SHOULD YO U MEASURE YOUR EVERY MOVE?
Can wearable devices really make you a fitter, healthier cyclist? Deena Blacking straps on a plethora of gadgets and endeavours to find out
Ducks weren’t the only new thing being worn by Education First pro cyclists last year. On 31 August 2020, Whoop was announced as the team’s official fitness wearable. Less than a month later, Canyon-sram and Team Jumbo-visma started sticking Supersapiens glucose biosensors to their triceps. Forever seeking a performance advantage, pro teams are turning to wearable technology to track their every move. But is the juice worth the squeeze? Are these devices destined to improve performance? Or are they just more noise in the ever intensifying data-storm of modern life?
For the average cyclist without a support team, making sense of all the tech – never mind the data they deliver – can be bamboozling. In an effort to help CW readers understand what all the fuss is about, we decided to find out more.
Wearable technology is any kind of sensor or computing device small and flexible enough to be worn. It is often used to measure markers of health, such as resting heart rate and sleep patterns, from which algorithms predict the athlete’s state of recovery and fitness.
Getting fitter and faster in road cycling – one of the world’s most physiologically demanding sports – requires good management of training load.
“In theory, the value added by wearable devices is that they help you to understand and manage how the body responds to training load, better than humans alone,” explains Nate Wilson, performance manager at EF Educationnippo. “There’s a point before you hit the wall but you might not sense it, and that’s where these devices come in.” Wilson’s colleague at EF, medical director Kevin Sprouse, describes it as “filling the data gap” in a way that gives “a retrospective view on what’s happening as well as a guide to the present and the future.”
From long-standing companies like Garmin and Polar, to recent entrants like the Oura ring and the Supersapiens glucose biosensors, there is an increasingly long list of wearables to choose from. All claim to help you monitor and improve your performance. But do they really?
Multiple metrics
Thanks to helpful marketing teams, we were able to get our hands on several of the leading wearables and put them to the test over the course of a month (see panel). Wearables are often wristbased, or in the case of the Oura, worn as a ring. The Supersapiens blood glucose biosensor requires you to insert a small needle into your arm to take live blood glucose readings. Happily, the two-pound-coin-sized sensor is almost unnoticeable; it sticks discreetly on the back of your arm.
With the exception of the Supersapiens sensor, most wearable devices measure some combination of the following: sleep, movement, heart rate, body temperature and blood oxygen levels. From this information, each wearable ‘scores’ your readiness to train or race, by means of its own trademarked algorithm.
Most devices require a smartphone to deliver the data to you via an app, but the watches (Apple and Polar) also provide data directly from the wrist. The Apple watch, more of an overall lifestyle than performance device, provides hectoring prompts throughout
“Wearables promise to tell you how ready to train you are”
the day: breathe, stand up, be active, etc. Some of the apps have additional features for qualitative input. For example, the Whoop has a daily questionnaire – the ‘journal’ – allowing you to log additional fields of information.
Heart rate is a key metric for wearable devices: most of them measure resting heart rate (RHR) and heart rate variability (HRV). RHR is the number of heart beats per minute while at rest; HRV is the variation in the time between consecutive heartbeats. An increase in fitness is generally reflected in a lower RHR, increased HRV and increased maximal oxygen uptake, i.e. VO2 max. In the case of the Supersapiens biosensor, it measures real-time blood glucose so that you can see the effect of your training and fuelling on the sugars circulating around your body.
The second most important metric for wearable devices is sleep – a variable squarely in the centre of the performance picture for everyone. But how is sleep measured? “Most wearables are looking for the same general patterns,” says Caroline Kryder, a comms manager at Oura. “For example, light sleep is usually signalled by a slowing respiratory rate and decreased heart rate. Deep sleep is detected by a stabilisation in heart rate and suppression of movement. Wearables tend to base REM sleep on detecting no movement.” By tracking not only the quantity but also the quality of your sleep, wearables promise to tell you how recovered and ready you are to train.
Real-world usage
How useful are these devices from an athlete’s perspective? We asked Isabelle Bryenton, a 20year-old pro cyclist who rides for UCI women’s Continental team Instafund Racing. “Using the Whoop band has made me reflect on my day and be more conscious of what could have a negative impact on my sleep and recovery,” she explains.
