HIIT – High Intensity Interval Training Explained

The training style I fell in love with from the first workout I ever did. This is HIIT – High Intensity Interval Training and it will transform your body in a way you never ever though it can.

If you want to achieve athletic body, with nice, toned and lean muscles, with ability to move your body in the most functional way, then HIIT workout is for you.

What is HIIT?

HIIT has exploded in the past years due to its promise of an efficient and effective way to meet fitness goals. Different trainers approach HIIT in a different way but the real HIIT always alternates short intervals of high intensity or your max effort with short intervals of rest or recovery. You can do HIIT with cardio exercises or you can do HIIT with any other bodyweight exercises. You can do HIIT in combination with cardio and strength exercises where you are using different portable equipment. HIIT is versatile and fun way of training. (1)

What many people love about HIIT is that it’s fast. If you’re willing to truly push yourself, you can squeeze an effective workout into 10 minutes and it will leave you breathless, sweaty and you will feel pumped and energized. All the good stuff, right?

Studies suggest that HIIT is much more effective than traditional cardio activities for burning fat and increasing both aerobic and anaerobic endurance. (1) With super fast switching from one exercise to another with little to no rest, you will constantly confuse and shock your body and it will never have time to adapt and go to “steady state” cardio. And this will give you an extra push to burn more calories and fat.

HIIT also offers you the “after burn” effect, which means you will burn your calories up to 48 hours after you have completed your workout. Steady state cardio will not give you this.

The most important aspect of HIIT is committing to the challenge. HIIT is hard. It takes a great deal of determination to sustain the level of output required to succeed. Sometimes my workouts are so challenging I want to quit. It hurts, it burns, my muscles are aching but then I refocus and ask myself what is my goal, what do I want to achieve and my motivation keeps me going. Sometimes I fail as well but it is ok. I get up and continue. And that is important. If we work hard, we will see results.

How HIIT actually works?

Although short in duration, HIIT has a big impact. Training at your maximum capacity for intense intervals in combination with short rest or active recovery will accomplish two goals: It will help accelerate fat loss and improve both aerobic and anaerobic endurance. HIIT causes your body to burn calories and lose fat in less time than traditional “steady state” training. (1) In traditional fitness approach (bodybuilding) is to do weights one day and cardio the next. With HIIT you mix those two training styles and thus your heart rate is elevated while the muscles are working. Not only is this efficient but it also develops strength under duress. (2)

The “high intensity” part of HIIT is key. You won’t see results if you’re not pushing yourself as hard as you possibly can during the work intervals of your HIIT routine. Studies have shown that just seven minutes of HIIT can create changes in your muscles at a molecular level that are comparable to one hour or more of jogging or cycling. But you have to work at maximal output.

The constant change of the “interval” part of HIIT is also critical. The brief rest periods allow your heart rate to come down and prevent your body from adapting to a steady workload. (1) With HIIT you can also achieve total fitness and well-rounded conditioning. What matters is training your body as a whole unit and not just one body part at once. Games and matches aren’t won or lost with one muscle group, end certainly life situations aren’t body-part specific. You need muscles for sure, but you also need coordination, endurance, agility and flexibility. (2) With ever changing HIIT routines you can get all those benefits and more.

The “after burn” effect or EPOC of HIIT will make sure you are burning calories also long time after the workout has been finished. EPOC (excess post-exercise oxygen consumption) is measurable increased rate of oxygen intake following strenuous activity intended to erase the body’s oxygen debt. In other words, your body will need to get back to the state it was before the start of a workout and it will need to bring the oxygen levels back to normal. For this to happen, your body will burn more calories. Your fatty acids are released and used as fuel for recovery. You cannot take advantage of this after burn by doing low-intensity exercise.

Most common question about HIIT is: “How do I know if I am working hard enough?” The answer is simple: During a HIIT you will not be able to answer a question in one go. You should be able to talk between short gasps of air, but if you are carrying on a conversation, you’re simply not working hard enough. (1)

What are the benefits?

Effective weight loss

One reason HIIT is so popular is that it promises measurable and sustainable weight loss. If you are willing to work hard and monitor your nutrition, HIIT really is more effective than other forms of exercises for losing weight.

It’s fast, fun and flexible

Most HIIT workouts last from 15-30 min and they can be done anywhere. So it is perfect choice if you are tight on time and can’t squeeze in full hour at the gym every day. (1) HIIT saves time and it can be super fun workout. You can combine all body weight exercises and equipped exercises in countless ways and combinations. The ever-changing format of these HIIT routines will provide a unique and fun stimulus and motivation. And they can be done anywhere.

Lose fat and not muscles

Studies show that HIIT workouts allow the preservation of muscle mass while losing weight through fat loss. This is because HIIT boosts testosterone and human growth hormone (HGH) levels, which are responsible for lean muscle gain and fat loss. HGH is also responsible for increasing your metabolism and stoking your fat burning furnace, but it also slows down the aging process. (1) And I must admit the last sentence really is true. A lot of people can’t really guess my age and I can proudly say I am currently 38 years old but I look much younger. I guess it must be HIIT and plant based nutrition.

HIIT for healthy heart

Most people have never worked as hard as HIIT demands. Pushing yourself into an anaerobic zone, where your heart is beating out of your chest, can actually improve your aerobic and anaerobic endurance. (1) During the short amount of given time (15-230 min) you will train your entire body, not just part of it, and you will be doing resistance training at the same time as you’re doing cardio. (2)

I was born with heart disease and by doing HIIT workouts my heart health improved drastically. Without HIIT I would have probably needed a surgery. I trained my heart step by step until it became stronger and stronger. And now I can do all this advanced workouts, which are very demanding.

Mitochondrial growth

The mitochondria are the power plants of your cell. They supply the cell’s energy and are also involved with regulating cell growth. HIIT triggers mitochondrial biogenesis, the process by which new mitochondria are formed within a cell. Mitochondrial biogenesis begins to decline with age, so the ability of HIIT to trigger this process could be described as age defying. (1)

HIIT really is a challenging workout when done to the best of your ability. For sure you will get uncomfortable, sweaty, sore and at times you might find it hard to continue. But HIIT is so much more than just a physical workout. It challenges you on other levels as well. It will make you stronger mentally. At times you will want to quit but through HIIT you will learn to push through the barriers and move on. This strength will enable you to strive for success in all areas of your life, not just your fitness. And that’s why HIIT is truly the most rewarding fitness method I came across.

(1): Sean Bartram: High Intensity Interval Training for Women (2015)

(2): Zuzka Light and Jeff O’Connell: 15 min to Fit: The Simple 30-day guide to Total Fitness; 15 min at a Tim (2015)