I have had my Forerunner 235 for about two years and have been very happy with it. However, the last two times I have used it in a trail race, it does not accurately pick up my heart rate, For example, never going over 90 bpm when I know, from experience, it should be in the 130's. Do the sensors need to be clean or maintained in some way? Or is it just time for a new watch?
