Hi Jimbo,

Your Maximum heart rate is the highest heart rate you are generally able to sustain under normal circumstances. The Frontier X uses (207-(0.7 x age)) to estimate your maximum heart rate. In case you would like to modify maximum heart rate, you can do so through the settings > edit profile > Max heart rate.

Heart rate zones are ranges between your resting heart rate and maximum heart rate that help you understand the demand of exercise on your heart, as well as the impact on your fitness, energy reserves and recovery you may require after. These zones are personalized to your fitness and health using your maximum heart rate.

Yes. There equations for max HR vs age are gross approximations and are only valid on a population scale. There can easily be a +/- 20 bpm variation from those equations for the individual. Your values are on the lower end of what I would expect. The only way to figure out your max HR is to get warmed up and then do an effort, such as running up a hill (or whatever your sport is) and gradually increasing the effort.