I've had my 305 for a couple of months & all has been well, so far. During this week's runs I've noticed some strangely high HR readings. It has gone from low 130s into mid 150s in a matter of seconds on the flat.
Today on a long run i wondered about some of the readings but I was very surprised when towards the end it was in the 160s & 170s when I expected only 140s. Has anyone else experienced anything similar? Should I get in touch with Garmin or do I need to keep it for longer & see what happens?