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The Apple Watch 6 and the future of health tracking on smartwatches

Blood oxygen, blood pressure, heart-rate monitoring and even stress tracking are becoming increasingly common in wearable tech. We explain how it all works.

The Apple Watch 6 and the future of health tracking on smartwatches

Apple’s new smartwatches – the Apple Watch Series 6 (from £379) and the cheaper Apple Watch SE (from £269) are being advertised as sophisticated healthcare tools. Most notably, the Series 6 has built on Apple’s healthcare focus and can measure blood oxygen saturation.

It’s not the first time Apple has hung a USP on health and lifestyle functionality – series 4 introduced us to fall detection and ECG (electrocardiogram) measurement, and heart rate measurement was available from series 1.

Others have followed suit, and the wearables market now seems firmly focused on a broader range of tracking, as well as fitness.

Read on to find out about some of the key health-tracking features on offer from Apple and wearables brands, and what you could expect to see in the future. 

Just want to know which wearables aced our tests? Skip straight to our page on best smartwatches or best fitness trackers

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Apple Watch series 6 introduces SpO2

The Series 6 doesn’t represent an enormous step forward from the Series 5 when it comes to features (we’ll let you know about performance when we’ve fully tested it), but the new blood oxygen sensor has certainly grabbed attention.

Other claimed updates for the Series 6 include a screen that can get much brighter in sunlight and a new dual-core processor designed to be faster than the Series 5.

Apple has also just launched watchOS7, available on the Series 5, 4 and 3 as well as the Series 6. WatchOS 7 now includes a Sleep app – previously you needed to use a third party app, and it allows you to pair family members’ Apple watches with your iPhone, so you can buy Apple Watches for people who don’t have an iPhone themselves.

Blood oxygen (SpO2) monitoring with a smartwatch

Apple Watch Series 6

Blood oxygen monitoring, aka SpO2 monitoring, aka pulse oximetry testing, measures the oxygen saturation of your blood.

The new Apple Watch Series 6 (pictured above) can take on-demand readings of your blood oxygen and background readings during the day and night.

It works by shining red and green LEDs and infrared light onto your wrist, and measures the amount of light reflected back. An algorithm then estimates the colour of your blood – blood with more oxygen is bright red; blood with less oxygen is darker.

Apple isn’t the first brand to incorporate pulse oximetry in some format into wearable tech. We tested a number of watches and trackers with pulse oximetry features recently. Some impressed us, giving us readings in the same ballpark as our medical pulse oximeter, while others struggled – particularly on darker skin.

Pulse oximeters have been in the news a fair bit this year, as it’s been suggested they could help spot early signs of coronavirus. However, it’s unlikely to be a standalone solution. Londonwide LMCs, a representative committee of NHS GPs in the capital, says that: ‘Pulse oximetry can be a useful aid to clinical decision-making but it is not a substitute for a clinical assessment, nor sufficient for diagnosis by itself.’

We’ll be putting the Apple Watch Series 6 through our pulse oximetry tests in due course, but we’ve already tested a range of models with this feature – see below for links to our reviews.

Apple Watch 6 taking blood oxygen measurements

Smartwatches and fitness trackers with built-in pulse oximetry

  • Fitbit Charge 4 – £128. The latest member of the popular Fitbit Charge family. Can take night-time readings, but not on-demand, so it’s not useful for alpine enthusiasts – but could pick up signs of sleep apnoea (don’t treat it as a medical device though).
  • Garmin Venu – £300. A high-end fitness watch with a premium look and feel. Can take on-demand pulse oximetry readings.
  • Huawei GT2e – £118. A watch for fitness enthusiasts – again, able to measure your pulse oximetry on-demand.

If you’re a healthy person, you shouldn’t need to buy a pulse oximeter, nor should you rely on one to detect coronavirus. But if you’re a keen sportsperson who often exercises at high altitudes, a wrist-based pulse oximeter could help you by flagging signs that you’re over-exerting yourself.


Heart-rate monitoring on a smartwatch

Monitoring your heart rate can help you make sure you’re pushing yourself hard enough during your workouts, and, if you keep an eye on your heart-rate patterns long term, educate yourself about your overall cardiovascular health.

Most wearables, other than the ultra-cheap ones, offer heart-rate-monitoring now, but some go a step further – for example the Apple Watch Series 4 (£329), Apple Watch Series 5 (£399) and Apple Watch Series 6 can take ECG readings.

Taking an ECG with Apple Watch

Heart rate is taken using sensors that measure electrical signals in your heart and check for AFib (atrial fibrillation, irregular heart-rate rhythms). They can also send you alerts if your heart rate goes above or below the normal range.

Dr Heather Morgan, lecturer in applied health sciences at the University of Aberdeen and a specialist in digital health and fitness tracking, told us the Apple ECG feature: ‘could be a great feature in helping to prevent strokes. There have been a few cases where the Apple Watch has picked up an issue as a ‘pre-screening’ tool and the number of inaccurate diagnoses seems low.

But she added: ‘It’s not something you can use to track, monitor or manage a heart condition. It tells you that you either have AFib or you don’t, but not what kind it is, or what treatment you might need. Medical advice is always required and, once a condition been diagnosed and is being medically managed, the feature is useless.’

