You've heard about it. You've tried it. You've probably not quite nailed it. Here’s everything you need to know about HIIT, from its origins to a beginner workout to why it’s so good to sweat so much.
In a very short space of time, high-intensity interval training (HIIT) has emerged as the training method of choice for everyone from online fitness influencers to Olympic athletes and, most likely, you too.
No longer is a slow puff around the park and a few press ups and sit-ups enough to keep you in shape. To really reap the rewards, you have to get as sweaty as possible, in as little time as possible. Which makes HIIT great for the time-poor, and those genuinely looking to take their fitness abilities to the next level.
But as simple as it seems, there’s actually some complex physiology behind all those treadmill sprints and kettlebell swings. HIIT promises the exercise holy grail – more results in less time – and it genuinely delivers. But only if you do things in a very precise way. Otherwise, you’ll just end up training less and getting less out of it.
Here we break down where exactly HIIT came from, its science-backed benefits, and how you can incorporate it into your exercise regiment.
HIIT gained widespread popularity in the 2010s, but some enthusiasts trace its origins back to Peter Coe, an athletics coach who, in the 1970s, began experimenting with periods of high-intensity exercise followed by short recovery periods.
An off-shoot of HIIT, Tabata, came to prominence in the mid-90s, at Ritsumeikan University in Kyoto, Japan, when Professor Izumi Tabata was among a group of researchers studying interval training in Olympic speed skaters.
The terms ‘Tabata’ and ‘HIIT’ have become somewhat conflated, but for the purposes of this article we’re defining HIIT as any repeated exercise pattern with a short rest period (sometimes this is done to exhaustion, but we’re not that sadistic). Or, as HIIT trainer extraordinaire Shane Collins of Circuit Society explains: “HIIT workouts should alternate between bursts of high-intensity exercise with short recoveries in between.” In the contrast between those two ways of working lies HIIT’s magic.
“HIIT sessions have become so popular because they can pack a huge range of benefits into a relatively short time frame, often ranging from just 10-30 mins,” says Collins.
The benefits are myriad. So let’s list them:
Aerobic exercise like HIIT helps boost your cardio ability. A study published in the World Journal of Cardiology found that those who performed a 20-minute HIIT workout four times a week improved their oxygen consumption by 9 per cent in just five weeks.
It can also reduce blood pressure in those with a higher than average initial body mass index (BMI).
A review of 50 studies found that HIIT can reduce blood sugar and improve insulin resistance to a greater degree than continuous exercise, like a 10km run. Which in turn reduces your risk of type 2 diabetes.
Cardio kills gains, right? Wrong. Studies have found that HIIT may actually promote muscle growth, especially in the legs.
HIIT workouts have been proven to burn a greater number of calories than alternatives like cycling and treadmill running within the same time period.
Your metabolic rate is proven to stay elevated for a period of hours following a HIIT workout, meaning your body will continue to burn calories. Even after you’ve stopped sweating.
Thanks in part to the last two points, HIIT has been found to be effective in encouraging fat loss, including in overweight or obese individuals.
It’s also been found to decrease anxiety, stress and depression as well as increasing mental resilience. Go HIIT!
“Although HIIT has become one of the most commonly used terms in the fitness industry, it is also one of the most misunderstood,” says Collins. The main thing we’re getting wrong? The rest periods.
During those high-intensity periods, you need to be working at the absolute limits of your effort. Which means you need to give just enough time to recover so can you work as hard in the next round. “Often so-called HIIT training sessions focus on maintaining a relatively high intensity with little to no rest,” says Collins. “That is impossible to maintain, so this type of training ends up falling within the moderate intensity training bracket, even if advertised as HIIT. Real HIIT sessions can often involve more rest time than activity time (40sec rest, 20 sec high-intensity).”
With that in mind, Collins explains that to make your HIIT training session as effective as possible you need to make your rest periods feel like rest periods, while focusing on performing at maximum output during the active sections of your workout.
HIIT is one of the most versatile workouts out there. The beauty is that it’s scalable to any fitness level – whether you’re just starting out on an exercise journey or are targeting Paris 2024, it’s all about working as hard as you can, however hard that happens to be. That means you can create a circuit using a solitary kettlebell, or use everything in the gym from ropes to sandbags to boxes and TRX rigs. Really, the sky – or your imagination – is the limit.
Which isn’t to say the basics should be overlooked. For a no-equipment HIIT workout – and a great alternative to your morning plod around the block – Collins suggests this simple sprint routine.
Take five minutes to warm-up. Jog at your usual steady state to get the joints loose and the blood flowing.
Now, for 30 seconds you’re going to sprint at 80-100% intensity. Go for it, arms like Liquid Terminator, heart hammering in your chest. Push over the line then…
Go back to your steady state jog for 90 seconds. This is your rest period so don’t overdo it (and remember, this is just round one). You should be aiming for 20-50% intensity here, but if you’re struggling, take it down to a walk.
Repeat this five times for a completely new take on your morning workout – one that will have you shedding fat, boosting your lung power, building explosive strength in your legs, and leave you a sweaty mess in no time at all.
For best results, incorporate this into your regime three to four times a week. If it gets too easy, add in extra repetitions or try explosive bodyweight moves like burpees – when it comes to HIIT, there’s no end to the innovative torture routines out there.
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