Heart rate slowly decreases with age, due to changes in the heart muscle as it ages. Therefore, the resting heart rate of the elderly will usually be slower than that of a younger adult.
However there is no number to estimate exactly how much is normal to an 88 years old this will be evaluated depending on medical condition and symptoms and medications taken ,but approximately the range is between 50-100 considered normal and as i say that is dependent to every specific person due to factors .
usually elderly people may experience a heartbeat that is too fast or too slow.
A heart that beats more than 100 times per minute is a condition known as tachycardia and is most prevalent in the elderly.
Some circumstances can bring about this kind of fast heart rate including shock, pain, anemia, exercise and strong emotion. Some beverages and medications may also cause a rapid heart rate including coffee, tea, alcohol, epinephrine, isoproterenol and atropine. The symptoms of tachycardia include dizziness, heart palpitations and sometimes chest pain.