Just 15 minutes of HIIT could improve your health

Thursday, 29 April 2021

High-intensity interval training (HIIT) workouts have become popular in recent years for a number of reasons. They don’t take as long as regular workouts and research shows they improve fitness, lower blood pressure and help manage blood glucose levels.

All of which can help with weight loss and prevent conditions like type 2 diabetes.

And a recent review has found that a form of HIIT workout called low-volume HIIT has benefits for heart health. This means low-volume HIIT could improve cardio fitness, blood glucose control, blood pressure and cardiac function.

What is HIIT?

HIIT is characterized by alternating between low and high-intensity intervals of exercise. For example, this might include cycling at an easy pace for a few minutes before increasing effort to a high level for a short period of time then returning to an easy pace.

This is repeated throughout the exercise session with the total time spent at high-intensity typically low. Different categories of HIIT exist depending on the intensity of exercise required.

About this study

Researchers involved in this study performed a topical review of current evidence on low-volume HIIT and its benefits for heart health.

Topical reviews provide an up-to-date overview of the latest information in a particular field or area of research that’s developing rapidly.

They looked at a total of 11 studies. They defined low-volume HIIT as exercise in which the total time spent in active intervals (not including rest periods) was less than 15 minutes.

The benefits of low-volume HIIT

Overall, low-volume HIIT was found to improve a person’s capacity to burn fuel (such as carbohydrate and fat) as well as their blood glucose control.

The researchers also found that supervised HIIT in healthy people, those living with obesity or type 2 diabetes is a safe form of exercise.

Improved heart health

Low-volume HIIT was shown to improve the heart’s structure, increasing the volume of blood the heart pumped to the body with each heartbeat.

These benefits were true for people without underlying health conditions, as well as for those with heart failure. This is where the heart is unable to pump blood around the body properly because it has become too weak or stiff.

The fact that this review has shown low-volume HIIT also improves cardiorespiratory fitness is significant. Even moderate improvements to heart health have been shown to reduce adverse cardiovascular events like heart attack and stroke by as much as 30 percent.

No time for exercise, no excuse!

These results show that even a short workout can improve health.

Current guidelines from the World Health Organization recommend adults do between 150-300 minutes of moderate-intensity exercise or 75-150 minutes of vigorous exercise a week.

Yet, lack of time is often cited as a barrier to exercise for many people.

Low-volume HIIT has the potential to be time-efficient and offer similar or greater health outcomes as longer workouts.

People also see it as being an easier and more pleasant way to exercise. This is important for motivating people to start and continue with an exercise regime.

It also makes it more appealing to people who are inactive or have long-term health conditions.

How does HIIT work?

Regardless of the type of HIIT program you do, it’s thought the health benefits come from the rate – rather than the amount – at which the muscle glycogen or the carbohydrates stored by the body for energy are used.

Muscle glycogen is an important fuel reserve – so our body tries to replenish it as a priority.

HIIT workouts deplete muscle glycogen at such a rate that the body increases the number and activity of cells in our muscles to meet the energy demands of exercise.

This in turn improves fitness, metabolic function, and health.

What does the research all mean?

HIIT is a definite exercise alternative to longer workouts. Especially as there is growing evidence to show it has similar benefits to other types of longer workouts.

Current thinking also suggests that every bit of movement counts. So focusing on quality (intensity) of exercise, rather than duration, and finding ways to incorporate higher intensity movement into everyday activities will help improve health and fitness.


This article was written by Matthew Haines, Head of Division of Sport, Exercise & Nutrition Sciences, University of Huddersfield. It first appeared in the Conversation and is republished under a Creative Commons license.

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