what you need to know.

What Is HIIT?

The accurately poetic acronym HIIT stands for high-intensity interval training. A HIIT workout mixes shorts bursts of activity with even shorter rest periods. Ideally, you work to your maximum capacity during the short bursts of activity, hence the use of “high intensity” to describe those intervals. Because you are pushing your limits, these workouts tend be shorter, rarely passing the 30-minute mark.

HIIT workouts are scalable to any fitness level, making it a popular format for group fitness classes. Your goal is push yourself to 90 percent of your personal max in the intense intervals, and this varies among individuals. Using the rate of perceived exertion scale to measure your efforts helps keep the workout individualized.


You can do a HIIT workout with almost any type of activity, including running, swimming, and cycling, as well as strength training with exercises like burpees, squats, and push-ups. HIIT is flexible and you can create different formulas for the work-to-rest ratio, but the most popular is 2:1. For example, you work for 40 seconds at your max and rest for 20, repeating this pattern for five to 10 sets. The Tabata Protocol might be the most well-known HIIT workout. Its eight rounds of 20-second intervals followed by 10 seconds of rest make it one of the hardest four-minute workouts you’ve ever done.

The Benefits

  • HIIT workouts are efficient; since you’re working to your max, you burn more calories in less time.
  • Adding intervals into your workouts helps you burn more fat during your sweat session.
  • Interval workouts, compared to steady-paced ones, have a higher afterburn effect, meaning you continue to burn calories after your workout is over for a longer period of time.
  • HIIT workouts also increase your endurance. So when you do go for a long, steady-paced run, you can go further.
  • Health-wise, intervals improve your cardiovascular health, cholesterol profile, and insulin sensitivity (which helps fight type 2 diabetes).

HIIT Workouts to Try

Here are some of our favorite HIIT workouts:

  • A 10-Minute HIIT Workout You Can Do at Home
  • A 20-Minute HIIT Workout For All Levels
  • This 7-Minute Workout Targets Belly Fat
  • A Tabata Mash-Up Workout Video
  • 30-Minute Interval Treadmill Run

Since HIIT workouts are so vigorous, it’s best to do no more than two a week and avoid doing back-to-back HIIT workouts. You need to give your body time to recover to truly reap the benefits of these workouts so you can go hard at your next sweat sesh.

Image Source: POPSUGAR Photography / Benjamin Stone

Here’s What Happens to Your Body During and After a HIIT Workout

Some people swear by HIIT workouts. Others wonder what they even are. In short, HIIT stands for high-intensity interval training, which involves a short workout and quick bursts of energy with quick resting periods. (Most HIIT workouts are not more than 30 minutes.) Trainers recommend these types of workouts because they burn serious energy, which helps you burn more fat and calories. Plus, the body keeps burning energy long after the workout. Here’s why that is, and what happens to your body during and after one of these speedy, intense workouts.

HIIT workouts have some serious benefits for your body. | Bojan89/iStock/Getty Images

When you give 100%, your body goes into overdrive

HIIT workouts should be done by giving 100% effort for 15 to 30 seconds. This is the optimal amount of time for an anaerobic workout (your body is “deprived” of free oxygen) before a 60-second rest period. According to Men’s Health, doing any less might mean you won’t see the results you want, and doing any more is too much on your body.

When your body works anaerobically, it produces lactic acid because you can’t get enough oxygen to your muscles to keep them working properly. Basically, your body supplements that oxygen with the lactic acid. When lactic acid is produced, adrenaline comes with it, which helps move fat throughout your body and creates that fat burn and muscle buildup you’re looking for.

After the HIIT workout, the body enters a rebuilding mode

When you deprive your body of oxygen, it needs to rebuild itself to get those oxygen levels back to normal. You’ll be very out of breath after HIIT because your body is trying to grab as much oxygen as it can to return to homeostasis.

After about a half hour, you might notice you’re pretty hungry. That’s because your body needs to replace glycogen fuel stores, too, so it tells you it needs food to help out with that. You’ll want to grab something with complex carbohydrates, such as whole wheat pasta or whole wheat bread, to refuel.

Hours after the HIIT is done, your body is still burning fat because your metabolism is on a roll trying to replace nutrients that were lost during the HIIT workout, such as carbohydrates and electrolytes. Your insulin sensitivity is at its best, so your body won’t store glycogen as fat. The effects of a HIIT workout can impact your body up to 48 hours after the workout.

