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When I wrote my review of the Whoop 4.0, I kept it to the basics—how the strap looks, works, and charges, and what activities it can track. Today, I’m going to dive in to all the metrics Whoop reports, and give a reality check on what’s most useful and what isn’t worth paying attention to. I'll leave out the activity tracking features here, since I covered them in more depth in the review. (Bottom line: I love the way it tracks how hard your workouts are—strength workouts included—but it's not going to replace a true fitness watch for most people.)
I don’t wear the Whoop band as regularly as I do the Oura ring, for which I was able to give a four-year retrospective. But to research both this article and my updated review, I’ve been wearing the Whoop for about the last six weeks, tracking my workouts and sleep regularly.
So here’s a deeper dive into what it’s actually like to wear the Whoop strap long-term, using it to judge and guide your habits and performance.
A typical day with Whoop
Let me take you through a typical day. I’m wearing the Whoop band on either my wrist or upper arm, and it’s probably been a few days since I last charged it. (I get about five days on a charge.) I made sure I had it on when I went to bed. If I look at my Whoop app first thing in the morning, it will sometimes tell me that it’s still “processing” my sleep, and there’s a button I can press to “end sleep” and get my recovery results.
The Whoop app will show you a survey called your “journal” the first time you open the app each day. I’ll talk more about the journal in a section below. Let’s say you’ve already filled out your journal, and you’re looking at the main app. From the home screen, I can see:
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My recovery at the top, color coded. Green is good, and you get that if your recovery is 66% or better. Yellow is OK (34% and up), and red is poor. Today, I have a yellow recovery, at 48%. (For the month of April, I got 19 green recoveries, 9 yellow, 0 red, and on two nights I forgot to wear the strap to bed.)
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Some notes about things I should pay attention to. Today it says that my HRV is lower than usual, which might be because of my hard workout yesterday.
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The health monitor, which tells me whether my respiratory rate, blood oxygen, resting heart rate, HRV, and skin temperature are within my normal ranges. Today, all five are within range.
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The stress monitor, which I guess tells me how stressed I am. I don’t find this useful.
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A "daily outlook" button I can press. This starts a conversation with Whoop Coach—more about that in a minute.
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Today’s timeline, showing when I slept. As I do other activities, like workouts, they’ll show up here.
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Recommendations for tonight’s sleep, including a recommended bedtime.
After this, there is a scorecard for my current “plan” (more about that below), and a dashboard with the individual metrics I might care about, like heart rate variability (HRV) and a count of my steps so far today, a feature that’s still in beta.
Along the top of the screen, I can select tabs that are specifically for Sleep, Recovery, or Strain. The Strain tab is interesting, since it gives a recommended Strain level for the day. Today, for example, it suggests that I take on a “moderate” level of Strain, between 8.9 and 12.9. You get most of your Strain from exercise, and a little from everyday activity like walking around. As I write this, I haven’t done any workouts or left the house, and I’m at 2.7 Strain just from a morning of sitting around.
The Whoop Coach can help you plan your day—but don’t ask it to get too specific.
Let’s return to that Daily Outlook button. Tap that, and you’ll be launched into a conversation with Whoop Coach, an AI chatbot. This is probably the only AI bot I converse with on the regular, because it does a decent job of explaining the app’s metrics and recommends workouts for the day.
Today it compliments me on completing a running workout yesterday, and tells me my workout schedule has been consistent, with 162 minutes in active heart rate zones so far this week. It then describes a few trends in my metrics, including that my resting heart rate has improved over the past few weeks, but that my recovery today is lower than my usual.
Then comes the fun part. It makes recommendations for workouts to do today, and habits to focus on. It tells me to aim for three liters of water today (that’s a little bit more than my usual) with plenty of fruits and vegetables. And for a workout, I can meet my recommended Strain score with something that is low impact to “support recovery,” since my heart rate and HRV suggested I may need a bit of a rest.
The Whoop Coach suggests three workouts to choose from, based on the kinds of activities it knows I like to do. They include a 30-minute run, mostly in zones 1 and 2, or an 80-minute weightlifting workout at a low-medium intensity. I can tap a button at the bottom of each workout that says “Commit,” and doing this will add it to my timeline for the day. I can do the workout later by just tapping that button, and it will start the activity timer for me.
I love that it can recommend these workouts for me, since otherwise “get 8.9 Strain” is an inscrutable instruction. Unfortunately, the little graphic showing time in heart rate zones is all you get. I’ve asked the Whoop Coach if it could time me through those intervals, perhaps beeping when it’s time to switch from one zone to another, but it doesn’t have that functionality.
