I am a 52 year old, over weight, out of shape woman. I have obesity related asthma and diabetes.. I have recently joined a gym but within 8 minutes of being on the treadmill, at only 2 mph, my heart rate is up to 132-135.. there is no chest pain or discomfort but the high numbers scare me.. I feel like I am not getting enough air into my lungs.. I am newly diagnosed with asthma. I am 5'2" and 238 lbs. Is the high heart rate dangerous? Oh, I have had tachycardia all my life but my heart rate is not THAT high except when I am exercising.