Over the past few years High Intensity Interval Training (HIIT) has become extremely popular. Athletes swear by it as a form of cardio to get in shape for competition and conditioning for their sport and its recognized as an effective way to lose weight.
In a nutshell, HIIT training is short bursts of high intensity exercise followed by a recovery period of less intense exercise or rest. The goal is to get your heart rate up and push yourself as hard as you can during the intense interval, and not give your body full recovery during the less intense interval or rest. HIIT workouts can range anywhere from 4 minutes to 30 minutes depending on what your fitness goal and ability is and the workouts can incorporate rowing, running, cycling, agility and weight lifting.
The idea behind HIIT training is that it improves both aerobic and anaerobic energy systems. So what does that mean?
Your body uses different energy systems when you are exercising.
Long distance runners and endurance athletes primarily use their aerobic system. The aerobic energy system runs off oxygen and uses fat as energy after a certain amount of time. Once we’ve used up all the available oxygen to our muscles, we’ve hit our lactic threshold or Vo2 max. That’s the muscle cramping burning feeling that we know as lactic acid, or that I can’t move my legs because they are going to give out feeling.
At the other end of the spectrum we have the anaerobic system. This system does not use oxygen. Think short bursts of power and 100 meter track athletes. This energy system gets used up very quickly before our body has to switch over to the oxygen using aerobic system.
So how will training these two energy systems with HIIT make you leaner and in better shape?
1. Increases glucose metabolism: The break down of sugars.
This is a good thing with Type 2 Diabetes on the rise. Keeping your blood sugar in check on a daily basis is critical. HIIT training helps your body breakdown carbohydrates and improves your body’s sensitivity to insulin; when you’re more sensitive to insulin you don’t have to worry about your levels staying elevated and you don’t store as much fat to state it simply.
2. Improves fat oxidation: This is your body burning fat!
HIIT training has been shown to increase your body’s natural ability to burn fat and use it as a source of energy. Primarily your body likes to use glycogen (think carbs converted into usable energy) as its main fuel source. Since HIIT training is using more than one energy source you can tap into those fat stores more efficiently and burn the most possible.
3. Creates an after burn effect: This is known as EPOC, Excess post-exercise oxygen consumption.
This is all the extra calories your body is burning while it’s trying to get back to normal after your tough HIIT training. During HIIT you’re going to be pushing your body to its limit and it’s going to take some time to recover. This after burn turns your body into a calorie burning furnace and you can burn calories at rest for 12-48 hours after your workout.
Now lets look at the combination of those three benefits of HIIT training. (Outside of these three there are many more.) First we are going to stop the storage of excess fat through increased insulin sensitivity, then, were going to burn some of our fat stores to give us energy for our actual workout and last were going to continue to burn fat after our workout due to EPOC. With all 3 components HIIT training becomes the most effective and efficient way to get in top shape.
Now, what about all the stuff we’ve heard about long slow distance??
Straight up aerobic work has a place in your training as well. Since most fat oxidation takes place after the 30 minute training window adding in a couple long slow distance days (easy cardio longer than 30 minutes) will help reach your goals even faster. HIIT training takes time to recover from and CANNOT be done daily. Adding in an endurance workout can help push nutrients to your muscles through increased blood flow and will help with recovery
HIIT workouts can be done in a gym, the comfort of your home or outdoors. When doing your workout use a RPE (rate of perceived exertion) scale for you to base your intensity on the workout. A 1 is no activity whatsoever… as if you were sitting. A 10 is pushing yourself so hard you may collapse and there is no way you could ever push yourself any harder. For these workouts you will be exercising from a 4-9 on that scale. If you’re not tired after the workout then you didn’t push yourself hard enough. The intensity of these workouts is up to you. If you incorporate lifting into your schedule (which you should) put your lift days on the same days as your HIIT workouts or incorporate your lifting exercises into your HIIT workout.
A typical weekly schedule could look like this:
Monday: HIIT
Tuesday: Distance
Wednesday: OFF
Thursday: HIIT
Friday: Distance
Saturday: HIIT
Sunday: OFF
Here is a sample workout:
Total time: 24 minutes
5 min warm up RPE-5 (jog)
45 seconds RPE-8-9 (sprint)
1 minute RPE-5 (jog)
45 seconds RPE-8-9
1 minute RPE-5
45 seconds RPE-8-9
1 minute RPE-5
45 seconds RPE-8-9
1 minute RPE-5
45 seconds RPE-8-9
1 minute RPE-5
45 seconds RPE-8-9
1 minute RPE-5
45 seconds RPE-8-9
1 minute RPE-5
45 seconds RPE-8-9
1 minute RPE-5
5 min cool down RPE-5
