HIIT - What You Need to Know
You may have images of a topless man with an 8 pack bigger than your biceps screaming motivational messages at you:
“Ready? Jack it out! We start to jack a little faster! Jack it out!”
For some this idea may go hand in hand with their worst nightmare. However, there is much more to High Intensity Interval Training (HIIT) also called High Intensity Intermittent Exercise (HIIE) or Sprint Interval Training (SIT). Perhaps you think this type of exercise is dangerous for your body, joints, muscles or that it increases the risk of heart attacks.
Well, either way, in this article we let you know all you need to know about high intensity interval training so that your health and fitness can benefit from the best bits!
So, what is high intensity interval training?
A simple explanation is it’s exercising until your heart goes up to nearly maximum – you know that feeling when your heart is beating so hard you can feel it pounding in your chest like it’s trying to get out - then resting or easing off for a bit. Then repeating again. Hard effort, rest, hard effort, rest and so on.
This is the typical formula for a HIIT workout:
- Warm up 3-5 minutes at a moderate to light heart rate.
- Followed by all-out effort of beyond 90% of your VO2 max (max heart rate)
Side note: quick simple equation. 220 - age = Max Heart Rate. That means if you are 34, 220 - 34 = 186, so 186 is roughly your Max Heart Rate. Above 90% would be above 167 beats per minute.
- Then either rest or work at around 50% of your max heart rate for recovery for around 3 minutes.
So, on an exercise bike you might warm up lightly for 5 minutes. Sprint for 20-60 seconds, then go back to a light intensity for 3 minutes and then repeat 3 to 5 times.
What type of exercise should you do?
There is no specific “must follow” formula for HIIT exercise as much of the intensity depends on your current level of fitness. For example; if you are sedentary for long periods of time your heart may lack the cardiovascular strength and efficiency to workout at intense levels and as a result something like walking the stairs may elevate your heart to near max after 1 minute.
“Wait, you mean, I can walk up the stairs and get fit!?” Well, technically, you have just completed a high intensity interval circuit at this point. Though typically exercises like star jumps and the dreaded burpee are common practice in many High Intensity Workouts in the marketplace. But, yes as long as you elevate your heart rate high enough - it qualifies.
How long should a HIIT Workout be?
This can go from as little as 4 minutes to 60 minutes. It depends on how many circuits you want to do and how fit you are already. The time-consuming part is the rest between the high intensity sprints. However, here at 7 Minute Mornings we have seen that a period of 7 minutes of high intensity interval training delivers fast fitness results. We also wouldn’t recommend a period longer than 20 minutes as it may overload your body.
IS there any science to really back HIIT?
Yes, in fact this approach showed some serious promise some 80 years ago by a man called Woldemar Gerschler. He was a German Coach and university professor. He used this approach (which he called interval training at the time) to help two different athletes win gold at the Olympics and even break worlds records.
More recently there are a quite a few people and studies to mention:
- Izumi Tabata – the Ice Skating study
You may have heard about the Tabata regimen before. It is often quoted as the origins of HIIT, of course as explained above, the interval training principle goes back some 80 years. However, in 1996 a study by professor Izumi Tabata (hence the name) involving Olympic speed skaters, he tested two groups with different workout routines to improve overall performance. Firstly, the high intensity group were set the task to exercise at max heart rate (VO2max) for 20 seconds, resting for 10 seconds and repeating for 4 minutes total time. Secondly, there was the steady pace group. They were instructed to exercise at 70% max heart rate for 60 minutes. The key difference is one group was going very high and then low while the other group was staying at the same heart rate.
The result: The HIIT group improved at a higher percentage for overall VO2 max and gained Anaerobic Capacity benefits that the steady group didn’t.
At this stage high intensity interval training started to enter the awareness of not just the athletic world but this time the fitness world too and personal trainers and fitness instructors alike started using it as a way of getting faster fat burning and fitness results.
