I am a 56 year old non-smoking, white male, in excellent condition. I have 4 older siblings who, to date, have not shown any heart problems. My father had stents put in after age 70 and lived to 86. My mother is 89 and has no history of heart problems. I enjoy mountain biking and road riding and often get my heart rate up into the 170s. I can maintain a heart rate of 170 for approximately 6-7 minutes and often do if I am in a long, steep, climb. My question is, is this healthy or dangerous? I have seen numerous articles which say a person shouldn't get their heart rate up over 85% of their max heart rate. If I limited myself to that number, I would have to slow way down, especially on the climbs. Can anyone give me some info on this?