SHOULD YOU DO HIIT TO GET FIT?

Have you ever found yourself at the gym on an elliptical or treadmill wondering if there was better and faster way to do cardio for fat loss? A new style of training known as high intensity interval training (HIIT) might just be your solution. Many fitness bloggers who advocate HIIT say that it is better than moderate intensity steady state (MISS) cardio because it burns more calories in a shorter amount of time as well as increases your metabolism and burns calories even after you are done working out due to something called the EPOC effect. On the other hand, there are some people who say that moderate intensity steady state cardio is better than HIIT cardio because MISS primarily uses lipids as a fuel source, and therefore burns more fat. But is one really better than the other?

In 1996, Dr. Izumi Tabata performed a study on the effects of moderate intensity training and HIIT, in order to better understand which method was more effective for preparing olympic athletes for events. For his experiment, he studied two groups. The first group exercised at 70% of their VO2max  five times a week on a treadmill. He compared this protocol with the Tabata protocol and found that the Tabata group was exercising at an intensity of 170% VO2max.  In the end, the two groups both had increases in aerobic capacity, but when anaerobic fitness was analyzed, the Tabata protocol group increased by 28% while the other group remained the same.  This means that high-intensity interval training actually improves both anaerobic (muscle building) and aerobic (fat burning) body systems, while moderate intensity exercise only improves the aerobic system. Additionally, the Tabata group lost more weight on average and gained more muscle than the MISS group. The results obtained from this study ultimately helped legitimize a movement away from chronic cardio and toward high-intensity workouts.

SO, WHAT IS HIIT?

HIIT is a type of training in which intensity and heart rate is varied throughout a workout, as opposed to MISS which is exercising on a treadmill, elliptical, etc. and maintaining your heart rate around 125 bpm for 30 to 60 minutes. During the high intensity intervals, your heart rate should be around at least 160 beats per minute, and during the low intensity intervals around 100 bpm. A typical HIIT workout might look something like this:

Exercise 1: Push-ups

Exercise 2: Jump Squats

Exercise 3: Burpees

Exercise 4: V-ups

Start with push-ups. Perform them for 20 seconds at a high-intensity. Rest for 10 seconds, and then go back to doing push-ups for 20 seconds. Once you complete eight sets of push-ups, rest for one minute. Next, move on to jump squats and repeat the sequence of 20 seconds on, 10 seconds off. Once you finish eight sets of jump squats, rest for one minute, and then do burpees. After burpees, finish the workout with V-ups.

EPOC: Excess Post-Exercise Oxygen Consumption

Since you burn roughly the same amount of calories during a HIIT and MISS workout, The big debate over HIIT vs MISS cardio for fat loss comes down to how many calories you burn after a workout. Most of the misinformation circulating around HIIT vs MISS cardio is centered around EPOC. This term simply refers to the process of restoring your body to a normal resting state after exercising. During this time, your body uses energy and burns calories while recovering and building muscle. The big debate is whether the EPOC after doing a HIIT workout has significant effects on weight loss or not. One fitness blogger said that “new age Tabata style workouts burn 50-70 calories during a workout and 300-400 post workout over the next 24 hours.” The truth is, you are more likely to burn around 300 calories during a HIIT workout and about 40 after. The claim made above would require an EPOC of over 100%, and since EPOC generally doesn’t surpass 30%, this claim was clearly not based on scientific evidence, and can be very misleading to uniformed readers. One study  reported an EPOC of 25% after a very intense and strenuous high intensity workout and 10% after a moderate intensity workout, but even though high intensity workouts have a higher EPOC than moderate intensity workouts, the amount of additional calories burned due to the EPOC effect is not very significant. It is important to keep in mind that although these numbers may appear to be convincing, the difference in calories burned, is only about 30 calories, which is much easier to achieve simply by dieting.

Even though the EPOC theory turned out to be false after all, one study  did show that HIIT training increases muscle mass and therefore increases the capacity to burn fat, so in the long run, HIIT could actually be booting your metabolism.  HIIT also has a lot of other health benefits to offer. For example, one study found that HIIT training greatly improved cardiovascular endurance and that subjects who went through two weeks of HIIT training experienced a drop in their resting heart rate, indicating better cardiovascular health. Some people forget that their heart is a muscle. If you keep it beating at a constant rate, then it doesn’t have to work harder, and therefore it isn’t getting any stronger. This can be a problem for people who regularly stick to the elliptical or treadmill and never reach at least 80% of their max heart rate.

Overall, there is not a big difference in the number of calories burned between HIIT and steady-state cardio, but HIIT may have some additional anaerobic and cardiovascular health benefits. Deciding whether to do HIIT versus MISS can also depend on a variety of other factors. For example, your diet. If you are on a low carb diet, or are carb cycling, you may want to do a MISS workout on low carb days rather than a HIIT workout because HIIT requires a lot of carbohydrate (glucose and glycogen), whereas MISS primarily uses lipids for energy. Also, if you are doing weightlifting in addition to cardio, MISS might be a better option because HIIT offers some of the same benefits as weightlifting. Another thing to consider is that HIIT is very strenuous, and it may be challenging to jump right into an advanced HIIT workout especially if you are just beginning an exercise program. That being said, if you are the type of person who prefers weightlifting and doesn’t need to incorporate as many body weight exercises into your workout regime to build muscle, then by all means, stick to weightlifting and steady state cardio. However, if you like doing HIIT workouts either because they take less time to do or because they don’t require any fancy gym equipment, that’s also fine. Whatever your personal fitness goals and workout preferences are, the most important thing is always to listen to your body and do what’s best for you.

 

Questions and comments:

Which do you personally prefer, HIIT or MISS?

If you previously did HIIT because you believed you were burning hundreds of calories post-workout, do you think you will still continue doing HIIT now that you know the after burn effect isn’t true?

Comment below if you’d like to share any thoughts about HIIT or if you have any questions.

Thanks for reading:)

 

Recommended Further Reading

Metabolic adaptations to short-term high intensity training: a little pain for a lot of gain,

Effect of Exercise Intensity, Duration and Mode on Post-Exercise Oxygen Consumption

Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max

8 Benefits of High-Intensity Interval Training (HIIT)

High-intensity interval training for health and fitness: can less be more?

Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women

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