I know I’m late to the party. I’m using the Polar OH-1+ (forearm/bicep heart rate monitor). Map my ride and Polar indicate around the same amount of calories burned when compared to Zwift. Zwift is way off. I weigh myself after my cycling workouts. I can assure you Polar or Map My Ride estimates are probably more accurate based on the article below. I don’t know why Zwift doesn’t give you the option of using data from Polar. Zwifts algorithm for calories is trash.
The researchers evaluated seven fitness-tracking devices with the help of a small group of 60 volunteers and found that six of the devices were accurate for heart rate to within 5 percent. None of the devices were from the Polar brand, but the findings are still helpful for understanding that even when heart rate accuracy was good, the accuracy of measuring energy expenditure was not: The most accurate device was off by 27 percent, and the least accurate was off by a staggering 93 percent.
But with Polar heart rate monitors so often functioning as the gold standard for measuring heart rate, is it possible that they fare better?
The answer is a mixed bag, depending on which model is evaluated and the activity that they were used to gauge. For example, in a study published in a March 2010 issue of the *[British Journal of Sports Medicine], researchers found that the Polar Activity Watch 200 fell within the accepted 10 percent error threshold of calorie estimates — when used while hiking. They didn’t evaluate the AW200 during other activities.