Polar M71 ti calculates the OwnCal energy expenditure based on the gender, weight, exercise time and heart rate. Therefore the weight and gender must be reset.
Changing the user also affects the calculation of the total calorie expenditure (T.KCAL). If the T.KCAL reading is not zeroed when the user changes, the Polar M71 ti adds the calorie expenditure of new exercise periods into its memory, even although the user information is changed. If you want that only your own energy expenditure is stored in the Polar M71 ti’s memory you must set the calorie calculator off in the USER mode when the equipment is used by someone else.
... THERE IS NO HEART RATE READING?
1.Check that the electrodes of the transmitter are moistened and that you are wearing it as instructed.
2.Check that you have kept the transmitter clean.
Care and maintenance.
3.Check that there are no sources of electromagnetic radiation in the close vicinity of the Polar wrist receiver, such as TV sets, cellular phones, CRT monitors
etc. 
Precautions.
4.Have you had a cardiac event which may have altered your EKG waveform? In this case consult your physician.
...HEART SYMBOL FLASHES IRREGULARLY?
1.Check that your Polar wrist receiver is inside the transmission range and not further that 3 feet/1 meter from the Polar transmitter you are wearing.
2.Check that the elastic strap has not become loose during exercise.
3.Make sure that the electrodes of the transmitter are moistened.
4.Make sure that there is no other heart rate transmitter within the reception range ( 3 feet/1
meter). 
Precautions/Crosstalk.
5.Cardiac arrythmia may cause irregular readings. In this case consult your physician.
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