Data in Your Hands – How is Your Heart?

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As consumers, we have more health information at our fingertips than ever before. What can it tell us about our health? At a population level, what can it tell us about trends globally? Consumers are also getting more sophisticated at looking at that data. In the early days of sensors, like pedometers, we got used to tracking our steps, and the 10,000 steps a day movement was born.

A new paper in the Lancet by Aravind Natarajan and colleagues from Fitbit Research and Harvard Medical School share heart rate variability data in eight million people. Sensor derived data can be a treasure trove when it comes to developing insights. A decade ago, perhaps only health systems and government health agencies would have access to data sets this extensive. Now companies like Fitbit, one of the most popular fitness tracking products globally, have access to real-time data sets.

The current paper examines heart rate variability (HRV), a measure of the time between heartbeats, in eight million Fitbit users. The study is cross-sectional and randomly sampled over eight million Fitbit users from their database over a 24 hour period. Additional measures like steps per day, age, body mass index in the 90 days prior were also added to HRV data.

Findings show HRV declines as we get older, which is consistent with results from other studies. We have systems that operate in the background to support body functions; the parasympathetic nervous system is responsible for rest and supporting digestive health. The sympathetic nervous system readiness the body to deal with stressful events. HRV has often been viewed in the context of cardiac events; this extensive data set shows a more rapid age-related decline in parasympathetic function compared to sympathetic function. Increased rates of physical activity were also correlated to improvements in HRV.

As a consumer, you are likely wearing your Fitbit to track your performance toward your daily goals. The value of seeing your data in the context of people your age can mean more actionable insights into your cardiovascular health. While we have a way to go before we can take population-level data to contextualize accurately for individuals, the value of these large data sets allows us access to real-time signals we could only have dreamed of before now. For now, it would seem the adage of getting thirty minutes of physical activity a day remains an important building block for health.

Thanks for reading – Trina
(Opinions are my own)


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