Measuring Physical Activity

To ensure you’re exercising efficiently, it’s useful to measure your physical activity and its level of intensity. Physical activity is generally categorised as light, moderate or vigorous, based on how much energy you use up in the process. There are several ways to measure the intensity of your level of physical activity:

1. The Talk Test. If you’re active at a light level of intensity, you’ll be able to sing at the same time. At a moderate level of intensity, you’ll still be able to hold a conversation. If you feel winded, or too out of breath to keep talking, then you’ve reached a vigorous level of intensity.

2. Measuring Heart Rate. The amount your heart speeds up during exercise also indicates its level of intensity. At a moderate level of intensity, your heart rate will be between 50 and 70% of your maximum heart rate, calculated according to your age. For vigorous activity, your target heart rate would be between 70 and 85% of your maximum heart rate. You can work out your maximum heart rate by subtracting your age from 220. So for a 50-year-old, the maximum heart rate would be 170bpm (beats per minute).

3. Perceived Exertion. You can also measure the intensity of your exercise by analysing how hard you feel as if your body is working, based on the sensations you feel during exercise: increased heart rate, faster breathing, increased sweating, and tiredness in the muscles.

4. Metabolic Equivalent (MET) Level. This method of measuring how intensely you’re exercising is based on how much oxygen your body is using during the exercise. 1 MET is how much energy your body uses while you sit at rest. A moderate level of exercise burns 3 to 6 METs, and vigorous exercise burns up to 6 METs.