Working your body in intervals burns more fat in the long run

If you jog at a steady pace, you’ll do your body good but definitely aren’t giving 100% effort. This means your body doesn’t have to work as hard to repair and rebuild its oxygen levels. A jog is a great form of cardio, but it requires a much shorter recovery time than HIIT. This means your body won’t feel its effects for as long, and you ultimately won’t burn as much fat from a jog as you would from a HIIT. Not only are HIITs a great time saver, they’re one of the best things you can do for your body.

Does HIIT work?

HIIT definitely has some great benefits, especially if you don’t have a lot of time to dedicate to working out. Spending 30 minutes on a HIIT workout will essentially be just as beneficial for your body as spending an hour or more at the gym (assuming you’re jogging or doing an exercise that doesn’t require 100% effort.) However, it’s important to know what your body can handle before implementing HIIT workouts into your routine. People sometimes think a 30-minute workout is no big deal even if they’re not in shape; actually, these 30-minute workouts are extremely intense. If your body can’t handle it, you risk injuring yourself. Make sure you to always listen to your body and know if you’re pushing yourself past the breaking point.

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By Obi Obadike

Have you ever watched a track meet on TV and been amazed at how sculpted the sprinters are? Well, you don’t get a body like that by just waking up and rolling out of bed in the morning. Those shredded physiques speak to the incredible fat-burning effects of sprint training and workouts. No wonder sprinting is gaining popularity among celebrities looking to stay in shape.

Sprinting is one of the most explosive exercises you can do. It’s a complete, total-body workout — targeting the butt, hips, hamstrings, quads, calves and abs — that builds long, lean muscle. In fact, many professional athletes incorporate sprints into their training for that reason.

Sprinting also promotes fat loss and increases your metabolic rate for several days after the workout, a phenomenon known as the excess post-exercise oxygen consumption (EPOC) effect. EPOC — also known as “afterburn” — allows you to continue burning calories long after the workout is over.

Sprinting is arguably the best way to tone your legs and butt without incorporating any resistance training. Don’t get me wrong: Squats, lunges and hack squats are all great ways to train your legs, but sprinting is an excellent alternative. We all get bored sometimes, going to the gym every day and lifting the same weights over and over, and sprinting is a great way to change things up and get outside. All you need is a track or a flat, grassy surface.

You don’t have to run sprints at top speed to obtain a quality workout. In fact, I always suggest doing sprint workouts at 75-percent speed or less, to avoid injury. Your body isn’t conditioned to run full speed, and you don’t want to pull a hamstring or groin muscle.

If you want to really push your body, add an extra cardio component to your sprints. I came up with a special workout that does just that. I call it Sprint Burpees. Sprint Burpees aren’t easy to do, but they’ll help you burn more calories, build lean muscle and increase your endurance. This weekly workout will burn a minimum of 500 to 700 calories:


Do eight 100-meter sprints at 50 to 60 percent of your top speed. After each sprint, walk back to the starting line and do 5 burpees before running the next sprint. (40 burpees total)


Repeat the Monday workout, but increase the number of 100-meter sprints to 10. (50 burpees total)


Repeat the workout, this time increasing to 12 100-meter sprints. (60 burpees total)

Burn More Fat By Sprinting!

Admit it—you too have spent countless hours at the gym doing “low intensity” cardio to burn more body fat. C’mon, it’s OK, we’ve all wasted hours walking on a treadmill…a moving belt with no real destination because, well, the belt doesn’t take you anywhere. At least at an airport the moving belt moves you forward.

Isn’t it strange that we get in our cars, drive however many minutes to a gym, to walk in place? We’re really no different than rats that run around their wheels hoping to get somewhere.

And while I’m picking on treadmills, all the cardio equipment is the same; you pedal on a bike at a low intensity to go nowhere, or whatever other piece of cardio equipment you may use. I digress.

The Misconception Of Low Intensity

Many folks have turned to low intensity cardiovascular work to “burn more body fat than carbohydrates.” First, let’s get that theory out of the way. Carbohydrates and fat are the body’s primary fuel source during activity. Carbohydrates are used first and in terms of carbohydrate sources, it will first be blood glucose that’s utilized for energy.

Next, stored carbohydrate (glycogen) will be turned into glucose and utilized. As exercise continues (and I’m talking hours, like a marathon), fat will become the primary fuel source.

Keep in mind that there is never only one fuel source, it’s always a mixture of fuels for the body; however, the ratios change (e.g. 90% carbohydrates, 10% fat at the start of exercise, then the carbohydrate percentage decreases and fat percentage increases as exercise continues.).