- Gibala – Mcmaster University, Canada
Professor Martin Gibala and his team at the McMaster University in Canada have been researching high-intensity exercise for several years. To find out more about his science and unique exercise routine check out his book titled “The One Minute Workout”. In it he details how they reach the title based off the result of his experiments:
“The experiment showed that approximately ten minutes of hard exercise a week boosted overall fitness to the same extent as four and a half hours per week of traditional endurance training. It’s mind-blowing.”
In their study on students they used a simple formula of maximum intensity (at 95% of VO2max) for 1 minute and resting for 75 seconds between and repeating 8 times and doing this routine 3 times per week. While the other group exercised for around 50 minutes at a steady heart rate (50-70% VO2max) 5 times per week.
The result: It was a draw. The group that did 8 minutes of intense high intensity 3 times per week got the same results as the group doing around 50 minutes per day 5 times per week. Achieving the same VO2max improvement (fitness), the same mitochondria improvement (key for endurance) and even the same fat loss results.
Does HIIT burn more fat?
Personally, we are biased on this one as we have seen incredible fat loss results with our case studies following a calorie-controlled diet plan and our 7 Minute Max High Intensity Interval Training and Bodyweight exercise plan. See pictures below:
However, a study in 2007 found that short bursts of HIIT at 90% of VO2max improved whole body fat oxidation and increased the muscles’ ability to oxidise fat in moderately active women. Also, another 2017 study summarised that HIIT can result in modest reductions of subcutaneous fat (fat we see on the outside of our bodies), but it had greater reductions for overweight individuals. Additionally, a study done in 2017 found better than average fat loss results with HIIT.
To clarify, to lose weight calorie deficits diets have been shown to be simple and effective in the short term. We are NOT suggesting that a daily 7 Minute Workout is going to make you burn a miraculous amount of body fat more than any other type of exercise. Our experience and studies are showing that you can get the same results as the average gym workout if you exercise hard for less time than steady for a longer period. This approach is about getting results for those people that don’t have time and yes its works. Try MAX for Free here.
Doesn’t HIIT increase the risk of heart attack?
Ok, let’s be real here; nothing increases the risk of heart attacks more than inactivity. Exercising using HIIT in short periods for those who don’t have time will decrease the overall chances of a heart attack compared with their inactive counterpart. But there is legitimate concern around exercising in the right way.
Let’s review what type of effects this type of exercise has on your cardiovascular system:
In 2015 a systematic review on High Intensity Interval Training concluded the following: Endurance improves with HIIT (short and high intensity training) and with slow and steady exercise (continual endurance for a long time). Meaning your heart gets just as strong from HIIT as it does from slow and steady paced exercise. However, that’s not the end of the story. They also found that greater VO2max results were seen in the HIIT group. Furthermore, a separate review found that HIIT was more effective at improving blood vessel function and blood vessel health.
Basically speaking, to decrease the risks of a heart attack having a strong and healthy cardiovascular system is essential and HIIT has been shown to be as effective, if not more effective at developing a healthier cardiovascular system.
However, here is what we suggest if you are concerned about the intensity being too much for your health:
- When exercising you should warm up for around 5 minutes beforehand and only elevate your heart rate to around 70% of your VO2max (that (220 - your age) number we spoke about, 70% of that).
- When you start a high intensity program you should start by doing a fitness test (we start our programme with a fitness test so you can establish the right intensity for you current level of fitness) go here to learn how to do a home fitness test or sign up to our free MAX programme which includes a fitness test at the start here.
- Consult your GP. Especially if you are over 45 and have been inactive for an extended period of time.
Does it decrease the risk of type 2 diabetes?
In short, yes. Some studies have suggested that it is more effective at lowering insulin resistance than the traditional slow and steady paced workout. This is due to the muscles and liver using glycogen more rapidly as a result of the intensity of the workout and when consuming simple carbohydrates afterwards they are recruited to replenish glycogen stores in the liver and muscles.
Does it improve Intelligence?
Wouldn’t that be something!? We can’t claim that doing HIIT can make you more intelligent unfortunately. But, we can tell you though, is about a protein that has been labelled 'miracle growth for the brain’ by John J Ratey.
