Whoop 4.0: The fitness tracker that stops you from overdoing it

It has no screen, but it’s a smart piece of training kit that tracks effort and recovery

Whoop 4.0
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Price: €30
Where To Buy: join.whoop.com

If you haven't quite bought into the trend for wearable technology, the Whoop 4.0 might be slightly mystifying. It isn't trying to beat the Apple Watch or outdo Samsung's Watch 4. It doesn't bounce your notifications to your wrist, or track your running route with GPS. It doesn't even have a screen, although you can strap it to your wrist.

But the Whoop 4.0 is probably the smartest bit of training kit you should buy if you are trying to improve your athletic performance. The small sensor tracks your heart rate, your blood oxygen level, your skin temperature and your sleep, silently collecting data and shuffling it over to the app on your smartphone to be assessed.

Unlike a smartwatch, the Whoop 4.0 is part of a subscription service you pay for each month. You don’t buy the band; you pay a fee for the service to get all the insights into your health and athletic efforts, and the band comes for free.

And that’s what it is designed for: it is purely to track your athletic efforts and recovery, although Whoop has thrown in haptic alarms to wake you up in the morning.

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Whoop has made some improvements to the new version of its tracker. It is smaller than the 3.0, although it’s not as subtle as you might like, and it adds new sensors over the previous version, including the skin temperature one, which comes in handy in the ongoing pandemic.

The battery pack is wireless and now IP68 rated, so you can wear it to charge the band even when you are in the shower. There is no real need to take the band off, which is great as it is designed to be worn around the clock to get the most complete data about your activity and recovery levels. Keep it close, because replacements are neither cheap nor plentiful right now.

Using it is also straightforward. When you are about to start an activity, you can use the app to select your chosen sport, and let the band track your exertion. There are plenty of options, from the standard running, cycling, crossfit training, dance or diving to circus arts, manual labour, skating and even ice baths. As you wear the band for a few days, you unlock new insights including a strain coach that will let you know when you have reached the optimal effort for that activity. It’s quite clever, and gives you an idea of how hard you need to work to improve or maintain fitness, or recover from previous workouts.

You can also go back and add workouts afterwards if needed, and a journal option allows you to track Covid-19 symptoms, menstrual cycles and other factors that can affect your recovery and wellbeing.

The band seemed reasonably accurate on heart rate, tracking another wrist-based heart rate monitor closely on the same workouts, so there was no concerns over whether the Whoop overestimates heart rates.

The strain/recovery balance was an eye-opener. On days when the Whoop band recorded my recovery as less than optimal and recommended I take it down a notch for the day, sticking to the recommended strain target for activities meant I actually felt good by the end of the day instead of exhausted. Likewise on days where my strain target was set higher, I felt more able to take on harder workouts.

On the other hand, there were times when I felt I’d pushed myself more than the band had recorded, and seeing that strain bar remain below my target was a reality check. But the Whoop – and heart rate – doesn’t lie, I guess. It became a daily goal to get the blue bar to meet the strain target that the Whoop app laid out for me; ditto for the recovery target, which doesn’t just depend on sleep but also heart rate variability.

The detailed performance assessments are also helpful, giving you better insights into how you are performing and tracking your improvements over the weeks. You can export them too, to send to your doctor or other health professional.

The good When it comes to fitness insights, the Whoop 4.0 will provide you with the additional information you need to improve your fitness, or tell you when to dial it down to avoid injury. It is reasonably light and although not the most subtle of trackers, the Superknit bands are comfortable to wear for long periods of time. Silicon bands usually irritate my skin; there was no reaction from the Whoop, even though I wore it for days at a time.

The not so good Keep a close eye on that charger. The battery pack charges with a USB-C cable but lose the pack – I mislaid it a couple of times – and you won't be able to charge your device until a replacement arrives. Also, if you own a 3.0, the accessories are not compatible with the 4.0.

In saying that, battery life is good, so you can usually go several days without needing to charge.

The rest You don't have to wear the Whoop as a wrist band. You can strap it to your upper arm, or invest in some of Whoop's clothing, with sports bras, underwear and shorts that have pods to fit the sensor. That is handy if you already wear a smartwatch but want the strap to keep track of your exertion during your activities.

The verdict If you want insights into your athletic training, the Whoop 4.0 is a great tool that will help you hit your goals and hopefully avoid injuring yourself.

Ciara O'Brien

Ciara O'Brien

Ciara O'Brien is an Irish Times business and technology journalist