WHOOP 4.0 Strap Review: Is the Subscription Worth It?

The gym hums with determination. Around you, athletes push their limits—rowers power through their sets, lifters push with purpose, and runners pound the treadmills. WHOOP 4.0 sits quietly on your wrist, collecting the data defining your next move. It’s a next-gen tracker—a coach, a guide, and a motivator rolled into one. As your session intensifies, WHOOP ($239pa, $199) adjusts, measuring strain, heart rate, and recovery potential, silently working to tell you exactly how to optimize your performance tomorrow.

Updated: 29 November 2024

This is where WHOOP excels. Unlike traditional fitness wearables, the WHOOP 4.0 band doesn’t distract you with notifications or flashy screens. Instead, it focuses on what matters: your readiness, recovery, and strain levels. Designed for athletes who demand actionable insights, it’s much less about casual step tracking and more about performance optimization. Whether you’re a seasoned competitor or a fitness enthusiast chasing new personal bests, WHOOP meets you where you are, guiding you toward better results.

At $30/month or $239/year, WHOOP’s subscription model is a commitment to yourself. But does it deliver enough value to justify the cost? This review will explore how the subscription provides benefits like free hardware upgrades, an intuitive app experience, and actionable coaching insights. We’ll also compare WHOOP to leading alternatives like Garmin Forerunner 965 and Apple Watch, breaking down why WHOOP’s focus on accuracy, recovery, and readiness sets it apart while addressing where it falls short.

By the end of this review, you’ll clearly understand whether WHOOP is worth the investment—whether you’re in the gym, on the trails, or simply looking to optimize your health. Get a free WHOOP Band and trial your membership here (promotion automatically applied).

Let’s start with a summary review of WHOOP, which includes more detailed insights below.

WHOOP 4.0 Strap: Detailed Review Starts Here

The remainder of the review is highly detailed, covering product history, specs, use cases, related science and more. Skip ahead to the sections that most interest you.

The Downsides of WHOOP 4.0: What You Should Know Before Subscribing

I like WHOOP and have used it for many years since its launch. It’s not perfect, and I know why. Here are the negatives for you.

• Cost: From $17/month subscription fee. Like an expensive sports watch, you can waste your money if you don’t use it to its full potential. Unlike an expensive sports watch, superseded every 18-24 months, you get a free WHOOP if one is released during your contract.
• Subscription: Contracted for the agreed duration after a one-month trial.
• Battery life: up to five days on a single charge. This can be inconvenient, especially if you travel or forget to charge your band regularly. WHOOP’s USB charging puck also contains a battery and can be separately charged while you still wear your WHOOP. You can even keep wearing the WHOOP and charge it with the puck.
• Missing features: No screen, no inbuilt GPS, no map, no music controls, no smart notifications. You’ll need the Whoop phone app for a map, GPS tracking, music controls, and smart notifications. The WHOOP app can record your GPS track. Alternatively, your GPS track can come from a bike computer, provided you also record the ride with WHOOP. Whoop’s lack of built-in GPS complicates the production of a VO2max estimate; thus, VO2max is not currently available.
• Endurance Strain Accuracy: Not 100% accurate for some sports due to wrist movement. Despite what reviewers tell you, that’s true of every wrist-based optical HR watch. You might get lucky because of exactly when and how you use it, but you might not. Workaround in sport: Always wear WHOOP on your upper arm with a sleeve or, failing that, an inch or so up from your wrist bone. If you opt for Garmin or Apple, always use a chest strap with your watch; otherwise, you’ll still face identical issues with accuracy.
• Strength-based Strain Accuracy: Don’t kid yourself; while heart rate is a good measure of strain for endurance athletes, heart rate alone cannot correctly account for the strain/load from strength activities. That’s why WHOOP acquired technology from PUSH, which incorporates elements of velocity-based training. No other mainstream wearable does that. So WHOOP will still be a bit inaccurate but far more accurate than the methods you currently use…even if you use a Polar H10 chest strap, interpreting its data for strength training is still wrong! You’ll need to follow a strength workout so that WHOOP can interpret movements in the context of the muscle groups used. There is no other way around that unless you have smart weights or gym stations that communicate their weight and movement dynamics to a wearable (rare).
• Sleep/Recovery Accuracy: Inaccuracies can occur due to the capture of raw HR data and other factors shared by all wearables. WHOOP uses the correct algorithms/calculations based on your HRV. So, if you get incorrect HRV/recovery stats, errors are mostly due to the raw HR data. Other inaccuracies come from how you might sleep on one side of your body, plus other factors shared by all wearables.
• Sleep Stage Accuracy: All wearables cannot accurately determine sleep stages—that’s just a fact! However, Whoop should be OK at two-stage accuracy.
• Readiness Accuracy: There is no one agreed-upon scientific way to measure readiness as a whole. Wearables use different algorithms to estimate readiness, and WHOOP’s algorithm is based on heart rate variability (HRV), a proven scientific measure of how your body handles stress. However, HRV is not the same as readiness.
• Obsessive/addictive: Technologies like Whoop can exacerbate high-level sportspeople’s obsessive and dedicated nature, leading to unhealthy training habits.
• Suitability: Whoop is designed for athletes and fitness enthusiasts, not those seeking general health goals. If you’re looking for a dedicated step tracker, even though Whoop does track steps, it is not for you.
  

