I'm a 60 year-old female. When I exercise, I always seem to surpass my target heart rate. If I watch and stay under it, it feels like I'm not really getting a work-out. Can that rate be considered a minimum? My exercise is usually a treadmill or various nautilus machines.

Target heart rates will vary significantly based on one's age, health, weight and other factors. Please consult your family physician for his recommendations.

What is your heart rate?

Age x .65 = BPM (target heart range)

Always talk to a doc first.

If you surpass it, how? Is it the machine estimating it, or is it a measurement of your actual rate?

Also, if you are going to a gym, don't neglect eliptical machines...

In my opinion, they can offer a better workout with less stress... more bang for the buck.