In 2018
In my first test, WHOOP's biggest issues were:
- Heart rate readings were roughly accurate, but horribly imprecise.
Decent accuracy makes it fine for vanity metrics and broad generalizations, but not useful enough to hit specific training targets. - The app had no options for personalized thresholds.
To use a generic zone formula is the first sign of an unsophisticated—and unrealistic—approach to heart rate monitoring. - Optical heart rate monitoring is indirect and unreliable.
This is a broad industry issue with wrist-based monitoring. Of course, it doesn't stop the wealth and fatness industry from selling people gadgets they don't need.
In 2025
Day 1 - June 15
The app now has personalized zones.
This is a great first step. Let's see what happens.
WHOOP can broadcast heart rate, but not receive it?
Fail. If WHOOP would integrate with chest straps, the training data might be much more useful for athletes. At a minimum, just one device would have to be worn.
The combination of all-day wrist monitoring and precise measurement from chest straps during training sessions seems like an obvious bonus. But to do so, WHOOP would have to admit that wrist monitoring is not ideal. (Surprisingly, another part of their app reveals that. Read on.)
Will tracking sleep worsen it?
I don't like the idea of tracking sleep. Almost all of my sleepless nights are from wheel spinning, so tracking my sleep seems like a great way to make that wondering worse.
WHOOP should go after the heat training market.
I'm also testing a CORE. It's mostly a hassle, and doesn't seem worth it. However, for a device that's intended to be worn 24/7 like the WHOOP, tracking heat exposure makes way more sense.
With CORE, the sensor goes on a heart rate strap, so it's only recording during training sessions, and it doesn't allow for manual heat training entries, just passive exposure. (Forgot your strap? Tough.) While training is always session-specific, heat exposure can happen any time, during training or just suffering on the beach. A 24/7 device like WHOOP would be a much more convenient way to monitor heat adaptation.
What does WHOOP classify as an activity?
In the app, activity detection is defined as "sustained, significant cardiovascular exertion"? But...
- 15 minutes is "sustained"? For who? This is a big reveal that WHOOP is really targeting chronic exercisers, not necessarily focused athletes.
- And what defines "significant"? In my 2018 test, cleaning the house triggered a recording.
Day 3 - June 17
Activity detection is weak.
Although personalized zones and thresholds are necessary, WHOOP doesn't adjust its algorithm to account for high levels of fitness.
As someone gets fitter, their training needs to become more polarized. The hard sessions get harder, and the easier sessions get easier. On the easy side, an athlete that starts out with lots of Zone 2 work will need to shift more and more of it to Zone 1 or Zone 0 as the years go by and their speeds increase.
But WHOOP classifies Zone 1 as recovery work, so it doesnt' trigger an automatic activity recording.
Day 5 - June 19
WHOOP admits that wrist monitoring kinda sucks.
In 2018, I only got semi-reasonable data from the WHOOP when I wore it on my arm as tight as possible over my brachial artery.
In 2025, manual activity entries now ask for a device location... The options are: wrist band, bicep band, arm sleeve, compression top, shorts, leggings, underwear, bra, performance tank, swimsuit, cycling bib.
While some of those locations seem much worse than a wrist band, it seems like an acknowledgment that location affects the reading. So why not just integrate with chest straps?
Day 7 - June 21
Recovery metrics don't match energy levels.
On June 19th, I slept nine hours, felt great, and woke up with really high energy levels. But WHOOP Recovery was in the yellow zone with a 66. (I guess yellow means mediocre?)
Last night, I slept seven fitful hours and woke up tired and groggy. WHOOP Recovery was in the green, 77, and posted an atta-boy of "enjoy the increased focus!"
Day 8 - June 22
I did four 25-minute sessions in a track car. (I was surprised to see that WHOOP has an activity option for "motor racing".) While picking up on my stress was accurate, assuming it was a workout is nonsense.
Stress detection is strong.
Although curious what it would register, I didn't look at the WHOOP app until later in the day. I was surprised to see that the timing of the stress measurement matched when I started getting my car ready. (And it was hella hot, which didn't help.) And it picked up on the timing of each track session thereafter.
Stress = Strain = Fitness = Nonsense
While a BMI score may be more universal, fitness is specific to a goal. Equating all Strain with "fitness" is nonsensical. Fit for what? Four track sessions is not going to make me fitter for anything but heat resistance.
Heart rates in amateur racing are in Zone 1 or less, and the elevated rates come from heat, stress, and dehydration, not from physical exertion. WHOOP defines an activity as "sustained, significant cardiovascular exertion," but this is not what happens in a track car. Significant cardiovascular exertion has such a high respiration rate that talking is impossible. Talking while driving—even while racing—is common and easy to do.
Day 9 - June 23
Does activity detection improve?
This morning I did a typical 45-minute Zone 1 run. My pace, breathing, effort level, and heart rate were the same as usual.
For the past week, I've had to note these manually in the WHOOP app, but today it picked up on it accurately. Is it learning?
Day 10 - June 24
Is the web app abandoned?