This link gets the best WHOOP discount possible anywhere.

What Is WHOOP 4.0? Features, Benefits, and How It Works

WHOOP 4 is a band with an integrated optical heart rate monitor, several other sensor types, and state-of-the-art battery tech. The bands are optional and swappable and can instead be worn in locations other than the wrist using WHOOP-specific apparel.

More than that, the app uses heart rate data for readiness guidance and coaching advice, all powered by novel interpretations of aspects of your heart rate variability (HRV) and other physiological metrics. It uses real sports science that I would classify as trusted sports tech – some competitors invent metrics instead of using sports science.

How the science works

Your nightly HRV, captured at low Heart Rate (HR) levels and tweaked by HR trends and other data, provides insights into readiness and data that support the sleep coach.

Your workout strain comes from heart rate x duration. The higher the heart rate, the more weight is given to the time spent at that level.

Recovery insights come from complex maths. Signals in your heart rate at night determine how the nervous systems in your body are balanced. An average of those signals gives a nightly score weighted alongside your resting heart rate, sleep performance and respiratory rate. To an extent, these are all different measures of the same thing but looked at from different physiological perspectives.

The result of the algorithm is a simple, single readiness number. As you rest during the day, the more your readiness score improves.

Over time, WHOOP analyses how your body performs and can suggest the volume of sleep you need tonight to achieve a certain level of readiness tomorrow.

The details are complicated, but that’s the gist of it.

Where the science fails

During strength workouts, your heart rate will never truly reflect the muscular strain your body experiences. Determining muscular strain from heart rate will always be wrong, even if you use a chest strap, Garmin, or Apple Watch. However, WHOOP DOES correctly assess the recovery and readiness from HRV as your body adapts to a completed strength workout. Better than that, since mid-2023, WHOOP has used uniquely new tech to get more correct strain from strength workouts when no one else can.

WHOOP 4.0 Strap Review: Who Should Use It and Why?

WHOOP could be for you if you are a cross-fitter, HYROX lover, biohacker, endurance athlete, competitive athlete or gym rat. Let me elaborate

• Team sports: WHOOP will cover your sport and the gym training that supports it. If you are on a pro team, your coach will likely want your team to use the same tech. Some pro teams use WHOOP.
• Cross Fitter/Hyrox – WHOOP is CrossFit’s de facto tech standard. However, I recommend wearing the band away from your wrist, generally on your upper arm. The lack of glass on WHOOP makes it better suited for the rough and tumbles of CrossFit. If you did more detailed research, you would find that no current product correctly identifies the strain component of strength work. Once WHOOP integrates PUSH algorithms, it will have the ability to be the market leader for several years.
• Gym rat: Similar to the Cross Fitter, you will be especially mindful of the accuracy of WHOOP, or any wrist-worn wearable, during high-impact workouts.
• Biohacker—WHOOP is good here and covers some metrics like SpO2 and respiratory rate. However, deeper-leaning products like Biostrap EVO exist, although WHOOP is significantly more polished and accurate in the round.
• Triathletes, cyclists, and runners—You can probably find other products to track your HR over all those miles. WHOOP is a good sleep and readiness tool that is more easily worn throughout the day than a Garmin. Plus, WHOOP’s recovery scores are less gimmicky than Garmin’s Body Battery (which is not science-based). Furthermore, cyclists can easily broadcast WHOOP’s heart rate to their Wahoo Bolt / ROAM to avoid duplication of tech sensors.
• Ultra Athletes – might consider Garmin, Coros, Polar, or Suunto.

What’s New in WHOOP 4.0: Features and Upgrades from Previous Models

The new WHOOP looks similar to the Gen 1, 2, and 3 products but is smaller and wholly different inside.

New Format

• It’s now a third smaller but with a similar clasp mechanism
• The strap is attached to the pod in an improved manner that can be more easily removed or changed
• Unique WHOOP apparel has pouches that allow the WHOOP pod to record on different parts of your body, e.g. with an arm sleeve (#recommended as essential)

New Sensors

New sensors form the core of WHOOP, and these are entirely new

• More accurate heart rate sensor with more LEDs
• Skin temperature sensor improves sleep & fertility algorithms and the future inclusion of illness tracking.
• Blood oxygen (SpO2) sensor that improves the sleep & recovery algorithms
• Introduces vibration that can be used to optimise the wake time from your sleep stages

New Battery

• Leading-edge tech – a more energy-dense silicon anode battery
• The five-day battery life is the same, but the battery is physically smaller and seems to charge slower.
• New battery pack charger: WHOOP’s cradle holds a charge, which can be used to boost WHOOP’s battery life even while on your wrist.

