Optical Heart Rate Monitoring: Everything You Need to Know

Optical Heart Rate Monitoring: Everything You Need to Know

Are you into keeping fit and want to ensure you know your heart rate when you are in the thick of your workout exercising away at the gym? You may even be jogging on your normal every-day route or climbing up a mountain just for the sheer thrill of it. While you’re doing these things you want to keep track of how your heart is functioning? Solution: get yourself a heart rate monitor.

There are many types of heart rate monitors on the market, so which type of heart rate monitor should you buy? Let’s briefly check out Optical Heart Rate Monitoring (OHRM) and see what you should know about these.

A heart rate monitor is much more advanced as compared to a basic step counter that just counts the number of steps you take, accuracy may not be that crucial in this case. A OHRM device on the other hand, tells you how hard your heart works, when you are at rest or physically exerting yourself. You want to get very accurate results here.

How Does Optical Heart Rate Monitoring Work?

Have you heard of a method called photo plethysmography (PPG) to measure heart rate? Well! Most wearable ORHM devices use this method that shines light into our skin and measures the amount of light that our blood flow scatters when our heart rate and blood flow volume changes.

History of PPG:

Though PPG is more than 150 years old, it has been revolutionized in these modern times. In a dark room, people would hold their hand up to a candle to check blood flow and blood vessel structure. Two alternating LEDs were used in the first pulse oximeters in hospitals during the early 1980’s to measure blood oxygen and pulse rate. You still see these used in the finger or ear clip devices used in healthcare facilities, today.

Relevant developments within the last decade have concentrated on motion-tolerant PPG as motion and activity creates a lot of internal noise that needs to be eliminated from the equation to find the blood flow signal.

Relevant Technology:

The four technical components used by PPG to measure heart rate are:

  • Optical Emitter – this is a component that emits light into our skin using a couple of LED’s.
  • Digital Signal Processor (DSP) – this component captures the refracted light from the device user and translates those signals into data reflecting heart rates.
  • Accelerometer – this measures motion and combined with the DSP signal is input into motion-tolerant PPG algorithms.
  • Algorithms – the algorithms process the DSP and accelerometer signals into data that quantifies heart rate, calories burned, blood pressure and blood oxygen levels.


Once you get the motion tolerant PPG reading right, then some of the biometrics you can derive are:

  • Breathing rate
  • Blood oxygen levels
  • Heart rate variability
  • Blood pressure
  • Cardiac efficiency
  • VO2 Max (maximum volume of oxygen)

Various Forms of OHRM Devices:

Today in the market you can easily find a variety of wearable OHRM devices of all shapes and sizes, including, but not limited to:

  • Wrist bands
  • Smart watches
  • Leg bands
  • Audio earbuds


OHRM devices today are almost ubiquitous and every fitness minded individual has some form of OHRM device with them. Whether it is in your lifestyle for personal health or in active workout sessions in the gym, jogging up a mountain slope or running down a track, every person concerned with fitness tends to do optical heart rate monitoring in some form or the other.

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