I posted a Facebook video the other day that went off on HIIT (High Intensity Interval Training). The video was shared a number of times and most of the feedback was people thanking me in agreement. Some people were upset that I was driving while taking a hands-free video. A few people said they love HIIT, but really couldn’t say that I was wrong. Some people asked me why am I so adamant about this topic; why do I care so much? The biggest reason is, the “HIIT training” that is being marketed by the gym chains and trainers popping up on every corner isn’t true HIIT. It’s a bastardization. The way HIIT is being practiced and taught by these so called fitness professionals puts most people at risk for burnout, injury, and only short-term success rather than long term life habits. Did I mention is it really isn’t even HIIT?
Lets Break it down
HIIT isn’t a weight training protocol. It is a cardiovascular training protocol. That means if you are lifting weights really fast it isn’t HIIT. You can call it High Intensity Training, but it it isn’t true HIIT. I will get more into this a later on, but let’s look at the most basic level first.
PHYSIOLOGICAL RESPONSE TO HIIT
Why is HIIT sought out now as a primary form of exercise? The benefits of HIIT can be great for:
- Increased Resting Energy Expenditure hours after exercise which means more energy is being burned. EPOC (Excess post-exercise oxygen consumption) is the buzz word people like to use
- Increased hormonal levels of testosterone and adrenaline post workout
- Shorter workouts with more effectiveness
All of this should lead to improved levels of body composition, correct?
The answer is, it really depends. Research does show these things are true to an extent, but when you really break it down, the additional calories burned with HIIT over steady-state cardio may be statistically significant for research papers, but not physiologically significant for actual weight loss when you compare the two or at least not the huge dramatic improvements you would expect. Nerd Fitness did a break down of this in an article. Yes, you can burn 40 more calories over the entire day, but does that really relate to improved weight loss, and is it appropriate for everyone? Are the increased intensity requirements more beneficial or harmful? The other issue is the inconsistency between the research and application. People sometimes take that research and make up their own rules, forgetting the principles of the research. Maybe they read that High Intensity Interval Training is great for burning more calories, but forgot the very important interval part of that High Intensity INTERVAL Training. HIT (just High Intensity Training without the Interval portion) and HIIT are not the same thing, but if someone uses cool sounding terms like EPOC, Epinephrine, and ‘improved hormonal response’ it sounds legit, right? This is like a research paper (this is a hypothetical situation) saying something like, “those who sweetened tea with honey are thinner than those that use table sugar.” Then you see honey stores popping up on every corner telling people that it is the next weight loss secret… never minding that these hypothetical study participants used less honey and only had 1 serving per day instead of 5. But if don’t look at all the facts then yes, it looks like honey = weight loss. This process is actually how most supplements come to life, but most people take them without doing any research.
Usually a heart rate north of 80% of a person’s max heart rate can be a good starting point for high intensity work. Based on the length of the interval, intensities can range between 80-95% of Max Heart Rate. Much of the exercise science research that has studied HIIT training is conducted according to the Wingate Protocol which uses a a bike or Ergometer for 30 seconds of High Intensity getting the HR up to 80-95% of max followed with a rest interval.
Interval is defined as:
a) a pause; a break in activity.
Yes, it’s actually in the name! In many of the studies, after the High Intensity Interval of 80-95% is reached for 30 seconds it is followed by 3 to 4 minutes of rest or decreased activity to let the heart rate recover. [Recover: return to a normal state] <<<< This is the actual definition!
In most cases normal state can be considered somewhere at or below 70% max HR. This work is repeated between 4-6 rounds for a total of 3-4 minutes of total exercise time out of 16-24 minutes of intervals… Yes that is the #SCIENCE. The other interval variations that are commonly used in research are the 8s/12s protocol in which the subject does 8 seconds of higher intensity bouts of training followed by 12 seconds of rest for a total of 20 minutes, which breaks down to 8 minutes of high intensity work and 12 minutes of recovery. This method is used for those that cannot handle the higher intensities for 30 seconds. Other methods such as the Tabata Protocol call for 20 seconds of work followed with 10 seconds of rest for 8 rounds, totaling 4 minutes of intervals (2 minutes, 40 seconds of total work). This always gets me when I see hour long Tabata classes, because they aren’t Tabatas. When a Tabata is done correctly it is only 4 minutes and it is so nasty you will most likely be on the floor. If you want a great read on Tabatas and interval training check out Andrew Reads article on it, it is worth your time and breaks it down better than I ever could..
Here is the other really important aspect. All of these studies are done on bicycles/ergometers or treadmills. These are cardiovascular training protocols, not strength training protocols. Let me repeat this…. HIIT training is done on cardiovascular pieces of equipment because it is not at weight lifting protocol. Though heart rate does increase in response to weight training it doesn’t usually correlate to improved cardiovascular fitness. Rowers, bikes, airdynes, or treadmills are going to be the most accurate modes to recreate the results that the research has discovered. Other modalities of body-weight exercises such as body-weight squats, jumps, lunges, mountain climbers, and burpees could begin to be a part of a HIIT protocol. Kettlebell swings, and snatches with light to moderate weight, medball slams, and ropes could also be appropriate forms to achieve the cardiovascular response desired. Some of the fine print here is that a baseline of strength is needed for many of these body-weight exercises to be appropriate. Many times these body-weight exercises require an extensive amount of strength for those that are beginners or holding extra body weight. It is easy for a conditioned person whip out BW squats 20-30 reps at a time where as a de-conditioned person is using a completely different energy system to accomplish the same task. Having a 150lb fit person do burpees is a much different task to the energy systems and nervous system of a 200lb beginner with no baseline fitness or strength. HIIT is about training an energy system, not overtaxing the muscular system or destroying the nervous system. Again, doing High Intensity Cardio Sessions with weight isn’t the most effective way to actually improve cardiovascular health and it isn’t the most effective or efficient way to get stronger either. There are specific ways to accomplish each of these goals and it isn’t by producing a mashup. Yet people will buy it because companies know #marketing better than applying #science.
