HIIT Training: The What and Why
HIIT Training is a very broad scope style of exercises that is referred to as High Intensity Interval Training. This is not defined by 1 exercise type. In truth, you can turn anything into a HIIT workout. Let’s break it down. High Intensity: this is defined by effort. You are putting a maximal effort out to create high intensity. It is not defined by heart rate, but if it was, we’d say 85-100% of your maximal heart rate (220-your age). However, this could also be put on a perceived effort scale. If 1 is laying down, and 10 is getting ready to throw up, High Intensity would sit between a 7-9. Ok, but you can’t do that forever, so how long? Well, let’s look at the next part, Interval. Interval is a rep or timing sequence that defines a work (or heavy work) phase or a rest (low intensity) phase. This can be defined by time, reps, or heart rate. Time is your easiest bet. Work hard for a short period of time, and rest or work light for a short period of time. So, in the basic definition, HIIT is working at a high intensity for a period of time and working at a low intensity for a period of time. So, what does that mean, and is it better or different than non interval based exercise.
Let’s get this out of the way, so you keep reading… research does show that HIIT workouts can be as effective if not more effective than longer steady state workouts. So get ready to work. Why does it work? There are probably multiple reasons, from energy system to muscle fiber type usage, but the easy answer is this… It is easier to work harder if it is for a shorter time. Mind blowing, I know. If I say run as fast as you can for 20 seconds, you’ll give a good effort. If I say run as fast as you can for 5 minutes, it will turn into a moderate effort, it has to! So, If I can go all out and then get a little break, that is more incentivizing to most people then just ongoing effort. It’s a law of averages. Option 1, I run for 30 minutes at 70% heart rate max. Option 2, I work 30 second high, 30 second low for 30 minutes. The high is at 90%, low is at 50%, then both will average 70%. However, take into consideration that it will take 15-30 seconds of the low phase just to get the heart rate to drop to 50%. So, you will actually average to something in the vicinity of 80-82% effort. That will likely burn the same calories in 15-20 minutes that the steady state burned in 30. There you go, more calories, less time, and a fun competition against yourself during the intervals.
So what exercises can I use? Well, anything, but to be the most effective, it will need to be multi joint and require a reasonable effort. That being said, the only thing that eliminates is probably biceps curls, tricep extensions, and abs. But, you can use anything from calisthenics, large compound strength exercises, cardio machines, or good ol fashion running. My current favorite is sled pushes or kettlebell swings. But what are the intervals?
Here there is no magic recipe, but this is the basic template.
Do intervals from 10-20 minutes. (Longer than this and fatigue begins to diminish the high effort).
Keep intervals at 30 seconds or less. They can be higher, but for maximal effort, you want an attainable goal.
Start with a ratio of 1-2 effort to recovery. Give the highest effort you can for the high interval, but stay moving for the low interval. 1-2 ratio for example would be 10 second effort and 20 second recovery. If you are just starting out, or performing a complex athletic pattern such as sprints or box jumps, you can do a 1-3 or 1-4 ratio.
Eventually progress to a 1-1 or 2-1 ratio. 2-1 is the ratio of the famed “Tabata” interval. That is 20 sec work and 10 sec rest for 8 rounds. As the ratios get closer together or inverse, consider taking the recovery as a no effort rest. Trust me, your heart will still be pumping.
Warm up please! High intensity means you are shooting for maximal contraction. To avoid injury, you have to prime the nervous system and tissue to that kind of effort. Going all out when you are unprepared or cold is a recipe for injury. So take 5 minutes to do moderate effort in the exercise that you are planning to use for your HIIT to prepare yourself. Scale up the intervals as you go. The first couple intervals should be 75-90% before you start hitting your perceived 100% efforts.
Finally, recover! 10-20 minutes may not seem like much, but 100% effort taxes the nervous system and the musculature more that you think. Recovery is where muscle grows and fat continues to burn. So if all you do is crush HIIT workouts everyday, you may find yourself tired, sore, and hitting a weight plateau. Use moderate cardio, mobility such as yoga, sleep, meditation, and proper nutrition to reinforce the effort and help you recover for you next workout.
I could probably ramble on for a while, but I am sure you are already bored :) So work hard, work safe, and keep moving.
Ryan Golec | Director of Movement and Education