Diuretic use: Medications used to treat high blood pressure or fluid buildup work in the kidney and flush excess fluid from the body, causing frequent urination. Prostate problems: An enlarged prostate can press against the urethra and block the flow of urine, causing the bladder wall to become irritated.
These fitness machines can read the chest straps and display the heart rate on the equipments' keypad. Either heart rate monitor is a more accurate than an exerciser manually taking his cardio pulse rate in the middle of exercise. Stage One: 60% to 70% of Maximum Heart Rate. Sometimes called the cardio fat burning zone, the first heart rate stage is between 60% and 70% of maximum heart rate.
It's not normal, but it's not dangerous at your age. Your maximum heart rate at age 21 is around 200 bpm ... getting up to that is dangerous. Your exercise target rate for cardio exercise is 150 bpm ... and in theory you could do that rate for a lot of the day without problem.