Heart rate tracking

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Heart rate variability[edit | edit source]

Definition[edit | edit source]

HRV is defined as the changes in the time interval between successive heartbeats.

Common Uses[edit | edit source]

People are interested in HRV primarily because it is regulated by the autonomic nervous system (ANS), which also regulates heart rate and blood pressure. This means that HRV can potentially provide useful information about questions pertaining to our overall nervous system, including information about stress, rest, recovery, and immune response.[1] The two components of the ANS, the sympathetic and the parasympathetic nervous system, both influence HRV.

Measurement Approach[edit | edit source]

Since HRV measures the change over time of the interval between heart beats, there are many options available for producing a value relevant to a specific question. The heartbeat itself is not instantaneous, of course, but for the purpose of HRV measurement, the time is measured between ECG peaks known as R-R intervals. However, many people have irregular heartbeats, and so HRV is better calculated using NN intervals; that is, the time between ECG peaks when the heart is in a normal rhythm. Four common ways of determining HRV values, with their commonly used associations, are:

  • Standard Deviation of NN-Interval (SDNN)
    • Risk of mortality in cardiac patients
  • Standard Deviation of 5-minute averages of NN-Interval (SDANN)
    • Predominant circadian rhythm
  • The Root Mean Square of Successive NN-Interval Differences (rMSSD)
    • Vagal modulation of heart rate.
  • The Percentage of NN-Intervals that Are Greater than 50ms Different than Prior NN-Interval (pNN50)

Any instrument that reliably provides continuous heart rate data can be used as a basis for calculating HRV. Of course not all instruments are equally reliable and convenient,[2] but the suitability for HRV is determined both by the instrument quality and by the situation of measurement. Less precise instruments can be used when the measurement context is well controlled.

Projects[edit | edit source]

  • Paul LaFontaine: “We never fight on Wednesdays”

People[edit | edit source]

  • Andrew Ahn
  • Marco Altini

Tools to track heart rate[edit | edit source]

There are many tools that measure and record heart rate, aka pulse, either continuously, during an exercise session or periodically throughout the day. There are lots[3] and lots[4][5] of such devices and so not all have been evaluated. Heart rate is most common vital in Biofeedback.

Bands and Watches[edit | edit source]

Most smartwatches and fitness trackers that are worn as wrist-bands provide heart rate data in one form or another. Virtually all of them do so through Pulse Oximetry and try to avoid measurement artifacts through the use of accelerometer data. Cheap devices might actually not be able to reliably read heart rate from the pulse oximetry and rather "make up" heart rate "readings" solely based on the amount of movement as measured by the accelerometer. Widely used wearable devices that include heart rate data are:

  • Fitbit's have many studies using them and Quantified Scientist says that they are one of the most accurate ones. Fitbit devices typically record continuously while worn.
  • Apple Watch of all generations include a heart rate sensor. During normal wearing they only sample heart rate data every few minutes but provide continuous data during workout recordings. Additionally, more recent models also include the option to record ECG.
  • The Xiaomi Mi Band are a cheaper option. But according to DG's (talk) experience with the miband6 they are still not perfect at measuring HR during exercise.
  • The Polar Verity Sense sits on the upper arm.

Finger[edit | edit source]

There are devices that also use pulse oximetry but are worn on a finger, rather than on the wrist, in this sense they are similar to medical devices that use pulse oximetry.

  • The Oura Ring mostly records heart rate data during rest and sleep. Since the 3rd generation of the device it also measures throughout the day and can additionally support workout recordings.
  • Contec Medical System 50F/CMS50f. According to DG's (talk) experience, they are bulky to wear and not accurate during movement but accurate during rest.
  • Wellue (not recommended by DG (talk))
  • The Biostrap is rather expensive ($400) but includes two heart rate sensors and many others.
  • Welltory [6] Can detect HRV when finger is placed in front of phone camera.

Chest Straps[edit | edit source]

Chest straps are considered the gold standard for measuring heart rate during exercise[7] but do not work well for continuous monitoring in particular during sleep as they are typically not comfortable to wear in bed.

Many manufacturers offer chest straps, including:

Few Lead ECG Patch[edit | edit source]

These devices make us of electrocardiograms and are based on electrical pulses. Some devices are designed to only record spot-measurements, while others are designed to collect longitudinal data. For these latter to work they have to be temporarily glued on to a patch of skin, typically on the chest.

Due to their design these are more comfortable to wear than chest straps and can be used for recording data during sleep, but as they require to be stuck onto the skin with temporary glue, these might be less appropriate for continuous longitudinal data collect for more than a few days at a time.

As such they might be less appropriate for long-term data collection, similar to chest straps.

