Intensity: How and Why You Should Track It


When it comes to deciding what exercise will be most beneficial for an individual it is important to consider the Frequency, Intensity, Time & Type of exercise or the FITT principle.  This article is going to focus on one component of this principle – Intensity, and explain why it is important to track.

A common misconception is that for exercise to be effective it must be completed at a high or vigorous intensity. Not only is the not true in certain instances, it may be unsafe. The intensity at which we exercise determines the physiological demands or how hard our body is working during a given workout. This is important when considering what we are aiming to achieve from exercise – it may be that we are trying to improve body composition or decrease our overall chronic disease risk or improve mental health.

All are great goals, and intensity will play a role in how achievable these goals are. For general health, improving chronic disease risk and well-being, the Australian physical activity guidelines recommend that adults aim for a minimum of 30 minutes of moderate intensity exercise 5 days/week. We also know that high intensity exercise has been shown to be safe and very effective in improving blood pressure, blood glucose levels and cholesterol. But how do we determine these intensities?

One common method for determining exercise intensity is through tracking heart rate.  This may be done through wearable technology such as a watch or manually calculating through the radial (wrist) or carotid (neck) pulse. To determine how hard you’re working based on heart rate it’s easiest to break it down to a percentage where 100% is maximum effort. To do this use this simple formula (220 – age) = max heart rate and then multiply by the intensity you wish to work at. For instance, for someone who is 40 years old who aims to work at 70% effort ((220 – 40) *0.70) = 126bpm.

However, for some people using heart rate may not be a reliable way of determining exercise intensity particularly those taking blood pressure medications including beta blockers. In this instance a reliable way to determine intensity is through rating of perceived exertion (RPE) which is typically rated on a scale between 6 – 20 or more simply 0 – 10. Each of these ratings have phases which assist in determining the appropriateness of that intensity as seen in the figure below.

If you would like further information about safe individualised exercise advice speak with an Accredited Exercise Physiologist.