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Heart disease is the leading cause of death both worldwide and in Australia [Australian Institute of Health and Welfare]. Research has shown that the fitter you are the less likely you are to develop heart disease and the longer you will live [Blair 1996]. This held true even if you smoke, have high cholesterol and high blood pressure. This is one of the primary goals of cardiac rehab.

The best way to increase your fitness is to do aerobic (AKA cardio) exercise. This includes things like walking, jogging, swimming, cycling and dancing. The current guidelines recommend at least 150 minutes per week of moderate intensity exercise. 150 MINUTES PER WEEK. What???

This can seem like a lot, especially if you work full time and have family and social commitments. It’s equivalent to about 30 minutes per day.

Alternatively, you could include higher intensity aerobic exercise. This will usually be completed in intervals rather than extended bouts since it’s really hard work to maintain a high intensity for long periods of time. And that’s how we got high intensity interval training (or HIIT).


What does high intensity interval training look like?

HIIT training involves alternating periods of higher intensity exercise with lower intensity exercise. There are endless ways to do this. HIIT was initially used with athletes to improve fitness and performance. More and more research has been using this type of training in clinical populations such as those with heart disease and diabetes.

High intensity is different for everyone. It doesn’t mean you have to sprint up and down the oval or run up a flight of stairs. High intensity exercise could be walking on the treadmill at 3 km/hr or walking up a very slight incline or hill.


What are the benefits of high intensity training?

Some of the benefits of HIIT include:

  • Increased fitness
  • Less time commitment
  • Better heart and blood vessel function
  • Improved blood flow
  • Better muscle function
  • Weight management
  • Improve mood and confidence

This is in both healthy people and those with heart disease, including coronary heart disease and heart failure.


Are there risks with high intensity exercise?

There are risks associated with any new exercise.

Rognmo and colleagues [2012] found that the risk of adverse cardiac event (e.g. heart attack or sudden cardiac death) was low during either moderate or high intensity exercise in people with existing heart disease.

The American Heart Association and American College of Sports Medicine [Thompson 2007], described the rates of adverse cardiac events associated with a single exercise bout (i.e. the acute risk of adverse event associated with exercise). They concluded that the risk is higher in those who are new to exercise or are returning to exercise after a period of time off.


Pre-screening and assessment are a must

Before you embark on a new exercise journey (and especially if you have a pre-existing or new heart condition), you should be screened by an appropriate health professional such as an exercise physiologist. If you are attending a cardiac rehab program, this will be included before you start.

An appropriately trained exercise professional will be able to tell you if you’re at high risk of an adverse cardiac event during exercise and how you can reduce your risk.

They will complete some form of exercise test and measure, at the very least, your heart rate and blood pressure responses both during and after the test.


So, what intensity should you be doing?

A recent review [Pattyn 2018] demonstrated that HIIT was more effective than moderate intensity training at improving fitness and peak heart rate. They also showed that both types of training were equally effective at reducing body weight, blood pressure, cholesterol, glucose (sugar) and resting heart rate.

This tells us that both types of training can and should be included into your weekly exercise routine.

However, you should consult a health professional before start including HIIT. Typically, you should do some baseline conditioning at moderate intensity before you include HIIT training. But there are other factors that should be considered first. Your local cardiac rehab program can give you guidance on this.


Need help or guidance? Book in for a one-on-one consultation with us to find out what’s best for you and your health.

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