Tuesday, March 08, 2011
Thanks again, SparkPeople!
Some time ago I asked about why my heart rate monitor suddenly jumped from the 120s to well over 140 even though I hadn't changed my pace or exertion. It scared the tarnation out of me! I posted questions on a board or two and didn't really get a satisfactory answer. I called my marathon/Ironman running neighbour who is also a nurse and asked her and she said it happens to her as well but the following is the clearest answer I have received on the matter:
"Cardiac creep, also called cardiac drift, is a rise in heart rate even though your pace remains the same. This is often caused by dehydration in response to rising temperatures and humidity. This causes the heart to pump faster in order to deliver the same amount of oxygen to your muscles. This is one reason heart rate monitor-based training during the summer can be difficult and misleading, while using the rate of perceived exertion may be best in hot, humid weather. "
I also asked my doctor about it and she was unconcerned but did say that if it suddenly jumped to over 200 to call her, pronto!
Just thought I would make a point of sharing that because it was quite unnerving for me at the time. It still happens from time to time but now I don't really worry about it and I find that dehydration does seem to be part of it.
So there you go, your lesson for the day. *lol*