High-Intensity Interval Training Makes Fitness Fast

Ever since Dr. Kenneth Cooper introduced the concept of aerobics, we’ve been conditioned to believe that steady-state exercise at a moderate pace is the best, perhaps only, way to increase cardiorespiratory fitness. Jogging, treadmills, and the like, done for 30 minutes or more at a time, have been deemed best. So, lots of people have spent countless hours doing these things, but it increasingly looks like they spent lots more time than they need have. The question is, why are you still jogging? High-intensity interval training makes fitness fast, much faster than jogging or other aerobic exercise. It’s simply more efficient.

High-intensity interval training

High-intensity interval training  abbreviated HIIT (or HIT), uses the intensity of exercise as the most important variable. Instead of steady-state, moderate-intensity exercise, HIIT has you going all-out for brief periods of time, followed by a short rest period, then another brief, all-out bout, and so on. While the exercise done in HIIT is much more intense, it’s also much shorter in time.

It’s been known for some time that HIIT is effective at increasing fitness, but what we would like to know is how it compares to moderate-intensity, steady-state exercise in that regard. Does it increase fitness as much?

To answer that, a group led by Martin Gibala, the exercise physiologist whose name has become linked to high-intensity exercise, studied a group of young, sedentary men.

Half the men did sprint-cycle interval training, consisting of three 20-second all out bouts of stationary cycling, interspersed with two minutes of low-intensity cycling.

Half the men did moderate-intensity cycling at 70% of their maximum heart rate, for 45 minutes.

Both groups worked out 3 times a week for 12 weeks.

According to standard exercise dogma, the moderate-intensity cyclists should have improved their fitness more. After all, they were doing aerobics (“cardio”), the HIIT exercisers were doing mainly anaerobic training, and took a lot less time.


  1. Peak oxygen uptake, a direct measure of cardiorespiratory fitness, increased 19% in both groups.
  2. Insulin sensitivity increased similarly in both groups, 4.9 in HIIT, 5.0 in moderate-intensity (no significant difference).
  3. Muscle mitochondrial content increased similarly in both groups.

The high-intensity group worked out a total of one minute per session, 3 x 20 seconds, with a total time commitment of 10 minutes per session when warm-up and time between all-out bouts are included. The moderate-intensity group worked out 45 minutes, or 50 minutes with warm-up and cool-down periods.

No more time excuse

The number one reason people give for not exercising is lack of time. This study shows that in less than 30 minutes a week, you can get in great shape. The aerobic, moderate-intensity group spent 2.5 hours a week to get the same results.

If you make your warm-up and cool-down periods shorter, as well as the intervals between bouts, you could get in shape in probably 15 minutes a week.

It’s intense

High-intensity interval training is intense. You have to give it everything you’ve got in those 3, 20 second intervals. For that reason, some people find it unpleasant.

Personally, I don’t find it unpleasant at all. However, I do enjoy walking as a form of low-intensity exercise. If you want to, you could certainly do both. Just keep in mind that if you do both, walking doesn’t generate the kind of intensity that increases the 3 indices of fitness: peak oxygen uptake, insulin sensitivity, and muscle mitochondria. You need to get over a threshold of intensity before that happens.

Aerobics dogma overturned

This study, along with others of a similar nature, shows you don’t need long hours of exercise to increase cardiorespiratory fitness. I think it also shows that, just as with lifting weights, intensity is the most important exercise variable.

Not volume. Intensity.

Exercise intensity lies on a continuum, from low (walking) to middle (jogging) to high (high-intensity intervals). Getting more fit depends on exceeding an intensity that makes your body work harder than it’s used to.

If you exercise with low to medium intensity, and become fitter, the only ways to increase your fitness are a) increase the amount of time exercising, or b) increase the intensity. Most people choose an increase in time, and some who want to get very fit end up spending hours and hours a week exercising. That’s not necessary. In HIIT, you are always working at the threshold of your physiological ability. So long as you exert the utmost effort when you do it, you will always be getting fitter without an increase in exercise time.


If you do another form of exercise, such as lifting weights, you should be aware that if you combine it with HIIT, it could be easy to get into a state of overtraining. I can attest to this myself. HIIT workouts ideally ought to be treated as a separate workout, separated from another by at least a day. Too much exercise isn’t healthy and your enjoyment of the rest of your life will decline due to fatigue. Of course, the amount of training an individual can handle varies based on age, current condition, diet, sleep, and other factors.

The exercise of the future?

Ever since the concept of aerobics came about, we’ve been stuck in a paradigm that the only way to increase fitness and decrease the risk of disease, especially heart disease, is to exercise aerobically. Is it a coincidence that the rise of aerobics coincides with the rise of the obesity epidemic? I don’t think it is a coincidence, although obviously other factors are involved.

Now that we know that long hours of plodding are not necessary for fitness and for protection against heart attacks, HIIT could be the wave of the future.

I’ve already embraced it thoroughly — and I used to be a distance runner.

HIIT It Hard for Your HGH Boost

This article was written and published on GarmaOnHealth.com by Joe Garma, and has been reproduced here in its entirety.

Our human growth hormone speedily decreases after adolescence, and with it goes the lean body mass, energy and healing capacities of our youth. You can supplement with HGH, but by far the best way to get your HGH boost is by high intensity interval training. In this post, I’ll tell you why this is so.

high-intensity-interval-trainingWHILE DOING some research for an “age-proof course” I’m developing, I wanted to get the skinny on whether Human Growth Hormone (“HGH”) supplementation actually works.

I knew that some people with hefty wallets can afford the cost of monthly injections, but was there some other way that the rest of us could benefit from augmenting our HGH?

“Why bother”, you ask?

Let’s start with a picture:

If you’re younger than 20, please return to this post in a few years. The rest of you, read on…

OK, so HGH declines precipitously soon after puberty, and then slows down by age 40, at which point we have less than a third of the HGH production of our youth.

Should we care?

It depends on what kind of life you wish to experience. HGH is rejuvenating. If you want to feel youthful longer, then your HGH production will be important to you.

The rejuvenating powers of HGH are no secret to those affluent enough to afford the more than $1,000 per month tab, and willing to get injected up to twice a day.

