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9 Amazing Benefits of Interval Training (HIIT) – Backed by Science


HIIT or High Intensity Interval Training has taken the health, sport and fitness world by storm.

For most people, time is the most precious currency, if this sounds like you, HIIT is your new best friend.


If fact, one of my most successful transformation programs – The 30 Day HIIT Kick Start is based on just 10 minutes of HIIT training for 30 days. People are shocked about how much fat they lose after 30 days with these advanced HIIT workouts!


If you don’t currently use HIIT on a regular basis it is without doubt the quickest and most time effective strategy you can use to accelerate your fat loss and physique.

Here are 9 reasons you should be performing HIIT…

Reason #1: Enhanced Glycogen Storage

When it comes to performing high intensity activities, carbs are our main fuel source, stored in the muscle as glycogen.

Thus, to do more high intensity work in our main gym session or sport we need a larger reserve of muscle glycogen stores. Just like having a bigger gas tank in your car, your body can increase the size of its fuel reserves by using specific strategies such as HIIT.

This will allow you to train harder, for longer, without the onset of fatigue or reduced performance that you may normal experience near the end of your gym session. In addition, it’s going to allow for a greater carbohydrate tolerance, meaning you can eat more carbs and store them for fuel, rather than fat.

In this study, subjects performed repeated 30-seconds of all-out cycling efforts with 4 minutes of recovery between tests. The subjects completed 4 – 7  rounds of sprints per session, for a total of 3 sessions per week over a 2 weeks (Burgomaster et al., 2006).


What we see above is that following the 2 week HIIT protocol muscle glycogen stores are a whopping 50% higher throughout the day, both during rest and exercise! As mentioned, this confers many benefits for your performance in the gym, dieting flexibility and carbohydrate tolerance.

Reason #2: Improved Vo2 Max (Aerobic Fitness)

In research terms, your Vo2 max is a numerical calculation or test of your body’s ability to consume oxygen during exercise.

A higher VO2 max is a good thing because it means that your body can take in more oxygen and deliver it to your muscles, enabling you to perform longer and faster for a given effort.

Multiple studies have shown that HIIT increases Vo2 max, even in trained athletes. In fact, HIIT is now regarded as one of the best ways to increase your overall fitness and health (Paton et al., 2014; Nybo et al., 2012; Rakobowchuk et al., 2008)

In this study, participants performed 30 second all out sprints on the Wingate Bike, with a whole 4.5 minutes rest in between (if you’ve ever done this protocol, you will know why the rest period is so long!).

They performed three sessions per week for 4-7 intervals. The interval training group was compared to a endurance training group who cycled for 40-60 minutes three times per week. Time wise, the HIIT group do  2 – 3.5 minutes of actual exercise, compared to 40 – 60 minutes in the normal endurance group. Here’s the results…


Despite performing only 5 – 9% of the exercise time, the HIT group saw greater increases in Vo2 max (Burgomaster et al., 2008).

Even if you aren’t an endurance athlete, you could basically obtain similar health and fitness benefits without hours of cardio. In fact, less than 10 – 12 minutes per week to reap the same benefits as a whopping 2 – 3 hours of normal exercise!



Reason: #3: Greater Fat Burning

Long ago, people strived to be in the “fat-burning zone” with steady-state cardio. The goal of that session was not to run or exercise for longer or faster, but to try and burn more fat.

While this is somewhat of a myth, what if I told you that we can increase your fat burning efforts to a much greater extent, in only 10% of the time!

For 2 weeks and a total of 7 sessions, participants performed ten intervals on a bike. After the two weeks, the HIIT group’s whole body fat oxidation rates increased by a whopping 36% (Talanian et al., 2007). In other words, the HIIT taught their body to burn more fat during exercise for the long term.


This is not an uncommon finding in interval research, with HIIT consistently being shown to increase fat burning (Perry et al., 2008; Alkahtani et al., 2013). The ability to use and burn more fat in exercise is going to accelerate your fat loss in every future gym session!

