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Benefits of High Intensity Interval Training (HIIT)


High Intensity Interval Title

Most people don’t realize that overtraining can actually be worse for them than not exercising at all. This may sound crazy because I’m sure that you’ve heard the typical recommendation that everyone should exercise at least one hour every day, right?

In reality, nothing could be further from the truth!

Danger of Over-Exertion

Woman RunningNo activity better highlights the dangers of over-exertion than long-distance running. Dating back to Pheidippides, the ancient Greek icon who ran across the plains of Marathon to announce the Athenian victory over the Persian army, marathon running has been a point of controversy. Why? Because, upon his arrival, Pheidippides exclaimed, “Rejoice, we conquer,” and then dropped dead on the spot!

Although some claim that this traditional account is untrue, the fact that marathon running (and over-exertion in general) is quite dangerous for the human body has now become indisputable. According to Dr. James O’Keefe, head of Preventive Cardiology at the Mid America Heart Institute at Saint Luke’s Health System,

The heart pumps about 5 quarts per minute when we’re sitting. When we’re running it goes up to 25 to 30 quarts. The heart wasn’t meant to do that for hours, day in and day out. You end up overstretching the heart and tearing muscle fibers. Up to 30 percent of those who finish marathons have elevated troponin levels, which is a marker for heart damage. That’s the marker we look for to see if someone’s having a heart attack — it’s irrefutable evidence of heart damage.” (1)

This is one of the reasons why too much running has been linked to shortened life expectancy. In fact, a recent study has shown that long-distance runners have the same life span as couch potatoes! (2)

High Intensity Interval Training Gains Support

Thankfully, global health authorities are starting to catch on to a more effective way of exercising and have changed their activity recommendation to include high intensity interval training (HIIT workouts). The World Health Organization (WHO), for example, now advises:

“Adults aged 18–64 should do at least 150 minutes of moderate-intensity aerobic physical activity throughout the week or do at least 75 minutes of vigorous-intensity aerobic physical activity throughout the week or an equivalent combination of moderate and vigorous-intensity activity.” (3)

Although the WHO still recommends “moderate-intensity aerobic physical activity to 300 minutes per week,” or 60 minutes of cardio five times perweek, it’s encouraging to know that high intensity workouts are starting to receive the global attention that they deserves.

High Intensity Interval Training in a Nutshell

Burst ExercisesHigh intensity interval training combines short, high intensity bursts of exercise, with slow, recovery phases repeated throughout one short 15–20 minute session. It’s done at 85–100 percent of one’s maximum heart rate rather than 50–70 percent in moderate endurance activity. Essentially, burst training (as I like to call it) can be done anywhere, doing any type of exercise and is best described as working out like a sprinter rather than a marathon runner.

One of the major benefits of high intensity workouts is that they can be done in the comfort of your own home with no or minimal equipment.  An easy example a typical session would be going to a track and walking the curves and sprinting the straighter sections. If you prefer bike work, you can get on a spin bike and cycle at max speed for 20 seconds, go easy for 20 seconds, and then repeating that cycle for between 10 to 20 minutes.

Burst training isn’t necessarily new. Elite athletes and Olympians have known this secret to exercising and have been doing interval training for years. The research proves that anybody – not just elite athletes – can do it and achieve amazing results, no matter your experience or fitness level.

Watch this short video to find out what burst training (or my program, BurstFit) is, and then I’ll show you how easy it is to do it yourself at home!

Two Key Benefits of High Intensity Workouts

The reason why I like burst training so much is because it has been proven to have a positive global effect on the body.

1. Anti-AgingExercise is Anti-Aging

According to a paper presentation at the 2012 European Society of Cardiology annual meeting: (3)

  • There is a direct relationship between physical activity and life expectancy
  • Exercise can activate telomerase, a well-known anti-aging enzyme
  • A single workout can activate telomerase in circulating cells
  • High intensity interval training increases telomerase as well as reduces p53 expression, a very interesting protein in humans that contributes to premature aging and tumor suppression

In addition to affecting DNA, the wide variety of anti-aging HIIT benefits include:

  • Firmer skin/less wrinkles
  • Increased energy
  • Boosted metabolism
  • Improved libido
  • Muscle tone improvement
  • Reduced body fat

2. Balancing 3 Key Hormones with Burst Training

In addition to be “anti-aging,” the most important benefits of high intensity interval training is that it can help balance hormones responsible for weight gain and unhealthy eating habits.  