The specific reasons they would take the time and spend the money for HGH injections is to experience a handful or more of this:

  • Fat loss
  • Higher energy levels and enhanced sexual performance
  • Regrowth of heart, liver, spleen, kidneys, and other organs that shrink with age
  • Greater heart output and lowered blood pressure
  • Improved cholesterol profile, with higher HDL (“good”) cholesterol and lower LDL (“bad”) 
  • Superior immune function
  • Increased exercise performance
  • Better kidney function
  • Stronger bones
  • Faster wound healing
  • Younger, tighter skin
  • Hair regrowth

I’m going to tell you how HGH can do all this, but first I need to mention that there are now alternatives to expensive injections. One is easy to do, relatively inexpensive and controversial; the other is hard to do, costs basically nothing and is indisputable.

The easy, but controversial way to get your HGH boost is to supplement with homeopathic remedies.

The hard, but indisputable way to get your HGH boost is by HIIT – “High Intensity Interval Training”.

How HGH Works

Remember that bullet-list of magic results above? How does HGH make all that happen?

Let’s begin by presenting a basic description of what hormones are and how they work, and for that I’m going to rely on Jon Barron’s excellent ebook, Lessons from the Miracle Doctors (pages 78 and 79).

Hormones are the body’s chemical messenger system that tell the body what to do and when. As the name suggests, HGH is a hormone. It’s produced in the pituitary gland and released in a series of microscopic “pulses”, mostly in the evening, but throughout the day as well.

These HGH pulses are basically signals that instigate a number of body functions relative to aging and the production of other hormones, such as DHEA and melatonin, and various parts of the endocrine system, including the hypothalamus (considered to be the “master gland”).

HGH’s most important function is telling the liver to produce insulin-like growth factor 1 (“IGF- 1”), the main key to anti-aging. Specifically, the benefits of HGH can be measured in terms of how much it increases the body’s production of IGF-1.

Any number above a 20% increase in IGF-1 is significant as it relates to anti-aging.

What about prostrate cancer?prostrate cancer

Well, there were some in vitro studies that showed IGF-1 stimulated tumor cell growth, and a Harvard School of Public Health  study that equated high levels of IGF-1 with an increased risk of prostate cancer. In addition, we’ve all read with amazement stories about people nearly eight feet tall that die of cancer due to an overactive IGF-1 that stimulated both height and tumor cell growth.

On the other hand are numerous studies involving thousands of patients receiving growth hormone over many years with no observed increases in prostate cancer. This makes sense, because both HGH and IGF-1 levels decline as we age – as that graph up there prominently shows — yet the incidence of prostate cancer increases as these levels decline—the exact opposite of the expressed concern.

What about mad cow disease?

Yeah, well, that concern did put the brakes on using HGH harvested from human cadavers.

Thirty years ago, the only source of HGH was human cadavers. As mentioned, injecting this was expensive, but that paled in comparison to the fact that this method occasionally caused the human equivalent of mad cow disease.

Not to be deterred from such madness, scientists learned how to alter the DNA of a single-cell from yeast so that it would produce large amounts of growth hormone –molecularly identical to real HGH — safely and inexpensively. Because this growth hormone is identical to HGH, people often use the terms growth hormone and human growth hormone interchangeably, but it should be referred to as a “plant-based growth hormone.

OK, so now you have this good, inexpensive source of growth hormone, but another problem remained: the growth hormone molecule contains 191 amino acids, which it too large to be absorbed when taken orally. That meant it could only be administered by injection, which required a doctor and, as already pointed out, is very expensive.

Scientists and marketers went to work and developed three alternatives to HGH injections.

Homeopathic, Secretagogues and Sprayable HGH

If wallet-emptying injections are not for you, there are three alternatives to consider, hopefully with your doctor in the jump seat to help ensure that you don’t harm yourself.

The three HGH alternatives are not as powerful as growth hormone injections, but some medical types (see below) insist that these formulas are effective (provided your pituitary is functioning well) without the downside of injections.

The three HGH supplements are:
  1. HGH secretagogues, amino acid–based formulas typically containing ingredients such as glutamine, tyrosine, GABA, arginine, and lysine;
  2. Homeopathic HGH, which makes use of real plant-based HGH diluted down to homeopathic levels; and
  3. A new form of real plant-based HGH that could be sprayed into the mouth and absorbed orally.

The two downsides to the three HGH supplements are that they might not work and there’s little quality control.

The controversy surrounding all three can be more or less distilled down to the arguments against the effectiveness of homeopathic medicine.

Homeopathy is a branch of science whereby minute quantities of organic material are introduced into the body to stimulate its natural healing response.

My sister has used a whole medicine cabinet of various homeopathic remedies to heal her daughter of the typical avalanche of illnesses that beset children before their immune functions are fully developed. So, she’s a believer, and she has some good, if not sparse, company among the medical establishment.

Consider two medical doctors, Leon Cass Terry and Edmund Chein, who ran a study on homeopathy that produced
affirmative results. After being injected with small doses of high-frequency HGH for six months, participants showed measurable improvement in levels of strength, healing, flexibility, energy and vitality. (Source)

In his book Feeling Younger with Homeopathic HGH, Dr. H. A. Davis states,

When growth hormone is combined with homeopathic preparation, the results are truly on the leading edge of anti-aging benefits. People taking the homeopathic growth hormone have noticed the same effects as the molecular (injectable) HGH.


But, as mentioned, there are plenty of naysayers, particularly among those in mainstream medicine. On his popular site, Quackwatch, Dr. Stephen Barrett eviscerates homeopathic medicine, and concludes his post on Growth Hormone Schemes and Scams saying:

So called “growth-hormone releasers,” oral “growth hormone,” and “homeopathic HGH” products are fakes.

The bottom line here is: buyer beware.

High Intensity Interval Training

Most supplement formulas will increase IGF-1 levels by a minimum of 20%, with some even approaching 100%, if two things are true: Drs. Terry and Chein are right/Dr. Barrett is wrong; and the supplement you use maintains consistent quality batch after batch.