Several additions have been made to the WHOOP app, the online platform, and the reports it produces. This covers the new data that is now captured, but the WHOOP platform is continually evolving. One of the more recent innovations is the journal, which correlates tags/feelings/behaviours with performance so you know what to avoid or repeat in the future.

WHOOP 4.0 Strain Metric: How It Measures Effort and Activity Levels

WHOOP’s strain advice comes primarily from your heart rate. WHOOP builds up a score linked to your heart rate and the amount of time you spend at progressively more intense levels, and then that score is further contextualised within your normal range. It’s a highly personalised score and a complex algorithm, so if you need more details, this article explains every aspect of WHOOP’s strain score.

Case Study: Whoop Strain – Everything you need to know

WHOOP’s strain score calculation was significantly improved for strength workouts in April 2023 and follows the science of velocity-based training (VBT). When you follow a routine, WHOOP tracks reps, intensity, and weight and applies that to a known profile of the rep you perform to determine the impact of muscular strain on all muscle groups. These are then added to give you a simple breakdown of the cardio and muscular strain and how that follows through to recovery and sleep needs. No other mainstream wearable does this; it is the only way to assess strength workouts. Even a Polar H10 properly won’t be as accurate (honest!).

Case Study: WHOOP Ground Breaking Strength Training or Damp Squib

The downside is that you need to build and follow a strength routine on the WHOOP app, and while that part of the app looks good, it could be streamlined.

WHOOP 4.0 Recovery Insights: How It Tracks Your Readiness to Train

WHOOP calculates recovery and estimates readiness to train.

Q: The average nightly recovery for WHOOP owners is 58%, but where does recovery come from?

A: WHOOP’s calculation looks at HRV, resting heart rate, sleep performance (actual vs. needed), and respiratory rate and shows a simple percentage number to guide you. Your recovery is contextualised within your personalised range.

How Do I use The WHOOP 4.0 Strap?

This is perhaps the most straightforward question of the lot. It’s a case of wear it and forget. All the information and insights you want will be on the app, plus some larger and prettier charts on the web platform.

The only two exceptions to the wear-and-forget mantra are when you want to charge it, remove the strap or broadcast the heart rate to gym equipment or a bike computer.

Unboxing

You get the pod, a strap, a cable, and bits of paper you will never read. Charge it up and put it on; you know what to do. It needs to be snug but not tight. Wear it at least 1cm from the wrist bone during sports.

Charging WHOOP

You can charge the device by sliding the charging cradle onto the strap while wearing it. Of course, you can also take the band off to charge, and the cradle itself charges via a USB-C cable.

While the WHOOP strap is sufficiently waterproof for pool or sea swimming, the charging cradle isn’t. It is splash-proof, meaning you could shower with it if you want.

Tip: Update the Charger firmware

WHOOP 4.0 Review Broadcast Heart Rate

WHOOP App> 3 bar menu> Device Settings> Broadcast Heart Rate>Enable

When you enable the WHOOP strap to broadcast HR, you will use a tad more battery and have to pair it with a Bluetooth-receiving device manually. You could rename WHOOP to change how it appears to other wearables when you could connect it to your bike computer or some gym equipment. Simply put, you could broadcast to your Zwift, Peloton bike or Carol/Nordic Bike or work alongside your RUNN on the treadmill. Used in this way, WHOOP is a generic Bluetooth heart rate monitor and will connect to many pieces of sports kit.

Change or Remove the strap, e.g. for WHOOP clothing.

One end of the strap slides off the WHOOP pod, and the other clips on/off. Attaching a different strap is super easy. Maybe you want a different colour strap? You got it! There are even custom straps available.

With the WHOOP Body clothing options, you can put your WHOOP somewhere other than your wrist during exercise, which is generally a good idea. My favourite is to wear the arm sleeve as this is probably the most accurate place to wear any optical HR tech, including WHOOP/Garmin/Polar/Scosche/Wahoo. Special WHOOP bras, shorts and tops give you other options, too.

Alternatively, remove the metal clasp before inserting the WHOOP pod into the clothing.

Warning: I wore the arm sleeve around the bicep/tricep in a few positions. I found the sleeve too loose to wear on the forearm (I bought it for the biceps). When I wore it on the triceps, it worked fine. Still, there wasn’t a line-of-sight to my sports watch, so the signal had to pass through my body and thus wasn’t always received and recorded by the watch; the solution to that was to wear the sleeve so that WHOOP was on the outer side of the upper arm, the same arm you wore the watch on. Like this…

Case Study: Testing WHOOP on the calf with WHOOP apparel.