Sweet & Salty FoodsGhrelin

Ghrelin is the hormone responsible for long-term weight gain and short-term eating habits (aka the “munchies. Also know as the “hunger hormone,” it is produced in the stomach is believed to be the only hormone that can stimulate appetite. Essentially, it’s the main contributor to sweet, salty and fried food cravings. It is interesting to note that ghrelin also has the unique tendency to slow down fat usage and is a critical piece of the food reward-cascade controlled by the mesolimbic dopaminergic system in the brain. Some other key facts about ghrelin that you should know about are:

  • It is released directly in response to stressful situations, which explains why so many people have the tendency to eat when they are stressed. (4)
  • It perpetuates the stress-cycle, which contributes to weight gain.
  • It also “primes the brain” for post-traumatic stress disorder. (5)

According to UT Southwestern Medical Center Associate Professor Jeffrey Zigman, MD, PhD, ghrelin has such a profound on stress that, “This helps explain certain complex eating behaviors and may be one of the mechanisms by which obesity develops in people exposed to psychosocial stress.” (6)

Gas GaugeLeptin

Leptin is known as the “starvation hormone” because it gives you the sense of feeling “full.” By notifying your brain that you have eaten enough food, leptin is key to maintaining that your energy levels are sufficient. Normally, your fat cells produce just enough leptin to maintain the internal energy balance needed for vital cellular function and proper weight management. Typically, when people initially gain weight their blood leptin levels increase and weight loss will (generally) result as their body feels “full” quicker when eating food.  However, when people ignore these warning signs and eat beyond their comfort level, they become “leptin-resistant,” which contributes to further weight gain and obesity.

3 points to remember:

  • Ghrelin is a fast-acting hormone that plays a vital role in meal initiation and contributes to weight gain.
  • Leptin mediates long-term regulation of energy balance and suppresses food intake, thereby inducing weight loss.
  • High intensity training can control both hormones (and balances other hormones) naturally!

Research from the past decade continues to report that high intensity interval training actually balances both leptin and ghrelin, which increases fat burn and weight loss. In fact, burst training is one of the best ways to best manage unhealthy hunger behavior and maximize ghrelin and leptin to lose weight.


These four facts about hormones have perplexed researchers for years:

  • Elevated levels of testosterone promote weight loss.
  • Testosterone inhibits the release of leptin in the body.
  • Decreased levels of leptin promote weight gain.
  • Both hormones have been observed to increase after HIIT.

In theory, high intensity interval training produces a seesaw effect on these two key hormones that usually counteract against each other, but promote the same desirable weight loss effect. The question has been,

“Would the amount of leptin produced as a result of HIIT be enough to counteract testosterone’s ability to slow down leptin release?”

Well, according to a study published in the journal Endocrine, the answer is YES! (7) Apparently, high intensity workouts promote a very unique environment where leptin is relatively impervious to the negative effects of testosterone elevation, as no relationship between the two could be in a clinical trial. By doing burst training exercises, you’ll receive the benefit of both weight-loss promoting hormones!

In addition, Health and Exercise Science researchers out of the University of Bath (UK) have shown that various hormone levels in individuals who participated in burst training resulted in: (8)

  • Ghrelin declines after 30 min of recovery
  • Caused growth hormone (a hormone attributed to weight loss) incline, which suggests that burst training affects other hormones in addition to ghrelin & leptin

Just two from a myriad of research studies, it is becoming clearer than ever that high-intensity, burst training is quite effective at curbing several appetite and weight gain hormones

Woman doing pushupsImportant Note:

Like any activity, it is important to perform it in the most effective way.  The same is true for high intensity interval training. To maximize your burst training, it is best to exercise first thing every morning to control gherlin and leptin.

According to a study published in the Journal of Physiology, exercising on an empty stomach has also been shown to improve glucose tolerance and insulin sensitivity. (9) Not only contributing to type 2 diabetes prevention and weight loss, this has been proven to curb the munchies and the desire to eat unhealthy snacks in conjunction with ghrelin and leptin.

Read Next: 3 HIIT Workouts

From the sound of it, you might think leaky gut only affects the digestive system, but in reality it can affect more. Because Leaky Gut is so common, and such an enigma, I’m offering a free webinar on all things leaky gut. Click here to learn more about the webinar.

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