Buzz
Activity-tracking wearables have excelled at monitoring cardio exercises. Running or cycling provides a clear heart rate indicator of effort. However, strength training impacts the body differently, and wearables have historically struggled to measure it effectively—until now, perhaps.
Whoop, the minimalist wristband that monitors sleep and workouts, has long included a “weightlifting” option for logging sessions similar to cardio: start the timer, complete your routine, and receive a score. However, it often came with a caveat: “Your Strain score might not reflect your actual effort.” Essentially, the device acknowledges its limitations in accurately gauging workout intensity.
If this functionality proves effective, it could revolutionize the industry.
However, things are evolving. Whoop has launched a new feature named Strength Trainer, designed to monitor the impact of every repetition, set, and exercise on your body. If this proves effective, it could mark a groundbreaking advancement in the industry. Unlike other consumer wearables that treat strength training as a variation of cardio, Whoop’s approach is unique. (Garmin does offer rep counting, which is impressive.)
For fitness enthusiasts currently using devices like the Oura or Apple Watch, this new functionality might be compelling enough to consider switching. But does it truly live up to its claims?
The growing need for wearables to accurately monitor strength training
Heavy lifting demands a lot from your body. While soreness is a common experience, seasoned lifters understand that the effects extend far beyond that. For instance, pushing my deadlift to its maximum (adding weight until the bar won’t budge) leaves me needing significant recovery time, regardless of whether I feel sore.
To gauge recovery post-workout, wearables typically rely on heart rate variability (HRV). HRV assesses the consistency of your heartbeats—less regularity is actually a sign of better recovery.
This is useful for assessing my current recovery status, but it fails to distinguish between scenarios where a tough workout lowered my HRV despite adequate sleep and nutrition, and situations where my training was normal but recovery was neglected. For now, human intuition remains the most reliable method. My coach can predict my fatigue levels at the end of an intense training phase without even glancing at my HRV data.
Beyond HRV, recovery-focused wearables utilize multiple metrics to evaluate your recovery status or needs. (Here, “recovery” primarily refers to sleep.) They analyze factors like your sleep duration, nighttime heart rate, and attempt to factor in your exercise volume—this is where the Strength Trainer plays a role.
Experiencing Whoop’s Strength Trainer firsthand
The Strength Trainer is located in a separate section of the Whoop app, distinct from standard workout options. By tapping the plus icon in the bottom right corner, you can access the Strength Trainer, where you can either design a custom workout or select from Whoop’s pre-designed routines.
After using Strength Trainer for a week across four weightlifting sessions, I failed to log any of them accurately.
The workout creation feature shines with its extensive exercise library, offering around 200 options. I was delighted to discover a range of Olympic lifts and their variations, including snatches, power snatches, hang snatches, and hang power snatches. While it lacks the ability to create compound movements like “snatch pull + snatch,” which I hope is added later, you can manually add exercises not listed under “Other.”
The most frustrating aspect—and a potential dealbreaker—is the need for constant attention. When setting up a workout, you input exercises, sets, reps, and weights (reps and weights can be adjusted mid-session). During the workout, you must tap to start and end each set, which becomes cumbersome if you’re multitasking, such as recording videos on your phone.
Mistakes are hard to correct. While you can add missed exercises or sets, there’s no way to undo accidental entries. Here are some unfixable errors I encountered:
I completed six sets of clean-and-jerks, only to discover I had mistakenly logged them as jerks alone. Now, they’re permanently recorded as jerks.
I forgot to stop the set timer after my final snatch set, resulting in three extra minutes of weight changes and setup being logged.
I missed starting the timer for multiple squat sets, so Whoop incorrectly shows only one set instead of the five I actually performed.
Occasionally, I’d realize after a set that I hadn’t started the timer. To fix this, I’d start and stop it quickly to maintain the set count. However, this meant logging a set of bent-over rows with data from me standing idle for five seconds. Is this better or worse than skipping the set? I’m honestly unsure.
Over the course of a week, I used Strength Trainer for four weightlifting sessions and failed to log any of them accurately.
Reflecting on my experience, the data is largely unreliable. While the visualizations are impressive—theoretically showing which exercises correspond to specific heart rate spikes—errors like mislabeled exercises, incorrect set counts, and entries marked as “Other” make it hard to decipher. (Users have been vocal about wanting the ability to label “Other” exercises, so hopefully, this feature is added soon.)
Interesting data, but is it practical?
The Strength Trainer excels in one area: it assigns higher Strain scores to workouts logged with this feature compared to the old method. Conversations with other Whoop users and Reddit discussions confirm this trend, with some even questioning if the new Strain scores are excessively high.