Case Study: Using WHOOP on TYR Swimwear

The WHOOP 4.0 App Review

For a quick overview, WHOOP’s app has these key sections:

1. Home – All your current and recent trend data is here on eight sub-screens
2. Coaching – Here, you get straightforward, actionable advice on how hard to train today and how much you need to sleep tonight. There’s also a dashboard of key health metrics plus access to highly impressive and detailed weekly/monthly performance reports #IndustryLeading
3. Camera – Take a video overlain with live performance metrics.
4. Team—Join a team, sports interest, or regional-based team and check the awesomeness of your sleep, strain, and recovery on the leaderboards. Warning: there are a lot of excellent athletes on WHOOP who are hard to beat, and it’s insightful to see how they recover even if you can’t beat their strain scores.
5. Hamburger Menu—This menu contains lots of learning resources and administrative stuff. It also has limited links to other software like Strava, and you can set your WHOOP to broadcast HR here, too.

Here they are in more detail…

Home Screen

The WHOOP 4 home screen was revamped and expanded in March 2023, containing links to over 20 more screens. The app can initially seem daunting, as so much detail, insights, and supporting information can be clicked on from various parts of the screen. However, the main flow is easy to grip, and the matrix of screens shown here works exactly as shown. Swipe left or right for different views as you move from one screen to the next, and swipe up or down for more or less detail.

That’s a lot of information and insight all in one place. But there is more to discover as you delve into the app’s depths. For example, the first screen lets you tap on an activity or sleep period for minute-by-minute information on your heart rate or, in the case of sleep, some quite detailed stats that include sleep disturbances, efficiency, latency, and more.

Similarly, more information is linked to other screens, where, for example, you can change the workout metric that is graphed on the 7-day trends.

WHOOP Coach Screen

The WHOOP coach advises you on the strain you should aim for today and the sleep you should aim for as recovery.

Based on your recovery, the strain coach ‘knows’ your optimal strain level for today. In the example below, I can check that I need to aim for a strain of 10.8 today. Now, I can just go ahead and do such a workout or use the coach to guide me during the exercise. I need to take the app with me to do that, and the app essentially tracks a more detailed workout and displays continually updated strain.

Similarly, the sleep coach gave me the headline guidance of needing under 8 hours in bed. But it can also coach me while I sleep by setting a smart alarm to wake me when I’ve achieved a particular readiness state. Of course, I can also guide WHOOP by saying that I want enough sleep to get by or full sleep to be on peak performance tomorrow.

Clever stuff.

And it’s clever stuff, presented straightforwardly.

The third page, above, is the Health Monitor, which gives you a current snapshot of some key bodily metrics like respiration rate, temperature, and SpO2. At the bottom of that page is a super-detailed log of those metrics over the last month or so, which you might be interested in looking at or which might be helpful to print and share with a doctor.

You can probably guess some of the contents of The Weekly and Monthly Performance Assessments. You get excellent insights from novel ways of displaying strain data and how each workout places you within productive ranges. The Monthly report is more like the doctor’s health report and is highly detailed and, I must say, professionally presented.

WHOOP 4.0 Review – Camera Page

A camera does what you’d expect with some nice added touches. For example, you can add filters and change the metrics captured on the video of you sweating profusely mid-workout.

System/Hamburger Menu

There’s not too much exciting to talk about here except to note that this is the place you rename WHOOP for when other devices might want to connect to the heart rate you allow it to broadcast.

If you want to see your data on other platforms, there are connections to Training Peaks and Strava. You can create a custom graphic for the latter in your Strava feed.

WHOOP Widgets

Widgets in both iOS and Android are made good use of by WHOOP.

In this image, you can see how widgets give you key, glanceable snippets of information without the need to open the app.

Is WHOOP 4.0 Accurate? Test Results and Detailed Review

This is a topic that is going to get a lot of people overly excited.

Q: What do I mean by the accuracy of WHOOP in the context of this review?

A: I use the word accuracy to mean repeatable and actionable. IE that you can rely on an accurate device over the long term to meaningfully guide your training.

I’m sure that most of us would agree that athletes like us can find a reference point to determine the correct HR at any given time (a Polar H10 chest strap), and such a device can also produce correct RR beat information for HRV. Similarly, we could also find comparators for WHOOP’s other data points like respiration rates, temperature, SpO2, etc.

However, WHOOP gives us a ‘Readiness’ Score. But where is the comparator for that? A: No accepted industry standard or scientific definition exists because each vendor has its algorithms and readiness scores.

Then we might ask. “What is Strain?“. Those of us familiar with HR Zones and TRIMP could come up with a definition of strain, but heart rate zones vary from person to person and could vary based on your fatigue state or whether you’ve just used stimulants like caffeine. Some of those factors are unknowable. In November 2024, Whoop updated its Heart Rate Zone algorithm, basing zones on Heart Rate Reserve.

