Resting heart rate has long been considered a critical health metric that can predict if you’re vulnerable to heart attack, stroke and lung disease.
The lower the score, the fitter you are said to be — as the organ is working efficiently to pump blood around your body when you’re not exercising.
Now, millions of us will be familiar with our magic number every minute of the day thanks to the smartwatches that cling to our wrists.
Some devices even issue warnings if the number exceeds a certain level.
But experts have issued caution, arguing that the resting heart rate we see on our tracker isn’t as reliable an indicator of heart health as you might think.
While the NHS suggests a resting heart rate between 60 and 100 beats per minute (bpm) is normal for adults, studies show the ideal figure can vary depending on age.
One study showed that men in their 50s with a heart rate above 75bpm were twice as likely to die within the next 20 years, compared to those with 55bpm or less.
Results also suggested that every additional bpm was linked to three per cent higher risk of death, a one per cent higher risk of cardiovascular disease and two per cent increase in coronary heart disease.
Resting heart rate, the measure of how often the vital organ beats per minute, is considered a critical health metric and why a dozen smart devices now offer to track it
Meanwhile, data from the US Centers for Disease Prevention and Control (CDC) suggested that optimum cardiac fitness means having a bpm of below 60, roughly between 47 and 57.
It’s thought only around 10 per cent of people fit into this category — most of whom are professional athletes.
Other figures suggest an athletic resting heart rate for men between the age of 18-25 is between 40-52bpm, whereas the equivalent figure for men over 65 is 52-55bpm.
The average figure for men of all ages is a bpm in the low 70s, whilst those in poor or below average health are considered to have a bpm in the high 70s or over 80.
For women, an athletic 18-to-25-year-old would get a resting bpm of 40-48 whilst an athletic 65-year-and-over woman would get 52-55bpm.
An average result for women was 74-78bpm at the younger end of the scale and 73-76 at the older end. Like men, a bpm in the high 70s or over 80s for women was considered below average or poor.
While 60-100bpm is the normal range for adults, and many smart watches will tell you this is healthy, the general consensus is the lower a person is within that scale the better.
A resting bpm of over 100 for example is considered far too fast for most people and could be a sign of something abnormal in the body.
Studies suggest people with lower RHRs on the whole have better heart health, as they’re generally healthier overall, whilst those with higher results are more likely to have risk factors for heart disease like high blood pressure or obesity
Experts are keen to point out that individuals vary, and some people will have different ‘normal’ resting heart rates, especially if they an existing heart condition.
Heart rate variability (HRV), the term for variation in time between heartbeats, is also a heart health variable smart devices track.
Some experts consider a high HRV just as important as resting heart rates, as it represents the organ’s ability to respond quickly to demands placed on the body.
HRV naturally declines as people get older. Healthier people in their early 20s have a HRV of about 50 to 105 milliseconds while for 60-65-year-olds its normally between 25-45 milliseconds.
Despite smart health devices offering to monitor heart health metrics for us, experts warn not to become over-reliant on the devices as they have their faults.
Most wearables track heart rate using a small sensor on the back of the device. But this means not wearing it tightly enough — or too tightly — can influence the accuracy of the data.
Additionally people with darker skin, and those with tattoos on their wrists, can also suffer from more inaccurate results.
This is due to darker skin tones absorbing more light, which in turn can interfere with the green light the devices use to measure heart rate.
The same issue applies to tattoos in the wrist area as the substances that give them colour also absorb light.
While some warning signs (pictured) are easy to spot — such as severe chest pain — others are more vague and hard to pinpoint
Additionally, some devices switch off heart rate monitoring functions when the battery runs low to conserve energy.
Finally, like any device, malfunctions can happen either by faulty manufacturing or software, damage, or simple wear-and-tear.
It’s for these reasons that medics urge people with any symptoms of heart problems to speak to a doctor even if their smart device is giving normal readings.
One device-proof way people can check their resting heart rate is via the following exercise.
Place your pointing and middle finger on the inside of your wrist or on one side of the neck just below the jaw.
Once you find your pulse count the number of beats over the next 60 seconds to get a bpm figure.
To get the most accurate results people are recommended they do this test at rest, so sitting or lying down.
Experts also advise not having coffee or nicotine before measuring your pulse as these substances can artificially boost heart rate.
For accuracy, complete the test at the same time every day, to get an average over time.
Another heart health metric devices frequently measure is target heart rate (THR), which is a measure of how fast the organ should be beating during exercise.
THR is first calculated by subtracting your age from 220bpm and then taking this figure and figuring out what 50 and 70 per cent of this is.
For example, a 50-year-old will have a THR of between 85-119bpm.
Some experts bump this up to between 50 and 85 per cent of 220bpm minus age, though the 50 to 70 per cent range is recommended by the British Heart Foundation (BHF), who also have a free tool you can use to find out yours.
Those wanting to keep their heart fit use a THR range to ensure they are doing the optimal level of exercise. For example, a jogger not achieving their THR while running knows they need to pick up the pace.
Exercising at a THR beyond the upper limit of what is recommended can be dangerous.
Those without a smart device to track their heart rate while exercising are instead advised to do what is known as the ‘talk test’ while exercising.
If you can still talk while doing the exercise but also feel warm and are breathing a bit more heavily than normal, you’re working at the right pace.
But if you can’t talk at all you might be doing too much.
As always, medics urge people to listen to their bodies and if an exercise feels uncomfortable to stop.
While not as accurate as specific medical equipment, experts say devices that track heart rates can be useful as patients can be inspired to come to a medic for advice and any potentially concerning results can be properly investigated.
[Notigroup Newsroom in collaboration with other media outlets, with information from the following sources]