I haven't checked since 2018, but comparing screenshots suggests that not much has been changed in the WHOOP web app.
I don't like wearing two gadgets.
Because I want to monitor my training with a real heart rate monitor (with a chest strap), I train wearing a watch and wear the watch—but not the strap—even when I'm not. Always having a second gadget on my other wrist is unappealing.
I don't like increasing my phone usage.
I'm always schemeing about ways to use my phone less, not more. So 24/7 monitoring with all of the data in my phone is the opposite type of behavior modification that I'm looking for.
WHOOP is expensive.
WHOOP plans vary between $199, $239, and $359 per year. For (a lot) less than $100, I'd consider it, but without any integration with real training data, it's not worth it. (Wrist-only heart rate monitoring and equating "strain"-ing with training doesn't cut it.)
Instead, it's simple enough to use WHOOP through the free trial and then continnue with the positive behavior modifications: sleep more, avoid alcohol, prioritize recovery.
Day 12 - June 26
Motor racing is not anaerobic...
In a recent summary, WHOOP suggested that motor racing would give me the anaerobic boost that I needed:
Alternatively, Motor Racing offers a high-intensity option that could provide the anaerobic boost you need, with a strain of 10.1.
Track days and racing are stressful, but from heat, dehydration, and decision-making, not from a significant cardiovascular load, and certainly nothing anaerobic. (If you can talk while you do it, the cardiovascular load is low.)
Day 13 - June 27
VO2max estimate seems likely.
I haven't had a VO2 test in five years, but I was always in the low 60s. WHOOP estimates my current VO2 max at 59. I'd be surprised if I didn't have a bigger drop due to age and a lack of training, but my guess would still be in the 50s.
Day 14 - June 28
HRV still seems whack.
If WHOOP is estimating HRV via the optical monitor, then it could be the algorithm that's whack. (Perhaps actually measuring HRV has become more useful.) But what WHOOP is reporting for HRV is inconsistent with how I feel each morning, similar to how it was with ithlete.
Day 18 - July 2
The novelty has worn off.
Reality has set in. Whoop is helpful for nudging behavior in a healthy direction, but in huge contrast to its marketing, it is not a training device.
Final Conclusions
It's helpful for health.
So far—and similar to the first time—the WHOOP does do a good job of nudging me toward healthier choices: avoid alcohol, avoid screens at night, get lots of sleep, prioritize recovery.
But genuine goal-specific fitness? I don't see how generic algorithms can connect the dots between an individual's idiosyncrasies and the maximized performance necessary for a specific goal at a specific time and place.
Fatigue is not fitness.
Equating every "strain" with a training stimulus is absurd. Heart rate itself is a stress metric, but not every rise in heart rate will lead to an increase in fitness. (Waiting to see the principal is not going to make a high school track star any faster.)
But WHOOP seems to not know the difference between a stressor and a stimulus. And without the ability to sync with a real heart rate monitor—and an accompanying setting that says, "only use chest strap input for training stress"—WHOOP's "fitness" metrics are useless.
(But really, I wouldn't be surprised if the inner circle at WHOOP has known this for years, even from the outset. The serious athlete market is microscopic, while the near-sedentary market is gigantic. And that market is primarily concerned with fatness, not fitness, and "straining" is probably enough to improve a person's beach body.)
Consumer devices are for consumers.
Although market-adjacent to—and marketed by—athletes, I doubt that anything but the health and habit functions are useful. For general, beach-ready "fitness", Strain might be enough to look good. But to perform well when you need to, real training technology is required.
What would make WHOOP useful?
Despite the marketing, Whoop cannot help athletes prepare for their goals directly. But Whoop could be a great auxiliary device if it would:
- Substitute optical heart rate recording when a chest strap is worn. The fact that Whoop records where its worn reveals that they're aware that location has an influence on the quality of the recording. Pairing it with a chest strap—and overwriting the optical data with the chest strap data—would provide a much more accurate picture of the physical load and precise-enough data for training.
- Monitor heat adaptation. The fatal flaw of CORE is the necessity to designate when heat training is happening. Heat acclimatization happens more frequently than in training sessions. Only recording training sessions will underestimate the process. In contrast, a 24-hour device that monitored body temperature and heat acclimatization would be very useful.
- Distinguish between "straining" and training, both in data types (optical monitor versus chest strap) and activity types (actual training activities vs life activities). "Strain" might be useful for monitoring life stress, but it's nonsense for training purposes. Likewise, non-sport-specific activities should not be included in the training metrics.
- Update the web app to be as useful as the mobile app. For a device that nudges people toward better health decisions, it's surprising that they invest much more in a mobile app. Reducing phone usage is a nudge that benefits everyone. However, just like marketing for "training" is better for business than marketing health, investing more in their mobile software likely serves the same purpose. Their design priorities reveal their true motivation.
- Allow outright purchases. I don't have an Oura ring, but I much prefer their business model. Paying hundreds once and having the device forever is much better than an exorbitant subscription that never ends.
Two tests seven years apart and the conclusion is the same: Whoop has a great business strategy, but it has little in common with goal-specific training or high performance.