It’s no wonder why people are getting so lean during the 90 Day Bikini plan, well, they are likely burning way more fat than you are, even when doing the same workouts!

Reason #4: Improved Body Composition

We all want to drop fat while retaining muscle. Whether you are looking to add large amounts of mass or just tone and firm up while dropping body fat, HIIT can help!

Interestingly, multiple studies have shown that HIIT is one of the few methods in the world to help you reduce fat mass while increasing lean mass, tested in both normal weight and overweight individuals (Trapp et al. 2008; Tremblay et al. 1994; Heydari et al. 2012; Sijie et al. 2012)

In this study, subjects who performed cycling sprints (8 seconds of sprinting and 12 seconds of slow rest) for 5-20 minutes over 15 weeks lost more abdominal and total body fat than the groups who did either no exercise or did 200% the amount of normal cardio exercise (Trapp et al., 2008).

Reason #5: Improved Capacity for Exercise

For anyone playing sport or doing more metabolic type weight training then they must improve their aerobic capacity, meaning the amount of work they can handle before fatigue, at a set intensity

By increasing our aerobic capacity we can go longer and harder, burning more calories in the time we have. Or, if we are competitive, it can help us to win a race or set a personal record. Even if you aren’t an athlete or play sport, by increasing your aerobic capacity we can perform more Metabolic Resistance Workouts, which are the superior method of training for fat loss!

Interestingly, using HIIT has been shown to increase the time to exhaustion with exercise, meaning that you can perform the same amount of work for a longer amount of time, a win win for fat loss and muscle growth (Gist et al., 2014; Gibala &McGee, 2009)

In this study, subjects doubled the length of time their performance could be maintained at a fixed intensity, increasing from approximately 26 to 51 minutes after only 6 HIT sessions over 2 weeks (Burgomaster et al., 2005).


Reason #6: Improved Insulin Sensitivity 

The prevalence of type 2 diabetes (T2D) is major world wide concern and is rapidly becoming an epidemic (Lam & Laroth, 2012). One major risk factor for developing diabetes is reduced insulin sensitivity (Forbes & Cooper, 2013).

In short, insulin sensitivity describes the ability of the hormone insulin to control the carbohydrates you eat and our body’s blood sugar levels. When this crucial process is disrupted or dysfunctional, serious health conditions and even death can occur.

For the normal healthy person, improved insulin sensitivity can help you shuttle carbohydrates into muscle cells and not fat stores.

Current recommendations for improving blood sugar and carbohydrate control involve performing moderate intensity aerobic and resistance exercise for several hours per week (12,13).

However, using HIIT exercise has now been shown to improve insulin sensitivity in a similar manner, with a much shorter time commitment (Richards et al., 2010; Gibala & Little, 2010).

In one study, subjects performed only 2–3 minutes of actual sprinting during 6 sessions. Insulin sensitivity, as measured by the Cederholm index, was improved by 23%, with significant reductions in other markers such as plasma insulin, glucose, and NEFA (Babraj et al., 2009).


Reason #7: Appetite Suppression

Another benefit of HIIT in your physique could lie in its ability to reduce hunger and appetite, two key factors in long-term weight loss success.

Current research suggests that a single exercise session likely affects your appetite regulating hormones by decreasing the hunger hormone ‘ghrelin’ and increasing peptide YY (PYY), glucagon-like peptide-1 (GLP-1), and pancreatic polypeptide (PP). These are all key hunger hormones, which play a role in controlling the brain’s hunger and fullness signals  (Hazell et al., 2016; Metcalfe et al., 2015)

HIIT Graphics-08


As these hormones are altered in a positive manner, HIIT may suppress hunger and reduces energy intake (Alkahtani et al., 2014, Crisp et al., 2012, Sim et al., 2014).

Remember, eating less total food or calories per day is the number 1 factor in fat loss, so again this research into HIIT demonstrates just another way in which it can enhance your physique and fat loss efforts!

