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How to Calculate your Heart Rate and Exercise Intensity

Do you know how to calculate your heart rate zones and how to prescribe exercise intensity, so that you can get the full benefit from your cardio training efforts?

Nowadays it’s pretty easy to get a relatively accurate, real-time reading of one’s heart rate during exercise, along with the approximate calories that are burnt during a given workout. Whenever I’m driving to my personal training sessions, for example, I can see that nearly half of the outdoor exercisers around Mont Kiara and Sri Hartamas are wearing a smartwatch (most of which are capable of tracking heart rate) while they’re running. In this article, I’m going to show you some methods that personal trainers use to prescribe intensity levels for their clients.

hear rate training in different zones

Two basic numbers you’ll need are the Resting Heart Rate (HRrest) and the Maximal Heart Rate (HRmax).

The best time to get your HRrest is in the morning, straight after you wake up. Before you even get out of bed, either with your smartwatch or by palpating your pulse on your wrist with your finger, count the number of heartbeats for 1 minute (or for 15 seconds and multiply the number by 4). Repeat this five days in a row and the average of the numbers will determine your HRrest.

To get the HRmax, use the following formula:

HRmax = 208 - (0.7 x Age)

Now that you have these two numbers, it’s time to calculate and establish the correct training intensity or Target Heart Rate (THR), based on your HRrest and HRmax:

THR = [(HRmax - HRrest) x Desired Intensity] + HRrest

For example, if you’re 45 years old and you’ve calculated that your average HRrest is 55, and want to exercise at 80% training intensity, then the formulas would read as follows:

HRmax = 208 - (0.7 x 45) = 176.5

THR = [(176.5 - 55) x 0.8] + 55 = 152.2

This data can be very useful when planning your interval or zone training. Let’s have a look at the 3 zones and what happens when you work in them!

Zone 1 is the recovery or cardio base zone, while training at 65-75% of the HRmax. Exercising in this zone will help to improve your oxygen consumption for a while, but as you get better it can plateau, and the only way to progress is to keep increasing the length of the workout, so at some point it’s better to move to zone 2 training.

Zone 2 is when oxygen no longer provides enough energy to the working muscles, and so they need to utilise other energy sources, such as fat. It means that the longer you train in this zone, the more calories you’ll burn from fat! The Target Heart Rate for this zone is 76-85% of the HRmax, but once again after a while adaption can occur, and training in this zone can lead to plateau as well.

Zone 3 is training at over 90% of the HRmax, which is high-intensity training, and can lead to peak exertion fast. Train in zone 3 for 20-60 seconds, then recover in zone 1 or 2 before you return to zone 3 again. This training, for example, can include several sprints with recoveries in between, also known as High Intensity Interval Training (HIIT).

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