HIIT: What It Is & How It Works


HIIT: What It Is & How It Works

HIIT dates back to the early 1900s and was first created as a tool for endurance athletes to prepare for the olympics. Impressive, right? 

There’s no doubt HIIT has gained popularity in recent years — it’s become the go-to workout for those wanting to make the most of the little time they have, while they work towards their fitness goals. 

After all, we all want to improve our health and wellbeing

So, what is HIIT and why does it work? We break it down. 

What is HIIT?

‘HIIT’ stands for High-Intensity Interval Training.

HIIT is repeated intervals of high-intensity exercise coupled with periods of lower intensity exercise which act as recovery.

Typically, a HIIT workout involves short, intense circuits. 

This could include cardio exercises, such as skipping, running, rowing and cycling, or fast-paced resistance exercises like burpees, jump lunges and squat thrusters. 

For example, 30 seconds of skipping followed by a 30-second rest, repeated for five rounds is a form of HIIT.

What are the benefits of HIIT?

HIIT is popular for a reason — these benefits speak for themselves.

HIIT doesn’t require a lot of time 

A HIIT workout is a lot shorter than a regular training session, due to the fact that you’re working at such a high level of intensity. 

For example, you can burn a similar amount of calories in a 5-minute sprint interval session as you could during a 30-minute low-intensity cardio session. 

High Intensity Interval Training

HIIT increases your excess post-exercise oxygen consumption

Because of the high level of intensity involved, a HIIT workout increases your excess post-exercise oxygen consumption (EPOC). 

EPOC results in you burning more calories after you’ve finished your exercise session.

HIIT exercises are typically performed anaerobically (without oxygen) and in turn, this puts your body in an oxygen deficit. 

To overcome this oxygen deficit, your body uses energy which is stored in muscle tissue, the liver or converted from body fat.

HIIT improves your VO₂ Max

HIIT works to improve your VO₂ Max, which is the maximum rate at which your heart, lungs, and muscles can effectively use oxygen during exercise.

HIIT Training

HIIT increases your anaerobic threshold

Expect an increase to your anaerobic threshold, which improves your body’s ability to utilise oxygen and buffer lactic acid. This improves your ability to maintain a higher exercise intensity for longer periods. 

Why HIIT is so effective 

This is where it gets technical. 

HIIT works for a number of reasons:

HIIT creates a metabolic demand 

The higher intensity periods during a HIIT workout create a metabolic demand. This demand is very effective for long-term fat loss and overall conditioning when implemented consistently.

How To Do HIIT

HIIT uses your aerobic energy system

The lower intensity periods during a HIIT workout let you recover and use your aerobic energy system.

HIIT helps you lose body fat 

HIIT helps you to lose body fat while retaining lean body mass (muscle). It does this by using the aerobic energy system to recover from intense repetitions of an exercise. (The aerobic system uses carbohydrates and fat as the main fuel sources to supply energy to the body.)

What Is HIIT

HIIT strengthens your cardiovascular system

HIIT strengthens the cardiovascular system by forcing adaptation to high-intensity repetitions of an exercise that go beyond your normal daily activities.

HIIT challenges your muscle fibres

HIIT challenges your fast-twitch muscle fibres (the larger muscle fibres that are great for strength and power). These fibres also require more energy to operate and grow, which in turn, increases your basal metabolic rate (the amount of energy you burn while resting).

Is HIIT right for you?

So, how do you know if HIIT is right for you? 

One of the most attractive benefits of HIIT is the opportunity to burn a high number of calories in a short period of time.

If you’re time-poor, HIIT is a great workout to do during your lunch break or to squeeze into your schedule before work in the morning.

If you want to improve your cardiovascular system, maintain lean muscle mass or lose body fat, then HIIT could be for you, too.

What if HIIT isn’t right for you? 

HIIT isn’t for everyone and that’s totally OK. There are plenty more programs out there to try!

Ultimately, the desired outcomes from HIIT are dependent on your capacity to adequately recover and rest after a workout. 

Because you’re working out at an intense level, you must have the downtime needed for recovery between exercise sessions. Otherwise, HIIT can be a big stress on your body.  It can actually dish up a similar hormone response to when you’re dealing with stressful situations in everyday life. 

With that in mind, HIIT isn’t for you if you’re the sort of person that’s always running from one thing to another or you find yourself overly stressed. 

While manageable in short bursts, it can be unsustainable for long periods of time. 

Before taking up HIIT, it’s really important to ensure you lead a balanced lifestyle. This includes well-rounded nutrition, healthy sleep habits and minimal stress. Again, it’s important that your body has time to properly recover after working out and your body can’t do that if your stress levels are high. 

HIIT Alternative

What to do instead

If you’re someone who should give HIIT a miss, instead try LISS cardio or a form of low-intensity exercise. 

This will work to aid recovery and trigger your parasympathetic (rest and digest) nervous system as opposed to your sympathetic (fight or flight) system. 

You might even opt to do a minimum effective dose (MED). This could be as little as five push ups, five bodyweight squats, 10 Russian twists and 10 minutes of walking daily. 

How to do HIIT

To get the most from your workout, make sure you warm up beforehand. 

Simply, this means warming up your muscles (skipping, butt kicks and leg swings are all great) and getting your heart rate up. 

As tempting as it may be to skip this step (especially if you’re short on time), you should consider it mandatory. If you don’t, you run the risk of potential injury.  

No warm-up = no workout!

Don’t forget to hydrate, too. Drinking water prior to your workout, as well as during your workout, contributes to healthy muscle recovery after you’ve finished moving your body.

If you don’t hydrate enough, you’re more likely to suffer from muscle cramps or general fatigue.

Interval Training

Time’s up 

This is an obvious one, but pay close attention to the time on your stopwatch as you’re working out. 

It’s important to push yourself as hard as possible during the allocated work time, but it’s equally important to slow down during the rest breaks. 

How often can you do HIIT?

If you’re just introducing HIIT workouts to your fitness routine, it’s best to start small and build your way up. 

One to two sessions a week — with time for your body to recover between  — is a safe bet. 

If you’re a keen trainer and move your body often, you might like to aim for three to four sessions a week. 

Again, remember to allow time between sessions for your body to rest and recover.

The appeal is real

It’s not hard to see why HIIT is so appealing — it creates a metabolic demand, uses your aerobic energy system, helps you lose body fat, strengthens your cardiovascular system and challenges your muscle fibres. Talk about getting the most out of your workout!

Whether you’re just beginning your fitness journey or a seasoned gym-goer, a HIIT workout is one of the most efficient ways to train. 

Is there something more you would love to learn about HIIT? If so, please comment below!

* Results may vary. Strict adherence to the nutrition and exercise guide are required for best results.

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