HIIT, stands for high intensity interval training and is any type of training that is both physically demanding and short in duration.
If you’re new to HIIT then it’s useful to think of it as a way of doing exercise and not a type of exercise itself.
It is characterised by short periods of intense exercise followed by slightly longer periods of recovery repeat for a set duration.
For example, sprinting for 30 secs, resting for 60 secs and repeating 6 – 8 times.
HIIT training is versatile and can be done in many ways, including but not limited to;
To qualify as proper HIIT training you want to be pushing yourself to the max in every set. This is because you want to be reaching between 90-95% of your VO2 max, which is where you get the benefits from. (3)
Your VO2 max is the amount of oxygen readily available to the body to use for exercise, and research shows that those with a higher VO2 max lose more fat and get more from exercise. (4) To achieve this, you’ll only be working for 10 – 90 seconds at a time with anywhere from 20 – 180 seconds (or more) rest in between.
The idea is to go all out during the ‘work’ set and then give yourself proper time to recover so you can do it all over again. If you’re a beginner and new to HIIT then a good place to start is with a 1:2 ratio of work to rest.
For example, you might go all-out sprinting for 20 seconds then rest for 40 seconds before doing it all again. You might aim to do this for a total of 20 minutes.
Aside from being short in duration (as little as 10 minutes) there are a host of other benefits to doing regular HIIT training;
Researchers looking at the difference in calories burnt between 30 minutes of HIIT, weightlifting, cycling and run found that HIIT can burn up to 30% more calories than other forms of exercise. (5)
You might this isn’t much but if you consider the fact that the participants doing HIIT were doing 20 seconds of maximal effort, followed by 40 seconds of rest and it becomes much more significant. This is because the HIIT participants were exercising for about one-third of the time the other groups were.
This is perhaps the greatest benefit of HIIT training, it can be done quickly and still give you great results.
This increase is known as EPOC or excessive post-exercise oxygen consumption and is the technical way of saying ‘calories burnt through the increase in metabolism as a result of exercise and additional oxygen needs of the body once you’ve finished.’
Whilst this seems like gold dust it’s actually not that big of a deal. You see all exercise create EPOC and whilst HIIT result in a larger but shorter-lasting effect, longer bouts of exercise create a smaller but longer-lasting effect, which means over the course of 24 hours the effects are the same.
However, an interesting point that did come out of these studies is that HIIT appears to result in the body more readily using fat for energy as opposed to carbs which could provide greater overall fat loss when compared to steady-state cardio. (9)
This is particularly important for those who want to improve endurance as oxygen consumption refers to your body’s ability to use oxygen. HIIT has proved to be particularly effective at improving oxygen consumption just as much as traditional long bouts of cardio but in less time. (10, 11, 12)
One of the great things about HIIT is that all the above benefits can be gained without needing to join a gym or buy any expensive equipment. HIIT can easily be done in the home or outside with no equipment, just your own bodyweight is necessary.
Whilst there are undoubtedly numerous advantages of including some HIIT in your training plan, there are also a few potential downsides.
If you’ve never done HIIT before or are coming back from a long layoff or injury, then it’s a good idea to avoid it, to begin with. HIIT, when done properly, is a very intense form of exercise and can be very tiring for the body and muscles.
Instead of jumping straight in, build up a base level of fitness with traditional forms of cardio or more easy-going intervals. Once you’ve built up the fitness then you begin doing HIIT with shorter work periods and longer rest periods, slowly increasing the amount of work you do over time.
As with all forms of exercise, there is always a risk of injury, however, with HIIT this risk may be higher. This is largely because of how tiring HIIT is and the tendency for your form to break down as you get more and more tired.
This combination of being tired and your form deteriorating is what’s most likely to result in injury. To avoid this, you want to;
Depending on your goal this is not necessarily a concern. If you want to improve general fitness and endurance this is not something you need to worry about. However, if your primary goal is muscle building or muscle retention, then you need to be aware of how it can impact your workouts.
HIIT is intense, it’s meant to be, it should push you to your limits and you should be tired. It increases your recovery needs and puts you at a higher risk of muscle loss and burn out if you’re not careful.
For this reason, you should always avoid doing HIIT before weightlifting.
The answer to this question will largely depend on your goals.
However, I’ve found these recommendations to be suitable for most people, particularly if you’re trying to either build or maintain muscle mass;
As we touched on before HIIT is a type of training and then can be performed in numerous different ways with different equipment and for different goals.
However, right now we’re going to have a look at my 4 favourite HIIT circuits for fat loss.
Sprints, both the flat and hill variety, are a fantastic way of doing HIIT. Not only can they be done quickly but when done with intensity they provide maximum benefits.
You can do sprints without needing any equipment or having to spend money which makes them ideal for those of you who aren’t members of a gym. An example workout could look like this;
It’s as simple as that. You can play with the work and rest periods and the total repetitions to better suit your needs. If you don’t, can’t or won’t run, then you could use a bike, rower or elliptical instead.
Tabata is a type of HIIT circuit developed by a Japanese Scientist of the same name, Dr. Izumi Tabata and a team of researchers in Tokyo. The system consists of rounds which last 4 minutes in total and use the following structure;
Tabata is fantastic because it’s versatile, which means you can choose any exercise you want and still do it. You can also choose the number of rounds you perform as well. For example, a Tabata circuit could look like this;
If you were short on time you could stop here, with 4 minutes of intense working out. However, if you were looking for a bit more you could add;
Rest 1 minute between the different exercises and you’re good to go. If you want to change it up a bit you could use dumbbells, kettlebells, a skipping rope, add more exercises or use fewer exercises, the options are endless.
A barbell complex is a series of exercises done in succession without the bar touching the floor. It’s HIIT done with weights. A barbell complex is usually made up of 4 – 6 exercises done for 6 – 8 reps, with the focus on good form and the work, not the amount of weight you lift.
However, as with all the circuits here you can add or remove exercises and reps to better suit your needs and goals. An example of a barbell complex is;
You want to pick a weight you can do for your weakest lift that allows you to hit your rep goal with a couple of reps left in the tank.
You will use this weight for the whole complex.
For example, in the circuit above overhead press will be the weakest lift, so you’ll then aim to pick a weight you know you could do 8-10 reps with, this way you know you’ll be able to complete the complex without needing to change the weight when you get to the overhead press.
Aim to complete 3 – 5 rounds with 2 – 5 minutes rest in between depending on the difficulty.
HIIT training is a useful tool if your fitness toolbox to improve your fitness and help you lose fat.
It’s characterised by short periods of intense work and longer periods of recovery and can be performed in many different ways and include almost any exercise you can think of.