I have no direct experience with HGH supplementation, and therefore can not share anything personally about it. But when it comes to high intensity interval training (“HIIT”), I can breathlessly gasp that I pummel myself sprinting stairs twice a week, and it might be one contributing factor to why I seem to be aging more slowly than most.

The science backs up my gasp.

HIIT promotes longevity in at least two ways:
  1. It activates the enzyme telomerase which in turn keeps telomeres long ; and
  2. It boosts HGH and IGF-1 which reduce or reverse age-related degenerative processes. (Source.)

And get this… with HIIT we’re not talking an increase in IGF-1 increase of 20 or even 100%, but over 700% during the workout and for some hours afterwards.

Yes, it’s harder than spraying potions in your mouth, but with HIIT you’re assured that your HGH is increasing, and you’re getting fit to boot.

Here’s what to do for your HIIT sessions:
  • Choose an activity that you can get completely breathless, bent over heaving, after 30 seconds of full-out effort.
  • Perform up to eight sets of that activity, 30 seconds “on” and 90 seconds “off” with active rest, like walking.
  • Do it twice a week, unless you’re a well-conditioned athlete, as you’ll need time to recover.

I do my HIIT by sprinting stairs. I find that it’s easier on my Achilles tendons than sprinting on flat ground.  Drs. Mercola and Campbell use either a recumbent stationary bike or standing elliptical machine.

Sprinting up stairs boosts HGH production

Start slowly, even if you exercise regularly.  Do the first two or three at half speed.  I didn’t heed my own advice and wound up bruising an Achilles tendon which then sidelined me from HIIT for several months, so what did I achieve by pushing myself before my body was ready?

Don’t make this mistake.


Your Takeaway

Remember the following points:

  • Human Growth Hormone is what keeps us youthful.
  • It naturally declines real fast after puberty.
  • You can boost it by supplements and HIIT.
  • HITT works better and improves many other psychological conditions as well.

If you want to supplement, read what Web MD has to say about it, and then get a high-five from your doctor.

This article was written and published on GarmaOnHealth.com by Joe Garma, and has been reproduced here in its entirety.

The Importance of Exercise Intensity

Exercise is a uniquely beneficial health practice, one that improves health, decreases mortality, and that just generally improves overall quality of life. Anyone who exercises regularly knows the feeling of well-being that exercise causes, both during it and afterwards. But there are obviously both different kinds of exercise, and different levels of intensity. To improve physical fitness, the goal of exercise, one must pay attention to the importance of exercise intensity.

What exercise does

The effects of exercise are many. Exercise

  • improves insulin sensitivity
  • increases cardiorespiratory fitness (VO2max)
  • increases strength of bones and muscle
  • decreases risk of cardiovascular disease
  • decreases cancer risk
  • improves mental health
  • prevents frailty and decline in aging
  • helps weight control.

All of these effects are intertwined and can’t be readily separated.

The effects of exercise can be viewed according to the FITT principle: frequency, intensity, time (duration), and type.

For frequency, intensity, and duration, in general, the more the better, but it’s possible to overdo it. Why is that? Because exercise means the placing of stress on the body with the aim of improving health, and is therefore a form of hormesis, in which a low dose of a stressor or toxin results in better health and stress resistance. As such, exercise is characterized by the J-curve typical of hormesis; see chart below. (Source.)

Image result for exercise j-curve


A low to moderate amount of exercise improves health compared to being sedentary, while a very high amount (such as hard daily training at elite level athletics, or ultramarathon running, for example) can lead to overtraining and worse health. In this article, we’ll be concerned with how much exercise is necessary rather than with excessive exercise and overtraining.

Since exercise is by definition a stress, any physical activity that does not place a stress on the body doesn’t improve fitness. While any physical activity itself can improve health and is far better than being sedentary, aerobic (cardiorespiratory) fitness is a much stronger determinant of health. See chart below – aerobic capacity is twice as strong a reducer of cardiovascular risk as is physical activity.



Therefore, to lower your health risks, just moving around isn’t enough. The activity you do must be intense enough, or long enough, or frequent enough, or some combination of these, to increase fitness. Type of exercise is also important, since some forms of exercise are inherently more demanding than others. Boxing, for example, places a greater demand on the body than zumba.

Levels of exercise

Intensity of exercise appears partially to override the factors of frequency and duration. For example, higher intensity exercise improves aerobic fitness more than lower intensity, even when duration is adjusted so the the same number of calories are burned.

High-intensity interval training improves cardiorespiratory fitness as much or more than traditional steady-state aerobic exercise, in far less time.

In bodybuilding, other things equal, intensity trumps volume and frequency.

Low intensity exercise improves fitness only in people with a low level of fitness.  This is an important point.

Walking, for example, improves insulin sensitivity in obese, type 2 diabetics. These people have a low fitness level and high insulin resistance, and walking therefore represents enough of a stress on their bodies to improve their health.

Now, suppose you’re a regular reader of this site, you lift weights and/or do other forms of high-intensity training, you are of normal weight and have good insulin sensitivity. Will walking improve your health further?

Not likely. You need either more frequent exercise of the same intensity you’re already doing, a longer duration of it, or an even higher intensity.

Fitness level determines whether an exercise improves it

If you have low aerobic fitness, almost any exercise will help. Someone who’s been ill and in bed for a long time will improve just by getting out of bed. Likewise, walking can improve the fitness of someone who’s overweight and sedentary.

But how can we determine whether a given bout of exercise improves our fitness or not? In other words, how can we put this matter on a more scientific basis?

Exercise physiologists have done this, and have determined that exercise intensities below 45% of VO2 reserve in subjects with high fitness do not increase fitness, while for those with low fitness, at least 30% of VO2 reserve is necessary.

So, what’s VO2 reserve? It’s the difference between resting oxygen consumption (VO2) and maximum oxygen consumption (VO2max). VO2 reserve differs greatly between fit and less fit individuals.

In the real world, without the assistance of an exercise physiologist, probably the best way to look at exercise intensity is through metabolic equivalents, or METs.

One MET is the amount of energy expended at rest. Different types and intensities of exercise can be expressed in multiples of METs.


Image result for mets exercise chart

The above chart shows some sample exercises in terms of METs. A more comprehensive list can be found here.

