Digital Life Central is reader-powered. We are a participant in the Amazon LLC Associates Program and other affiliates programs. As an Amazon affiliate, we earn from qualifying purchases.
Garmin devices are some of the best for tracking your performances, following up on your training, hiking without getting lost, and measuring key health metrics. The Heart rate and Heart Rate Variability are critical vitals but also is the blood oxygen saturation (also referred to as pulse Ox, or SpO2).
Many smartwatch manufacturers, such as Apple, Fitbit, Xiaomi, Huawei, and many others, have integrated a built-in oximeter. So even if Garmin gained its reputation based on the accuracy of its navigation systems, the company is now expanding its range of wearables to include a pulse oximeter feature.
We tested the pulse ox accuracy of two of the most recent Garmin models: the Vivosmart 5 fitness tracker and the Forerunner 255 smartwatch. Unfortunately, the results were not what we expected!
How could a $50 finger pulse be more accurate than a $500 smartwatch? Can you trust the Garmin blood oxygen saturation readings? Or should you forget about using a smartwatch for pulse oximetry?
What Is Blood Oxygen Saturation, and why does it matter?
Blood oxygen saturation gained a lot of interest during the Covid-19 pandemics. We all have heard that pulse oximeters were used to measure the levels of oxygenated blood. One of the critical jobs of the blood flowing through our veins and arteries is to carry oxygen to our brain, muscles, and organs.
In a nutshell, the heart will push non-oxygenated blood up to the lungs, where oxygen will be grabbed by the hemoglobin of the red blood cells. So the blood oxygen saturation reading is the percentage of red blood cells that will be oxygenated and will continue their trip through the body to deliver fresh oxygen molecules and keep us alive.
The higher the percentage of oxygenated blood cells, the better. Normal levels are in the range of 95-100%, according to the Mayo Clinic. There are plenty of reasons why the SpO2 may drop: lung diseases, sleep apneas, and of course, Covid. If you want to get into the medical elements of blood oxygen saturation, I recommend that you read this excellent article from the Cleveland Clinic.
Measuring oxygen saturation is helpful to know if your lungs are doing just fine if you suffer from sleep apnea and is also useful when exercising. Even though a drop in oxygen saturation is normal at the beginning of a workout session, the body will adapt and increase your respiration rate to let the muscles get the levels of oxygen they need.
How is Blood Oxygen Saturation measured?
Blood oxygen levels are measured in the same way with finger pulse ox devices or wrist-based pulse oximeters. In a medical environment, a pulse oximeter is used to determine the level of oxygen saturation in the blood. This sensor can be attached to the earlobe or the tip of the finger. It operates by shining different wavelengths of light through the skin to determine the amount of oxygen in the blood.
For instance, blood with the appropriate level of oxygen will be able to absorb more infrared light (while allowing a greater quantity of red light to pass through). Still, blood with an inadequate level of oxygen will be able to absorb more red light (and let infrared light pass). In a pulse oximeter, the blood oxygen sensor can monitor the variations in the amount of light reflected. In a nutshell, red and infrared light LEDs and accurate sensors are vital for measuring the blood oxygen level.
Which Garmin Watches Have SpO2?
Not all Garmin Smartwatches and Fitness trackers come with a Pulse Ox. Garmin have now introduced the oximeter in money of their devices, including the Fenix 7, Fenix 6X, Fenix 5X, Vivoactive 4, Venue 2 Series, Forerunner 245/255/645/945/955, and the newly introduced Vivosmart 5.
Considering that Blood oxygen saturation has benefits for health and fitness but also for people climbing in mountainous regions to check on their altitude acclimatization, it is fair to think that most if not all the Garmin devices to come will include such a feature.
The key to broader adoption is to ensure that the blood oxygen saturation levels are in line with reality.
Is Garmin Pulse Ox Readings Accurate?
Garmin devices are not medical devices, and they do not intend to replace medical pulse oximeters. However, it doesn’t mean that they should not be relied upon. First, let’s check how to get a reading.
One of the main benefits of Garmin smartwatches is that the measures can be set to occur at different time sets: during the night, all day long, or just on a spot basis. Continuous measurements of the blood oxygen levels are instrumental in helping detect sleep apneas. Be aware that none of the Garmin devices are considered medical devices and that the results will only be informative and will not constitute a diagnostic.
For Spot checks, the results will be accessible on the watch, while if you choose to check your blood oxygen during the night, they will be part of the Sleep results.
In several scientific studies, researchers aimed to define the accuracy of commercial wrist-based pulse oximeters. A team from Baylor University found that “Except for readings taken at 12,000 ft of simulated altitude, the Garmin fēnix® exhibits minimal overestimation of SpO2 and minimal underestimation of HR during simulated altitude exposure.”
All should like fine then, well, not really. Another international and multicentric team did the same type of analysis and found a different result indicating that the same Garmin fēnix® 5x Plus “demonstrated poor validity and cannot be recommended for monitoring SpO2 at high altitude.“
Who should we believe? Is the Garmin Pulse Ox accurate, and is a wrist-based pulse oximeter equivalent to an approved medical device.
To go to the bottom of this question, we did the test ourselves using a Garmin Vivosmart 5 and a Garmin Forerunner 255 compared to a medically validated commercial finger pulse oximeter. Again, the results were surprising and a bit worrying.
When doing a blood oxygen level spot check, the Forerunner reading was 95% when the oximeter found 99%. The Vivosmart 5 results were even more confusing. In one of the tests, the Garmin Vivosmart and our medical grade oximeter were in perfect agreement: 98%. But a few minutes later, the Vivosmart 5 reading dropped to 95%.
So what is the conclusion? Are the Garmins accurate or not for measuring the percentage of oxygenated blood? Well, it is our opinion that a wrist-based pulse oximeter will never be as accurate and reliable as a dedicated finger pulse device. Still, it doesn’t mean that they have no value. They need to be handled carefully and the results confirmed with a medical device in case of doubt.
How Can I Improve My Garmin Pulse Oximeter Readings?
Measuring blood oxygen can be influenced by the color of the skin, but the main factor is ensuring that the Garmin device is fitted correctly.
On its support page, Garmin states that:
- the sensor must be in contact with the skin at all times,
- an excellent way to check that the device is fitted correctly is to feel the skin moving with the watch,
- the arm should be at the heart level,
- it is crucial to remain still while the Pulse Ox measurements are in progress,
- the skin and sensor must be clean and exempt from any sunscreen, lotion, and insect repellent.
To Wrap Up?
Measuring blood oxygen levels with a Garmin Watch or Garmin Fitness tracker is a great feature but getting accurate readings is not easy. I always found the results to be on the low side of the spectrum, and I systematically add a couple of percent to the results. It is not ideal and limits this important feature’s usability.
With patience, it may be possible to find the perfect tightness and location for Garmins’ device to provide Pulse Ox results that will be consistently accurate. However, it is a bit confusing not to be able to get results you can trust just right out of the box. Technology is evolving fast. The website Techradar recently reported that Garmin filed a new patent for a more accurate and reliable blood oxygen saturation sensor. We can not wait to test its accuracy.