I have a congenital heart murmer, which appears only occasionally. I have struggled with heart rate issues ever since I started wearing a HRM six years ago. I am 57 now and at age 51 started taking hormone replacement therapy (HRT) to alleviate menopause symptoms. (Before anyone jumps me on this, I get migraines when I don't get regular estrogen. I'd rather worry about affects of HRT then have migraines). I also take synthroid, due to hypothyroidism.

The summer I started the HRT, my heart rate would get up to 160+ (I go anaerobic at 162) and not come down, even when I came off the bike. It would take at least 30 minutes to come down. Not very comfortable. I went to cardiologist and did all the tests and then back to my regular doc. He is the one that figured out that, with the HRT, my thyroid was overactive. He lowered my synthroid dose and I've had no real trouble like that until recently.

However, lately, with high temps and humidity I have again suffered from my heart rate rising and staying. Last weekend a former pro cyclist rode with me and a buddy. He said that there is a sympton called "cardio compensation " (I think that is it), in which your body gets very hot, you are sweating, but it is too humid for your sweat to really cool you. To lower your temp, your heart starts pumping faster, which raises your heart rate, which make syou work harder, etc., etc., etc. Makes sense. I was glad to have what may be a logical explanation for my latest heart issue.

I highly recommend anyone who works out regularly get testing done to configure your max heart rate (mine is over 200), and your anaerobic threshold. Then train in the endurance heart rate to help your heart work for you, instead of against you. If you only train at high heart rates, your heart will only work at those levels.

TMI? read up on heart rates, listen to your docs and have fun. you burn more fat (as opposed to carbs) at a lower heart rate!