Not all that long ago, we used to do workouts based on 'feel', or maybe heart rate if you were really serious, and things like power meters were reserved just for pros. Now, with technology improving and pricing coming down, everyone can spout off their current FTP, and most of us have a pretty good understanding of watts per kilo, normalised power, TSS and what they all mean.
Technology has opened the doors to a new level of data, now Average Janes and Joes have access to metrics which can help them get faster. One such piece of tech in this space are the optical heart rate monitors on the latest crop of fitness trackers which provide insights into what your body is doing 24/7. Beyond just counting your steps, these trackers have allowed athletes of all levels to better understand how sleep, diet, and general everyday stress play into the effectiveness of their training.
One such fitness tracker brand that has been gaining steam is Whoop, and we’ve seen the likes of former XCO World Champ Kate Courtney, the not-so-good-at-retiring Phil Gaimon, and the entire EF Education First squad bringing the platform into their training.
I received the Whoop about a month ago and have held off putting together the hands-on first look because it's a device that utilizes algorithms and machine learning to make its recommendations. Frankly, according to Whoop, it takes a while to establish the baselines before it can provide useful information.
What is Whoop?
Whoop has been around since 2012 and was initially developed to be a training tool for professional athletes. Two of the first 100 users were Lebron James and Michael Phelps, and overtime, the platform has trickled down into the consumer realm.
Founder Will Ahmed came to the idea after his time as the captain of the Squash team at Harvard. He realized that the training schedules that he and his team were abiding by were a little bit arbitrary, and beyond feel, didn't really offer an insight into how their bodies were coping with the training load.
The Whoop 3.0 strap itself isn’t all that revolutionary, it’s really just an optical HR sensor, an accelerometer, a gyroscope, a battery, and a Bluetooth chip all held on with an elastic strap. The optical HR sensor uses dual green LED's to find your pulse, and it's all IP68 rated, so wearing it through the shower or on a rain-soaked ride won't kill it. With the standard length strap (there is a longer version for your bicep), it weighs just 18g, the battery seems to last for about five days.
Looks may be deceiving as this strap records an extraordinary amount of information. According to Whoop, the HR sensor logs between 50-100mb of HR data over 24-hours, taking 100-readings per second, every second of every day — the Apple Watch, for comparison, may take an HR reading as little as once per minute outside of an activity.
The third generation of the strap (which I have on test) can be paired with any Bluetooth device and used in the same way as most of today's best heart rate monitors too. I can't speak to the sensor's accuracy just yet, as I'm still in the process of testing it against a chest strap and second optical sensor in terms of its accuracy out riding.
With the sensor itself having no display, all the information is tabulated and presented inside the Whoop app. A lot is going on in here, and with all the tap or swipe to open menus and graphs, it takes a little while to figure out precisely what you are looking at; but the information is primarily broken down into daily strain, recovery, and sleep.
Strain and recovery are presented as rings, not too dissimilar to the Apple Watch activity rings. Daily strain looks at your heart rate throughout the day, calculating calories burned and assigning it a score from 1 to 21. Using the accelerometer and gyroscope built-in, the band can automatically detect when you start moving, and over time learns to differentiate between activities you commonly do, for example, the Whoop can now figure out whether my ride was a road ride or a mountain bike ride without any input from me.
It's not just your workouts that play into your daily strain score; it takes into account the rest of your day too. Have a stressful meeting at work that causes your heart rate to spike? Or maybe you spent all day running between floors in your office, or chasing your mini shredders around the house? Yep, that counts towards your strain score.
As the algorithm gets to know you, it tailors your optimum daily strain to hit targets, which will help you toe the fine line between improving fitness, and overreaching and becoming sick. There is even a strain coach in the app, which essentially displays the range you should aim to hit, but, unless you're riding the trainer, it's not a lot of use.
Recovery and Heart Rate Variability
Your recovery score is based on several factors, including sleep performance, resting heart rate, and heart rate variability. The first two are relatively self-explanatory, and for going on half a century, resting heart rate has been the most widely available measure of fitness and recovery. However, thanks to the advent of the 24/7 optical heart rate monitors found on today's best smartwatches, heart rate variability (HRV) has proved to offer robust insights into whether or not your body is primed for strain.
