Exercise intensity is a measure of how hard your body is working when you do physical activity. It can be measured accurately in an exercise laboratory, assessing how much oxygen you are using, or measured a little less accurately in a home or gym setting by one of these three methods: the talk test, your heart rate, or the exertion rating scale.
Note that if you aren’t doing much exercise (less than 150 minutes each week) then you need to take it slow and steady with only light to moderate intensity exercise until your body gets fitter, then you can increase the intensity.
Low Intensity Activity
This is an aerobic activity that does not cause a noticeable change in your breathing rate, like walking on the flat, and it can be sustained for at least 60 minutes. With the talk test, you could easily walk and sing at low intensity activity.
Low intensity exercise is measured as a heart rate of 40-54% of your maximum heart rate* or at 1-2 RPE** – see below for more on this.
Moderate Intensity Activity
This is an aerobic activity, such as fast walking, walking up hill or slow jogging, that is able to be done while maintaining a conversation uninterrupted, and the activity may last between 30 and 60 minutes.
Moderate intensity exercise is measured as a heart rate of 55-69% of your maximum heart rate* or at 3-4 RPE**.
Vigorous to High Intensity Activity
Vigorous intensity aerobic activity is something where you cannot hold an uninterrupted conversation as you are breathing pretty heavily. You can only do this intensity of activity for up to 30 minutes. A heart rate of 70-89% HR max* or an RPE** of 5-6 also indicates vigorous intensity activity.
High intensity aerobic activity is one where it is difficult to talk at all. You can only maintain the activity for 10 minutes and it is measured as a heart rate of 90% or higher of your maximal heart rate* or an RPE** of 7.
*What is Maximal Heart Rate or HRMax?
Your maximum heart rate or HRMax is measured by subtracting you age (measured in years) from 220.
So if you were 40 years old your HRMax would be = 220 – 40 = 180 beats per minute.
Your moderate intensity activity Heart Rate would be = 55-69% of your HRMax.
So in our example of our 40 year old, her moderate intensity Heart Rate = 55-69% x 180 = 99-124 beats per minute.
**What is Rate of Perceived Exertion or RPE?
The rate of perceived exertion or RPE is a subjective measure, that means you do the rating based on your own feelings of how hard you heart is beating, how hard you are breathing, how much you are sweating, and how tired your muscles are.
Research has found that the RPE is pretty accurate compared with more objective measures of intensity.
In our programs, we use a scale from 1 to 7, based on the Adult Pre-Exercise Screening System (APSS) which Australian fitness organisations recommend.
