We all love HIIT, right? Well not necessarily all of us love it, but most of us know that high intensity interval training works. People like results, we will jump on anything that screams “you will see results” and without all of the gimmicks and infomercials that gaurentee a “tighter stomach in just 5 days and spend only 10 minutes a day” HIIT is easy to perform, and I love it because it can be performed in a number of different ways on a number of different cardio machines.  HIIT is a form of cardio in which moderate intervals are alternated with high intensity intervals. You can perform HIIT on a treadmill, elliptical, upright bike, stairmaster or even with no machines at all! (a OneFitFoodie Favorite) I call it Bodyweight HIIT

I know that mentally it may be hard for people to only spend 15 or 20 minutes performing cardio, and seeing that somewhat ‘lower’ calorie burn than you would if you were on the elliptical for 45 minutes. I myself used to be a slave to cardio, spending 45-60 minutes a day between the elliptical, stairmaster and treadmill. My body was overtrained. Here are some reasons why TOO much aerobic activity is a negative thing.

• Too much aerobic activity can cause the adrenal glands to become stressed in a way that can throw off balance leading to adrenal fatigue. Adrenal fatigue is associated with such symptoms as: tiredness, fearfulness, allergies, frequent influenza, arthritis, anxiety, depression, reduced memory, and difficulties in concentrating, insomnia, feeling worn-out, and inability to lose weight.
• Too much aerobic activity can also cause oxidative stress which casuses a breakdown of tissues in the body.
• Too much aerobic activity can cause excessive muscular fatigue which can n make it difficult  to perform everyday tasks and other physical activities. This can cause a muscular weakness.
• The dominant fiber type used is slow twitch, and too much cardio can cause the loss of fast twitch fibers, which are of extreme importance as you age due to the fast twitch fiber properties of speed and power.
• Too much aeorbic activity can cause overtraining and excessive, continual force throughout the body

The reason why HIIT works is because of the afterburn. People ask me all the time “how will HIIT allow me to lose more weight (or fat) when I am seeing less total calorie burn on the machine after a workout than when I would go for 45 minutes on the ET?”  HIIT causes your body to continue to burn AFTER your session and for the next several hours as well. EPOC is the science behind the post burn. EPOC stands for Exercise Post Oxygen Consumption. EPOC can last up to 35 hours after a HIIT session. When the EPOC is elevated, your body will burn calories far after your exercise session.

HIIT–> GREAT way to build up endurance:  Working at higher intensity means you are able to increase both your aerobic and anaerobic (without oxygen) endurance while burning more fat than before. Improving both aerobic and anaerobic endurance is very important for fitness. Most people understand the need to improve aerobic conditioning, but many people are unaware that the anaerobic energy system is what provides energy for all maximal effort up to 1 minute. Therefore to improve overall conditioning it is also important to improve anaerobic endurance

HIIT is not for everyone: I would not recommend HIIT training for those just starting out on an exercise program. It is a bit more of an intense form of exericse, therefore it is important to establish a solid base first. beginners CAN perform HIIT, but just not make it as intense. Before starting any High Intensity Interval Training (HIIT) program, you should be able to exercise for at least 20-30 minutes at 70-85% of your estimated maximum heart rate, without exhausting yourself or having problems.

Not for everyday: Just like anything else, it is possible to overtrain with HIIT. Because of the high intensity of HIIT workouts, it is not something that should be performed everday. Make sure you are giving your body adequate rest, fuel and hydration!