It does offer a specific workout plan that I could punch into a workout timer app of my choice—in theory. The Whoop Coach, like many AI chatbots, cannot do math and can’t make sense of its own output. I asked it for specific intervals for the 30-minute run it recommended, and instead it gave me three different workouts I could try, none of them adding up to 30 minutes. I asked again for a 30-minute workout that meets my strain for the day, and it gave me a “30-minute run plan” that adds up to 25 minutes, and does not include any zone 2. It helpfully provides this as a card with a “commit” button, but the workout on the card is different still—a 28-minute workout, with three minutes in zone 2, and none of the numbers adding up to what the bot wrote to me in the text of our conversation. You can see the screenshots above.
Sometimes, after enough back-and-forth, the AI can provide something useful. But it’s just not good enough to rely on for workout ideas. I found that the best way to use it is to see what it recommends, then use that as a sort of vague guidance if I have flexibility in my training program or my real-life plans for the day. For example, I have a hard 45-minute running workout planned today, but based on Whoop’s feedback I might see if I can swap that with an easy run that is scheduled for later in the week.
How to use Whoop’s sleep metrics and features
Whoop gives you so many sleep metrics, it can be hard to know where to start. I see two major, useful features here: the report of how long you slept compared to how much sleep you needed, and the smart alarms that you can set in any of a variety of ways.
On your Sleep tab, you’ll get a score for your sleep “performance,” comparing the amount of sleep you got to the amount it calculates you needed. Today I slept more than I needed, which doesn’t match with how I felt groggily dragging myself out of bed. The timing seems right, though—I was extra tired yesterday so I both got to bed early and slept a little late.
I think it’s a fool’s errand to worry about how “accurate” sleep tracking is, since no wearable is truly accurate, but most of them are good enough. But for a comparison, the total sleep time is usually similar to what Oura reports, and the sleep phases are often more-or-less in the same ballpark. Here’s what I get today:
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Light sleep: 5:02 (Oura: 5:22)
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Deep sleep: 2:36 (Oura: 1:41)
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REM sleep: 1:46 (Oura: 1:37)
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Total: 9:18 (Oura 9:22)
Total sleep matters more than the other numbers, in my book. Increase your total sleep and you’re likely to sleep better. (I have data backing this up from my long-term Oura trends—total sleep correlates closely with other metrics and scores of sleep quality.)
Whoop also tracks your “sleep debt,” or how much sleep you needed but didn’t get. Six times in the past month I’ve had a “high” sleep debt of 45 minutes or more. Nine times it was moderate (30 to 45 minutes), and 14 times it was 30 minutes or less.
Sleep coach and smart alarms
One of Whoop’s most intriguing features is the sleep coach, which can advise you when to go to bed, and even help you decide when your alarm should go off. (It’s also one of the most hidden features. Tap on the “tonight’s sleep” card on your overview screen.)
From this screen, called the Sleep Planner, you can choose whether you want to “reach my sleep need” (making up any sleep debt, as needed); “improve my sleep,” which will recommend times that help you to be more consistent in your sleep schedule; or “reach my weekly plan goal,” which I’ll say more about below.
And then, there’s a second set of preferences. When you try to set an alarm, the app will ask if you’d like to wake up at an exact time, or when you’ve met your sleep goal for the night, or as soon as you’re “in the green.” That last one refers to a 66% or better recovery, which may not be ideal, but should ensure you’re not going to be dead on your feet.
Realistically, I don’t use these features too often. I do have a sleep goal set in my weekly plan, but I’m not fiddling with an app every night to decide when to wake up. On the other hand, if I had a chaotic schedule, like that of a student or a pro sports player, I could definitely see making more use of this feature.
Tracking your habits with the Journal
Left: the journal screen you'll see each day. Right: the screen where you can choose your journal questions. Credit: Beth Skwarecki
The activity and sleep tracking happen more or less automatically, and pretty much any fitness tracker or smartwatch can do those things. Where Whoop really shines, from a wellness perspective, is in helping you track all the little habits and factors that may be affecting your sleep or your athletic performance.
This is where the Journal comes in. You can fill it out at any time during the day, but it will also pop up first thing in the morning and ask you what happened yesterday. Did you eat a late meal? Did you have any alcohol? Did you hydrate well? If you don’t like these questions, you can set it up to ask you different ones. It can also pull in data from other parts of the app or from connected apps—for example, if you log your menstrual cycle in Apple Health, that can show up here as well.
Each habit or factor only becomes useful if you log at least five yeses and five noes. Anything that you almost always do, or that you almost never do, isn’t going to be very helpful. So I’ve narrowed down my Journal questions to only include things I’ll answer differently from night to night, or things I’m trying to improve on.
One important caveat: leaving the question blank doesn’t count as a yes or a no. At first I only answered a question if I could say “yes,” and otherwise I’d leave it blank—for example, answering “yes” if I’d had alcohol that day. But when I looked at my results later, I found that with seven yeses and zero noes for alcohol, Whoop couldn’t give me any reports that used that information. I was able to backfill the last few days’ worth of journal entries, but you can’t go back more than about a week.
