How can you increase fat burning with interval training?

The term "High Intensity Interval Training", or "HIIT" for short, has been circulating in the fitness scene for some time now. HIIT is based on the principle that short and intense training units are more effective than extended training units at low intensity. Numerous studies confirm the effectiveness of training consisting of short, very intense intervals followed by regenerative intervals. Classic cardio training is even said to have a comparatively negligible effect on body fat percentage. The effect on fat metabolism is a whopping 36% higher with a HIIT unit than a cardio session.

Why interval training is so effective

The reason for this enormous difference in terms of body fat percentage is seen in the so-called "afterburn effect". This is because intensive interval training causes the body to continue burning fat for up to 48 hours after the actual workout. What is particularly interesting, however, is that frequently repeated but short intensive intervals (13 x 30 seconds) followed by 15-second regenerative phases are more effective than longer training sessions with few repetitions (4 x 5-minute intensive intervals followed by 2.5-minute regenerative intervals). 

Get fit quickly with interval training

Are you a fan of high-intensity interval training (HIIT) or have you heard of it? Then you already know that it is a super fast and extremely effective workout. Basically, high-intensity interval training consists of short but intense training sessions that alternate with less intense movements or complete rest phases. It is highly effective. This means you spend less time in the gym and still reap all the benefits in terms of burning fat, boosting metabolism and heart rate. Still not convinced to try HIIT for yourself? Then read on and find out more.

Have you ever compared the physique of a first-class long-distance runner with that of a short-distance runner? The short-distance runner looks like a Greek Adonis: muscular arms and powerful thighs. The skinny long-distance runner, on the other hand, makes Richard Simmons, the American comedian, look like a participant in Mr. Olympia.

This difference in physique shows that not every cardio workout is structured in the same way. It is therefore important that you inform yourself in advance and choose the workout that best suits your desired goal. A recent study compared two training groups. One group completed a thirty-minute steady cardio workout three times a week. The other did high-intensity interval training (HIIT) three times a week for 20 minutes each time.

Both groups showed similar weight loss. The HIIT group also lost two percent body fat. In the cardio group, it was only 0.3 percent. In addition, the HIIT group gained two pounds of muscle mass, while the cardio group lost almost one pound.

Excessive aerobic training can lead to reduced testosterone levels, increase cortisol production, weaken the immune system, prevent strength gains and destroy any hope of getting bigger muscles. But that doesn't mean you can't increase your muscle mass and gain strength while you train. It just means that you should design your cardio workout carefully.

Familiarize yourself with different types of training and get in shape the smart way - without compromising on your strength or muscle building.

The triumph of interval training

Since the mid-1990s, numerous studies have shown the effectiveness of interval training in terms of fat burning. A Canadian study, for example, looked at the corresponding effects and compared interval training with traditional slow cardio training. The traditional cardio workout burned twice as many calories as interval training. Nevertheless, the test subjects lost more body fat during interval training.

Just recently, a study in the "Journal of Obesity" showed that 12 weeks of HIIT reduces body fat and increases muscle mass. It also showed a significant reduction in fat tissue in the abdomen and organs as well as a build-up of lean mass and aerobic performance. But the most astonishing thing was that the test subjects maintained their eating habits over the entire test period.

As fat loss mainly takes place in the kitchen, this study is further proof of the effectiveness of high-intensity interval training.

The spread of Tabata

Different types of Tabata are practiced all over the world: from fancy commercial gyms to sparsely furnished garages.

The training method is named after the Japanese scientist Izumi Tabata, who conducted intensive research into interval training. The method involves exercises that are performed at the limit for 20 seconds. This is followed by a rest phase of ten seconds. This sequence is repeated again and again - for a total of four minutes.

One of his most famous findings is the effectiveness in terms of maximum aerobic capacity (_VO2 max). Tabata was able to show that 20 seconds of cycling at the highest level followed by ten seconds of slow cycling for four minutes is just as effective as 45 minutes of slow cardio training four times a week.