Then, we might want to compare wrist-based optical heart rate with a lab-standard HR chest strap. The wrist is an AWFUL position to capture heart rate during exertion, so it will be prone to the vagaries of your exercise or the environments you train in—the same is true for Garmin and Apple sensors!

Beware. Every wrist-worn competitor product for Crossfit is somewhat inaccurate—Apple, Garmin, and all compounded by person-specific factors. On the wrist, WHOOP’s recording challenges are no different. It’s the same for all sports that require a lot of wrist movement.

All competitors’ optical heart rate monitors, including Garmin, Apple, and Fitbit, are somewhat inaccurate. Whether reviewers and ambassadors tell you WHOOP 4.0 is accurate or inaccurate, the simple truth is that it is probably as accurate as the competition in the round. You might get lucky or unlucky with a Garmin; it’s the same with WHOOP and Apple.

Here’s what I did

• I undertook 14 bike and run workouts at different levels of exertion. I compared WHOOP 4 on the bicep with its HR data saved on a Coros Pace 2 and compared that to various devices, including a Garmin HRM-TRI, Apple Watch Series 7, 45mm SS and Polar Sense.
• For Morning Readiness/Recovery: I compared WHOOP’s HRV score when worn on the wrist with HRV4Training+H10, Oura Ring’s HRV score and Garmin’s HRV scores.
• With permission, I’m including FitGearHunter’s extensive video results for CrossFit.

WHOOP 4 Band Accuracy – Bottom Line

Q: Is WHOOP 4.0 Accurate?

A: Yes. WHOOP 4 is accurate for sports when worn on the biceps and gives actionable results at night when worn on the wrist.

If you are concerned about absolute HR accuracy, wear a chest strap 24×7.

Sports – Running & Cycling HR Accuracy

These results from 14 detailed tests show trivial differences between the accuracy of WHOOP, Garmin HRM-PRO and Polar Verity Sense. Surprisingly, the Apple Watch was the worst.

The only criticism of WHOOP would be minor discrepancies at the start of some workouts. As those results are low-level HR, the strain impact is trivial to the point of irrelevancy.

Other details of WHOOP 4’s accuracy found similar results to mine, including those on Reddit and in the reviews from Michael Kummer and DC Rainmaker.

Sports – Crossfit HR Accuracy

I worked with the YouTube channel FITGEARHUNTER on the accuracy section of this review. He majors in Cross Fit and has performed detailed tests for that sport, specifically looking at the accuracy of different wear positions. The conclusion is the same as mine: don’t wear it on your wrist for sports! A further conclusion is that if you want to wear it on your forearm, the outer gives the best results.

Check out the details in the videos if you want to know more. Hunter is a trustworthy reviewer.

Check out these videos for forearm accuracy and wrist accuracy.

Q: What is the accuracy of wearing Whoop on the wrist?

A: It can be accurate, but there is a higher chance it will be inaccurate for several reasons (sport, wear, physiology, environment). However, Whoop has released three accuracy updates in 2024 and one addresses wrist accuracy. I’ve used it since it was released but haven’t explicitly tested its accuracy against other products yet. More: Whoop Accuracy Update

Overnight HRV and Readiness Accuracy

As a professional (athlete or coach), it should be obvious that the physiological response is what matters. @MarcoAltini

WHOOP calculates overnight ‘HRV’ using an averaged rMSSD calculation with more weight given to periods of slow-wave sleep. The result is shown as a single nightly figure in the app. This (HRV) value is then just one of several inputs to a broader, proprietary readiness algorithm that gives a continually updating, single-figure percentage indication of your readiness to train hard at any given time.

HRV methods from different vendors might instead use an SDNN calculation, look at a single sample of 1-5 minutes when you wake up or use multiple periodic measurements from the night.

Similarly, different vendors use different inputs and weights to fine-tune their unique take on readiness.

You might even want to compare any or all of these to how recovered you feel. Which might be irrelevant (it is for me but not for others). What is undoubtedly relevant is physically/mentally how recovered you are and, perhaps more so, precisely to what level are readiness scores a predictor of your peak performances?

Maybe rMSSD/HRV is a better predictor when considered in the proper context?

In a nutshell, you really can’t compare any of this data, so let’s do it anyway!

WHOOP 4.0 vs Garmin Forerunner 955: Which Fitness Tracker Is Right for You?

The Garmin Forerunner 955 introduces new readiness metrics. Like WHOOP, any readiness metric is proprietary and can’t be compared to a ‘gold standard’ of readiness as there isn’t one. However, we can compare the data quality behind the readiness assessments. Garmin’s Elevate sensor on the 955 does not correlate HRV with a Polar H10 chest strap. Garmin’s readiness assessment can’t be as good as WHOOP’s because a fundamental component of the base data is less accurate.

