HIIT: PHYSIOLOGY OR FICTION?

I’m not sure about you but my dream workout would be one that I could do anywhere, burn a ton of calories and not take up a ton of time. High intensity interval training (HIIT) claims to meet all these criteria but is it too good to be true? As I was getting ready for spring break, knowing that an hour a day exercising would not be an option, I decided to look at HIIT in hope of finding a magic bullet.

What Is HIIT?

HIIT is any activity that alternates between high levels of activity and shorter periods of less intense activity. From a physiologic perspective, HIIT alternates between anaerobic and aerobic metabolism.

Anaerobic metabolism literally means ‘without oxygen’. During this type of exercise, the body uses glycogen, a carbohydrate, as it’s primary fuel and excess amounts of ATP (Adenosine Triphosphate) are created. The breakdown of ATP leads to a decrease in pH and a relative acidosis. That really doesn’t sound like burning fat to me. Looking a little deeper though, anaerobic metabolism helps burn fat for many hours after exercise as opposed to during exercise. EPOC, excess post exercise oxygen consumption, is the true measurement of the energy required to repair cells and stimulate fatty acid oxidation. This is what burns fat and increases metabolism.

Our bodies can only tolerate short bursts of anaerobic metabolism so alternating with aerobic activity keeps the muscles supplied with oxygen. The effect, more energy to exercise with less fatigue and more fat burning. HIIT has several other benefits as well.

• Increases cardiovascular endurance. After 8 weeks of HIIT, you will notice a significant increase in endurance. You can run faster, dance harder, jump higher.
• No equipment is needed. Just put your own maximum effort into all movements.
• Lose fat not muscle. The goal is feeling fit and being toned, not a number on the scale.
• Can do it anywhere. The only challenge is yourself.
• Slows aging. During increased metabolism, human growth hormone (HGH) is increase by up to 450%, this increases calorie burn but also slows aging.
• Once you reach your VO2 max (anaerobic) you cannot talk and you truly feel like you are working hard.
• Research shows that doing a HIIT workout for 15 minutes 3 times a week is more effective than jogging on a treadmill for an hour 3 times a week.

HIIT

After researching HIIT and looking at the components that make it effective, short bursts of high intensity followed by lower levels of exertion I decided that my favorite activity, REB3L Groove may actually meet these criteria. I put on my heart rate monitor and decided to take a look using myself as the test subject. My results confirmed it, Groove is a HIIT activity. The yellow spikes are my aerobic zones and the red spikes represent anaerobic metabolism.