Kerry, don't put any credence in the gym machine's heart rate monitors. While you were certainly being scientific in your approach, swapping machines with your friend to test, there are two things you didn't account for:
1) Differences in technique of pressing your hands on the sensors, you versus your friend, and
2) Differences in conductivity of your skin
If you were doing high impact cardio with a heart rate of 65, most likely you'd wake up on the floor with a bunch of people around you asking if you were OK. Since that hasn't happened, my suspicion is faulty equipment relative to it's ability to pick up your specific electrochemical pulses.
Go get yourself a Polar or similar strap-on monitor (they also make the straps as an integral part of a sports bra), and then test your heart rate. I bet you get different results.
Hi
Thanks for your advice. However I have ben going to the gym regularly for a number of years and heart rate has always much higher on the machines. Its only the last few months that I have noticed it is considerably lower, and I am not holding the machines any different to how I always have. Also I am overwhelmed with tiredness, headaches and dizziness at the moment and wondered if this could be related.
It's certainly possible.
Your heart rate while resting seems pretty normal, and unless you are having the dizziness and feeling like you're going to pass out while exercising, I doubt that the reading on the machines is accurate, your findings notwithstanding. If you were at full exertion and your heart was beating 60bpm, you'd be unconscious, plain and simple. Your heart can't push sufficient volume to keep you conscious AND exercising at 60bpm.
You are of childbearing age, and those symptoms do sound a lot like the ones my wife had when she was pregnant with our two children. Just a thought.
It could also be stress - family issues, job issues, relationships, etc.
Next time you're on the treadmill, take your pulse at your neck and count the number of beats you have in a 10 second interval - multiply that number by six and see if it doesn't come out to be more than 60.
Some of those machines are capable of receiving a signal from a chest strap - maybe you can ask at the gym if they have one you can use?