Finally, my data for HRV recovery shows that Garmin’s baseline HRV (0.27) does not correlate with a Polar H10 and HRV4Training, although the less important day-to-day correlation (0.51) is better.

Surprise. WHOOP does have a good baseline correlation with the raw HRV numbers (0.78). Now, who would have thought that based on criticisms you hear from some reviewers about WHOOP’s accuracy? Such influencers wrongly assume that HRV accuracy at rest is somehow linked to HR accuracy at sporting exertion levels.

HRV accuracy requires algorithms that clean the noise from the recordings, and WHOOP appears to be excellent at this, unlike Garmin.

WHOOP Sleep & HRV Accuracy vs. Apple Watch vs. Polar Vantage vs. Oura Ring

Scientific studies showed that the previous generation of WHOOP Band was 99% accurate in 2022. WHOOP beat all competitors, though it must be noted that all vendors’ tech in this study was their previous generation, including WHOOP.

Case Study: Garmin beaten by Whoop

Similar sleep accuracy tests are performed on the YouTube channel Quantified Scientist. Rob is a trustworthy reviewer and finds WHOOP the most accurate device in his area of expertise: sleep stage accuracy vs. a low-grade polysomnograph. One update for 2024 is slightly improved accuracy on the wrist and with Whoop apparel.

Check out Rob’s reviews.

WHOOP COACH with AI from ChatGPT

WHOOP’s GPT4 AI gives personalised responses that combine science with YOUR data and YOUR goals

In September 2023, WHOOP boosted its coaching capability with a ChatGPT “plugin”. You can now interact with the AI on the app on many levels, ranging from simply using it as a manual to asking it to explain and contextualise your performances or biometric status. This can leverage the AI’s knowledge of sports science principles, peer group data and insights into your JOURNAL entries. To tailor forward-thinking advice to your circumstances…it can even write you a 20-minute 5k plan.

Case Study: WHOOP Coach uses AI

WHOOP 4.0 & Wider Review Thoughts

For over ten years, my thoughts on readiness accuracy have been mentally triangulating these three indicators to arrive at my decision intelligently.

• Predicted readiness – via a Training Stress Balance (TSB) model
• Measured recovery – via an HRV algorithm like WHOOP
• Felt readiness – simply your feel for you right now.

Anecdote: My best-ever race performance followed a night of zero sleep. Yet I felt good and predicted TSB readiness was near perfect based on the historical load. My HRV level was pretty good (as I had been tapering). Still, the entire readiness algorithm factored in factors like sleep continuity and duration, so my overall readiness score on the day was FAR below optimal. Conclusion: It is NOT that the readiness algorithm was wrong but rather that I would have performed even better had I slept properly. Measured readiness/HRV is not the sole predictor of today’s performances.

WHOOP 4.0 Review: Detailed Strain and Sleep Tracking Insights

WHOOP’s strain score is algorithmic and ranges from 1 to 21. Thus, getting a ten is easy but much more challenging than pushing a score of 19 toward 20.

This seems like a fair approach, but some people argue that low-level strain points are added too quickly (although it’s kind of like the RPE scale if you think about it)

I’ve been looking at sleep HR/Sleep-Stage data for over a decade, and the more I look at it, the less I want it. It’s all fascinating, but when you compare different tech tools, you realise they’re all often wrong by some measure or other. If you’re looking for a simple tool that records your hours of sleep, then I’m not sure why you would buy into an advanced sports coaching platform like WHOOP.

If you’re an athlete, you might be interested in quantifying the amount of deep sleep when your body restores itself physically. But if you’re a scientific athlete, you’ll look into Polysomnography and realise that EVERY tech gadget’s sleep stage estimations are inaccurate. No reviewer on the net compares sleep to proper Polysomnography (@thequantiiefsceintist does NOT do this); it’s tricky/expensive to do.

So, I like how WHOOP quantifies the volume of sleep I should aim for to achieve my desired outcome on the ‘Get By’ to ‘Perform’ spectrum. That’s valuable advice to receive.

WHOOP 4.0 Body, WHOOP Pro & Accessories, Review Highlights

With everything from WHOOP underwear to a new WHOOP strap, you can be different and improve the accuracy of your HR readings simultaneously.

You can easily customise your WHOOP 4.0 experience.

Get extra fabric straps in different colours or, more usefully, get an extra Superknit Bicep Band to switch the WHOOP from your wrist to your bicep when you exercise. Shop: Bands

Get some excellent quality apparel that can also hold your WHOOP band. You’ll get MUCH better HR accuracy and keep your regular wristband much cleaner and more hygienic. So I’d recommend a sports bra, arm sleeve 4.0 or waterproof arm sleeve. Shop: WHOOP Body

For a fully customised look to differentiate yourself from anyone wearing a WHOOP 4.0, you can change the colours of every device aspect, including the metal. Shop: Custom Bands

I also use several WHOOP-branded pieces of apparel. They are excellently made, and I love how they let me put WHOOP in a correctly positioned and customised pocket. The accuracy of readings is probably ‘good enough’ and better than I expected when using the apparel.