High-intensity vs steady-state exercise

Steady-state exercise (“aerobics” or “cardio”) has long been prescribed as the exercise that uniquely increases cardiorespiratory fitness, but we now know that high-intensity exercise does that as well, and in less time.

One problem with steady-state exercise, such as jogging or treadmill running, is that the only way to increase the exercise stress is by increasing the duration of exercise. You see this method of training in distance runners, for example, who end up running for hours daily to increase the amount of training they do.

In contrast, using high-intensity training, you are always working out at the edge of your physiological capabilities.

So, with high-intensity training, there’s never a question whether you’re exercising intensely enough to increase your fitness, because you are always doing so.


Low-intensity exercise improves fitness only for those who are not fit. As you move up the fitness ladder, exercise needs to become more intense to improve fitness.

Best exercises for fat loss (not weight loss)

Weight Loss Vs. Fat Loss: Why The Scale Isn’t The Best Indicator Of Fitness

How many times have you heard someone say, “I need to lose weight?”

While that can certainly be a worthwhile endeavor, what they usually really mean to say is, “I want to lose fat.” Though most people use the terms weight loss and fat loss interchangeably, they are not in fact the same, and require different methods to achieve each goal. Here, we explain why fat loss — not weight loss — should be your primary focus, and why the typical methods used for weight loss may not always work for fat loss efforts.

Weight Loss

Our bodies are composed of primarily fat, muscle, water, bone and other tissue. All of these things combined make up our total weight. When someone says that they want to lose weight, they usually mean that they want to see a lower number on the scale. Thus, weight loss often comes from a combination of fat, muscle, and water to shift those pounds.

Depending on your fitness level, the average, healthy person’s weight comes from:

  • Muscle: 30 to 55% of body weight
  • Fat: 10-30% of body weight
  • Water (not in muscle or fat): 10-25%
  • Bone: 15% of body weight
  • Organs and tissues: 10-15%

Fat Loss

Fat loss is accomplished when we burn stored fat, while preserving or building muscle at the same time. Fat loss doesn’t always result in a lower number on the scale, but it will change the composition of your body. Some people think that fat can be turned into muscle through diet and exercise. You should be aware that this is a myth.

Losing Weight

losing weight- what matters

Most weight loss programs have you do two things:

  • Eat no more than 1200-1500 calories per day
  • Perform aerobic exercises 5-6 days per week

Any combination of drastically reducing calories and adding aerobic exercise will most certainly result in weight loss. The problem with this is that not all of the weight lost will be from fat. Some of it will be water weight, which is temporary, and some will be muscle. If you lose muscle along with fat, you’ll simply be a smaller version of your previous flabby self.

Aerobic exercises like jogging have their benefits. However, there are better cardiovascular exercises, such as HIIT-style full-body moves (including burpees, jump squats etc.), as well as things like swimming or uphill spinning, that will provide much better fat loss results.

Losing Fat

How To Burn Fat And Build Muscle With Training Complexes

Losing fat without also losing muscle is a bit more complicated than simply losing weight. Fat loss programs involve paying more attention to the types of foods you eat, rather than just focusing on reducing calories. They also includes different kinds of exercises that burn fat and preserve muscle at the same time, like weight-lifting and strength-training moves. This can sometimes lead to higher numbers on the scale, but the end result will be a smaller, more toned shape.

Why Muscle Matters

why muscle matters in losing weight or fat

Muscle burns more calories than fat even when you are doing nothing. This is called your basal metabolic rate, or BMR. One pound of muscle burns 6 calories per day, while one pound of fat burns only 2 pounds.

A study in the April 1999 issue of the Journal of the American College of Nutrition proved the calorie-burning benefits of muscle. The study put two groups of obese individuals on a very low-calorie diet. One group did only aerobic exercises four times per week while the other group did only resistance exercises three times per week. After 12 weeks, the aerobics group lost more weight than the resistance group. However, in the aerobics group almost one third of the weight lost was muscle. The resistance group lost only fat.

Even more importantly, the aerobics group’s resting metabolic rate was 210 calories less than it was before they lost weight. The resistance group’s resting metabolic rate was 63 calories more. What all of this means is that the more muscle you have the more calories you can eat to maintain or even lose fat.

Another important benefit of muscle is that it is less dense than fat. One pound of fat is four times larger than one pound of muscle. That means that someone who weighs 150 pounds of mostly fat will look larger than another person who weighs 150 pounds of mostly muscle.

The Best Way To Lose Fat (And Not Muscle)

The Best Way To Lose Fat (And Not Muscle)

  • Subtract no more than 500 calories from what you are currently eating
  • Add more protein to your diet and reduce refined carbohydrates
  • HIIT workouts 2-3 days per week
  • Strength training 2-3 days per week

Fat-Burning HIIT Workouts

Fat-Burning HIIT Workouts

Any activity that repeatedly raises then lowers the heart rate over a period of time can be considered HIIT (high-intensity interval training).

This can include basic sprints, spinning with sprints and/or hills,pylometrics, Tabatas, or bodyweight HIIT workouts that use a variety of exercises to give you a full-body workout with a cardio boost.

If your goal is to lose weight just to generally see a smaller number on the scale, eat fewer calories and exercise 5 to 6 days per week.

However, If you want to lose fat and build-calorie torching muscle, a combination of proper nutrition, HIIT workouts and strength-training is the most effective way to achieve a smaller, toned body.

7 Benefits of High-Intensity Interval Training (HIIT)

While most people know that physical activity is healthy, it’s estimated that about 30% of people worldwide don’t get enough (1).

Unless you have a physically demanding job, a dedicated fitness routine is likely your best bet for getting active.

Unfortunately, many people feel that they don’t have enough time to exercise (2, 3).

If this sounds like you, maybe it’s time to try high-intensity interval training (HIIT).

Young Woman Sprinting

HIIT is a broad term for workouts that involve short periods of intense exercise alternated with recovery periods.

One of the biggest advantages of HIIT is that you can get maximal health benefits in minimal time.

This article explains what HIIT is and examines 7 of its top health benefits.

What Is High-Intensity Interval Training?

