I take my dog out every morning to throw his frisbee, something I do every day. Even though my health is pretty bad right now it's something I can do daily with no PEM. It's just a few steps out the door and a few throws (my dog is really old so he doesn't need a ton of exercise.) Since it's been cold this daily ritual is exhausting me. It was 18 degrees F this morning; I wear a down coat, boots, mittens, etc. and a heated scarf to cover my mouth because the cold air triggers asthma. I noticed my heart starts pounding, and it first I thought it was the asthma but the warm scarf keeps the cold air out of my lungs, and I don't wheeze, have chest pain or tightness or any of the other symptoms. After two or three throws my muscles start to weaken and I want to lie down. This morning I took my resting heart rate (76bpm), and then again when I was outside in the cold throwing the frisbee (124bpm.) My blood pressure was taken right after I came in the house panting (which is purportedly supposed to rise on exertion in normal people) was 96/62. WTF. The only thing I can think is that it's from the temperature change. Has anyone else experienced something like this?