Answer to Question 1
The heart rate usually is at its lowest point (resting heart rate) late in the evening after you have been sitting quietly for about half an hour, watching a relaxing TV show or reading in bed, or early in the morning just before you get out of bed.
Answer to Question 2
A small but real risk exists for exercise-induced abnormalities in people with a history of cardiovascular problems, certain chronic conditions, and a higher risk for disease. Among the exercise-induced abnormalities are abnormal blood pressure, irregular heart rhythm, fainting, and, in rare instances, a heart attack or cardiac arrest.