HIIT involves short bursts of intense exercise alternated with low-intensity recovery periods. Interestingly, it is perhaps the most time-efficient way to exercise (4, 5).

Typically, a HIIT workout will range from 10 to 30 minutes in duration (4).

Despite how short the workout is, it can produce health benefits similar to twice as much moderate-intensity exercise (6, 7).

The actual activity being performed varies but can include sprinting, biking, jump rope or other body weight exercises.

For example, a HIIT workout using a stationary exercise bike could consist of 30 seconds of cycling as fast as possible against high resistance, followed by several minutes of slow, easy cycling with low resistance.

This would be considered one “round” or “repetition” of HIIT, and you would typically complete 4 to 6 repetitions in one workout (4).

The specific amount of time you exercise and recover will vary based on the activity you choose and how intensely you are exercising.

Regardless of how it is implemented, high-intensity intervals should involve short periods of vigorous exercise that make your heart rate speed up (4, 8).

Not only does HIIT provide the benefits of longer-duration exercise in a much shorter amount of time — it may also provide some unique health benefits (4).

1. HIIT Can Burn a Lot of Calories in a Short Amount of Time

Hand Holding a Stopwatch

You can burn calories quickly using HIIT (9, 10).

One study compared the calories burned during 30 minutes each of HIIT, weight training, running and biking.

The researchers found that HIIT burned 25–30% more calories than the other forms of exercise (9).

In this study, a HIIT repetition consisted of 20 seconds of maximal effort, followed by 40 seconds of rest.

This means that the participants were actually only exercising for 1/3 of the time that the running and biking groups were.

Although each workout session was 30 minutes long in this study, it is common for HIIT workouts to be much shorter than traditional exercise sessions.

This is because HIIT allows you to burn about the same amount of calories, but spend less time exercising.

Summary: HIIT may help you burn more calories than traditional exercise, or burn the same amount of calories in a shorter amount of time.

2. Your Metabolic Rate Is Higher for Hours After Exercise

One of the ways HIIT helps you burn calories actually comes after you are done exercising.

Several studies have demonstrated HIIT’s impressive ability to increase your metabolic rate for hours after exercise (11, 12, 13).

Some researchers have even found that HIIT increases your metabolism after exercise more so than jogging and weight training (11).

In the same study, HIIT was also found to shift the body’s metabolism toward using fat for energy rather than carbs.

Another study showed that just two minutes of HIIT in the form of sprints increased metabolism over 24 hours as much as 30 minutes of running (14).

Summary: Due to the intensity of the workout, HIIT can elevate your metabolism for hours after exercise. This results in additional calories being burned even after you have finished exercising.

3. It Can Help You Lose Fat

Tape Measure

Studies have shown that HIIT can help you lose fat.

One review looked at 13 experiments and 424 overweight and obese adults.

Interestingly, it found that both HIIT and traditional moderate-intensity exercise can reduce body fat and waist circumference (15).

Additionally, one study found that people performing HIIT three times per week for 20 minutes per session lost 4.4 pounds, or 2 kgs, of body fat in 12 weeks — without any dietary changes (16).

Perhaps more important was the 17% reduction in visceral fat, or the disease-promoting fat surrounding your internal organs.

Several other studies also indicate that body fat can be reduced with HIIT, despite the relatively low time commitment (17, 18, 19).

However, like other forms of exercise, HIIT may be most effective for fat loss in those who are overweight or obese (20, 21).

Summary: High-intensity intervals can produce similar fat loss to traditional endurance exercise, even with a much smaller time commitment. They can also reduce unhealthy visceral fat.

4. You Might Gain Muscle Using HIIT

In addition to helping with fat loss, HIIT could help increase muscle mass in certain individuals (16, 21, 22, 23).

However, the gain in muscle mass is primarily in the muscles being used the most, often the trunk and legs (16, 21, 23).

Additionally, it’s important to note that increases in muscle mass are more likely to occur in individuals who were less active to begin with (24).

Some research in active individuals has failed to show higher muscle mass after HIIT programs (25).

Weight training continues to be the “gold standard” form of exercise to increase muscle mass, but high-intensity intervals could support a small amount of muscle growth (24, 26).

Summary: If you are not very active, you may gain some muscle by starting HIIT but not as much as if you performed weight training.

5. HIIT Can Improve Oxygen Consumption

Man Looking at His Watch While Working Out

Oxygen consumption refers to your muscles’ ability to use oxygen, and endurance training is typically used to improve your oxygen consumption.

Traditionally, this consists of long sessions of continuous running or cycling at a steady rate.

However, it appears that HIIT can produce the same benefits in a shorter amount of time (20, 21, 27).

One study found that five weeks of HIIT workouts performed four days per week for 20 minutes each session improved oxygen consumption by 9% (6).

This was almost identical to the improvement in oxygen consumption in the other group in the study, who cycled continuously for 40 minutes per day, four days per week.

Another study found that eight weeks of exercising on the stationary bike using traditional exercise or HIIT increased oxygen consumption by about 25% (7).

Once again, the total time exercising was much different between groups: 120 minutes per week for the traditional exercise versus only 60 minutes per week of HIIT.

Additional studies also demonstrate that HIIT can improve oxygen consumption (25, 28).

Summary: High-intensity interval training can improve oxygen consumption as much as traditional endurance training, even if you only exercise about half as long.

6. It Can Reduce Heart Rate and Blood Pressure

Heart and Blood Pressure Measurement

HIIT may have important health benefits, as well.

A large amount of research has indicated that it can reduce heart rate and blood pressure in overweight and obese individuals, who often have high blood pressure (20).

One study found that eight weeks of HIIT on a stationary bike decreased blood pressure as much as traditional continuous endurance training in adults with high blood pressure (7).

In this study, the endurance training group exercised four days per week for 30 minutes per day, but the HIIT group only exercised three times per week for 20 minutes per day.

Some researchers have found that HIIT may even reduce blood pressure more than the frequently recommended moderate-intensity exercise (29).

However, it appears that high-intensity exercise does not typically change blood pressure in normal-weight individuals with normal blood pressure (20).

Summary: HIIT can reduce blood pressure and heart rate, primarily in overweight or obese individuals with high blood pressure.

