Hi all, I have a Garmin Forerunner 235 and I did 2 mile repeats to test out 2 different masks. Here is a graph of the heart rate data:
The course was flat the entire way, but for some reason there is a very steep slope in the data at 0.25 miles for the blue line, and at roughly 0.4 miles for the red line in the image above. Obviously since I only did 2 reps, the confidence interval in this data is extremely poor, but I was wondering what y'all thought the possible reasons could be for this jump in heart rate. Is it normal??? I kept the pace at an even pace the entire time and warmed up beforehand. I know the Garmin Forerunner 235 doesn't have the best heart rate monitor, but I would assume that the inaccuracies of the heart rate monitor wouldn't cause a sudden jump, but rather just contribute to a larger overall uncertainty. Let me know what you think could be the cause of this jump, thanks.