Reason #8: HIIT is More Fun Than Cardio

Despite knowing all the health benefits from exercise, only 10 – 20% of us actually engage in regular  exercise. The remaining 80-90% will state “lack of time” and “lack of enjoyment” as  two contributing factors as to why they don’t hit the gym. As you have seen so far, time is really not an issue when it comes to HIIT, only requiring 10 – 30 minutes per week (Leslie et al., 1999; Stutts, 2002; Trost, Owen, Bauman, Sallis, & Brown, 2002).

While I admit, slogging away on a single cardio machine for 30 – 60 minutes, 3 times a week is pretty brain numbing, it doesn’t have to be this way.

When assessed in research, HIIT has been shown in multiple studies to be more enjoyable than steady-state cardio (Bartlett et al., 2011; Smith-Ryan, 2015)

For example, a recent study found that people tended to enjoy shorter, high-intensity bouts of exercise more than longer, steady-state activity (Bartlett et al., 2011).


As a result, if people enjoy the activity, they are more likely to adhere to a consistent regime and obtain the benefits of exercise. As i’ll always emphasize, you must build a sustainable and enjoyable plan. For most, HIIT can be more enjoyable and eliminate any time constraints!

Reason #9: You Boost your Metabolism & Get The ‘Afterburn’

By now, you can see the benefit of including interval training, performed on any form of cardio machine such as bike or running sprints. But what about lifting weights using an interval style of training, such as my Metabolic Resistance Training?

Your Resting Energy Expenditure (REE) is the largest component of the daily calorie or energy budget.

Therefore, any increase in REE in response to exercise could play a large role in weight loss, allowing you to eat more while burning fat. This is why many people joining the 90 Day Bikini Transformation plan switch to a diet eating 300 – 500 MORE calories while burning MORE fat (Take a look HERE for details).

One unique study compared a high-intensity interval resistance training method versus traditional resistance training. The HIIT (termed HIRT in this study) technique consisted of: 6 repetitions, 20 seconds rest, 2/3 repetitions, 20 seconds rest, 2/3 repetitions, sort of like a mini drop or giant set.

After they completed a full set they had 150 seconds rest and used three exercises for a total of 7 sets.

The other traditional training group consisted of eight exercises of 4 sets of 8–12 repetitions with one/two minutes rest with a total amount of 32 sets. So again, we are comparing only 7 sets against a whopping 32 sets!


As shown above, the HIRT group burned significantly more calories throughout the day after the workout and also increased the percentage of fat that burned, as seen in the graph on the right  (Paoli et al., 2012). This further demonstrates how my Metabolic Resistance Training can turbo charge your fat loss, increasing both the amount of fat burned in the workout and the amount of fat burned after the workout!

Add HIIT in Your Routine Today

If you’re not currently using HIIT now, then it is one of the quickest and most effective methods to accelerate your results!

Just 10 minutes per day can transform your training and results. If you want to learn more about programming and using HIIT for fat loss click HERE.

Best of all, you can join my 30 Day HIIT Kick Start workout, complete with a full 30 day home and gym HIIT workout plan, 7 day diet plans, supplements and my bonus ab shred guide all for the lost cost of $9 with this 80% off coupon!

This is possibly the most advanced HIIT fat loss program on the internet, condensed into 30 days and just 10 minutes of HIIT per day!

Click to claim your one-time discount coupon now…




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About the author


Rudy Mawer, MSc, CISSN

Rudy has a 1st class BSc in Exercise, Nutrition & Health and a Masters in Exercise & Nutrition Science from the University of Tampa. Rudy currently works as a Human Performance Researcher, Sports Nutritionist and Physique Coach. Over 7 years he has helped over 500 people around the world achieve long last physique transformations.

He now works closely with a variety of professional athletes and teams, including the NBA, USA Athletics, World Triathlon Gold Medalists, Hollywood Celebrities and IFBB Pro Bodybuilders. If you would like to get in contact or work with Rudy please contact him on social media.

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