WHOOP 4 – 10 Top Tips

Here are some frequently asked and some lesser questions; hopefully, these will help some of you.

Q: Can I use my WHOOP 3.0 Bands?

A: Yes. The material is the correct width, and the fixed metal end of the band, although bigger, will secure the WHOOP 4.0. However, the end of the band that threads through the space on the pod has a new removable attachment. So, yes, you can reuse old straps, but there are limitations.

Q: Is WHOOP worth it?

A: Yes, good training decisions are priceless. Do you want to buy an expensive sports watch only to discover an updated version 6 months later? You always have the latest version.

Q: Can I use WHOOP with older Garmin sports watches using ANT+?

A: No. WHOOP is not compatible with ANT+. You could buy a clever NPE Wyur device to convert the Bluetooth Signal to ANT+. Nowadays, most bike computers and sports watches will accept WHOOP’s data using Bluetooth.

Q: What happens if I break or lose my WHOOP Strap?

A: If the strap is defective, then WHOOP will replace it. But if you misuse or lose your strap, then you would submit a non-warranty replacement request directly to WHOOP

Q: What if there is a WHOOP 5? Would I pay for it

A: No. (Qualifying) subscribers would get one for free. Usually, you would need at least six months of your subscription remaining, although predicting what will happen in the future is impossible!

Q: Is WHOOP More Accurate Than a Garmin?

A: Chest straps are more accurate than wrist optical HR sensors. As I show above in extensive accuracy tests, WHOOP is accurate when worn on the biceps. If you are concerned about high levels of accuracy, then you will not use ANY VENDOR’s optical HR monitor for sports on your wrist. It is that simple. Regarding resting HR measurements, e.g. whilst at sleep/rest, I’m certainly not convinced of the accuracy of Garmin’s HRV, and neither are the sports data scientists I know. Just because one piece of tech may ‘feel’ right doesn’t mean it is correct.

Q: Where is the most accurate place to wear WHOOP?

A: I’ve tested all of the alternative wear positions with WHOOP. The biceps are a good spot to use, and I expected that to be the case. The calf was also an accurate place, but butt-measured HR was somewhat variable when swimming or running. My recommendation is to wear it on your biceps.

Q: Is it worth upgrading from WHOOP 3.0 to WHOOP 4.0

A: Yes. Just do it. The only caveat would be original WHOOP Pioneer members, who may be able to continue indefinitely with their free access to the app’s current features without paying a subscription.

Q: Is WHOOP better than the Oura Ring?

A: They are different. Oura Ring Gen 4 is a great sleep tracker that estimates your readiness based on HRV and sleep parameters. However, Oura is unsuitable as an athletic-grade activity tracker or HR monitor, i.e., it cannot accurately measure strain.

Q: Is WHOOP better than Biostrap EVO?

A: Yes, WHOOP is better. Biostrap is similar to WHOOP but not as athletically focused and has a less good app.

Q: How do I wear WHOOP?

A: You can wear it anywhere. You will get the best results from wearing it on the upper arm and get good-to-mixed results wearing it with WHOOP apparel. Wearing it so that it touches the wrist bone is the very worst place for accuracy during sport for any wearable! If you have to wear it near the wrist, wear it two finger width away from the wrist bone and further up the forearm

Q: How do I charge WHOOP?

A: Charge the WHOOP by simply sliding it into the charging puck. You will first have to close WHOOP’s metal clasp. The puck has inbuilt battery storage, which can be used on the go or when plugged in. A neat feature is that you can charge WHOOP with the puck whilst wearing it. A realistic battery life is 4 to 5 days based on WHOOP’s state-of-the-art battery tech.

Q: Is WHOOP better than the Apple Watch, Garmin Forerunner, Garmin Fenix, Polar Vantage, or Fitbit?

A: WHOOP lacks a screen like watches! If you want a screen, don’t buy WHOOP. WHOOP is a wear-and-forget, unobtrusive band better suited for specific sports and wearing while sleeping. Most major platforms have some form of readiness assessment, but with WHOOP, you get a whole platform geared toward readiness and coaching.

Q: How do you cancel a WHOOP Membership?

A: You can cancel your WHOOP membership at the Membership section of app.whoop.com. Cancelling is free within 30 days, but after that, you will be charged until the end of your contract period

Best WHOOP Strap Alternatives compared to Apple Watch, Garmin & Biostrap

WHOOP has a wholly unique band+app platform offering with no direct competitor. However, several alternatives track activity and address your readiness to do it.

