Expert: Todd Bublitz, RCEP - 4/26/2006

Question
I am a 36 year old female, in reasonably good shape. I have participated in regular exercise both aerobic and strength training since about age 18. My question is why does my heart rate get too high during aerobic activity? By too high, I mean above the 85 percentile for my age/gender. I have not found that I am able to improve my endurance. I perform a variety of exercises - elliptical, treadmill, stairs, bicycle. I exceed my target heartrate every time, but my rate of perceived exertion is around a 7 out of 10 at a pace that I can sustain for 30-60 minutes. During speed intervals, my heartrate will exceed 200 bpm. At normal (workout) pace, it usually hangs around 160-170 bpm. I consider myself to be stronger than average for my age, as far as strength training goes. I have no problem with reaching new goals there, but I am frustrated with my lack of progress in cardiovascular conditioning. I am 5' 4", 144 pounds. My normal heartrate before exertion is usually in the 80's. I have low blood pressure (90's/60's) and have been told I have low cholesterol numbers. I do not smoke, or have any health problems. I also do not take any medications and drink only small amounts of caffeine (1 up of coffee per day). Any ideas?

Answer
Natalie,

First, I want to start by saying that a visit to your doctor to address these concerns is the best way to evaluate what is happening to you.  

I can give you some general information on exercise, heart rates, perceived exertion and blood pressure.  I am not trying to explain what may or may not be happening with you.  That would be against medical ethics and against AllExperts policy for asking questions.

During exercise your perceived exertion should be around 4-6 on a 1 to 10 scale.  A "7" could mean that you are exerting yourself too hard, and your heart rate may go over your "target".  If your heart rate gets anywhere near 200 bpm, that may be unsafe and I would advise against working that hard.  Lower blood pressure usually means higher heart rates.  The ability of your cardiovascular system to deliver blood to the body is a function of heart rate times blood pressure.  You need a certain level (HR x BP) to maintain exertion.  If your BP is low, your HR will increase to compensate.  

You will need to talk face-to-face with an exercise specialist to evaluate your concern; "I have not found that I am able to improve my endurance."  A workout heart rate for a physically fit 36 year-old of 160-170 bpm is perfectly normal (about 85%-90% of your age-adjusted maximum).  I would expect that these heart rates would give you a perceived exertion of "7".  Physically fit people can sustain HRs above the generic age-adjusted numbers (220-age=max HR).  I see nothing unusual with these numbers.

Natalie, you have to realize that there are limits to the gains that we can make in our endurance.  If you have participated in regular exercise both aerobic and strength training since about age 18, you may have gained all that you can with the amount of time you spend exercising.

Best wishes.

Todd