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Review: finger on the pulse with Masimo’s MightySat

Masimo MightySat pulse oximeter - multi-view

Global medical technology company Masimo is outreaching to the endurance sport community with its MightySat pulse oximeter product offering. The company’s technology is being leveraged in athlete monitoring; and Masimo argues that athletes should consider regular monitoring via a pulse oximeter (placed on the finger, ideally each day for a pattern of data to be established).

MightySat can help determine if an athlete is optimally oxygenated (with sufficiently oxygenated blood for optimum performance). Alongside other biomarkers tracked by the device, an optimal pulse rate can be established to assist with ‘better training, recovery and athletic performance’.

Incorporating its pulse and sensor technology, Masimo’s MightySat Fingertip Pulse Oximeter has two simple claims that encompass its brand strapline:

  • Better Data = Better Health
  • Better Data = Better Performance

Over the past few months we’ve been putting the MightySat through its paces in order to understand the product a bit more and delve into its benefits…

With a list price of US$299, the MightySat doesn’t come cheap for what is essentially a finger sensor. However, on closer inspection, the device has a number of interesting features and claimed benefits.

The first main claim about MightySat is its level of accuracy. Masimo notes that its pulse oximeters are… ‘the leading brand in hospitals because of Signal Extraction Technology (SET), which provides accurate measurements when other hospital-grade pulse oximeters fail – during movement and low blood flow.’

MightySat is used at rest as a monitor of an athlete’s fitness levels. Typically, an athlete would use the device first thing in the morning having just woken up and ensuring a relaxed body position, with slow and steady breaths. Another interesting feature of the product is ‘Heart Rate Recovery’, which was introduced as an update to the accompanying iPhone & Android app during the test period. (More on this later.)

When first placing the MightySat on a ring finger (for the best possible pulse signal), and having connected the device to the MasimoHealth app via Bluetooth, the ‘SpO2’ and ‘PR’ readings immediately appear on the app display screen. Here the MightySat device is picking up the oxygen level in the blood alongside the pulse rate (heart rate). The SpO2 is expressed as a percentage; and, if used at sea level, should be in the 97% to 99% range.

(When used at altitude, or in tandem with an altitude simulator, the SpO2 percentage would drop. This is due to the drop in effective oxygen concentration and the reduced concentration of oxygen inhaled.)

The team at Masimo point out that SpO2 has been known to drop to 92-93% at sea level ‘when an athlete has dug incredibly deep in a given training week’. So, if an athlete was particularly fatigued, he or she may see a reading of around 94% in the morning at sea level. If so, the device is effectively flagging that it would be best to back down on training intensity. (97% and above indicates that an athlete is ‘properly oxygen saturated for a strong/intense workout’ on that day.)

Likewise, if the pulse rate (PR) reading, expressed as beats per minute is higher than expected, this could be an indication of fatigue, stress or an early marker of overtraining. Again, having an immediate reading, taken early in the day via MightySat, helps the athlete plan any training for that day.

Pulse rate can of course be picked up by any quality heart rate monitor. What makes the Masimo MightySat interesting is the combination with SpO2, tracking blood oxygen levels, and a range of other biomarker readings built into the device and app.

A few seconds after placing MightySat on the finger the next reading to display on the device & app is the perfusion index (PI). This is effectively the strength of the blood flow or signal picked up by MightySat. Having previously had issues getting a sufficiently strong PI signal with standard pulse oximeters, it becomes clear at this point that the MightySat is more of a top-end product than a regular hospital grade product offering. The pulse oximeter supplied with the Altium i10 altitude simulator, for example, is a hospital grade product. This device generally works OK. However, there were occasions with the regular hospital grade oximeter when there were issues obtaining a sufficiently strong perfusion index (PI) due to weaker blood circulation in certain instances, such as when room temperatures were colder.

With MightySat, the resulting PI score achieved is much higher than that obtained previously with other pulse oximeters, indicating that the device is sensitive enough to get the strongest possible reading.

There are two other biomarkers captured by MightySat. These are: respiration rate (RRp), which essentially shows the number of breaths per minute, and Pleth Variability Index (PVi), which looks at the relationship between perfusion index (PI) and breathing cycle or respiration rate (RRp).

