All of the heart rate monitors tested here do a pretty impeccable job at tracking your heart, but what does all of the data actually mean, and what is it actually telling you?
Heart rate zones
If someone tells you they’ve been doing Zone 2 training for instance, they’ve been doing a heart rate zone-based workout time. Heart rate zones are basically a way of breaking down your ranges of effort during exercise. It’s based on your maximum heart rate (more on that below), representing working at a percentage of that maximum heart rate. Zones go from 1 to 5, with 5 indicating working at 90 to 100 percent of your maximum heart rate, so your maximum effort. Zone 2 represents training at 60 to 70 percent of maximum heart rate and represents light training. You can calculate your heart rate using this simple calculator that Polar has built.
Maximum heart rate
Some monitors can inform you of your maximum heart rate, which is the number of beats your heart can reach during exercise. Knowing this information is useful for exercise to better understand when you’re training at your peak intensity and can be used to create heart rate zones. Aspects such as age and level of fitness can influence what that maximum heart rate will be. You can generate an estimate of your maximum heart rate by simply subtracting your age from 220 and use that at a starting point. You can also perform your own test to more accurately reflect that information. Again, Polar offers a good example of a test you can do yourself to calculate this.
VO2 Max
This is a fitness metric that has been around for a long time and has been rebranded or renamed by some smartwatch makers. It wants to tell you how strong your cardiovascular fitness is, and provide a useful indicator of your endurance to sustain intense exercise for long periods. The term VO2 Max stands for maximum rate of oxygen your body can consume during exercise. Seeing a high VO2 Max score is a sign of a boost in the rate of oxygen you can consume. Calculating this accurately is done in lab conditions, so heart rate monitors and watches will use their own algorithms to replace some of that lab testing to provide a simpler way to present that metric.
Heart rate variability
There’s been more talk about heart rate variability (HRV) than there has ever been in respect to wearables and that’s because the heart rate measurement is becoming key to unlocking what they can tell us about recovery, stress and even when you might be getting ill. Heart rate variability measures the intervals between heart beats and is measured in milliseconds. Seeing high HRV readings is generally considered better than seeing lower ones where low readings could be an indicator that the body is under stress. What a high or low reading is for one person can differ for another because it can be influenced by age, health and even when the measurement was taken.
Resting heart rate
This is the number of times your heart beats in one minute when at rest. It’s information because it can be a simple indicator of your current level of cardiovascular fitness and general wellbeing. Typically, your heart rate is supposed to sit anywhere from 60 to 100 bpm at rest. A lower heart rate reading than that could be a possible indicator of an underlying issue, though it is also associated with athletes because their heart has been trained to be more efficient at pumping blood to help maintain performance. So, lower is better, but seeing it low or extremely high when you’re not a very active and fit person could prompt that something isn’t quite right.
Calories burned by heart rate
This is essentially a heart rate monitor’s way of estimating calorie burn based on your heart rate data. It’s looking at your effort based on heart rate and using the company’s own algorithms to offer an indicator of how many calories you’ve burned during a workout. Using heart rate, which is one of the strongest if not strongest indicators of effort, makes it one of the more reliable ways to work this information out.