Everything you wanted to know about heart rate

Jogging girl

While there’s nothing quite like the post-exercise endorphin rush, chances are you’re a gym regular for other reasons. Perhaps you want to shed a few kilos, tone your tummy or train for a fun-run. Whatever you goal, exercising at the correct intensity – that sweet spot between too much and not enough – will help you get the most out of each workout. And using your ticker as a timer is a simple, accurate and fast way to measure your exercise intensity. Here’s how.

The three categories of exercise

Exercise typically falls into three categories of intensity: low, moderate and vigorous. For maximum health benefits, experts recommend working hard but not too hard, aiming for at least 30 minutes of moderate-intensity exercise on most days.

“For most people, if you’re doing a moderate to high intensity form of exercise, we know that burns fat and is good for reducing visceral fat, that deep-down body fat around the organs that is associated with health problems like diabetes, heart disease and high blood pressure,” says clinical exercise physiologist Dr Bill Sukala.

There are several ways to measure your workout intensity to make sure you’re running, lifting or pedalling at a moderate intensity. Objective measures that look at how your body responds to exercise can be used in combination with external measures like speed and distance. The most popular are: exertion rating scales that measure workout intensity according to the body’s physical signs during exercise; the “talk test”, which matches how hard you’re working with how easily you can speak; and heart rate, which increases in proportion to exercise intensity. Research also shows that perceived exertion correlates well with heart rate. So, if you think you’re working hard, your heart rate is likely elevated.

While experts recommend using several methods to accurately monitor exercise intensity, tracking your heart rate is often easiest, especially for new exercisers, because it offers a clear, unambiguous measure of how hard your heart, and therefore your body, is working. Plus, it’s a great tool for keeping the motivation monster at bay as you can’t hide behind the number and trick your mind into believing you’re working out at a higher intensity.

“We generally encourage a variety of methods,” says Katie Williams, spokesperson for Exercise and Sports Science Australia. “Heart rate is a great tool for motivation and tracking. If you want to see a clear figure or number, it can give you a good idea of where you’re at.”

Dr Sukala agrees: “At the most simple, elementary level, heart rate brings everything down to one single parameter. When it comes to fat loss, ultimately the higher the intensity the more energy you burn. It is an indicator of intensity and that’s important for losing body fat.”

Calculating your heart rate

To measure how hard your heart is beating during physical activity, you first need to calculate your maximum heart rate – the absolute most your heart can handle during a workout. The fitter you are, the higher the heart rate you will be able to obtain and sustain.

Most experts and calculators recommend a simple formula that subtracts your age from 220. For example, if you’re 35 years old, subtract 35 from 220 to get a maximum heart rate of 185 – the maximum amount of times your heart should beat per minute while you’re at your absolute workout limit.

However, Dr Sukala says these sorts of formulas aren’t a perfect fit for everyone and should be used only as a guide. “Human bodies come in all shapes and sizes and human hearts come with different types of hard wiring. These formulas are only giving you a theoretical maximum heart rate to work from. Your actual measured maximum heart rate, unless you put someone on a treadmill and take them to complete max and measure their max heart rate, no one really knows.”

What should my heart rate be?

Next, you can calculate your desired heart rate, which Williams says for a moderate workout is about 70 per cent of your maximum heart rate. So a 35-year-old woman would aim for a target heart rate of 130 (0.7 x 185).

If you’re new to exercise or returning after a stint away from the gym, Dr Sukala recommends finding a light-to-moderate intensity that you’re able to sustain for 10 to 15 minutes. “Once you get to that level, take note of what that heart rate is and when you exercise the next session try to match that heart rate and maybe even do a tiny
bit more,” he says.

So how do you know if you’ve made it to your desired heart rate? It can be tricky to take your pulse manually, especially if you’ve reached your desired heart rate, so a heart rate monitor – which measures your heart’s beats per minute – can be a useful workout companion. “A heart rate monitor is definitely more accurate,” says Williams. “If you’re manually taking your pulse it can be quite hard, particularly if you’re puffing, and it does take a bit of practice.

“When taking a pulse you count the number of beats for 15 seconds and multiply that by four to get an idea of your heart rate beats per minute. A heart rate monitor will give you a live count of your heart rate without having to wait for that 15 seconds where your heart rate might decrease in that time.” Most gym equipment has a build-in heart rate monitor, and portable and smartphone versions can also be purchased relatively cheaply. 

Words by Angela Tufvesson