Beating 81 means reaching more than 81% of your maximum heart rate for at least 15 minutes during the workout. Above that mark, you work out in your Optimal Training Zone and earn extra benefits like post-workout calorie burn, better cardiovascular health, and more endurance. Our heart rate monitoring gives you real-time feedback on how intense you are working and how many calories you are burning. By that, you can make sure that you are really getting the most out of your workout without pushing too hard. Be prepared: It’s exhausting. But fun.