Head to our story on monitoring your heart health with a smartwatch to find out more.

Smartwatches and fitness trackers with heart-rate monitors

  • Samsung Galaxy Watch Active 2 – £239. A good alternative to an Apple if you don’t have an iPhone. It can also alert you to signs of AFib and take ECGs (but the latter isn’t available in the UK yet – it’ll be pushed out through a software update).
  • Xiaomi Mi Band 3 – £20. The cheapest tracker we’ve reviewed with a heart-rate monitor.
  • Zepp E Circle – £250. Aims to reduce your chance of cardiovascular-related death by combining your heart rate with other metrics to give you a Personal Activity Intelligence score.

Blood pressure monitoring on a smartwatch

Measuring blood pressure with Qardio

If you have hypertension, there are two ways in which you can use wearable tech to monitor your blood pressure.

  • You could download an app such as Qardio onto your smartwatch. The watch doesn’t measure your blood pressure itself – it acts more like a diary or dashboard for your paired smart blood pressure monitor.
  • The Omron HeartGuide smartwatch (£499) does take a measurement from your wrist, incorporating the cuff that would normally go around your arm into an inflatable watch strap. It’s the first FDA-approved blood-pressure monitoring smartwatch. It’s extremely hefty, though. And, inconvenient as it might be to measure your blood pressure the traditional way, especially if you need to do it a few times a day, it’s hard to imagine anyone preferring to have something this size strapped to their wrist constantly.

Packing an accurate blood pressure monitor into a slimmer device will be no small challenge, but we’re excited to see where Omron and other brands take this technology in the future.

Omron HeartGuide smartwatch

Stress and emotion monitoring with a smartwatch

A growing number of wearables will attempt to measure your stress levels and we’re even seeing models that claim to gauge your emotional state.

As far-fetched as that sounds, it’s really just a case of analysing patterns in measurements – though that’s not to say it works, or is accurate. Wearables with these features measure stats such as your heart rate and your heart rate variability (HRV) – the variation in time between your heartbeats – and assign you a stress score, although the name may vary from brand to brand.

They will then offer you help in the form of guided breathing exercises. When you breathe in a more controlled way, you lower your heart rate and increase your HRV. And some will use this information to give you insights as to your readiness for a workout.

One interesting new product is the Amazon Halo, Amazon’s new fitness band.

The Halo doesn’t have a screen. It’s a fabric band containing a sensor that gathers a host of health data about you. As well as run-of-the-mill things such as activity tracking and sleep-tracking, it can also measure your body composition and body-fat percentage, make a digital 3D model of you and use machine learning to analyse your voice, with the aim of helping you improve your relationships and emotional wellbeing.

Amazon says that its Tone feature ‘may reveal that a difficult work call leads to less positivity in communication with a customer’s family, an indication of the impact of stress on emotional well-being’. It should also be able to tell you things like what events in your day prompt you to snack and whether walking further helps you feel less stressed.

You can’t buy the Amazon Halo just yet, as it’s currently only available via an invite-only early access programme in the US. It will cost $99 (approximately £77), plus $3.99 a month membership. We don’t know yet when it will be fully released to more countries, but it’s an interesting example of the way technology is headed.

How useful you find stress and emotion tracking will depend to some extent on your personality. You might find it really helpful for combating anxiety in these chaotic times. Or, you might find it a bit unnecessary if you’re already pretty in touch with your emotions, or even a bit creepy.

Wearables for tracking stress and emotion

  • Bellabeat Leaf Urban – £99. A necklace that will give you a stress sensitivity report. We found it fairly tacky.
  • Fitbit Charge 4 – £128 (pictured below). Fitbit trackers don’t give you a stress score but do offer guided breathing exercises.
  • Garmin Vivoactive 3 – £148. A comfortable to wear smartwatch that’s easy to use and packed with fitness functionality in addition to stress tracking.

The future of health-tracking wearables

With such a wide range of technology already available, and further developments on the horizon, wearables have come a long way since the days of cumbersome, limited, glorified pedometers.

Dr Heather Morgan told us: ‘Accuracy and tailoring of exercise monitoring data is vastly improved and wearables can also perform cardiograms, detect falls, tell you when you’re being exposed to loud noise that could damage your hearing and some are even being developed to include proximity sensing systems to help with contact tracing during the COVID-19 pandemic’.

No surprise, then, that the wearables technology market is surging.

Information services company GlobalData says it expects smartwatches will increasingly be used in healthcare in the next five years, ‘driven by improvements in sensors and software and growing consumer adoption’, and that we’re likely to start seeing data gathered by smartwatches being used for early diagnosis and remote patient monitoring.

We’ve also heard speculation that companies and health insurers, particularly in the US, will take an increasing interest in wearables – as wearables incentivise healthy behaviour, and therefore could reduce the number sick days an employee has to take or hospital visits he or she has to make.

In the meantime, remember a wearable you buy today is no substitute for seeing a doctor. Wearables make educated guesses about your health and fitness, based on the data their sensors collect. They can be inaccurate and they can malfunction. However, they can help you get proactively engaged with your health, helping you build up a more rounded and detailed picture of how your body works, so that, if you do notice anything irregular, you can take it up with your GP.

Find out more about other factors you should consider in a smartwatch our guide on how to buy the best smartwatch.

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