The Grapevine

Resting Heart Rate Is Not A Factor To Determine Disease Risk, Study Finds

Resting heart rate refers to the number of times the heart beats per minute (bpm), pumping the least amount of blood needed as the body remains stationary. A new study said that a deviation of the resting heart rate from the person’s regular baseline is considered a cause for concern since it indicates an underlying health condition such as hypothyroidism and medication overdose. 

A high resting heart rate (RHR) is generally considered a risk factor of developing cardiovascular diseases, however, another previous study said that RHR lower than 65 bmp could be problematic too. Only changes from individual normal RHR over three years indicated heart disease risks, as per the study by Huazhong University of Science and Technology, Wuhan, published in Scientific Reports last year in April.  

In the latest study by Scripps Research Translational Institute, a similar conclusion was drawn about fluctuating heart rates and disease risk. “For example, a thyroid problem called hyperthyroidism, or overactive thyroid, can cause rapid heart rates, whereas hypothyroidism can cause slower heart rates,” Dr. Michael Goyfman, director of clinical cardiology at Northwell Health’s Long Island Jewish Forest Hills, said, as quoted by Healthline.

Researchers took advantage of the fact that 20 percent of consumers in the U.S. sport a fitness tracker on their wrists. The fitbit device passively measures heart rate, activity levels and sleep duration, thus being a highly convenient monitoring tool. 

From across the country, 92,457 individuals were recruited for a minimum of 35 weeks, from March 2016 to February 2018. They wore a heart rate tracker for at least two days every week, for about 20 hours per day. Age, gender, sleep duration and BMIs were factored into the analysis of daily RHR of nearly 33 million RHR values for an average duration of 320 days.

“Mean daily RHR was 65 beats per minute (bpm), with a range of 40 to 109 bpm among all individuals. The mean RHR differed significantly by age, sex, BMI, and average sleep duration. Time of year variations were also noted, with a minimum in July and maximum in January. For most subjects, RHR remained relatively stable over the short term, but 20 percent experienced at least 1 week in which their RHR fluctuated by 10 bpm or more,” the researchers stated in their paper published in PLOS ONE

Here are some of the other  findings based on various factors: 

  • Gender: RHR for men was between 50 and 80 bpm while RHR for women was between 53 and 82 bpm. 
  • Age: RHR increased gradually as people aged, however, beyond 50, the rate declined. 
  • BMI: Average BMIs corresponded with low RHRs than those with either high or low BMIs. 
  • Sleep: People who slept for 7 to 7.5 hours every night had low RHRs. 
  • Season: Every season, 2 bpm fluctuates. 
  • Individual RHR: Individuals have a daily RHR that is normal for them but can differ from another individual’s normal by as much as 70 bpm.

In the future, the devices could help detect chronic diseases and infection. For now, the researchers acknowledged the massive quantity of data available. “However, the question remains of how useful that data is. As technology evolves, it will be interesting to see if we can actually detect some patterns in the data that offer meaningful diagnostic or prognostic use,” Goyfman added. 

heart-attack-3177360_960_720 Normal resting heart rates are individual to each person. Photo by Pixabay (CC0)

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