Correlation, not causation—but interesting to see. Credit: Beth Skwarecki
That extra week’s worth of data was enough to get an answer on alcohol, though: it hurts my recovery, taking it down an average of 9% on nights I had a beer or two. Or at least that’s how Whoop represents it—these are correlations, and Whoop doesn’t actually know what’s causing what. For example, taking melatonin hurts my recovery by 4%. But is melatonin really the culprit, or is this just a correlation where I take melatonin when I’m already having trouble sleeping? You need to take these results with a big grain of salt. To Whoop’s credit, it includes a note that “this impact is significantly different than the Whoop average. Note that impacts can sometimes be affected by other correlated factors that you don’t track.”
The two things that do help my recovery, according to Whoop’s insights (which you can access from the top of the Journal screen), are sticking to a consistent bedtime—8% improvement—and being well-hydrated, a 4% improvement. The consistent bedtime was automatically filled out from Whoop data, while the hydration was just me answering a yes/no question each day.
By the way, you can speed up the process of clicking all the little yes and no boxes by tapping the box that says “use previous answers.” It will set the answers to whatever you marked yesterday, and then you can manually change the ones that are different.
Making a weekly plan
Weekly plans are a nice way to work on a small set of habits for a short time. Rather than trying to monitor everything for every outcome, you pick, say, three things you want to work on. Here are some examples that the app provides, and the habits or factors that each one tracks:
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Boost fitness: increase time in high intensity heart rate zones, meet a protein goal four days per week, do any strength training activity one day per week
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Feel better: increase daily steps, meet hydration goal four days per week, do “any recovery activity” three days per week
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Sleep deeper: increase sleep consistency, increase sleep performance, avoid late meals
After experimenting with some of these, I ended up creating a custom plan for myself. I chose:
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Get 7:30 hours of sleep on average
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Avoid using my phone in bed four days per week
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Meet my hydration goal five days per week
Throughout the week I can check in on how I’m doing, and at the end of the week Whoop gives me a little report and asks if I’d like to do the same plan next week, or change it up. I find this a useful way to work on a mini goal, and it’s a lot less overwhelming than poring over huge dashboards full of all the data Whoop can collect.
Viewing weekly and monthly reports
For when you do want to pore over all your data, there are detailed weekly and monthly “performance assessments” that Whoop can share with you. Each of these is a PDF with graphs showing what you did over the course of the week or month, and how it compares with previous data.
For example, my monthly report for April shows how my Strain and recovery compare with previous weeks throughout the year. I don’t wear my Whoop often enough to get any big insights from this—as I said, I only really wear it when I’m testing features or writing a review—but man, I would love this if it were available on one of the devices I do wear month in and month out. (As much as I admire the Whoop, I can only wear so many devices in addition to the ones I test for work.)
My weekly report is more narrowly focused. The most recent one starts with a statement: “Strain was optimal. Sleep could use improvement.” My Strain is also down slightly this week compared with the previous week, and my sleep consistency was poor. I like the graph that shows how my bedtimes and wake-up times line up (or don’t) with the times the app recommended for me.
What isn’t worth paying attention to
The Whoop app gives you a wealth of data, and honestly I would say most of it isn’t worth paying attention to. The app has so many data points and fractal little rabbit holes you can get lost in. You could spend hours perusing reports and tweaking settings. You could spend an unlimited amount of time chatting with the Whoop Coach AI. And you don’t need to do that.
What is useful is choosing a few things to pay attention to and letting go of the rest. Fortunately, the app gives you plenty of ways to do this. You can select a few things that matter to you in the Weekly Plan, and you can hide things from your Dashboard that you don’t need to check on every day.
As for the things I (almost) never pay attention to:
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Don’t overthink your sleep stages. Getting enough sleep, and consistent sleep, will cover your bases.
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Don’t read too much into the recovery scores; you are resilient enough to be able to handle your scheduled workout even if your sleep wasn’t perfect. The exception would be if you’re feeling truly awful—you’re sick or something—in which case, you would know because of how you feel, not because of a number on an app.
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Remember that the insights tell you about correlation, not causation—as in my melatonin example, where melatonin is correlated with worse sleep, possibly because I'm taking it when I expect to have worse sleep. These are not really "insights" at all, just data that you'll need to use your own brain (and further experimentation) to make sense of.
I have found that paying too much attention to a recovery app can drive me a little crazy. Instead of waking up and not really thinking about how I feel—I’m fine, probably—I find myself wondering if the app agrees that I feel tired and sore. Or I’ll think I’m OK, but the app says my HRV is down, and now I have to think about what may have caused that. I wouldn’t recommend intensive tracking like this for a person who finds they can easily get sucked in to obsessing over numbers. But if numbers bring you joy, the Whoop app can certainly give you plenty of them.