7. Blood Sugar Can Be Reduced by HIIT

Blood sugar can be reduced by HIIT programs lasting less than 12 weeks (20, 30).

A summary of 50 different studies found that not only does HIIT reduce blood sugar, but it also improves insulin resistance more than traditional continuous exercise (31).

Based on this information, it is possible that high-intensity exercise is particularly beneficial for those at risk for type 2 diabetes (31).

In fact, some experiments specifically in individuals with type 2 diabetes have demonstrated the effectiveness of HIIT for improving blood sugar (32).

However, even research in healthy individuals indicates that HIIT may be able to improve insulin resistance more than traditional continuous exercise (27).

Summary: High-intensity interval training may be especially beneficial for those needing to improve blood sugar and insulin sensitivity. These improvements have been seen in both healthy and ailing individuals.

How to Get Started With HIIT

Woman Exercising and Monitoring Progress

There are many ways to add high-intensity intervals to your exercise routine, so it isn’t hard to get started.

To begin, you just need to choose your activity (running, biking, jumping, etc.).

Then, you can experiment with different durations of exercise and recovery, or how long you are performing intense exercise and how long you are recovering.

Here are a few simple examples of HIIT workouts:

  • Using a stationary bike, pedal as hard and fast as possible for 30 seconds. Then, pedal at a slow, easy pace for two to four minutes. Repeat this pattern for 15 to 30 minutes.
  • After jogging to warm up, sprint as fast as you can for 15 seconds. Then, walk or jog at a slow pace for one to two minutes. Repeat this pattern for 10 to 20 minutes.
  • Perform squat jumps as quickly as possible for 30 to 90 seconds. Then, stand or walk for 30 to 90 seconds. Repeat this pattern for 10 to 20 minutes.

While these examples can get you started, you should modify your own routine based on your own preferences.

Summary: There are many ways to implement HIIT into your exercise routine. Experiment to find which routine is best for you.

The Bottom Line

High-intensity interval training is a very efficient way to exercise, and may help you burn more calories than you would with other forms of exercise.

Some of the calories burned from high-intensity intervals come from a higher metabolism, which lasts for hours after exercise.

Overall, HIIT produces many of the same health benefits as other forms of exercise in a shorter amount of time.

These benefits include lower body fat, heart rate and blood pressure. HIIT may also help lower blood sugar and improve insulin sensitivity.

So, if you are short on time and want to get active, you may want to consider trying high-intensity interval training.

Best High Intensity Interval Training workouts for Longevity

High-intensity interval training , also called HIIT workouts, have become known in the fitness and medical world as one of the most effective means of improving cardiovascular health, respiratory endurance, as well as metabolic function.

HIIT workouts are known to be an excellent way to burn fat in a short period of time and to help improve the physical performance of athletes of all kinds. (1)

For most people, because it’s one of the great metabolism boosters, the biggest draw to a HIIT workout is its ability to keep the body burning fat even after the workout is over.

What Are HIIT Workouts?

High-intensity interval training is a type of exercise that involves repeated short bouts of high-intensity, or “burst” exercises, followed by brief recovery periods. This sequence is repeated several times in a row usually for a duration between 20–30 minutes.

Considering the fact that many people use “not having enough time” as a popular reason to avoid regularly exercising, HIIT workouts are one of the best ways to overcome this block and get great results fast.

A HIIT protocol is a well-researched way to reap physical benefits as an alternative approach to steady-state exercise training but with less of a time commitment. (2)

For example, recently a study compared the impact of two different types of exercise training on body fat and muscle metabolism: HIIT workouts versus steady-state exercise.

The study investigated the effects of calorie expenditure and fat loss in young adults and found that although HIIT workouts actually burned fewer calories during the actual workouts than did steady-state cardio exercise (likely due to its shorter duration), the HIIT program produced more fat loss than steady-state exercise did overall.

Additionally, the study concluded that while the HIIT workout helped build muscle, the steady-state workouts actually broke muscle down. Researchers concluded that not only does HIIT burn more fat over the duration of the day, but it also builds more muscle and improves metabolic function. (3)

How to Perform HIIT Workouts … and Why

The exact type of exercise performed during the “intense” internal periods can vary, such as performing sprints or doing faster reps of a particular move. What stays the same throughout different types of HIIT programs? The act of performing these stop-and-go intervals, meaning alternating between periods of hard “work” and “rest” or recovery.

A popular example of a HIIT workout can be running on the treadmill, alternating between a very fast pace and one that is easier and slower. In order to follow an interval schedule, you switch between sprints that require roughly 90 percent of your energy, followed by walking or slowly jogging to rest and recover.

Steady-state exercises, on the other hand, usually stay within the same type of “work” zone over time, with the amount of effort needed remaining consistent. (4)

HIIT Workouts Provide Benefits Fast

HIIT workouts have the ability to transform your body and physical abilities due to their effect on at least three important systems within the body:

  1. Your cardiovascular health and endurance
  2. Your body’s ability to use oxygen
  3. Your hormone levels

Studies have shown that resistance-based interval training specifically benefits blood flow and blood vessel dilation. A study, published in the American Journal of Physiology — Heart and Circulatory Physiology, found that resistance-based interval exercising improved endothelial function in individuals that previously exercised, those that didn’t and those with type 2 diabetes.

When researchers measured blood flow before, immediately following and at one and two hours after working out, participants with type 2 diabetes saw improvements at each time. The other two participant groups experienced improvements one and/or two hours after exercising. (5)

 HIIT Workouts Boost Cardiovascular Health 

Many studies are now showing that internal training — including HIIT workouts — promote greater improvements in VO2max and general fitness abilities than steady-state exercises do.

In fact, VO2max is considered the best indicator of cardiovascular endurance. This is the measurement most commonly used in fitness studies to show the effects that the exercise is having on the body. VO2 max is sometimes also called “max oxygen uptake” or “max aerobic activity” and is used to measure how well the body can use oxygen for energy.

Specifically, VO2max is defined as the maximum amount of oxygen (in milliliters) that a person can use in one minute per kilogram of their body weight. This measurement is important because the amount of oxygen that a person can utilize within one minute is an indicator of their overall fitness level and also their lung and heart health.

