Sometimes, my Garmin does not record heart rate data for every track point. This would happen occasionally with my 205 and 305... but it happens a lot with the 310. Anyway, Topofusion displays this errant data as large spikes. I was hoping that Topofusion could "ignore" this errant / lack of data (if it is outside of a reasonable range) when displaying the heart rate plot. I will attach an image of what I'm seeing now.