Summertime exercise

Published: 05 Dec 2016

Summertime exercise

As we approach the busiest time of year, filled with Christmas parties and lazy summer days, it is hard to find the time to exercise. Often people loathe the thought of having to exercise in the heat and decide to avoid it all together.

The recommendation for physical activity in adults is at least 150 minutes of moderate intensity aerobic exercise (E.g. 30 minutes, five days per week) OR 75 minutes of vigorous intensity exercise. Therefore, if you are time poor, vigorous aerobic exercise seems like the obvious answer.

Studies have shown that similar cardiovascular and insulin sensitivity benefits occur when comparing continuous moderate intensity exercise with high intensity interval exercise.

But how do you know if the exercise you are doing is classified as moderate or vigorous?

There are 2 main methods used. The first requires either a heart rate monitor or the ability to count your heart rate through feeling your pulse. The other method is a subject perception of how strenuous you feel the exercise through the use of the Borg Scale.

Target Heart Rate training

The first way of monitoring the intensity of physical activity is through determining your heart rate (pulse). The Karvonen Formula is a mathematical formula which determines your Target heart rate training zone using the maximal and resting heart rates.

  Target Heart Rate=((max HR – resting HR) x % intensity) + resting HR

When performing any type of aerobic exercise, your heart rate should lie between the desired % of intensity.

An even simpler formula can be used:

  • For moderate intensity, heart rate should be between 50-70% of maximal heart rate.
  • For vigorous intensity, heart rate should be above 70-85% of maximal heart rate.

Rate of Perceived Exertion (Borg Scale)

Correlating how physically hard you are exercising with a number on the Borg Scale can give an estimation of how intense you are performing. This is a good representation of your hearts response during exercise.

6- No exertion at all


8- Extremely light

9- Very light


11- Light


13- Somewhat hard


15- Hard


17- Very hard


19- Extremely Hard

20- Maximal Exertion

Using this scale, a rating of 12 is equivalent to approximately 55% of your Training heart zone and 16 to approximately 85% of training heart rate zone.

But take careful note – it is not recommended for adults to exercise above 85% of their maximal heart rate unsupervised as this may increase the risk of cardiovascular and orthopedic problems.  There is such a thing as going too hard!