Has Bryenton’s performance changed since she started logging her every move? “The devices are less useful than advertised when it comes to training,” she says. “I don’t use my wearables to dictate training. They give me interesting information, but as an athlete with a coach, I still do my prescribed workouts even if the apps says I’m in the gutter.”
It seemed like the right time to get a coach’s perspective. Holly Seear is a performance cycling coach who describes herself as having a passion for datadriven performance. “The first questions I ask my athletes are, why do you want to use it? How will you make use of the information?” explains Seear. “The data can be useful to show trends, but there are some risks too.”
These risks include athletes paying less attention to their own physical sensations and becoming overreliant on the data – without questioning the accuracy of that data. “We need to keep it in perspective,” adds Seear. “A bit of common sense is sometimes needed too. Just because a device says you slept badly the night before your ‘A’ race doesn’t mean you cannot perform well, if you have done the preparation.”
Although the wearables companies were helpful in explaining general principles, they stopped short of sharing details on exactly how their devices work. This presents an obstacle in assessing their effectiveness. “The main issue with wearables is that you do not have access to the algorithm, so you get the results out of a black box,” cautions Dr Michael Kellmann, an applied performance psychologist and expert in recovery.
Kellmann’s reservations are echoed by Steve Mccaig, a training load specialist at the English Institute of Sport. “Many of the algorithms are based on an
assumption of what a ‘normal’ response is – but we are all different,” says Mccaig. His colleague Dr Emma Neupert, an applied performance physiologist, underscores the issue of data reliability and validity. “If the wearable tells you something has changed by two per cent, but there is a margin of error of five per cent, you’re not being provided with useful information, just noise,” adds Neupert.
This leads us to the second stumbling block. During my month of testing wearables, the data didn’t always match up from one device to the next. Heart rate readings taken from the wrist or bicep were often inaccurate (compared to chest strap readings); my RHR on one device was 44bpm, and 48bpm on another – a significant difference. Sleep data also diverged between devices – no two devices seemed to agree, with as much as two hours’ difference in REM sleep.
We decided to ask the wearables companies to help make more sense of the data discrepancies. Head of cycling at Whoop, Jeremy Powers, responds: “Whoop is invaluable for teaching you more about yourself. Think about your power meter. Power meters also have measurement errors, but they are still a useful training tool.” It’s a fair point: provided your device is consistent, it can still highlight trends in a useful way.
On the discrepancies between sleep readings, Oura’s Caroline Kruder tells us: “It depends which signals are being measured, and if the device is sampling at a high enough rate that it can really differentiate between sleep stages.” Put simply, no two devices are measuring exactly the same metrics in exactly the same way.
“It’s complicated; you need to know how to interpret the data”
Data versus judgement
Some of the wearables companies say that their ‘objective’ data is more reliable than subjective human reporting. So which is better, human or machine? We put this question to the experts.
“Wearables shouldn’t replace a coach nor subjective ratings of the training and/or competition experience,” advises Dr Kellman. “We consistently find that subjective ratings using welldeveloped instruments, such as the Acute Recovery and Stress Scale, are a very sensitive way to monitor training.”
Athlete monitoring specialist Mccaig says: “Performance and injury are complicated so you need to know how to interpret the data. Sometimes we see athletes and support teams getting hung up on the numbers and this gets them further away from making the changes needed to improve performance.” Mccaig recommends using a wearable to answer a specific performance question rather than to provide a continuous overview.
Without a doubt, there are tangible benefits from wearables: they can prompt you to improve your sleep, be smarter in your fuelling and hydration habits, as well as providing a feel-good factor from sharing data with friends. But when that data risks misleading us or doesn’t seem to correspond with how we’re feeling, it’s important to take a step back.
In my experience testing a selection of wearables and as a coach, I was frustrated at the level of certainty with which some wearables provided advice. For example, the Whoop monthly performance assessment data suggests causal links between behaviours reported via the journal and sleep and recovery metrics. Apparently, eating late in the day during April increased my time in Slow Wave Sleep by three minutes… Really?
There are undoubtedly potential benefits to be gained from using wearables. For pro cyclists who have data analysis help on hand, more data can add value because that data is expertly scrutinised and interpreted. For amateurs, especially those without a coach, it’s important to ascertain whether these devices are really going to provide helpful information and guidance. If you’re considering buying a wearable, first ask yourself: what is the performance problem I am trying to solve? Then you can decide whether wearable tech really is the solution.