Are Heart Rate Monitors Accurate for Calories Burned

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Wearable heart rate monitors have become a part of many people’s daily apparel. These devices don’t just help people monitor and track their health and exercise stats but have also developed into very trendy-looking accessories.

They are effective tools to aid in your weight-loss journey; however, while most heart rate monitors do a good job at their primary function – measuring your heart rate – they may not be as effective at measuring energy expenditure which is the main driver in burning calories.

Heart rate monitors are private observing instruments that record your heart rate in real-time. The two main monitors use either electrical or optical sensors to sense your heart rate. Electrical sensors are more commonly used in chest-strap monitors, while optical sensors are more common in arm straps or wrist watches.

In this article, we will look at how effective these devices are at calculating calories and discuss what you should be relying on them for. So without further ado, let’s take a look at heart rate monitors and how accurate they are at calculating how many calories you have burned during exercise.

How Does the Calculation Work?

The basic foundation of the calculation is based on the relationship between heart rate and the amount of oxygen consumed. In general, increased oxygen consumption means more calories are being burned, which is also the key factor used by heart rate monitors to estimate caloric expenditure.

Here’s where the discrepancy starts. Measuring your exercise intensity is not the only factor that goes into calculating the number of calories burned. Your monitor relies solely on your heart rate while applying averages or pre-programmed responses to other variables in their algorithms to deliver a final calorie figure.

Other variables that play a role in the rate of calorie shedding include the following:

  • Age
  • Gender
  • Weight
  • Height
  • Level of fitness

All of these figures are required to calculate your body mass index (BMI), which is an essential calculation to work out the number of calories you’re burning accurately. Most modern heart rate monitors ask for this information when you start using it; however, some don’t, and it is a clear indicator that the calories burned figure is likely to be incorrect.

Major Factors That Affect the Accuracy of Results

Different cardio and strength training exercises have different effects on your heart rate and overall metabolism. When muscles contract, the body’s reaction is to increase your heart rate and pump more blood to that area.

During cardio training like running or cycling, your muscles undergo repetitive expansion and contraction, which causes blood to flow to the muscles when contracted and away to the rest of the body when expanded. Therefore, the quick repetitive motion in cardio training causes a more constant blood circulation and heart rate.

Alternatively, strength-based training like bodybuilding and yoga works a little differently. The blood flow to the muscles is not pumped back as quickly. This reduced blood return from the muscles causes the brain to increase the heart rate even further. Therefore, your heart rate monitor will almost always overestimate the number of calories you’ve burned during these exercises due to the increased heart rate and the subsequent impact on your metabolism.

How Accurate Are Heart Rate Monitors

Chest straps are still considered the most reliable and accurate heart rate monitor but are not as easy to use throughout the day as other wearable fitness trackers.

The factors mentioned above suggest that wearable monitors are more likely to provide a “best guess” result since they do not utilize all the physiological data required to calculate an absolute accurate answer. It does not mean that the figure calculated by the monitor is completely useless, though.

The accuracy of heart rate monitors when tracking your heart rate alone is really good. Numerous studies have been conducted on the more famous brands of heart rate monitors, and results proved that the accuracy of wearable heart rate monitors in relation to tracking just heart rate was less than 10% different from ‘gold standard’ medical instruments, which is extremely impressive.

The discrepancy in results relating to calories burned ranged up to 27% between the same two instruments. That’s a significant difference but illustrates the potential issue with relying solely on your monitor to track your calories.

Runner with earbuds checking heart rate monitor watch

Tips to Keep Your Heart Rate Monitor Accurate

As mentioned, even with the discrepancies in results in calories burned, your heart rate monitor is likely still extremely accurate in tracking other important figures to your overall health. Here are a few tips to ensure you continue receiving the most accurate information from your wearable heart monitor.

Tip 1 – Favor strapped devices over strapless devices. While straps can be uncomfortable at times, they are a vital component to allow the heart rate tracker in the watch to receive a constant stream of data from your heart rate. They are also far more accurate than strapless devices.

Tip 2 – Clean your monitor regularly. When you exercise, your body releases several salts and minerals. These particles can block or interfere with the sensor responsible for tracking your heart rate, impacting the reading.

Tip 3 – Never set and forget your information. Most newer versions of wearable heart rate monitors ask you for several pieces of information before your start using them. It’s important that you keep this information as updated as possible as your fitness improves, especially regarding your weight.

These monitors are designed to re-calculate your weight continuously in correlation to the readings it takes from your heart rate. If your weight differs from the figure being displayed on your monitor after a week of training, it’s worth updating to ensure that the calculations are based on more accurate figures at more regular intervals.

Tip 4 – The final tip may seem straightforward but is worth mentioning because it can often be overlooked. Change or charge the batteries in your heart rate monitor frequently. Batteries become weaker as they lose charge or get old, which can affect the instrument’s ability to maintain optimal performance.

Conclusion

Heart rate monitors attempt to calculate calories burned by running the data they collect relating to your heart rate and the initial information you input, such as your height and weight, through a complex algorithm to deliver a result.

This result is not absolute and, therefore, cannot be entirely relied upon to track calories burned accurately. However, these monitors are still extremely helpful in tracking other vital stats that play key roles in achieving your desired fitness goals.

Now you know everything you need to know about heart rate monitors and how reliable they really are in calculating calories burned.

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