The Whoop Weight Machine Has Its Flaws, but It’s Still Better Than Anything Its Competitors Have

Two years ago, screenless fitness tracker Whoop took on a challenge that none of its competitors had been able to solve: answering the question “how hard was your weightlifting workout?” Its initial implementation was clunky and finicky. I don’t think I managed to record any of the workouts correctly. But now, with improvements over the years, this feature has become much more useful.

What’s the game changer? Possibility of connecting exercises to training after its completion. This way, you can’t mess up your tracking during your workout, but you’ll still get what you really care about—a strain estimate that’s accurate enough to provide the app’s sleep and recovery recommendations. Read on to learn more about how to use a weight machine, as well as what it can and (yet) can’t do.

What is the Whoop Strength Trainer?

Strength Trainer is a different way to track strength training than any other workout using Whoop. It was introduced in 2023 and aims to give you a more relevant strain rating (reflecting how hard a workout was on your body) compared to tracking it solely by heart rate.

To use Strength Trainer, you’ll need to create (or select) a workout in the app, telling Whoop exactly what exercises you plan to do, how much weight you’re using, and how many sets and reps. You can either have the app track your workout in real time, or link the workout to an activity after the fact.

Why Whoop’s Strength Trainer Gives It a Huge Advantage Over Other Wearables

Typically, when you track a workout using Whoop, you simply start an activity and your heart rate is measured during the activity. This is ideal for cardio workouts such as running. The higher the heart rate and longer, the higher the stress score you will get as a result. High loads are hard on your body and require longer recovery times. A lower strain rate is easier and perhaps even more regenerative.

However, this approach has never worked for strength training—and this caveat applies to strength training tracking using any wearable device with heart rate monitoring. A graph of your heart rate during a weightlifting workout will show plenty of rest time and only brief surges into higher territory. These spikes in heart rate don’t tell the full story of how hard your muscles worked to lift the weight. This is why I continue to advise ignoring your heart rate while lifting weights .

Before Whoop introduced Strength Trainer, my weightlifting sessions always showed up in the app as easy workouts, equivalent to a light run or a brisk walk, even if I had a killer, hard workout. But thanks to this feature, strength training now shows the appropriate amount of tension. And since strain metrics determine your recovery recommendations, this is very important. The strength trainer has transformed Whoop from a wearable device that only made sense for endurance athletes to one that makes sense for strength athletes and everyone in between.

The best way to use the Whoop strength machine is after the fact.

Below I will explain how you should use a weight machine during your workouts. But let me get to the point: using it during a workout sucks. Using it after a workout is a genius move from the Whoop team and gives me everything I really need from this feature.

All you do is:

1. Click Start Class and select a class type: Weightlifting, Powerlifting, Functional Fitness, or Boxing Fitness. Do strength training.

2. Complete the action and wait for Whoop to process it.

3. Tap an activity , ignoring its insultingly low “Strain” rating, and tap the box that asks you to connect a strength workout to calculate your muscle load.

4. Choose or create a workout that matches what you did.

5. Wait for Whoop to re-process the workout and enjoy your new, higher voltage rating.

While I’m doing my workouts, I write them down in a notebook so it’s easy for me to fill in the details later. You can use an app if you want – Heavy is one of my favorites . And yes, you could use the Whoop app, but it’s such a frustrating and error-prone experience that I can’t recommend it. Still, for the sake of completeness, let’s dig in.

How to Use Whoop’s Strength Trainer During a Workout (And Why I Don’t)

Before you start using a weight machine during your workout, you need to create a workout with the specific exercises you want to do. If possible, you will also need to include the number of repetitions and weight for each exercise.

To start a workout, go to the plus icon in the corner of the app’s home screen and instead of selecting “Start Workout,” select “Strength Trainer.” Select the workout you created and click “Start Workout” on this screen. The app will start a warm-up timer and you can begin your exercises by tapping “Start First Set.”

Ironically, one of the features that makes the Whoop ideal for weightlifting—that it can be worn on the biceps to keep the wrists free for wraps, straps, or kettlebell movements—is not kosher here. The app will ask if you will wear Whoop on your left or right wrist. This is your only choice. (I still wear it on my bicep. I don’t know if it will affect the results.)

To complete the workout, you’ll need to press a button in the app every time you start a set and every time you finish it. This is inconvenient if you don’t want to carry your phone with you, and doubly awkward if you want to use your phone for something while working out. For example, if I’m filming, I need to start filming, switch apps, start the camera, shoot, stop the camera, switch apps, and stop filming in the Whoop app. Skip a step and you’ll ruin your workout tracking.

During training you will be able to :

• Add set

• Remove the last set of the exercise (but not the specific set in the middle).