I didn’t notice a significant difference. I performed my Thursday clean and jerk workout once with the Strength Trainer and once without; the Strain score was 10.6 with the feature versus 9.9 using the traditional method. I also encountered some strange outcomes from the feature that breaks down your workout into “muscular” versus cardio percentages. Here are the three full-length sessions I completed, all involving heavy lifts with extended rest periods:
10.6 Strain, 0% (!) muscular load (jerks, clean and jerks, clean pulls, and an accessory circuit, totaling 1 hour and 17 minutes)
1 Strain, 47% muscular load (snatches, power cleans, squats, presses, rows, approximately two hours)
13.6 Strain, 64% muscular load (snatch balance, power snatches, deadlifts, front squats, 1 hour and 53 minutes)
There’s clearly an issue here, but it’s unclear whether the low percentages stem from an app limitation or my logging errors (which I’d argue is still an app flaw, even if technically my mistake).
Many Whoop users who focus on lifting appreciate the higher, presumably more accurate, Strain scores despite the tracking hassle. However, discussions about the feature often turn into wishlists: I wish I could edit workouts post-completion. I wish I could add notes, RPE, or 1RM data. I wish it integrated with my existing strength workout app.
Perhaps the biggest letdown is that, despite needing to wear the band during workouts, it doesn’t assist in logging the required Strength Trainer data. It doesn’t count reps or detect exercise starts automatically. Whoop’s CTO mentioned in a podcast that the Strength Trainer’s future feature roadmap is one of the company’s most ambitious—so they’re aware improvements are needed.
The Strength Trainer feels incomplete, but there’s potential for something remarkable
If this were the final version of the Strength Trainer, it would be laughable. Manually inputting every rep, set, and weight, plus tapping a button over 40 times per workout, just to slightly boost my Strain score—an already vague and subjective metric—isn’t worth the effort.
However, there’s likely more to the technology than what’s currently visible. Whoop acquired Push in 2021, leveraging their expertise to develop the Strength Trainer. Push specialized in wrist-worn devices designed to assist coaches with velocity-based training (VBT).
VBT involves attaching a device to the weight or your wrist to measure the speed of your lifts. Moving a heavy weight quickly indicates it’s manageable at that moment, while slower movement suggests fatigue or nearing failure. This mirrors a coach’s ability to gauge your performance and adjust accordingly.
It’s like having a digital coach who observes your lifts and decides whether to increase the weight or scale back based on your performance. Before Whoop’s acquisition, Push promised athletes “real-time feedback” through their sensor and app, and assured coaches that workouts would be “automatically logged.” (Their exercise library also boasted “400+” movements, more than double what Whoop’s Strength Trainer initially offered.)
As noted in an archived snippet of a Push blog here, the app “provided load recommendations during resistance training to achieve specific adaptations based on lift speed.” Essentially, it acted like a coach, analyzing your performance and offering guidance.
However, Whoop’s design decisions may limit the Strength Trainer’s potential usefulness
While I’m fascinated by the possibilities the Strength Trainer offers, I’m skeptical about Whoop’s ability to fully capitalize on it. Whoop acquired Push, but that doesn’t mean they’ve fully embraced its technology. Their marketing avoids terms like “velocity,” opting instead for “explosiveness” or references to “accelerometer and gyroscope sensors,” and they don’t label their new feature as VBT.
When I asked Whoop detailed questions about whether the Strength Trainer utilizes velocity data, the responses were vague: “It uses accelerometer and gyroscope sensors to calculate effective volume per repetition, measure intensity per repetition, estimate max volume based on workout history, and determine muscular load using performance profiles.”
This isn’t particularly groundbreaking, as reps and sets are manually entered by users, and volume can be calculated from those inputs. In traditional strength training, intensity refers to the weight lifted, which users also input. Essentially, a basic spreadsheet could replicate what Whoop claims its sensors and algorithms achieve. (And unlike Whoop, a spreadsheet allows me to input my one-rep-max for a more precise intensity measure, rather than relying on estimates.)
So, what exactly is the Strength Trainer doing? The answer remains unclear. Instead of evolving into a VBT app—which would be impressive even if it didn’t impact recovery scores—Whoop appears to be using velocity data in an unconventional way. A Whoop representative mentioned in a Reddit AMA that they classify a heavy load moved quickly as producing high strain, which contradicts typical VBT principles.
This aligns with an app help screen stating that intensity “measures how explosively you perform each movement.” Normally, if my max squat is 100 kilos and I’m lifting 90 today, I’d consider that high intensity. Whoop, however, would see the slow bar movement and label it low intensity. That’s definitely backwards.
Another distinction between VBT systems like Push and Whoop is that VBT is a tool for executing a training program. It uses velocity to determine the appropriate weight for the day’s desired stimulus. However, a coach must first define that stimulus based on your training goals. This means an app’s role is to guide your actions.
Whoop and similar wearables, aiming to cater to everyone, show no interest in directing your training. They focus on short-term feedback, lacking insight into your position within a training block or season. As I explained earlier, they suggest daily exercise levels based on last night’s sleep, unaware that you’re eight weeks from a competition and should be training at 70% to 80% intensity today.
Whoop does offer a platform for coaches to manage athlete teams, and optimistically, I could see them integrating Push-style coaching into it. (In the Reddit AMA, a Whoop spokesperson mentioned they’re “exploring” VBT-based coaching.) But for now, as an individual trying to complete a workout, Whoop’s Strength Trainer feels cumbersome and offers little tangible benefit.
