This is an acceptable range for normal, healthy adults. If in doubt, consult your doctor for the appropriate level or listen to your body and go on perceived levels of exertion. When you count your pulse during exercise, you only count for 10-15 seconds and then multiply by six or four to get the beats per minute and compare it to your target heart rate range. If you do water exercise you would subtract 17 beats per minute due to the effects of the water upon the heart rate. You would also take a six-second count to determine exercise heart rates and multiply it by ten.
Water removes the effect of gravity upon the body.
Water at normal temperatures of 80-82 degrees Fahrenheit cools the body and removes the heat caused by exercising.