I have noticed that at the beginning of most runs my HR will spike even though I don’t feel that I am all pumped up. It takes a mile or more sometimes to get the rate to drop and settle into the target HR for the session. I used to think it was because of caffeine or getting used to the cold, but I have learned from coach that it is the body engine priming to racing to match the acceleration from idle to active mode.
Coach Sue Comments: I tried to find a nice nifty link that stated what is happening simply and clearly, but no dice. It is not at all unusual for the HR to spike in the initial minutes of exercise, especially when the body is under a constant workload– there is an upcycling of rate to meet the change in work– from desk to road or rest to active– when you start, your body is primed for the level of activity it’s been doing. When you start working, there is a lag in the energy systems in the muscular level– to meet the initial surge, you use the anaerobic or more sprint oriented metabolism, even though you are not technically sprinting, because the aerobic/oxygen based metabolism has a start up time that needs to kickstart that the anaerobic system doesn’t. So, in order to manage the “sprint”, there is an increase in HR to clear waste and start delivering more oxygen to the now working muscles– one that ramps up, the aerobic/oxygen system takes back over and it is a more efficient system so that initial surge in activity can settle back into a steady state process
I hope that makes sense this morning!