Fitness trackers and smartwatches can make it easier to stay in your heart rate training zones. (Getty Creative) ...

Complicating matters even further, companies that produce heart rate monitors also have higher thresholds for each zone. For example, Polar’s zone 2 is up to 70% of maximum heart rate ...

Indicates whether the model employs a chest strap mounted sensor that transmitts to a watch, a chest strap mounted sensor that transmits to an iPhone app, a watch that requires the user to touch ...

Find out more about how we test. The Polar H10 heart rate monitor first launched in 2017 and has become known as one of the best heart monitors on the market, thanks to its accuracy and ease of use.

Zone 1 (55-65% of max heart rate): This is the "conversational pace" zone. You work at a light intensity, so you can easily chat without losing your breath. This pace is ideal for burning fat and is ...