The Nitty Gritty:
What is HIIT?
High Intensity Interval Training. Short bursts of intense exercise alternated with active rest.
- LISS – Low Intensity Steady State (HR under 130)
- MISS & MIIT – Moderate Intensity Steady State & Moderate Intensity Interval Training (HR 130-160)
- HIIT – High Intensity Interval Training (HR 160-180)
Why is HIIT so effective?
- Ramps up metabolism for hours after the HIIT session.
- Sessions are short and only a few times per week.
- Less time in a catabolic state.
- Recruits all muscle fiber types.
- HIIT retains and/ or builds muscle.
- HIIT may be Anti-Aging.
Should I only do HIIT cardio and nothing else?
Nope! A combo is best to work into your program. Individuals will have various needs to reach their goals.
How do I use the above cardio options?
- I use a combo starting with the addition of HIIT.
- Do cardio after lifting sessions or in a separate session.
It’s Not Nice to HIIT!!!
If you have ever done HIIT training, you know it isn’t nice! It’s torture but for only a short period of time and then you are done. For those of you that don’t know what HIIT is, it is a form of cardio that torches calories not only during the HIIT session, but for hours after your workout.
yeah, that’s me being awkward sprinting on the beach.
What is HIIT?
HIIT is an acronym for High Intensity Interval Training.
HIIT works like this: work in a 1:3 work rest ratio where you sprint all out as fast as you can go for 20-30 seconds, then slow jog or walk for 60-90 seconds. Repeat for the allotted number of intervals (interval times vary per program). You should reach your max heart rate by the 2nd or 3rd interval and on. If you can go beyond 30 seconds, you are not going hard enough.
Usually in the last 5-10 seconds of each sprint interval I want to quit big time due to the fact that I am convinced I am going to die or just plain fall off the treadmill (true fear and almost did once). I currently prefer HIIT by battlropes, sled, spin bike, sprinting outside or in a large gym area. If I have to sprint on a treadmill, I put in at a steep incline so that I don’t have to max out the speed to get that “I am about to pass out” feeling.
Doing HIIT feels like this: (all within 20 seconds mind you)…
0-5 seconds: You start and your inner Ninja Jedi kicks in and says ” I can do this!”
5-10 seconds: Then, the breathlessness and burning creeps in but it’s still doable. You are determined to finish strong… this is the fountain of youth!!! (you’ll see why if you keep on reading).
10-15 seconds: Then you get really winded, you are sure you are going to die if your interval timer doesn’t go off soon and you think “OH MY QUAD! Please END SOON”
15-20 seconds: Your interval timer finally beeps for some active rest when really you just keel over heaving as if you were having an asthma attack.
If you get through it, you are done in 15 minutes including warm up and you have just burned cals and ramped up your metabolism for the next several hours.
You can use many different types of exercises for HIIT such as a bike, treadmill (increase the incline for more of a challenge), battle ropes, sleds, box jumps and such. My fav is to just plain run outside but. In MN, there are a few tundra like months that make it even worse so, to the gym I go.
Why torture yourself with HIIT if it is SO flippin hard? There are many many reasons why HIIT is a great tool to keep in your fitness arsenal. But first, let’s see what our other options are.
Cardio in general is an effective way to create a calorie deficit aside from cutting calories. You can only cut so many calories from your diet before it becomes unhealthy (like under 1200 calories per day) . But, you CAN go overboard with cardio as well.
There are a few different types of cardio you can utilize:
LISS: Low Intensity Steady State. Heart rate under 130
MISS: Moderate Intensity Steady State Cardio. Heart Rate 130-150
MIIT: Medium Intensity Interval Training. Heart rate 140-165
HIIT: High Intensity Interval Training. Heart rate 160-180
Low Intensity Steady State (LISS) cardio is typically done at a constant pace for an 30-60 minutes or more keeping heart rate less than 65% of VO2 max. Usually under 130 beats per minute.
LISS is a great intensity for the body to utilize energy from fat (ref.1), which is why many will do this first thing in the morning fasted. Sounds easy right… here’s the catch.
During any type of cardio, your body is in a catabolic state. This means your body is not only breaking down fat but also breaking down muscle tissue. That’s bad news bears for a natural bodybuilder, bikini to physique! Being in this state for 1 hour a day every day is not ideal for muscle retention and, it takes up a lot more time to expend the same amount of calories compared to medium or high intensity cardio.
LISS also only engages type 1 muscle fibers (slow twitch) and does not active type 2 (fast twitch).
So, LISS is good for fat burning, bad for activating all muscle fibers.
Moderate Intensity Steady State cardio is typically done at 65%-70% of VO2 max keeping your heart rate in the range of 130-150 BPM.
Research has shown that fat oxidation (fat burning) is highest during MISS cardio (ref. 2). And, MISS cardio will effectively burn calories needed in a shorter time duration than LISS, thus, being in a catabolic state for less time.
Medium Intensity Interval Training is done in a similar VO2 max as MISS with the same benefits but, MIIT is done as intervals rather than as steady state. Heart rate range is around 140-165.
An example of MIIT would be doing a fast jog (hard but not all out as you would do for HIIT) for 45-60 seconds on with 1 min active rest like slow jogging or walking, then repeat.
High Intensity Interval Training cardio is done by alternating very high intensity cardio with an active rest period. Target heart rate range is typically 160-180 BPM or around 85% VO2 max.
HITT cardio is typically done with a 1:3 work rest ratio by going as hard as you can possibly go for 20-30 seconds, then actively resting such as slow jog or fast walk for 60-90 seconds, then repeat. That 20-30 second interval should be hard and you should be so winded you can’t easily talk until you actively rest. Don’t forget to warm up before hand!
HIIT should not exceed 30 minutes, averaging about 15- 20 minutes total
HIIT should be utilized 1- 3x per week.
