Whoop Strap 4.Zero introduced with a smaller design and new monitoring sensors


Enlarge / The new Whoop-Strap 4.0.


The subscription wearable manufacturer Whoop has just launched its successor to the two-year-old Whoop Strap 3.0. The Whoop Strap 4.0 doesn’t deviate from the company’s core goals, aesthetics, or subscription model. Instead, the performance-based exercise device records blood oxygen and skin temperature for more accurate health tracking.

Like all Whoop Straps before, the Whoop Strap 4.0 comes free with a subscription to the Whoop app. Starting at $ 18 a month for 18 months (pay more for shorter subscription terms), the service offers comprehensive, personalized training metrics, analytics, and guidance focused on training load, rest and recovery, and avoiding injury and overexertion.

The whoop strap itself is only intended to collect data. That means there are no screens, no buttons, and no vibrations. The device is simply an observer, and the latest version has shrunk 33 percent while adding SpO2 and temperature sensors into the mix.

  • The Whoop Strap 4.0 is available in different colors and offers different straps, sleeves and pieces of clothing to hold the device.


  • You can unlock and adjust the strap to remove the whoop device or adjust the fit.


  • There are new sensors for monitoring blood oxygen and skin temperature that complement the heart rate monitor and accelerometer.


  • Whoop Body is the company’s new line of clothing specially designed for the whoop. The collection includes underwear, leggings and shorts.


  • The Whoop Strap 4.0 in white and gold.


Also in this array is an optical heart rate sensor, accelerometer, and an upgraded battery to power everything. The company says the new silicon anode battery has 17 percent higher energy density than the Whoop 3.0, but that won’t translate into longer battery life than the five days that the Whoop 3.0 offered.


Like the Whoop 3.0, the 4.0 can use a clip-on battery to power the Whoop Strap while it is worn. Unfortunately, due to changes in the form factor, old versions are not compatible with the new Whoop 4.0.

Whoop did not provide any information on how the data from the new blood oxygen and temperature sensors would directly affect the accuracy of its wellness recommendations, but the company did tell us that there are more sensors, “five LEDs (three green, one red and an infrared “)), four photodiodes and advanced algorithms for even more accurate heart rate measurements.”

Blood oxygen and body temperature readings, taken together and separately, can also be helpful in assessing your sleep pattern and physical stress. Whoop uses these two areas to report their recovery and “stress” levels, which tell athletes when their body is best prepared for training (and at what intensity level). That workout feedback has long been Whoop’s priority, and it’s a feature Fitbit only recently introduced with the Charge 5.

The Whoop 4.0 collects data in order to inform the wellness recommendations displayed in the Whoop app. The recommendations focus on three main areas: sleep, recovery, and exercise. Metrics like your breathing rate, calories burned, heart rate variability, resting heart rate, and sleep performance all feed into separate recovery and stress ratings, according to the company’s website.

Sleep tracking uses phases, disturbances, efficiency and breathing rate to assess sleep quality. Taking into account each night’s sleep quality, Whoop rates overall sleep trends in terms of duration and consistency to get a more complete picture of sleep quality. Sleep data are included in the stress and recovery values, but stress can also serve as a guide to sleep by recommending more sleep on days with high stress, for example.


The app also tracks your “sleep guilt”, although the concept of correcting this imbalance is not as straightforward as catching up on lost hours of sleep. Rather, studies show that it can take days or weeks of optimal sleep to recover from any “debt”. Therefore, it is best to use the “sleep guilt” info as a general marker of sleep quality.

The company also launched a new metrics dashboard called Health Monitor, which gathers your live heart rate, skin temperature, blood oxygen, resting heart rate, and heart rate variability (i.e. the intervals between your heartbeats) on one screen. As with Apple Health, Fitbit Premium, Google Fit and Garmin Connect, you can export your wellness trends and present them to a doctor.

New ways to wear whoop and discounts for “professionals”

In addition to the Whoop Strap 4.0, Whoop is launching a clothing line called Whoop Body. The clothing line includes bras, underwear, shirts and leggings with pockets for the device. The collection is an extension of previous offerings that is limited to bracelets and sleeves. Whoop says a “novel location technology” will identify the whoop’s position on the body.

Whoop is also introducing a membership add-on called Whoop Pro. The $ 12 monthly upgrade (paid on top of regular subscription) gives subscribers free shipping, 20 percent off all items, early access to feature releases, and a free item every three months. This bonus item can be a free wrist or bracelet, batteries, sleeves or whoop body clothing.

The Whoop Strap 4.0 and Whoop Body are now available on the Whoop website. Membership is available for six, 12, or 18 months for $ 30, $ 24, and $ 18 per month, respectively. Current Whoop subscribers with a remaining membership of at least six months are automatically entitled to a free Whoop Strap 4.0. Members whose membership remains for less than six months must extend their term. Orders will be shipped the week of September 27th.

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