Due to the expansion of blood volume, the heart will undergo enlarging, or “hypertrophy,” during HIIT type of endurance exercises in order to allow the heart muscle to become bigger and stronger. (6)

By pushing your heart rate high during periods of intense work, you’ll be able to increase your cardiovascular ability and strengthen your heart. During the short rest intervals, you work on recovering more quickly and needing less time to rest. This is how you build stamina over time and increase your ability to perform physical exercises more effectively.

Performing short recovery segments in between the intervals where you’re working harder has the benefit of allowing you to keep the overall workout intensity high while still maintaining form.

While it’s hard to work very hard and maintain a high heart rate for an extended period of time because your body isn’t able to bring in enough oxygen, the rest/recovery periods of interval training allow you to catch your breath and for your heart rate to come down momentarily.

Knowing your VO2 max can help you to establish fitness goals to work towards and gives you a starting point as to how capable you are of maintaining a high level of effort over a period of time.

HIIT Workouts Trigger an Excess Post-Exercise Oxygen (EPOC) Effect

HIIT workouts also trigger something known as excess post-exercise oxygen consumption, or “EPOC.” EPOC is the phenomenon of an increased rate of oxygen that your body uses following strenuous activity (7).

Your body uses more oxygen after hard workouts like those performed during HIIT because it’s making up for the body’s “oxygen deficit” that occurred during the difficult “burst” periods of the exercise. EPOC has many functions for the body, including that following a HIIT workout, your body goes into a recovery phase.

A higher level of oxygen is needed during recovery in order to facilitate in the restoration of hormone levels, refueling your glucose stores, and repairing your muscle fibers and tissue.

The best part about EPOC? It’s accompanied by an elevated need for bodily “fuel” or energy in addition to more oxygen. After intense exercise, fat stores within your body are actually broken down and free fatty acids are released into the bloodstream. During the post-workout recovery phase, these free fatty acids become oxidized and your body uses them for energy.

As your body uses more oxygen to bring itself back into a resting state, more calories are burned in the process, even while you are done working out. This means you continue to experience benefits and fat loss during the remainder of your day following a HIIT workout.

Another benefit of EPOC that results from HIIT workouts? New ATP (adenosine triphosphate) — which is the fuel source or energy that your body works off of — is also synthesized. Additionally, post-exercise oxygen is used to reduce lactic acid.

Lactic acid is formed during exercise and is responsible for giving you the “burning” feeling in your muscles when they are working hard.

Lactic acid travels via the bloodstream to the kidneys, cardiac muscle and liver during workouts; then an increased amount of oxygen is necessary to convert the lactic acid back to pyruvic acid so that your pain subsides and body enters a resting state.

Yet another use of EPOC is to fuel the body’s increased metabolism that results from the increase in body temperature experienced during exercise. Due to all of these vital tasks that the body must undergo during a period of EPOC, you can see why HIIT workouts have such a huge effect on your strength, stamina and health.

HIIT Workouts Release Muscle-Growth and Fat-Burning Hormones

Intense interval training circuits also stimulate muscle-building hormones while simultaneously using up calories and burning fat. The body produces the growth hormone known as IGF-1 during HIIT, for example, which allows the body to build lean mass muscle.

Who Are HIIT Workouts For?

Certain studies have shown that high-intensity exercise can be potentially unsafe for sedentary middle-aged adults. It’s best performed by those who are already somewhat active and have a healthy cardiovascular system.

That being said, anyone can work towards practicing HIIT workouts for their multiple benefits. However, if you aren’t already exercising, then it’s best to start slowly to avoid injury or more serious problems.

In conclusion, an exercise plan that includes consistent high-intensity interval exercise has been shown to improve body composition, boost cardio-metabolic health, lessen the risk for heart disease, and help improve exercise tolerance, even in obese and overweight participants. (8)

Research has shown that HIIT workouts are safe, efficient, well-tolerated and could help to improve adherence to exercise training given the limited time commitment that they require.

As long as you practice HIIT workouts responsibly and ease your way into a HIIT program, you can experience great results using HIIT workouts in combination with other forms of exercise that you enjoy.

How to Build Your Own HIIT Workout

No matter what your exercise preference is — whether running, biking, swimming or lifting weights, for example — you can practice HIIT workouts to improve your abilities. Even seasoned athletes use HIIT workouts to gain stamina and bust through plateaus that they are experiencing after practicing one particular type of exercise for a long time.

HIIT workouts are a great way to “shock” your muscles and to kick your body into high gear, allowing you to continue experiencing results and improvements after your body has gotten accustomed to your usual workout routine.

According to studies, it’s believed that an optimal HIIT workout produces maximum cardiovascular benefits when athletes spend at least several minutes per session in their “red zone” — yhis generally means reaching at least 90 percent of maximal oxygen uptake (VO2max).

In order to estimate when you are working at 90 percent of your VO2max, you can think about your level of perceived effort on a 1–10 scale; you should be aiming to give it “your all” and reach a score of nine out of a possible 10 for at least a few minutes during a 20–30 minute HIIT workout. (10)

In addition to focusing on your perceived level of effort and targeting a high VO2max, there are also other variables to consider.

Keep these physiological variables in mind, which researchers have noted are all-important for practicing HIIT workouts and continuing to show improvements:

  • The amount of time you spent in your “intense” working interval 

The longer you spend in your intense zone, the more of an effect the exercise will have. Start off with shorter bursts of intense periods and increase the duration as you build strength and stamina.

  • The amount of time you spent in your “rest” and recovery interval 

You will likely notice that you need less time to recover as your body adapts to HIIT workouts. Pay attention to how long of rests you are taking and aim to shorten the restful period duration as your abilities improve.

  • The amount of reps you perform during your intense bursts 

Instead of aiming to improve the duration of time you spend in an intense interval, you can also focus on how many reps you are able to do in a row, for example, or your speed of work.

You will likely notice your ability to do reps quickly improves as you become accustomed to HIIT workouts and that you need less recovery time in between sets. You may also notice that your sprints get quicker or your cycling pace gets faster if you choose to run or bike during your HIIT workout.

