What method is recommended for accurately measuring the heart rate of rapid subjects?

Counting for a few seconds and multiplying is recommended for accurately measuring the heart rate of rapid subjects because this method allows for a more feasible and efficient measurement without tasking the subject too much, especially if their heart rate is elevated. When the heart rate is rapid, it can be challenging to count accurately over a full minute; therefore, taking a count for a shorter duration—such as 15 or 30 seconds—and then multiplying that number to estimate the heart rate per minute provides a quick and effective way to obtain an accurate reading. Additionally, this method helps to minimize errors that could arise from fatigue or variability during longer counting periods.

Other methods, such as counting for the entire minute or relying on direct observation without tools, may be less efficient or prone to inaccuracies, particularly when dealing with rapid heart rates. Using only a stopwatch does not enhance the counting accuracy but merely times the observation, thus not effectively addressing the rapid nature of the subject's heart rate.