As _VO2 max is generally considered the best indicator of an athlete's cardiovascular fitness and aerobic endurance capacity, this study was groundbreaking. It convincingly demonstrated that the positive health effects of traditional aerobic training can also be achieved with high-intensity interval training.

What does that mean for you? Lengthy training sessions are a thing of the past when you do a fast sprint instead of running slowly on a treadmill.

Caution: interval training only with moderation and purpose

But of course there are two sides to interval training. Just because you are advised to get a lean figure does not mean that you should do interval training every day. On the contrary, please don't do it.

Real interval training has nothing in common with a quick jog, you have to really push yourself. The central nervous system (CNS) is heavily stressed during this high-intensity workout and needs at least 48 hours to recover. Canadian sprint coach Charlie Francis compared the CNS to a cup of tea - you can only pour in a certain amount and then the cup overflows.

Too much training leads to overflow. Then you overstress your CNS and cause muscle damage, mechanical tension and metabolic stress. As with weightlifting, your body needs enough time to recover during interval training.

Interval training once a week can improve your body composition and endurance. If you are interested in a more intense workout, do interval training twice a week.

Breaks are an elementary component of interval training

What doesn't immediately spring to mind when you think of high-intensity interval training? Rest. But here comes the crux of HIIT: rest periods between individual exercises are a fundamental part of the workout - if you don't take the time to recover, you're not doing the training correctly.

The recovery phase between intervals is extremely important. Here's why: forcing your body to constantly alternate between peak performance and rest is an excellent cardio workout. When the body has to adapt from an anaerobic (high-intensity) phase to a low-intensity recovery phase within HIIT, this results in a loss of many calories, which can lead to fat loss. The body needs the rest phases to prepare for the next spurt and to perform at its best in the intensive phase.

Seven reasons why you should try high-intensity interval training

1. it strengthens the most important muscle

And that is undoubtedly your heart. According to Jordan Metzl, physician and author of the book "The Exercise Cure", your heart works harder as soon as you increase the intensity of your workout - as is the case with high-intensity interval training. The heart (like most other muscles) gets stronger when it is exercised regularly. That's why this workout is so beneficial for your heart health. According to a study by the American Council on Exercise, Tabata (high-intensity interval training, which consists of eight intervals performed within four minutes) promotes cardiovascular strength.

2. it is the fitness version of "take two, pay one"

Metzl explains that it may seem impossible to combine solid strength training and a calorie-burning cardio workout in one quick routine. But you are wrong. Interval training forces you to do your best and complete as many repetitions as possible in the allotted time. This will ensure that you reap the cardiovascular benefits of the training. Incorporate elements of strength training into your intervals (as well as cardio movements) and you will secure the muscle-strengthening benefits of the workout.

3. you can adapt the training to your fitness level

You don't have to perform intense movements with heavy dumbbells for 30 seconds and then only rest for 30 seconds - only a well-trained athlete would work at this level. If you are not yet ready for this challenge, there are many ways to adjust the effort-rest intervals and the exercises performed.

4. you don't need a gym

Eve Overland, Carrie Underwood's trainer, confirmed that she loves the possibilities of interval training and always puts together short training sessions for the country singer when she is on the road (and doesn't have access to a fully equipped gym).

5. you keep your blood sugar level in balance

A new study published in the journal Diabetologia suggests that interval training is better at keeping blood glucose levels under control in patients with type II diabetes than continuous exercise. 

6. you boost your metabolism

During a "continuous" workout, like a long run, your body uses less oxygen than when you push yourself to the limit, as is the case with HIIT. And when you get to the point where you find it hard to breathe (because your body is using more oxygen), your metabolism starts to work at a higher level, burning more calories during and after the workout. This effect is known as the 'afterburn'.