In contest prep, HIIT may be utilized far more than above when closer to a show but only for short periods of time, like weeks, not months.
HIIT sessions can include sprints, incline sprints on treadmill, biking, car pushes, battle ropes, tire flips, rowing and so on.
Why is HIIT so EPOC?
First, EPOC is an acronym for Excess Post-Exercise Oxygen Consumption. This essentially means your body is burning more calories post exercise throughout the day. Score! Now, it is known that energy during high intensity cardio comes from stored muscle glycogen and not from fatty acids (or stored fat). So then what’s all this noise about HIIT? Well, lipolysis (fat burning) happens when energy expenditure exceeds caloric intake. (ref. 3) If you are burning more calories than you are eating, your body will utilize those saddle bags for energy (duh right?). And, the major upside to HIIT, as previously stated…. is that your metabolism is ramped up for hours after the HIIT session burning more calories! Bonus!
- HIIT boosts the metabolism burning extra calories for hours after your workout (ref 9).
- Spend less time in a catabolic state. HIIT sessions are much shorter than LISS and MISS so, the time that the body is in a catabolic state is much less thus minimizing muscle tissue break down.
- Less wear and tear on your body. You can obtain the same cardiovascular benefits as you would doing longer lower intensity sessions such as running for an hour which saves on time and your joints!
- Recruits all muscle fiber types. The intensity of HIIT cardio also recruits all muscle fiber types (I, II, IIa- slow twitch and fast twitch) where LISS only utilizes slow twitch fibers. (ref. 4)
- HIIT retains and/ or builds muscle. Testosterone is optimized. I stress optimized… not raised to manly levels causing you to look like big foot okay… okay. As mentioned above, Testosterone is an important hormone to help build and maintain muscle. During high intensity exercise there is an increase of testosterone (ref. 6).
Growth Hormone(GH) is also released in response to short HIIT sessions (ref 7). GH is responsible for cell growth and regeneration which is very important for muscle mass and bone density. The GH response to aerobic activity is determined by the % of VO2 max (ref 8). This means that the harder you push it during the interval, the higher growth hormone will go and continue to increase even after HIIT has been completed (ref 6).
- Anti- Aging There are few studies done to show how growth hormone can help in the anti aging department, but, it’s a theory and it’s one more reason to keep me motivated to finish my intervals strong!
As stated above, HIIT cardio causes a growth hormone response. Growth hormone (GH) levels have been shown to be associated with telomere length , a nucleotide sequence at the end of our chromosomes. This nucleotide sequence shortens every time your cells divide causing the aging process. But, a study published by The Journal of Clinical Endocrinology & Metabolism in 2009 studied 2744 men found that better telomere lengths positively correlated to serum IGF-1 levels. IGF-1 is the indirect measurement of Human Growth Hormone in the body. The higher GH levels, the longer the telomeres.
This could be good news to those over 30 as GH tends to decline after one hits the big three 0. It’s even worse if you are sedentary. This GH decline causes a domino affect in the body negatively impacting things such as increased body fat levels, decreased muscle mass, decreased physical fitness and decreased immune function (ref 5). So get out there and HIIT, if anything, it will fend off the aging effects of decreased muscle mass and immune function.
Woot! HIIT keeps me young (ish)!
Again, HIIT sessions need to be kept short otherwise, if performed too often or for long periods of time (in excess of 30 minutes or more than 3x per week) may cause baseline testosterone levels to decrease and lead to amino acid breakdown (aka: loss of muscle). When calories are low during the cut phase (in calorie deficit), HIIT is an excellent type of cardio to maximize key hormones for muscle growth and retention as well as boosting metabolism for hours after the session is complete.
Dr. Pompa explains the benefits of HIIT in this video:
Should I only do HIIT cardio and nothing else????
Now, after having gone on and on about HIIT, that doesn’t mean steady state is out of the question. A combination of HIIT and steady state is a good option. Everyone is different, has various goals and abilities and will respond differently to their programs.
How do I use the above cardio options?
Each sport will require different modalities to be utilized. A long distance runners’ program will be different than a bodybuilders program that’s fo sho.
For a non competitive person… by that I mean you are not training for any sort of game except life, one to two short HIIT sessions a week, is all you need. Do 2-5 intervals and call it good.
For bodybuilders, a few short sessions of HIIT during an off season is great to maintain fitness as it is a great option to add onto first during the cut phase/prep going into a show. The cut or prep phase is when you cut calories slowly to lose 1-1.5 pounds per week to shed fat and get those muscles to show through. Slowly building on those HIIT intervals and supplementing with steady state cardio in prep will be needed to create additional caloric deficit. Remember HIIT is limited to low volumes and shouldn’t be done in excess.
HIITing may not be nice, but it is definitely beneficial!
Here’s a video of John Gorman and Leslie Franklin, personal trainers of Team Gorman doing some HIIT.
Something to take home:
1. Kang, J., Bioenergetics Primer for Exercise Science, 2008, 83-84p.
2. Maughan, R., J., Nutrition in Sport, Volume 7, 2000, 186p.
3. Runge, M., S., Patterson, C., Principles of Molecular Medicine, 2006, 957p
4. Physiol, A., Muscle fiber recruitment and the slow component of O2 uptake: constant work rate vs. all-out sprint exercise, 2011
5. Berryman, DE., Christiansen, JS., Johannsson, G., Thorner, MO., Kopchick, JJ., Growth Horm IGF Res. 2008
6. Plowman, S., A., Smith, D., L., Exercise Physiology for Health, Fitness, and Performance, 2007, 42-43p.
7. Godfrey RJ1, Madgwick Z, Whyte GP.The exercise-induced growth hormone response in athletes. 2003. 599-613.