It is also important to note that fat requires oxygen to be burned as fuel, which is where the misconception about low intensity aerobics burning more fat comes into play. The thought is that if you have more oxygen available (e.g., you’re not gasping for air because your intensity is so low), you’ll be able to burn more fat.

Here’s The Truth

It is true that a greater percentage of calories burned will come from fat if exercising at a low intensity. However, because you’re exercising at a lower intensity, you will burn fewer total calories.

On the contrary, if you do a harder, higher intensity activity, like sprinting on a track, or a bike, you’ll burn an overall greater amount of calories.

So even though a lower percentage of these calories will come from fat, a lower percentage of a higher number is still greater than a higher percentage of a much lower number. Make sense?


Here’s an example with some actual numbers because it can get confusing. These numbers are used solely for ease; they are not exact for what actually happens.

Low Intensity Walking For 60 Minutes At 3 mph:

Since there are approximately 100 calories used for every mile, this 60-minute session would burn approximately 300 calories.

It was low intensity, so let’s say 60% of those calories came from fat (and by the way, it’s circulating fat, not body fat that you’ll first use). 60% of 300 is 180 calories that came from fat.

High Internsity Sprinting For 20 Minutes:

Next, consider a high intensity sprinting session. Since I used the treadmill in the first example, I’ll use the running for this (but it’s much easier to do these outside vs. a treadmill). If you are able to do sprints for 20 minutes, you may burn 600 calories (again, just an estimate).

Since you were doing these at a higher intensity, you used less fat itself for fuel and more carbohydrates. Let’s say that 40% of the fuel source utilized was from fat. That means 40% of 600 is 240 calories.

You still used more fat as fuel with sprinting and it’s not body fat directly that you’re using; it is circulating fat in the blood. Most importantly, it’s the overall calories you use that you should be concerned with vs. what the specific fuel source is anyhow.

A Couple Of Studies

Experimental Biology Study

Don’t believe me? Check out this recent study presented at the Experimental Biology meeting that showed fat “burning” may require those high intensity sprints we all love to hate.


This study included 11 men and 11 women in which they were cycling sprints at various intensities. The researchers learned that the maximal fat utilization occurred at an intensity near anaerobic threshold, which is essentially the state you’re in when sprinting.

Moral Of The Story:

Stop wasting endless hours doing some low intensity cardio—kick it up a notch to really see the results!

McMaster University Study

Maybe you’re less concerned about fat loss, but think that sprinting will negatively affect your endurance capacity. Well, looks like this isn’t true either.

A study conducted at McMaster University in Ontario and published in the highly-regarded Journal of Applied Physiology suggested that short sprint interval training increased muscle oxidative potential and doubled endurance capacity during intense aerobic cycling in recreationally active individuals.


Sixteen healthy individuals participated in this study. Out of the 16, 8 subjects were in the experimental (sprint) group and 8 were in the control group (no training intervention).


The sprinting sessions consisted of six sessions of sprint interval training spread over a 14-day period (not quite every other day).

The sessions each consisted of a 30-second “all out” effort on a cycle. Subjects then rested 4 minutes between sets and either completely rested or performed light cycling with little resistance.

In this short, 2-week intervention, it was demonstrated that brief repeated bouts dramatically improves endurance capacity during a fixed workload. Moreover, it was shown that intense exercise can rapidly stimulate improvements in muscle oxidative potential comparable to or greater than that of standard aerobic based training. This basically means the capacity to perform aerobic work over time.

Moral Of The Story:

Sprinting is more effective for fat loss sprinting vs. low intensity walking or cycling for hours on end. It also frees up a lot of time to get home and recover.

Aside from proper nutrition, there’s nothing more effective than hill sprints for fat loss.

And if you’re not doing them you’re missing out on huge benefits.

Don’t waste your time on cardio machines. They suck.

Get outside and find a hill instead.

If you are new to sprinting you need to take it easy when getting started.

I mean reeeeaaaally easy.

If the last time you ran a sprint was the week before senior prom you need to be very cautious or you’ll probably get hurt.

Hill sprints place your body in a safer position than flat ground sprints because of the angle, so there is far less impact.

The risk of pulling a hammy or popping an Achilles or something in your knee is greatly reduced.

That’s one of the main reasons they’re better than flat ground sprints.

And of course, because Walter Payton did them.

Since he was my favorite athlete growing up (along with Michael Jordan) I started running hill sprints way back in the 80’s when I found out that that’s what “Sweetness” did (and that poster, pictured above, was on my bedroom wall for years. You see how ripped Payton was?).

