I Tried The Whoop 4.0 & Learned A Ton About My Body

As a diehard Fitbit girly, I’m constantly glancing down at my wrist to see the time, my step count, and my heart rate. Checking my health stats is something I do 100 times a day, sometimes without even thinking. When I decided to switch things up and try the Whoop 4.0 — a fitness tracker beloved by athletes and serious exercisers — it turned my whole world upside down.

For starters, the Whoop 4.0 doesn’t look like your typical fitness tracker. Unlike a Fitbit or Apple Watch that shows all your info on an interactive display, the Whoop is a screen-less wearable that attaches to your wrist with a band. You could also opt for the bicep band if you’d prefer to wear it around your arm, or snag yourself something from Whoop’s Any-Wear line of activewear specifically designed to tuck your tracker pod into a swimsuit, sports bra, or a pair of leggings.

Instead of accessing your stats on a watch, the Whoop is constantly sending data to the corresponding Whoop app that you need to open to get in-depth info about your movement, recovery, strain, and sleep. The goal? To help you tune into your body and build healthier habits over time.

As soon as I opened the box I knew this gadget was fancy, high-tech, and totally unlike any other tracker on the market. Here’s my honest review of the Whoop 4.0 after testing it for a month.

Fast Facts

• Product Name: Whoop 4.0
• Price: $30.00/month for membership
• Best for: Tracking workouts, recovery, stress, and sleep
• Rating: 4/5

What Is The Whoop 4.0?

The Whoop 4.0 is a fitness wearable that uses a sensor to track your blood oxygen levels, skin temperature, respiratory rate, and heart rate metrics so that it knows what you’re doing at every turn. The device is designed to be worn 24/7 — whether you’re exercising, sleeping, showering, or walking around town — so that you collect all the data you could ever want or need about your body, including your resting heart rate (RHR), heart rate variability (HRV), recovery levels, and sleep quality.

Whoop also allows you to manually track over 80 different kinds of workouts and recovery activities, whether you’re taking a spin class, doing Pilates, or even getting a massage. All of this info is tracked and incorporated into your “strain” and “recovery” scores, which are meant to let you know if you need a recovery day, extra sleep, or if you’re all set to exert yourself.

Strain

The Whoop strain feature measures your cardiovascular exertion on a scale of one to 21. You get an activity strain score during a workout, as well as a day strain score that takes into account your activity and stress throughout the entire day. While the activity strain focuses on your heart rate during a workout, the day strain score includes mental stress as well as physical stress — so a tough, sweat-inducing meeting can impact your strain score the same way a workout would.

The longer your heart rate is raised, the higher your score. A strain score of zero to nine is considered light strain, 10 to 13 is moderate, 14 to 17 is strenuous, and 18 to 21 is an all-out effort. Note that the number you get is highly personalized since a tough exercise might be easy for someone else, and vice versa. In theory, as you continue to exercise and adjust your lifestyle, your strain score should start to go down (since your fitness level is going up).

Sleep

Wear the Whoop to bed and it’ll monitor your sleep performance by taking into account the duration, quality, efficiency, and consistency of your Zzzs. When you wake up, the app presents you with a graph showcasing all of this info as well as data on how many hours of sleep you needed versus what you got, plus the time you spent in bed.

As it collects data over the course of a few days, the Whoop sleep coach will start to recommend an ideal bedtime based on your circadian rhythm. Whoop can also gently wake you up at the ideal time in the morning using a haptic alert, which is a gentle vibration. All of these data are meant to improve your sleep so you can perform better the next day.

Recovery

When you wake up, Whoop also calculates your recovery and then recommends the perfect amount of strain for you to do that day. This score is based on a percentage that categorizes your recovery as either green, yellow, or red.

If you slept really well, you’ll get a green score (67 to 100%) which means you’re recovered and ready to work, exercise, or handle a stressful day. If you get a yellow score (34 to 66%), your body is maintaining and ready to take on moderate amounts of strain. This might mean you need to skip a super-tough workout and monitor how you feel throughout the day.

A red score (0 to 33%) indicates that you definitely need more rest. It means your body is working too hard to recover, possibly because you didn’t sleep well, or you’re stressed, overtraining, sick, etc. According to Whoop, the average recovery score for most people is 58%, which looks like it means we could all use an occasional rest day.

What’s It’s Like To Use The Whoop 4.0

Because I’m so used to glancing at my Fitbit, it was disorienting to look down and see nothing but a band on my wrist. It took a while to get in the habit of opening the Whoop app, but once I did, I was in data heaven. The app presents you with graphs and charts and other intricate details about your body’s current state, all so that you have a better idea of when to rest and when to push yourself. (This is likely why athletes love Whoop.)

The app’s home screen is where you’ll see your overview, aka your day strain and recovery score. Once I wore the Whoop for a few days and the data began to roll in, I attempted to plan my schedule accordingly. If I woke up with a green score — which meant I got enough Zzzs — I knew it was OK to exercise with abandon. (Hello, dance workout!) If I woke up to a yellow score, there was my excuse to take it easy with some active recovery.

As someone who’s all about walking as much as possible, I did miss tracking my steps. Whoop isn’t about that life. It does, however, allow you to track your fitness routine. Before I started a workout I’d manually tap on an activity session, keep the app open, and watch as it tracked my heart rate zones and exertion in real-time, all of which was ultimately added to my daily strain. I wore it during Pilates, cardio dance, and walks and runs, and it was super cool to see if I was pushing myself hard enough — or if I was pushing myself beyond my limits that day. The whole point is to hit the sweet spot for optimal results.

Another cool feature? While you typically have to take a fitness tracker off to charge, the Whoop has a battery pack that slides onto the device so it charges as you wear it. It’s even waterproof, so if you really wanted to charge your Whoop whilst showering, you could. This, of course, means you never lose any data. For serious exercisers, I can see how this constant flow of info would be a big draw.

The Results

I quickly became fascinated by my daily strain and recovery. If the latter was low, I’d go into a full chill mode so that my body could properly rest. The sleep data also became a guiding light. If Whoop told me I should be in bed by 10:30, that’s what I’d aim for — and it often resulted in a perkier me the following day.

If I woke up to a yellow recovery score despite my best efforts, I noticed that I was dragging a little more. A yellow score told me it wasn’t the right time to push myself to dance, jog, or stay up super late. Throughout the month, my recovery score served as a nice reminder to do what was best for me in the day-to-day versus what I wanted to do.

The Verdict

The Whoop 4.0 is way techier than your average step tracker. While wearables like Fitbit track your steps, workouts, and sleep, the Whoop is out here monitoring your every move and making suggestions that impact your day, kind of like a personal health coach.

The price reflects that, too. It costs $30 a month to have access to the Whoop app, which may be worth it for athletes, serious exercisers, or folks training for a marathon. It was fun to try for a few weeks, and I appreciated all the personalized info and advice. I can see myself sliding the Whoop back on whenever I’m feeling burnt out just to see what’s up or if I’m training for something specific, but for my everyday life and simpler workouts, the Fitbit will work just fine.

Studies referenced:

Avram, R. (2019). Real-world heart rate norms in the Health eHeart study. NPJ Digit Med. doi: 10.1038/s41746-019-0134-9.

Germini, F. (2022). Accuracy and Acceptability of Wrist-Wearable Activity-Tracking Devices: Systematic Review of the Literature. J Med Internet Res. doi: 10.2196/30791.

Rajendra Acharya, U. (2006). Heart rate variability: a review. Med Biol Eng Comput. doi: 10.1007/s11517-006-0119-0.