Study Finds Normal Resting Heart Rate Varies Widely

BOSTON (CBS) -- What is a normal resting heart rate? According to a new study from the Scripps Research Translational Institute, there is huge variability from person to person.

Researchers measured the heart rates of more than 92,000 people using wearable wrist sensors. They found the average resting heart rates between individuals varied as much as 70 beats per minute, from as low as 40 to as high as 109.

They also found average heart rates were highest in January and lowest in July.

They said day-to-day changes could indicate infection or menstrual cycle phases, while gradual changes could reflect decreased fitness or a development of a chronic disease.