When putting together any training program there are a few variables that can be manipulated to achieve a desired goal. When it comes to lifting weights many people think that just increasing the weight week to week is the only way to get stronger which isn’t the case. Adding an additional set with the same weight or additional reps over time will result in a much more favorable outcome for many lifters. The same aspect goes for developing a conditioning program. Just adding more intensity isn’t the answer. The purpose of training is to stimulate not annihilate the system. The “H” in HIIT is High. This means that the Intensity really needs to be north of 80% of MaxHr. The ideal range seen in many programs is 85-95% MaxHR. Spending time in these ranges can be uncomfortable and nasty, which is fine, but this is where fatigue and pain can creep in. Managing the amount of time in these ranges is crucial to seeing the most optimal results. It takes time to develop the ability to withstand the byproducts of these ranges(hormonal/muscular&nervous system). Also, putting someone on a bike has a relatively low risk of injury, but having someone in a so-called HIIT class doing squat presses with a HR of 95% is a recipe for form to break down and injury to occur. As discussed earlier, the research that shows the plethora of benefits use 30 seconds of work with 3-4 minutes of recovery for 20-24 minutes total of time? How does this get converted into hour classes of beat downs and close to no recovery? This isn’t saying the way i’m describing is the only protocol that works, but it could definitely be called a starting point of some sort. Using actual intervals could be beneficial.
WHY IS THIS IMPORTANT
One of the benefits of HIIT training is the hormonal response the body has to it. What must be taken into consideration is how the body adapts to these hormonal responses. Cortisol is one of the hormones that is released during high intensity exercise. Cortisol is a very powerful hormone, and it does help metabolize fuel in our body and gives us a bit of a kick in our training and allows us to break down and utilize carbohydrates. Cortisol in very high doses on a regular basis on the other hand can be detrimental to our systems. It is a catabolic hormone that will actually break down muscular tissue, physiologically inhibit fat loss, and promote fat storage! As people start a new training program it is important that intensity is increased over a period of time to allow the body to adapt to the physiological stress. Your body can adapt to these changes over time and not have the detrimental effects dealing with tons of cortisol due to high amounts of stress on the body. Ramping up the training over a period of time will prepare the body for the stress placed upon it and won’t cause these huge hormonal imbalances. Have you ever trained so hard you feel restless all night? Like you just can’t stop tossing and turning because you are amped up? Many people think that is a sign of a kick ass workout, nope this is a sign of over doing it and cortisol winning the battle. This is the sign of your body breaking down muscle and storing fat. This feeling should be associated with you getting further away from your goals not moving closer to them, yet I hear people brag about being so amped up at night because their training, “kicked their ass.” It is somewhat of a badge of courage on how intense they are, but really it is just the sign of a novice. There are numerous other issues with overdoing HIIT training such has draining the adrenal glands and subsequent adrenal fatigue. Exercise becomes your “crack” and you need it for a buzz – without it your body has trouble producing and releasing adrenaline on its own. Add any life stress into this mix and this is where you see signs of depression, mood swings, and other not-so-awesome side effects of training too hard, too often. This is also why people will literally melt down emotionally if they miss the gym once in awhile (this isn’t healthy either). I have witnessed people freaking out because I told them to take a few days off and to rest or just go for a walk. It was like I told them that someone had died. It is just exercise and if you are that overwhelmed by the thought of resting you may need to wake up and get a dose of reality.
Over the past couple years I have met numerous people that have come to me after participating in high intensity training programs for extended periods of time start to tell me about their thyroid being low. This isn’t a weird coincidence. It is actually known that prolonged stress on your adrenals can cause erratic levels of cortisol on the body which decrease thyroid hormones. Yep, their exercise program very possibly didn’t make them healthier it could have put them on meds. Sure, there could be other variables, but consistently combining high intensity training coupled with lower carbohydrate diets you have a recipe for disaster. It may get you a cool before and after picture for a minute but, you want #science, this is the science. Here is an article that talks about stress and cortisol on Thyroid. If you want more research just google cortisol levels and thyroid. It isn’t that High intensity Training is all bad it is just that it is misapplied and in the hands of some DVD programs, gym chains, and reckless trainers that care more about selling an image than understanding the science and how to apply it. Managing heart rate and interval time is a way to avoid these pitfalls and using heart rate monitors correctly (just having your heart rate on a screen isn’t enough, you do have to pay attention to what it’s showing and act accordingly). A friend of mine went to a HIIT training facility that preached science of HR training. This is what we got: first the numbers were off because the average of 171bpm (beats per minute) for her is 90%Max HR not 87% as the chart shows. For an entire hour her AVG HR was at 90% and she was not a conditioned athlete. This is what happened with the “guidance” of a coach. No exercise history was taken, just enter the class and lets beat you down for an hour with running, pressing, weighted squats, and mindless circuit training. Even most world class athletes only spend a small amount of total training time at 90% unless they are in a race or competition. Guess what, she burned 673 calories that workout, but didn’t want to train for the rest of the week because she was tired and not feeling great. So the rest of the week she burned next to nothing.