7. you burn more fat in less time

By constantly alternating between high-intensity and low-intensity phases, your anaerobic and aerobic fitness is strengthened. According to BJ Gaddour, certified strength trainer, fitness specialist and author of the Men's Health book Your Body is Your Barbell, this allows you to burn more fat in less time than with a longer workout.

Interval training is a great workout, but you should do more than that

And frankly, too much HIIT is not good at all. If you overdo it, you won't be able to perform at your best during the training session. Therefore, you should definitely not plan a HIIT session every day of the week. What is a better approach? Try HIIT twice a week and a moderate cardio workout on the other two days.

In addition, HIIT is not suitable for everyone. If you are pursuing a specific training goal or training for a competition, you need a program tailored to it. HIIT may or may not be part of that training program. Due to the high intensity of the workout, you should consult your doctor before starting HIIT - just like any other workout.

One last piece of advice: if you want to lose weight, remember the old adage: you can't train away bad eating habits, even if your workouts are more than strenuous. HIIT is not an excuse for a poor diet. Experts advise a clear strategy: calculate your daily calorie needs and plan carbohydrates around your workouts. If you incorporate effective HIIT into your training plan and eat a balanced diet, you will soon see impressive results.

What about walking?

Intensive interval training should only ever be practiced sparingly and for a short duration. You should therefore also walk as much as possible. After all, interval training performed at more than 75 percent intensity for longer than 30 minutes is detrimental to the intended benefits.

Therefore, low-impact walking is ideal for those days when you are not doing interval training. You'll improve your heart health and help your muscles and joints stay healthy. You'll even reduce stress.

You don't need to walk for more than 30 to 45 minutes a day, even 15 to 20 minutes is enough. Interval training paired with a few walking sessions a week will keep you slim and healthy and your pump running.

Who is interval training (high intensity interval training) suitable for?

However, it should be noted that such high-intensity interval training is not suitable for everyone. Training at the limit, even if only for a very short time, should only be carried out if you are in optimum health. A health check with a doctor is recommended. Regeneration phases should also be strictly adhered to. HIIT should be carried out a maximum of 2-3 times a week and for no longer than one hour to avoid overloading the body.

HIIT pushes exercisers to their physical limits, making it one of the most effective methods for building muscle and losing fat when performed correctly. In order to keep to the intervals as precisely as possible, there are various smartphone apps on the market that enable smooth interval training.

When you should avoid high-intensity interval training

If you feel tired and listless from the outset, interval training is not the right workout for you. It is often wrongly assumed that HIIT is always better than steady cardio training. Of course it is not.

HIIT is highly effective as it takes less time and burns calories during the resting phase. However, to get the full benefit of the workout, it needs to be approached with full energy. On days when you don't feel 100 percent fit or, more importantly, have sore muscles from previous workouts so there is a risk of muscle strain, continuous cardio training is likely to be more effective - and safer.

And finally, you have to ask yourself how often you can do a "proper" HIIT. It is true that HIIT can promote protein synthesis. However, it also causes protein breakdown. If you do several HIIT sessions per week, this could have the opposite effect. So while you lose weight overall, some of it would be due to muscle loss. If you want to build muscle mass, your main focus is still on strength training with HIIT as a supplement. A workout consisting of two strength training sessions and two HIIT sessions a week will not only keep you lean, but also ensure that you don't overtrain.

Remember: HIIT is short, intense and irregular and not a workout for every day.

 

Sources (in English):

Boutcher, S.H. (2011): High-intensity intermittent exercise and fat loss. Journal of Obesity, 2011: 868305,  doi: 10.1155/2011/868305

Rønnestad, B. R., Hansen, J., Vegge, G., Tønnessen, E. & Slettaløkken, G. (2015, April): Short intervals induce superior training adaptations compared with long intervals in cyclists – An effort-matched approach. Scandinavian Journal of Medicine & Science in Sports, 25(2):143-51, doi: 10.1111/sms.12165