Hill sprints bring out something that you can’t really get in the weight room, something that you really can’t get on the track. All the guys that I know that worked out on a hill, they were a cut above the other competition around the league and they had long careers.” – Mike Singletary

Another great thing about hill sprints versus other fat loss methods is that they also build muscle at the same time.

Can’t really say that for the stairmaster, can you?

Warm Up Properly

Wearing some neoprene knee sleeves might be a good idea just to keep the knees warm.

I recommend starting with about five to ten minutes of low intensity drills to get the body ready for the task at hand.

A good warm up might consist of:

• Jumping jacks

• Flings
• Seal jumps
• Ali shuffle
• Low pogo jumps
• High pogo jumps
• Prisoner squats
• Gate swings
• Wide outs
• Leg swings- front, back, side to side
• Walking lunges
• High knees
• Butt kicks
• Tuck jumps
• Lateral shuffling
• Skipping
• Etc.

The nice thing about sprinting up a hill is that you don’t require as much of a warm up.

After hitting 5-10 minutes of the drills listed above start with some lower intensity sprints. Do one at about 60%, then 70%, another at 80%, one more at 90% and then you’re ready to go.

Use the Appropriate Intensity

For the most part I recommend that your sprint work be done at around 95-97%. Very rarely should you go all out at 100%. I realize that the difference between 95-97% and 100% may seem very small but an athlete in tuned with his body can tell the difference.

And keeping the intensity just that much lower makes a big difference in overall recovery and CNS fatigue.

Again, if it’s your first sprint session in years you need to start way easier than you think. I recommend no more than FIVE sprints of no more than 20-40 yards the first day.

See how you feel after the first session and give it a go again in about five days. Slowly increase the intensity over time.

Rest periods can be as short or as long as you need them to be. You want to keep your heart rate elevated but you don’t want to rest so little that your form starts getting sloppy and you risk injury.

If you were training for speed you might be resting up to five minutes between each set. But since today’s topic is hill sprints for fat loss try to keep the rest periods a bit lower.

We don’t need complete CNS recovery here.

Sprint Mechanics

The next thing we need to discuss is proper running mechanics. This is where most people get it all wrong.

Since this is not a discussion on maximal speed training or mastering the 40 yard or 100 meter dash we won’t concern ourselves with the start so much.

Instead, to be safe, we will use flying starts, meaning you start by running at less than your maximal speed and work your way up to top speed over the course of 15-20 yards.

• Starting from the top down, the face must be relaxed. Do night clench your jaw or make any crazy faces. Relax.

• Keep the chest up and shoulders back and down.

• No side to side rotation of the pelvis, torso, shoulder girdle is allowed.

• Hips remain forward toward the finish line at all times.

• Arms should be bent ninety degrees with the hands open (no clenched fists or flailing, limp wrists).

• When you are running the arms must pump vigorously, forward and backward. NEVER LET THE ARMS CROSS THE MIDLINE OF THE BODY. Only forward and backward.

Little kids run with their arms side to side.

Don’t do that or we will all make fun of you.

• Think of pulling yourself through the air by driving your arms back as fast and hard as you can. The hands come up to a level even with the face and they come down and cross your pocket on the way back (but no further; don’t have them swinging way behind you).

• Drive the knees high and be sure that the foot strikes directly under your body; not out in front of you (although, on a hill this may be slightly different depending on the incline).

• Only the front portion of the foot should strike the ground; the heel should never make contact.

• When the ball of the foot makes contact with the ground think of yourself as an animal pawing at the ground and rapidly pulling it behind you.

• As Charlie Francis said, running takes place on the ground, sprinting takes place above it. If you do it right you should feel minimal impact or stress and should feel like you are flying effortlessly. If you’re taking a lot of pounding and it feels like a lot of work, you’re doing something wrong and should consider having someone watch or video tape you for some feedback.

What I listed above are basically the instructions for flat ground sprints but can easily be applied to the hill.

A few angles will change here and there but for the most part, if you follow those recommendations you’ll be ahead of the pack and your sprints will be a lot safer and faster.

So make like Walter Payton and Jerry Rice and go find yourself a hill to start sprinting up…

PS. Want an incredible body weight only workout to go along with your weekly hill sprint regimen? Check out Body Weight Body Building, which you can download right HERE.

Click HERE to download Body Weight Body Building right now.

High intensity workouts to burn fat

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