I had just completed 5 rounds of “Mjölnir” intervals on the rower….and I felt like I had nothing left in the tank.
I was sitting on the rower with my head between my knees trying to catch my breath, wondering how I was going to make it over to the sauna without toppling over.
What are Mjölnir intervals?
Mjölnir is the name of Thor’s hammer…that information alone should send chills down your spine. The workout prescribed you do 100, 200, 300, 400, 500 meter intervals separated by 30 second rest. Each interval has a prescribed wattage you need to hit and (try to) hold for that interval.
One or two rounds of this workout is manageable….five rounds is brutal!
This type of workout is referred to as HIIT, or high intensity interval training. HIIT workouts are where you give it your all for a short period of time then rest and do it again…and again….and again. The workout is meant to be hard, it is meant to make you exhausted, and it is meant to push you to your limits and beg for mercy….this is exactly what I was experiencing with the Mjölnir intervals.
Why do this kind of workout?
There is a lot of research which points to many positive benefits of doing HIIT.
In overweight and obese people HIIT has been shown to improve body fat percentage, waist circumferance, blood pressure, resting heart rate, VO2max, and fasting glucose! That is amazing!
Looking for performance gains?
HIIT has benefits for you as well.
In an 8 week HIIT study in non-obese males, researchers saw improvements in VO2max, max aerobic velocity, squat jump, countermovement jump, and five jump tests .
Interested in fat loss?
No worries, HIIT can help there as well. A meta-analysis found that HIIT can reduce visceral and abdominal fat in both sexes .
No matter what your goals are, HIIT can probably help you get there.
Yet HIIT’s best benefit has nothing to do with health, performance, or fat loss, it has to do with a very valuable commodity most people are lacking.
All of the health, performance, and fat loss from HIIT benefits can be achieved via other forms of exercise, but those forms of exercise take more time. When you are someone who’s time is a prized commodity, you look for the most efficient way to get things done. HIIT is meant to be hard, and because it’s so hard it takes less time.
It seems like HIIT is a win all around, so does that mean you should drop everything and start doing HIIT?
Not so fast.
Before you jump all in on the HIIT bandwagon we need to consider if it is right for you? And if so, what form of HIIT is appropriate?
For the person who has not exercised at all recently, is overweight or obese, and has several health conditions you might think starting a HIIT program would be quite beneficial given what the studies have shown.
However we need to consider what this person really needs at this point in their health journey. They are just getting started, so is going from 0 exercise, to the hardest form of exercise you can imagine the best thing for them?
I’m going to say, in almost all cases, probably not.
This individual can benefit greatly from doing some very simple things like just walking, or going for a bike ride. They probably would also get a lot more benefit from focusing on their diet, sleep, and stress management than trying to implement a HIIT routine.
My recommendation to anyone who is a novice exerciser or someone who has not exercised in a long time is to take it slow. Jumping too fast into exercise, especially HIIT exercise, can lead to injury and burnout. Once you’re injured or burned out you won’t be able to exercise at all and that is far worse than just going for a walk.
If you are more experienced, have spent some time exercising, and already for a challenge you can start to think about adding some HIIT into your exercise routine.
The question then becomes what kind of HIIT do you do?
Like any choice of exercise the best one is going to be one you enjoy and are most likely to do. That might seem like a silly thing to say about HIIT since the very definition of HIIT is that it won’t be enjoyable, so while it might not be the most enjoyable exercise you do, it should be tolerable. HIIT can take a lot of different forms, you could use a piece of cardio equipment like a rower, fan bike, elliptical, ski erg, treadmill, a bike on a trainer, or anything else. You can also use your body weight doing exercises like burpees, jumping lunges, pushups, squats, etc. If you have access to weight like dumbbells, kettlebells, sandbags, or a barbell you can add weight to your HIIT exercises if you would like. The only requirement is that you need to be working at a very high intensity for a short period of time.
As an example, my favorite HIIT workout to program for clients is on a rower and it is quite simple. I like the rower because it is low impact, form does not play a huge role, and we can get a lot of data we can use to track progress over time like wattage, heart rate, stroke rate and pace.
The HIIT protocol itself is simple, 30 seconds on 30 seconds off for a set number of rounds. This just means you row as hard as you can for 30 seconds and then rest for 30 seconds. To start I might have someone do this for 3 rounds. Then each week I might increase the number of rounds they do. More advanced clients get more rounds and shorter rest periods.
You can apply this 30 on 30 off protocol to any HIIT modality, it works on a bike, doing kettlebell swings, or doing burpees. It’s simple yet effective, and that is what HIIT is all about.
The number one mistake I see people do when incorporating HIIT into their exercise routine is they start making it the only form of exercise they do. Every workout is a HIIT workout. By doing this you start to defeat the benefits of HIIT. HIIT is only effective if you can give it everything you got. If it is just “somewhat hard” then it’s not effective, and not HIIT. So when you do a HIIT session you cannot come back the next day and do another HIIT workout, you just won’t be recovered enough. My general recommendation is to do no more than one HIIT workout a week. Your other workouts should focus on other forms of exercise. If you want to see the general formula I suggest to construct a week of exercise you can read this blog post.
How does HIIT fit into an ancestral model of health? I can see HIIT replicating a key component of our ancestral lifestyle. Our ancestors certainly had periods where they were exerting maximal effort for short periods of time. I think this would most likely happen during something like a hunt where our ancestors would exert maximal effort to catch their prey. After the hunt was over, and hopefully successful, they would most likely spend a lot of time relaxing enjoying the fruit of the labor. In other words they recovered. These maximal efforts were likely few in far between only occurring when they were about to catch their prey. This is part of the reason why we should program our HIIT sessions in the same fashion, work really hard and then recover so we can do it again when we need to again.
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