The normal human heart rate, also known as the resting heart rate, can vary depending on factors such as age, fitness level, and overall health. On average, for adults, a normal resting heart rate ranges between 60 and 100 beats per minute (bpm).

For example, a well-trained athlete may have a resting heart rate as low as 40 bpm, while a sedentary individual may have a resting heart rate closer to 80 bpm.

It's important to note that heart rate can also increase during physical activity or in response to stress or excitement. During exercise, the heart rate can significantly increase to meet the body's increased oxygen demand. In some cases, it can reach up to 200 bpm or higher.

Reference: American Heart Association. (2021). Heart Rate. Retrieved from https://www.heart.org/en/healthy-living/fitness/fitness-basics/target-heart-rates