• Changing the exercise order

• Repeat the set (if you started it by accident)

• Add an exercise

• Deleting an exercise

• Change the weight of the exercise (including one you have already done)

You cannot :

• Register the set as already completed (if you did this but forgot to click the Start button).

• Set a timer that will alert you when a certain rest period has passed.

The ability to edit a workout on the fly or cancel a set is a great addition that Strength Trainer didn’t have when it first launched. But there is still no way to solve the common problem (at least for me) of forgetting to start a set. When I’m filming my sets or using my phone for anything else during my workout, like answering a text message, I can easily lose sight of the Whoop app. I say, “Stop texting,” hang up, lift the weight, and then return to the phone and realize my mistake. Drives me crazy.

It would be useful if the weight trainer could perform active actions on the lock screen, like it does when I go for a run. Unfortunately, live strength training classes are only available on Android at the moment. (I use an iPhone.)

Why does weight training still disappoint me?

I still have mixed feelings about the weight machine. Pros: It gives me an appropriate tension rating for my weightlifting routine, and adding a workout after the fact is convenient and won’t ruin my workout. (I wish there was a push notification so I couldn’t forget, but as long as I remember, it’s good.) No other wearable device does anything like this; they all track the effects of strength training as if it were a form of cardio.

But the subsequent version requires special care, for example, looking after the baby during training. I always make mistakes that are not easy to correct. He also doesn’t want me to use a bicep band (sorry, but I can’t use a wrist band for some exercises). There’s also no way to introduce pause exercises (like squats, where you count to three before standing up) or complexes (like sit-ups + front squats + jerks for one rep).

These limitations seem to stem from Strength Trainer’s origins, with Whoop acquiring Push in 2021 , a company that tracked strength exercises using a wrist-based speed sensor. Whoop users were excited about the introduction of velocity-based training (VBT) to Whoop, but it never materialized.

In a VBT workout, the trainer (or app) measures how fast you moved—say, how quickly you can get up from a squat—and uses that data to tell you whether to add weight on your next set. This way, you will receive personalized training that is tailored to how you actually perform that day. If you’re tired and everything feels heavy, you’ll move slower and the app will prompt you to use less weight. If you’re feeling great and even heavy weights are moving quickly, the app will make you push a little harder.

But Whoop never made that promise to Whoop users. (If they have plans, they’re still under wraps.) Instead, they appear to have used some of the underlying technology to train their own algorithms to recognize exercises. If you perform a squat while using a weight machine, your Whoop device will presumably notice when your rep begins and ends and records how quickly you performed the squat.

However, it is unclear what Whoop does with this data. In company materials, such as the press release announcing the launch of the Strength Trainer, the word “speed” is never used. Instead, they seem to use the word “intensity” as a substitute, which only leads to confusion. In traditional strength training, an intense (heavy, hard on the body) repetition will show up in VBT as a slow movement. But a Whoop spokesperson said on Reddit that they suggest you work harder when you lift weights quickly.

Unfortunately, because Whoop is so tight-lipped about its algorithms, it’s very difficult to understand what it’s doing or even what you’re missing (if anything) when you’re recording a strength workout after the fact rather than monitoring it in the moment. When the weight trainer first came out, I emailed back and forth with the Whoop team trying to understand what calculations it was doing and why, but they kept sending me vague statements that didn’t explain anything.

I also haven’t found any validation studies comparing the results of a strength machine to anything else. Whoop now says that it “estimates max volume based on your training history,” but I don’t know if that’s different from the original implementation or not. They also say it “calculates your personal muscle load by taking the maximum intensity of each exercise from your profile.” Does it mean heaviest (using the traditional concept of intensity) or fastest (using intensity as a euphemism for speed)? Again, they don’t define their terms.

So, I’m disappointed on many levels. I’m disappointed that Whoop seems to have gobbled up the VBT company to provide something that doesn’t even support VBT. I’m disappointed that Whoop doesn’t tell you what the weight machine even does there. I’m disappointed that Strength Trainer is so difficult to use in its most fully featured version, and I’m disappointed that I don’t even know if I’m missing something by using the more convenient “Sign Up Later” feature.

Ironically, the part of the weight machine I use the most (logged later) probably never needed heart rate or speed tracking in the first place. Just enter your numbers and let the algorithm see how much and how hard you lifted. To do this, Whoop didn’t need to acquire a company or create a finicky follow-on feature.

But here we are. If you are comfortable monitoring your workouts through the app, great. You are luckier than me. But even with recording workouts after the fact, Whoop still managed to account for the fact that strength training is harder on your body than light cardio—something other wearable tech companies haven’t figured out how to do.

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