WHOOP 4.0 Band compared to Apple Watch

The Apple Watch can take HRV readings, which third-party apps can use to determine readiness. The best of these are Training Today and Athlytic. The former is visually appealing, but the algorithms seem wrong to me. The latter has good algorithms but presents the data overly complexly. Both require manual or periodic manual readings for the best accuracy, whereas WHOOP continuously takes automatic readings for extended periods.

You would choose one of the Apple Watch apps because you are already invested in the ecosystem. You may also own the Watch and use it for other things, like making calls and interacting with your iPhone.

Oura and Ultrahuman Smart Ring compared to Whoop 4

The two best smart rings are Ultrahuman and Oura, the former being subscription-free, but the two are otherwise similar to each other. Their sleep and readiness features are, in turn, similar to Whoop; however, Whoop can record strain/activity heart rate correctly, whereas the smart rings definitely cannot. Thus, a smart ring is unsuitable for athletes and will NEVER correctly record strain.

Garmin compared to WHOOP 4 Strap

My tests show that Garmin’s resting HRV appears less accurate than WHOOP. However, Garmins can calculate strain via heart rate from chest straps, which is usually correct. The Garmin app and watch present lots of pieces of data, often in quite haphazard ways, and are certainly not as focused on Strain, Sleep and Recovery as WHOOP. Indeed, Garmin has multiple conflicting measures that indicate recovery, including all-day stress and body battery. Which do you use? Supposedly, it’s Body Battery, but that is not based on any published science that I’ve seen, and I believe it to be Garmin taking generally good HRV data but then adding an unproven interpretation layer above it with ‘random’ assessments of other factors that might affect readiness.

You would choose Garmin if you were a committed endurance athlete who also wanted visual feedback on a watch and perhaps the ability to pair it to sports sensors.

Biostrap EVO compared to WHOOP 4 Band

Biostrap EVO is the most similar product to WHOOP and gets extra insights into sleep and strain from extra wearable sensors. However, the app could be slicker, and the band is poorly made and doesn’t look good when worn. Plus, you have to wear multiple sensors, even in bed. You would probably consider Biostrap if you wanted more unusual data about your body, i.e. you are a biohacker. Sporty people should buy WHOOP, not Biostrap EVO.

WHOOP 4.0 Strap compared to Fitbit

Fitbit’s advanced app features and watch require a subscription. The future of the Fitbit brand and app is uncertain after Google’s acquisition. Fitbit is a risky buy in 2023. Fitbit’s sensor quality is poor compared to Apple and Garmin. If you are an athlete or a wannabe athlete, hopefully, I’ve just dissuaded you from buying a Fitbit. Please don’t do it!

Eight Sleep vs WHOOP Band

Eight Sleep Pod 4 is the best non-wearable sleep tracker, and it also accurately records nightly HRV to predict your readiness. It cannot capture activity data but is excellent for sleep analyses as it gives you and your partner data without needing to wear a gadget. It also smartly regulates bed temperature to reduce the cost of air conditioning in the summer.

Polar Verity Sense compared to WHOOP

Polar Verity Sense (Polar Sense) is an excellent optical heart rate monitor worn on the upper arm for sports. But that’s it. Its battery will not last long enough to cover sleep tracking, nor does it have additional sleep sensors, as found on WHOOP.

WHOOP 4.0 Band Review – Take Out

When worn correctly, WHOOP 4 is accurate for me as a heart rate tracker. WHOOP’s sleep and strain coaching effectively guides your training with HRV principles.

Its form factor is ideal for sports usage and bed-wearing to track sleep. A watch is not the best thing to wear in bed—if you don’t wear your Apple/Garmin watch at night, then your recovery data is wrong.

It is hard to criticise WHOOP fairly. Perhaps the only notable omission by WHOOP and all its competitors is a proper accounting of strain from pure strength workouts. WHOOP’s integration of velocity-based training principles from its 2021 acquisition of PUSH (2021) gives WHOOP the edge over all competitors.

The WHOOP 4.0 Strap and its app are the market leaders in their tightly defined market —wannabe pro-CrossFit athletes, strength-based athletes, team sports athletes, and pro sports athletes. The relatively unique form factor and the superb app will also appeal broadly to athletes in other sports.

Subscription prices always seem expensive, yet if you replace a high-end sports watch every couple of years, the overall cost of ownership is surprisingly similar.

WHOOP 4 Price – Join For Free with a Free Band

Join WHOOP for free. Get a free band, a free joining fee and the first of 6 months’ subscription for free. That’s a lot of free. Starts at Eu17/$17/£16/mo here at WHOOP.com

New Membership Gift Offer, free WHOOP strap!

• 12M Membership $199 ($40 discount, 17%) – USD
• 24M Membership $359 ($40 discount) – USD
• Same deals for other countries.