Originally Posted by
generalkdi
I just use the maximum heartrate rule of thumb (220 - age) . He is 36 year old, it does 184 so I rounded it down and said "over 180" it could be dangerous. Of course, it depend of people condition... If you start to feel dizzy at 160bpm stop pushing it!
My doctor has told me that your max heart rate is literally the maximum your heart can pump. Mine is 203 at 27 and I average around 170 on most rides at good effort. The formula is just a ballpark.
The real danger is being in that 95%+ range for too long of if your heart rate does not come down after you chill out. If you're going hard and then back off, your heart rate should fall accordingly fairly quickly. I'm not talking down to resting but mine settles around 130 pretty a couple minutes after hard intervals.
Staying too high too long will result in dizziness, fatigue, and a sick feeling as you start starving of oxygen. This is fine if it's temporary (like toward the end of intervals) but prolonged periods are dangerous