Your Ultimate Guide to HIIT

Your Ultimate Guide to HIIT

Whether you’re a fitness aficionado or a total newbie, you’ve probably heard of HIIT. Helped along by the rise of fitness YouTube and Instagram profiles, HIIT has exploded in popularity over the last few years. It’s hailed by scientists and well-loved by personal trainers. But why exactly has this method of training garnered so much attention? We take an in-depth look into the science of HIIT.

What is HIIT?

HIIT stands for high-intensity interval training, a form of workout that consists of short, intense periods of exercise combined with short intervals of rest. The idea is that you give it your all during these bursts of exercise. You throw your heart, soul, sweat, car keys and pocket lint into this workout. This intensity causes an oxygen shortage in your body, which leads to excess post-exercise oxygen consumption (EPOC). EPOC is the amount of oxygen you need to restore your body after a workout. The more oxygen you consume, the more calories you burn. Because of the effort that goes into interval training, your body ends up with a bigger oxygen debt than it does with moderate exercise. This incurred oxygen debt makes a 30 minute HIIT workout more effective for your body than a trip to the gym. Typical HIIT workouts consist of between 20 and 30 minutes of interval training, but the length of the intense exercise periods depends entirely on your fitness level. For example, if you’re a beginner, you could start with 20 seconds of intense exercise followed by 10 seconds of rest. If you’re starting interval training from a more advanced position, try doing one minute of exercise followed by 15 seconds of rest. There are a huge variety of interval workouts tailored to different fitness levels. Get testing and see which one works for you. And don’t forget, HIIT workouts can make you feel like your lungs are on fire. That just means it’s working.

The benefits of HIIT

So, why exactly does everyone love HIIT? Here are some of the main reasons that interval training is so highly regarded in the fitness world:

It’s ultra fast

If you’re living the 9-5 life, it can be pretty hard to fit a workout into your day. Even hitting the gym once a week can feel like a stretch. That’s why HIIT workouts are such a great option. Whether it’s half an hour on your lunch break or 15 minutes with your morning coffee, interval training is easy to incorporate into your everyday life.

Anytime, anywhere

Because you don’t need weights or a treadmill, HIIT workouts can be done almost anywhere. At the beach, in the park, at the office, in your living room, at the pet store whilst you’re looking at hamsters. As long as you’ve got enough room to swing your limbs around, you can do a HIIT workout there.

It burns a lot of calories very quickly

As long as you put your back into it, HIIT can burn a huge amount of calories in a short amount of time. This makes it ideal if you’ve only got half an hour to cram a workout into, or if you’re trying to shed some weight in a rush before swimsuit season. When compared with other exercises, HIIT has been found to burn up to 30% more calories. One study analysed a variety of different exercises, with each workout lasting 30 minutes. In this study, the participants consistently burned more calories through the HIIT workouts than through the other exercises. Plus, due to the high rest periods during the HIIT workout, the actual total time of exercise was only 10 minutes. This means that 10 minutes of vigorous workout burns significantly more calories than 30 minutes of moderate exercise.

It ramps up your VO2 max

VO2 max is used as a way of measuring your aerobic capacity, which is your body’s ability to get oxygen to your muscles. Your VO2 max is a numerical measurement of the amount of oxygen your body can consume, and the higher this score is, the more energy you have for exercise. For example, professional athletes usually have very high VO2 max values. People who watch Netflix all day? Not so much. Any activity that gets you moving and increases your fitness levels will ultimately improve your VO2 max. However, when compared with endurance training and other traditional forms of exercise, HIIT workouts have repeatedly been found to have a greater effect on your VO2 max score.

It increases your metabolism

The vigorous exercise in interval training results in a large oxygen debt, which leads to excess post-exercise oxygen consumption. This oxygen debt actually increases your metabolism, meaning your body continues to burn extra calories even after you’ve finished your workout. These effects can last for up to 24 hours after you finish exercising, so you keep reaping the benefits from your interval training for a full day.

It reduces blood pressure

Various studies have shown that HIIT can be extremely effective for helping lower blood pressure in overweight adults. Whilst endurance training and moderate exercise can also be beneficial for lowering blood pressure levels, they have to be done more regularly and for longer periods of time than HIIT exercise. Because of this, HIIT workouts are easier to incorporate into exercise training programmes and might feel more achievable. One study found that the exercise intensity involved in interval training may even be better for reducing blood pressure than moderate exercise.

How to get the most out of your HIIT workout

Now you know a little more about interval training, let’s look at how to put together a good HIIT workout.


Because of the intensity involved, you need to warm up before you get into your HIIT workout. This is essential to avoid soft tissue injuries, which are extremely common in people who skip their warm up. Another mistake people make is to devote too much time to a HIIT warm up. Interval training is short blasts of exercise, and your warm-up should be treated the same way. All you need to do is get your body warm and your muscles fired up. You don’t have to invest a lot of time; around 3 minutes of leg swings, arm circles, jumping jacks and lunges will do the trick.

Think about your goal

There are tons of different HIIT workouts tailored to different goals. If you get sweaty just walking upstairs and you want to improve your overall fitness, almost any beginner HIIT workout will work for you. If you have a more specific goal, such as fat burning, muscle building or butt sculpting, choose a workout that’s specific to that goal. For example, if you’re after a good glute workout, you need a HIIT workout that’s packed with jump squats, donkey kicks and stiff leg deadlifts.

Cool down

Well done, you’ve powered through your HIIT workout! If you feel close to collapse by this point, that’s totally normal. But before you curl up in a ball and nap, you need to cool your body down. A cool down lowers your heart rate and breathing back to normal, and helps prevent muscle injuries. Cooling down after any workout is important, but it’s especially needed after you’ve pushed yourself through some high-intensity training. Similarly to your warm up, you don’t have to spend a lot of time on your cool down. Try jogging on the spot for two minutes, followed by a one minute walk around the room. Combine this with some simple arm and leg stretches, and you’re done!

So, should you try HIIT?

Absolutely. It might not be as relaxing as an hour of yoga or a jog around the park, but high-intensity interval workouts should definitely become part of your training. If you’ve got a busy week ahead, try and incorporate a HIIT workout into your routine. Just make sure your lungs don’t explode.
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