What is a significant drawback of manual heart rate measurement?

Manual heart rate measurement indeed has a significant drawback of being less accurate due to potential human error. When measuring heart rate manually, the individual must locate the pulse and count the beats for a specific duration. This process is susceptible to various factors, including the person's ability to accurately feel and count the pulse, as well as the timing of the count itself. Variability in counting, distractions, or incorrect placement on pulse points can lead to inaccuracies in the measurement.

In addition, the manual method tends to rely heavily on the skill and experience of the person taking the measurement. This variability can significantly impact the reliability of the results, especially in dynamic situations like exercise where the heart rate can fluctuate rapidly. Therefore, while manual heart rate measurement can be useful, its potential for human error is a notable drawback compared to automated monitoring systems that provide real-time and consistent readings.