I'm wondering if I have an overly-cautious Cardiologist, or if it's because of my family history (my Father died of an abdominal aortic aneurysm and my youngest nephew also has one). I'm 57 years old, but very physically active at the gym 3x/week and bicycling in between. My high heart rate during cardio activity was in the 150's to 160, but the doc advised me not to go over 130. So I don't know, but am wondering if its "interpretation" more than anything else?