In essence, the respiration rate indicates how well heart and lungs are functioning. A lower rate while at rest, coupled with a lower heart rate, would indicate an athlete who is well trained and who recovers effectively after exercise. Pleth Variability Index (PVi) is used to indicate changes in hydration, breathing effort, perfusion, or other factors.

Masimo MightySat pulse oximeter

Masimo has a number of pro athletes on board as brand ambassadors, across a variety of sporting disciplines. Within the endurance space, we spoke with US cyclist Dotsie Bausch, an Olympic silver medallist from the 2012 London Olympic Games, 7-time US National Champion, former world record holder and two-time Pan American gold medal winner.

Turning to the Pleth Variability Index (PVi) and other biomarkers, Dotsie explained how these should be used by athletes. She said, “With PVi measurement, you must be lying down and in a calm and relaxed state, and breathing calmly and fluidly. PVi is the difference in the pressure versus fluid in the thoracic cavity or chest cavity. I suggest that athletes lay down and relax for at least 90 seconds before taking a PVI reading (and using MightySat in general). By adhering to this every time, all readings will be in taken in consistent conditions.

“Biomarkers, like pulse rate, SpO2, RRp, etc., are very specific to each unique individual, so it’s important to track your numbers for at least two weeks to quantify your personal baselines to work from. That said, the latest version of the Masimo Personal Health app gives a reference of ranges for each biomarker.”

She continued, “The use of MightySat in athletic training is so new that ‘universal’ benchmarks are not established. They are highly individualized, based on the individual’s characteristics/traits (age, fitness level, etc.) as well as what type of athlete they are. For instance, a triathlete’s stats will be different than a football/soccer player. You need to use MightySat regularly for at least a month to begin to observe patterns, which will help you interpret the data for you personally.”

IRONMAN pro triathlete Michael ‘Michi’ Weiss is another athlete who is on board with Masimo and using the MightySat to monitor his biomarkers for his training and racing throughout the year.



Masimo MightySat biomarkers

Oxygen level in the blood to indicate changes due to heart or lung, oxygen use by your body, or altitude

Number of heart pulses per minute to indicate overall fitness or exertion levels at any time

Strength of blood flow to the finger to indicate changes in blood circulation.

Number of breaths per minute to indicate how well your heart and lungs are functioning or how quickly you recover after exercise

Variation in perfusion index over your breathing cycle, which may indicate changes in hydration, breathing effort, perfusion, or other factors

MightySat Animation

Heart Rate Recovery
An interesting new feature in the Masimo Personal Health app is Heart Rate Recovery. This is used immediately after exercise. The device is placed on the ring finger as usual and the Heart Rate Recovery feature is selected via a menu in the app. Here, the app/device measure the drop in heart rate over a 60 second period.

This is an interesting feature offering up immediate feedback on post-exercise recovery. Simply press ‘Start’ on the app, breath slowly and see how heart rate drops over 60 seconds. The app then gives a score based on the number of beats per minute dropped during the timeframe.

Another useful feature is the outputting of MightySat biomarker data to TrainingPeaks. Once the Masimo Personal Health app is connected with a TrainingPeaks account, each daily reading obtained via the app can be automatically synched to TrainingPeaks.

For athletes with a coach using TrainingPeaks this is a useful way for the coach to view biomarkers throughout a training block, alongside any notes that the athlete may include with each MightySat reading. This can offer up useful insights for the athlete-coach whilst also tracking training load via all other analytics features within the main TrainingPeaks platform.

At first glance MightySat can arguably be seen as essentially a rather expensive finger sensor! However, while the price point is on the high side, the data offered up from the device would be very useful to those athletes taking their training seriously. This isn’t about recording data for the sake of doing so. The device comes into its own when linked up with TrainingPeaks and is used as part of a wider training plan.

Masimo MightySat is certainly a considered purchase, but one that competitive age group athletes might wish to consider.

Masimo (NASDAQ: MASI) is a global medical technology company that develops and manufactures patient monitoring technologies, medical devices and a wide array of sensors. The company’s pulse oximeter technology is used by 17 of the top 20 hospitals on the US News & World Report Best Hospitals Honor Roll for the 2016-2017 year; and it is this pulse oximeter technology that is being leveraged in athlete monitoring.




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