What Are the Major Differences Between Cardio and HIIT Workouts?

Steady-state cardio is generally more suitable for a wider group of people than HIIT as it's lower in intensity. HIIT cardio, on the other hand, is not suitable for certain individuals, as it's a high-intensity workout.

Steady-state cardio exercise is one of the best forms of exercise to fight stress, as it's been linked to reduced cortisol (stress hormone) levels, according to a 2013 article in ACSM's Health and Fitness Journal. The biochemical changes that happen in your brain as a result of steady-state exercise help combat stress and improve your mood.

Cardio exercise is one of the most effective ways to improve your heart health. It helps lower blood pressure and clears the arteries by improving cholesterol levels. This reduces your risk of blood clots, stroke, high blood pressure and heart disease, according to a 2013 study in Blood Pressure.

Those who do cardio regularly have lower insulin levels, blood sugar and body weight, lowering their risk of cardiovascular disease, per a 2013 review from Sports Medicine.

One of the key benefits of HIIT is how time efficient it is. Unlike aerobic cardio, which needs to be performed for 30 minutes or more to allow you to enjoy the benefits, HIIT is short and sweet. In fact, Tabata, a type of HIIT, is only performed for four minutes!

A Tabata workout uses a training style that involves a 20-second all-out work period followed by a 10-second break. This is repeated for eight rounds, a total of four minutes.

It's based on a clinical trial conducted by Tabata and colleagues in 1996 that compared a group who did 60 minutes of moderate intensity (70 percent of VO2 max) to a group that did a four-minute Tabata session. Both groups were on stationary bikes five times a week for six weeks.

The Tabata group improved their anaerobic capacity by 28 percent, VO2 max by 7ml/kg/min, and increased their speed when retested—all key markers of improved aerobic fitness. Plus, the Tabata group yielded statistically better results than the group that exercised for an hour.

Another major benefit of HIIT is increased fat loss. A 2018 review of 39 studies published in Sports Medicine found that HIIT significantly reduced abdominal and visceral fat mass.

And a 2011 study published in The Journal of Applied Research found that participants who did interval training burnt 457 calories across a 24-hour period following the workout. Despite only burning 112 calories during the workout, the afterburn effect kept the metabolism elevated for a significant energy burn. This is particularly important for weight loss.

Compare that to aerobic cardio. According to Harvard Health Publishing, a person weighing 70kg burns 252 calories in 30 minutes of moderate-intensity cycling. There is no afterburn effect at play, so once the activity ends, so does the calorie burning.

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HIIT improves your muscles' ability to use oxygen, known as your VO2 max. A 2016 randomised controlled trial in PLOS One found that after five weeks of HIIT, participants improved their VO2 max by 9 percent.

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