  • The total number of interval series you are able to perform 

It’s a good idea to start out with about 15–20 minutes of HIIT intervals and work your way up to 25–30 minutes if you’d like. The more your body gets used to the intensity, the more series you’ll be able to perform and your total workout length will increase.

  • The time needed between HIIT workouts 

Most experts recommend practicing HIIT workouts 2–3 times per week, but not much more than this. The body needs an adequate break period between HIIT workouts to fully repair and grow stronger.

In fact, this is just as important as the workout itself and if you fail to properly give yourself enough rest, you miss out on some of the benefits of HIIT.

That being said, you will improve your ability to practice HIIT workouts closer to each other as your recovery periods become shorter. Even after you’ve seen great improvements, it’s still best to allow 48 hours in between HIIT workouts and avoid practicing them multiple days in a row.


How to do a HIIT workout


Three HIIT Workouts to GET YOU MOVING!

Keeping all of the above factors in mind, you can start practicing HIIT workouts using one of these example plans:

Treadmill Running HIIT Workout 

  1. Start with a warm up by lightly jogging for three minutes.
  2. Next, move into your interval period for about 10 minutes. Each minute you will do 20 seconds of intense work followed by 40 seconds of recovery. (Do this 10 times to start out, and as you become more fit you can increase to 15 minutes and beyond. If you’d like to challenge yourself more, do 30 seconds of intense bursts followed by 30 seconds of rest.)
  3. Cool down with a 3 minute jog.

Cycling HIIT Workout

This cycling interval workout is based on the “tabata” style of exercise, which usually consists of 20 seconds of hard work followed by 10 seconds of rest. In order to do interval training, this same ratio can be used in any other form of exercise as well.

  1. Start by cycling at a restful pace for three minutes to warm up.
  2. Move into your interval period for the next 10 minutes, where you will be cycling as hard as you possibly can for 20 seconds and then resting for 10 seconds. You can use a timer to keep track of the time or count in your head. Repeat this interval schedule 10–20 times depending on your abilities and current fitness level.
  3. Cool down with a slow, restful three minutes of cycling.

Circuit Training HIIT Workout 1

The three exercise moves below will make up your “intense” interval, then performing an easier form of cardio afterwards will make up your “rest” interval.

  1. Perform the following three exercise moves back-to-back according these reps: Start by doing 10 reps of each, then repeat the cycle doing 15 reps of each, then repeat the cycle doing 20 reps of each. Don’t take any breaks until after you’ve gone through all three sets.
  • Burpees
  • Mountain Climbers
  • Jumping Jacks
  • (In place of these 3 moves, you could also try performing fast alternating lunges, push-ups or kettlebell swings.)
  1. After you’ve completed these three sets, do a form of steady-state cardio for about three minutes. This can mean jogging, running in place, hopping on an exercise bike, etc. You want to be working at about half of your ability.

Bonus Advanced HIIT Workout: Circuit Training HIIT Style!

  1. Go through each move described below for an intense 20 seconds, moving very quickly through as many reps as you can perform in 20 seconds, followed by 10 seconds of rest. Then move on to the next move following the same timing. Once you’ve completed each move below, you are done with one intense interval.
  • Push-ups
  • Bodyweight Rows
  • Squats
  • Jumping Rope
  • Burpees
  • Jumping Jacks
  • Running in Place
  • Medicine Ball Chest Passes
  • Jumping Lunges
  • Planks
  1. Rest for two minutes after the circuit is complete. Then go through the entire circuit another two times or until you lose proper form.


Keep it Fresh

Is your exercise routine getting boring or just not providing the same kind of results as it once did? If so, you might wanna look into interval training.It doesn’t matter what you like to do… running, zamba, swimming, spin classes, etc. All you have to do to incorporate interval training is to push it extremely hard for a few minutes, then slow it down or rest for a few minutes (or maybe seconds).

What’s this do? You’re stressing the heck out of your cardiovascular system, that’s what! Why would you want to do that? Your muscles build up something called lactic acid. This acid improves your stamina, energy and strength. So while you’re on the down swing and easy mode (or rest) your body is actually preparing for the next push.

Professional athletes or at least life-long athletes have been using interval training for years. They know it’s the key to getting quick results and constantly improving your athletic ability. But for the general population, it’s still relatively new. Let’s look at why you should incorporate interval training into your routine…

It’s been shown that if you use interval training to its fullest, you can greatly improve your athletic ability. Your body learns to maximize the use of oxygen to gain energy when you need it – much better than if you always maintained the same level of difficulty in an exercise session. As your body learns to process oxygen better, you get stronger. You get faster. You up your game dramatically.

Are You Ready for Interval Training?

Of course, if you’re a beginner who has just started to exercise routinely then you may need to wait a bit before you try to push yourself too hard in interval training. You need to have a solid base level of physical fitness or you’re very likely going to risk injuries. If you don’t have any health conditions, shoot for 30-40 minutes of exercise several times per week at least. When you’ve been doing that and are comfortable with it, aim to get to a heart rate of 220 minus your age. i.e. if you’re 20, then aim for 200. That’s how you can figure your max heart rate.

Start Interval Training

Ok, you’ve been exercising regularly and you’ve established a healthy, strong fitness base. It’s time to up the ante. But don’t do interval training everyday. Your body needs 24/48 hours to fully recover from such intense exercise. Also keep in mind that with interval training, you’ll burn quite a bit more carbs than before. That means you should feed some extra carbs back into your body to refuel and recover. Don’t go crazy, but get a few hundred grams definitely.

Don’t Crash and Burn

When you start doing intervals you want to make sure that you’ll be able to finish. If you’re running, do a strong fast run during the high-intensity portions, but don’t flat out sprint if that means you won’t be able to finish. By being able to finish, we mean two things: You want to be able to finish the last few seconds high-intensity portions with the same speed and strength as the fist few seconds. You also want the last high-intensity portion to be as strong as the first one of the day. Remember it doesn’t have to be an ‘all or nothing’ type of thing. Some research has shown just as good results with medium-intensity portions as high-intensity. Just make sure you’re getting in those short burst of oomph!