There are a few options for few/single-lead ECGs:

  • Omron KardiaMobile EKG, a small device to do spot-measurements, not continuous recordings
  • uECG Open Source ($100), worn on the chest with sticky patches, records continuously
  • VivaLNK
  • Hexoskin ($600), includes many other sensors.

Medical Multi Lead Holster[edit | edit source]

Similar to the few-lead ECG patches above but these are typically tested medical devices that are used for long-term ECGs where the device is worn for up to 1-2 weeks. They are expensive and very bulky and less accessible for individuals outside the healthcare system.

  • Contec makes one for about $400, can sometimes be found on ebay or alibaba

Tools to Track HRV[edit | edit source]

QS forum list of, likely deprecated, ECG devices.[8]

Company Model or Series Release Date Metrics Sensor Still Produced?
Apple Watch Series 4+ September 12, 2018
Fitbit Sense
Fitbit Versa Optical heart rate monitor
Fitbit Charge

References[edit | edit source]

Linked content on this wiki[edit source]

(The content in the table below is automatically created. See Template:Topic Queries for details. If newly linked pages do not appear here, click on "More" and "Refresh".)

Tools related to this topic  
Apple Watch, Bangle.js, Biostrap, Coospo, Emfit, Fitbit, Oura Ring, Personal Science (book), Polar
Projects related to this topic  
A Life Of Fractals, A Million Heartbeats, A Quest for High Fidelity Activity Tracking, A Reversed Calendar, A Year of Diabetes Data, Arterial Stiffness, Blood Oxygen On Mt. Everest, Butterfly Project: Swimming Goggles To Measure Heart Rate, Connecting my Mind and Body, Data from my iPhone ECG, ECG and Activity Monitoring: What Can We Learn?, Effect of Ketogenic Diet On Heart Rate Variability, Every Heart Beat, Experience Sampling of My Stress, Finding The Optimal Training Zone, From April Zero to Gyroscope, Heart Rate Variability and Flow, How I Measured This Talk, How I Zapped My Brain With A 9v Battery To Overcome Analysis Paralysis, How My Life Automation System Quantifies My Life, Impact of work-related stress, Improving My Blood Pressure With Anaerobic Interval Training, Learning about Biases and Gaps in my Self-Collected Data, Lessons from a year of heart rate data, Lies, Damn Lies, and Correlations, Life in the Fast Lane: Learning from Vitals, Making Sense of My Bio-signals, Measuring Exhaustion and Readiness, Measuring the Moment, My Biological Rhythms In Sickness And In Health, My Life In 40 Variables, Online Activity Aggregation, Owning My Quantified Self Data, Parkinson's Tracking Update, Personal Comfort, Playing with my Breath, Putting Numbers to Sleep, QS Adventures with my Kids, QS Tools for Military Style Training, Quantifying Motivation with a Smart Shirt, Quantifying The Effects Of Microaggressions, Quantifying with Kids, Rhythmanalysis, Sensing Breath and Air, Stressing Out Loud, The Effects of a Year in Ketosis, Three Marathons On Zero Calories, Tinké: Monitoring Fitness Levels and Relaxation Indexes, Tracking Glucose As A Person Without Diabetes, Tracking My Sleep And Resting Heart Rate... further results
Self researchers related to this topic  
ErikBjare, Richard Sprague Justin Timmer, Crt Ahlin, Jamie Williams, Danielle Roberts, Doug Kanter, Renate Zwijsen, Fah Sathirapongsasuti, Hind Hobeika, Juliana Chua, David Albert, Maggie Delano, Paul LaFontaine, Gordon Bell, Ulrich Atz, Ralph Pethica, Anand Sharma, Paul LaFontaine, Bill Schuller, JD Leadam, Tahl Milburn, Gedankenstuecke, Siva Raj, Shannon Conners, Kiel Gilleade, Eric Jain, Stephen Zadig, Fu-Chieh Hsu, Philipp Kalwies, Ajay Chander, Azure Grant, Justin Timmer, Beau Gunderson, Aaron Parecki, Kevin Krejci, Stefano Schiavon, Olivier Janin, Maria Benet, Bill Schuller, Troy Angrignon, Kirill Gertman, Jordan Clark, Victor Lee, Kiel Gilleade, Erica Forzani, Steven Jonas, James McCarter, Mikey Sklar, Juliana Chua, Justin Lawler, Jakob Larsen... further results
We talked about this topic in the following meetings  
2021-09-09 Self-Research Chat, 2021-09-16 Self-Research Chat, 2021-09-30 Self-Research Chat, 2021-12-02 Self-Research Chat, 2022-01-27 Self-Research Chat, 2022-04-28 Self-Research Chat, 2022-06-16 Self-Research Chat, 2022-08-18 Self-Research Chat, 2022-09-22 Self-Research Chat, 2022-10-06 Self-Research Chat, 2022-10-13 Self-Research Chat