Anecdotally we have seen a huge transformation in reported brain ability and concentration levels. Check out this video to see what our case studies say happens with just 7 Minute HIIT exercise per day.
Though, it isn’t just adults that will improve their mental focus and cognitive performance during the day. In a 2017 study the effects of HIIT on cognitive performance among a group of children found that it had improved memory capacity when compare against board games, computer games and trivia quizzes. Basically, things that were designed to use the brain were less effective than HIIT at improving memory and cognitive function. Interesting right?
This is part down to a protein called BDNF…
What is BDNF?
Brain Deprived Neurotrophic Factor or BDNF for short, is a protein that has been shown in a study to improve memory and cognitive function. The interesting part about this protein is that it is released by exercise. Basically, if you want an improved brain you need to elevate your heart rate and nothing does that like high intensity exercise, because the higher the heart rate the more the chemical or hormonal release is needed.
Does HIIT help with Depression?
In short, the answer is a big fat YES. This is in part to the improved release and synthesis of serotonin into the body and brain with regular exercise. A study found that people who exercise more reported better moods overall and were more able to deal with depression and anxiety.
A study on moderate exercise vs high intensity found that when people worked at a higher intensity they had an increased release of serotonin levels.
Should I do HIIT if I have back or knee problems?
HIIT is designed to work the body at a faster pace than usual, and if your body has some weaknesses or injuries, then they need to be carefully considered. There are many different types of HIIT training. You aren’t fixed to a particular type of activity as such, as long as your heart rate goes up to 90% and above you will achieve the benefits of this approach.
Also, 7 Minute Mornings’ HIIT based exercises are primarily focused on movements that mimic that of plyometrics (star jumps etc). However, we also prescribe bodyweight exercises to build strength in your muscles and joints to decrease the risks of injury. We have also built a programme for people that are unfit or have joint problems so they can strengthen their bodies and decrease the overall risk of injury. If you have a serious injury or have had an operation recently then you would be wise to stay away from impact-based movements like that in traditional high intensity routines.
You can still get benefits from high intensity though:
- Go swimming and swim at a sprint at full intensity then rest at the end.
- Use an exercise bike or better yet an actual bike and go flat out for a minute and then go at a light intensity for a minute or so.
Where can I try HIIT Exercise?
We have a very easy answer to this one. You can simply sign up for free to 7 Minute Max. No card details needed. Just enter your name and email and you can access the full 8-week course to get your fitness on the right track.
It starts with a fitness test and you will be able to learn the right technique with our follow-along exercise videos too. You'll also get access to some of our favourite tasty and healthy recipes to try.
What to be aware of before trying HIIT Exercise.
There are potential issues with all exercises and sporting activities and HIIT is no exception to this. What is most important is to ensure you are doing the right exercises, and performing them correctly. Listen, in truth when you choose to go from inactive to active your body increases its risk as you are placing undue pressure on your body. Though, regarding HIIT there are two major areas and one suggestion below to help you make a choice whether this type of training may work for you long term.
- Injury: If your muscles are week then any impact (including running) will have a negative impact on your joints and may increase the risk of injury. For this reason, it’s important to also do bodyweight exercises like our 7 Minute Bodyweight Workout Here to strengthen your muscles and joints. We would also recommend a daily stretching routine. This will make sure that muscles don’t get too tight. Key areas would be Calfs, Hamstrings, Adductors, Hip flexors and Lower Back.
- Rhabdomyolysis. This is where intracellular muscle parts break down and leak into the bloodstream. This can lead to kidney damage among other problems. However, it’s important to note that this condition is something people experience with doing high intensity exercise for very long periods of time. It’s important to keep all HIIT to short periods of time.
- Heart conditions: though is has recently been reported in the media that there are no known risks of heart attacks with this approach, we would still suggest that if you have high blood pressure, are very unfit or have known heart conditions we would suggest consulting your general practitioner before doing HIIT exercise. Your risks are very low but safety first would be a wise strategy.
Good Luck on Your Fitness and Health Journeys!
Anthony Delamare (Co-Founder and Co-Director: 7 Minute Mornings)