HRV is a fairly complex metric, so I asked Dr Stephanie Shell, a Senior Physiologist specialising in recovery at the Australian Institute of Sport to demystify this data point.
"Heart rate variability is a measure of the time between heartbeats, and has been shown to be associated with levels of fatigue," she says. "It's actually desirable to have a high heart rate variability, which is a bit counter-intuitive."
Shell explains that the irregularity of the interval between each heartbeat provides a measurable insight into the function of your autonomic nervous system. This regulates your visceral organs at the subconscious level (heart, lungs, digestive system, etc.), and is composed of your parasympathetic and sympathetic nervous systems, which are in effect at odds with one another.
"When you start a training session, it activates your sympathetic nervous system which is getting everything ready to go; increasing your heart rate, changing where your blood flow goes for things like heat dissipation and is getting everything working," she says. "When that session finishes and you've transitioned back into rest, that's when the parasympathetic nervous system starts to increase its input and puts you back into recovery mode."
Heart rate variability is the result of these two systems vying for control of your body, and as Shell points out, if you're fatigued, your body will lean more towards one side or the other, reducing variability.
But it's not just exercise that can affect HRV.
"On a day to day basis it (HRV) can be affected by injury, illness, psychological wellness, the amount and quality of sleep you are getting, life stress, and the types of food and drink you are consuming — there are a lot of things that can influence your heart rate, and heart rate variability," she says.
Shell notes that high or low HRV on its own is not a definitive measure of freshness or fatigue, but is another piece of data that can be used to build the picture of your fitness and recovery.
The final piece that contributes to your Whoop recovery score is sleep tracking. Whoop does all the things your typical fitness tracker does regarding sleep, offering insights into how long you spent in each sleep cycle, how many times you woke up during the night, and resting heart rate, and gives you recommendations as to how much sleep you need to get by performing and peaking.
This is all collated into a sleep efficiency score.
The app also offers what it calls a 'Journal,' which gives you a series of questions ranging from how much alcohol, caffeine, and water did you have to how long you spent you 'doomscrolling' in bed last night.
After you have used the platform long enough for its algorithms to get to know you, it will generate regular performance assessments, profiling your strain vs recovery, your journal entries and how they correlate.
After about a month of using the Whoop, it has offered me a few interesting tidbits.
For example, about a week after I started wearing the Whoop strap, I crashed on my mountain bike, and having forgotten my knee pads that day (and jinxing myself by saying I wouldn't need them out loud on the way to the trailhead), I left quite a bit of skin behind on a loose and gravely corner — we are talking hamburger meat level abrasion.
For those that have experienced similar, you'll be well aware that fresh gravel rash weeps for a few days, and for the three days my abrasions were really active, my recovery scores were less than 50-per cent, despite high sleep performance scores. Once the wound calmed down, my recovery scores returned to normal, despite no modifications to my routine.
Looking at strain and recovery from a fitness standpoint, the recovery scores I have been seeing seem to quantify how I have been feeling out riding. The placebo effect could be at play here too (the app told me I'm tired, so I feel tired), but we shall see how things evolve.
The strain scores and recommendations have been to be more or less in line with my training plan, but I have some suspicions about the optical HR's accuracy in movement. A few initial head-to-head tests with a chest strap have had the Whoop lagging behind during spikes in efforts, but I will be running it through a more thorough head-to-head testing protocol.
Whoop's unique selling point is that it quantifies your fitness and recovery through the lens of everything else that is happening in your life. While metrics like TSS, ATL, and CTL put a number to your training load, quantifying recovery has been largely based on feel. Some other apps and devices can measure HRV — Garmin watches can measure it with a Connect IQ app, and the Watson Blue app will measure it with your phone camera. Having used all of these in the past, just in my short period with Whoop it seems to offer a decent summary of the cause-effect of training; taking into account all the factors that happen outside of your workout all in one place.
A lot is going on with the Whoop platform, and to find the nuances, I am planning to keep putting it through its paces and answer a few key questions. Beyond just working out the accuracy of the sensor, and functionality of the fitness and recovery insights, the main question for me is to work out if it’s worth the subscription fee, at $30 / €25 / AU$44, it ain’t cheap.