High Intensity Interval Training (HIIT) increases fitness and burns more calories

Woman sprinting

High Intensity Interval Training (HIIT) is a relatively new concept sweeping health clubs and gyms that is not only improving people's fitness but also allowing them to burn more calories and shed excess body fat in the process.

What is High Intensity Interval Training (HIIT) and how does it work?

Traditionally, gym users and people who exercise have trained for prolonged periods of time (for 30 minutes to an hour) thinking that the more running, cycling, rowing, swimming or aerobics they did, the fitter and slimmer they would become. However, sports science research has found that much smaller bouts of high intensity exercise followed by small rest periods is far more beneficial for health, fitness and weight loss than longer sessions of steady state exercise.

How 6 minutes of exercise a week is better than 90 minutes

For example, one study found that performing 2 minutes of all out exercise 3 times a week was better for fitness and calorie burning than performing 30 minutes moderate exercise 3 times a week. How is this possible? Well, high intensity interval training stresses the body so much that the heart, lungs and the ability to burn calories is forced to improve, even when relaxing watching TV. Whereas, steady state exercise at a moderate levels burns calories during a workout, but this ability to burn extra calories stops as soon as exercise ceases.

Excess post-exercise oxygen consumption and HIIT

Excess post-exercise oxygen consumption (EPOC), also known as the afterburn effect, is the increased rate of oxygen consumption following a highly intense form of exercise. In simple terms EPOC is the processed used during rest after HIIT to return the body back to a resting state. In order to do this the body burns extra calories in order to do so. THis includes the return to a normal state for the bodies hormones, lactic acid levels in the muscles, fuel stores and celluar repair.

Burning more calories even at rest with high intensity interval training (HIIT)

When performing high intensity interval training (HIIT) lactic acid builds up in the major muscle groups used. So, performing HIIT on a stationary bike would create huge volumes of lactic acid in the quadriceps, whereas rowing would do so in the legs, back and arms. Once the exercise stops the body must work hard to convert this lactic acid build-up back to pyruvic acid and in doing so the body continues to burn extra calories after exercise finishes - for up to 32 hours!

Also, high intensity interval training has the ability to increase the metabolic rate, meaning that during exercise and rest more calories are burnt by the body, aiding weight loss and weight management.

How to create your own high intensity interval training (HIIT) exercise programme

HIIT can include sprinting on a field, on a treadmill or uphill, cycling on a bike, rowing, swimming and weigh-training. The basic premise is that you will perform bouts of high intensity intervals interspersed with activity recover. This might mean sprinting for 30 seconds as fast as possible followed by a minute of walking, followed by another 30 second all-out sprint or 20 seconds cycling as hard as possible on a high level of resistance followed by 40 seconds of very slow easy pedalling, repeated a number of times.

Examples of high intensity interval training (HIIT)

Before you begin high intensity interval training (HIIT) pick a form of exercise that you enjoy and you feel you can perform in an allout intense fashion. This could be track running, treadmill running, cycling, swimming etc. After a 5 minute warm up simple perform repeated bouts of 15 second, 20 second or 30 second high intense intervals with low intensity rest of between 30 seconds to a minute. Aim to perform 5 to 10 all out bouts of exercise, starting at 5 bouts if your new to HIIT and working your way up to 10 bouts over the course of a month or two. Follow this with a 5 minute cool down and your done. So, a typical seesion might look like this:

  • 5 minute warm up
  • 30 second sprint, followed by 30 seconds walking x 10
  • 5 minute cool down

Total exercise time 20 minutes.
Total time working at your maximal level, 5 minutes