Whoop's new fitness tracker integrates with clothing - so users can wear a watch, again! Thank you for reading 5 articles this month* Join now for unlimited access

Whoop - the app which tracks fitness, recovery and health metrics - has unveiled its latest piece of hardware, which is smaller and has an upgraded sensor allowing it to be worn inside clothing.

Up until now, Whoop users have always given themselves away with the characteristic watch strap. However, whilst Whoop 4.0 can be worn on the wrist, it can also be tucked inside clothing against the torso, waist and calf.

Unlike many smartwatches, the Whoop strap doesn't display a clock face, so this will be music to the ears of those users who miss carrying the time on their wrist.

Whoop has released a range of clothing, including sports bras, compression tops, legging, shorts, and athletic boxers while the Intimates Collection includes bralettes and everyday boxers.

Moving the sensor from the wrist to other areas of the body is made possible via the use of an updated sensor, which is configured to provide more accurate heart rate measurements. The Whoop 4.0 is also 33 percent smaller than the outgoing 3.0, and comes with five day battery life.

Whoop hardware works alongside an app, which gives users a ‘recovery’ rating that can guide athletes in choosing or altering training for the day.

New features include a ‘sleep coach’ with alerts that will wake them via gentle vibrations, at the “optimum tome”, a pulse oximeter to calculate blood oxygen levels - something the Garmin Fenix 6 also does, though we didn't use the feature much - and a skin temperature sensor.

Whoop’s Founder and CEO, though arguably a little biased, says he can “promise that this is the most innovative product we have ever released.”

Will Ahmed added: “We’ve always aspired to develop wearable technology that is either cool or invisible. With the launch of Whoop 4.0 and Whoop Body, we have accomplished both.”

Membership to the Whoop app starts at £18. The hardware is free with membership.

Whoop users include EF Pro Cycling, and Cams-Basso rider and two-time National time trial champion Hayley Simmons.

Olympic gold medalist Tom Daley is also a user, commenting on the new release, he said: “I’ve been a Whoop member for almost four years and I’m excited for Whoop 4.0 with its smaller size and updated style. To be able to slide the band on and off makes it easier to customise which band you want to use.

"If you’re going out you may want to wear something smart, or when you’re training you may want something that’s more practical. I am super excited about Whoop Body. You can just slip the 4.0 device into your boxers and you’ll get all the same data and information. I think that’s something that’s going to be very useful.”