Whoop has announced the latest iteration in its fitness tracker line, the Whoop 4.0.

As ever, the company's focus is very much on logging the wearer's activity strain and providing recovery recommendations, though the subscription-based tracker is now able to be placed around the body through Whoop's own line of clothing - Whoop Body - as well as the wrist.

And though the latest generation's flexibility in placement is an interesting addition, there's actually plenty of significant change within the tracker itself. 

In what appears to be a bid to remedy some of the heart rate accuracy issues that plagued the Whoop Strap 3.0, there are now five LEDs on the underside's array - three green, one red and one infrared - as opposed to just two green sensors.

Within that, skin temperature and blood oxygen will now be tracked, too, as well as continuous heart tracking, which continues to factor in resting heart rate, heart rate variability and respiratory rate.

There's an all-new battery design, as well. Whoop says that the 4.0 tracker is the first product in the world to use Sila's new silicon anode battery, which should provide longer cycle life and a higher energy density. It's also now waterproof, and, despite being 33% smaller, can still achieve the same five-day life as previous models.

As we've seen with some Fitbit trackers, Whoop 4.0 will be able to monitor user's sleep and provide users with haptic alerts during the optimal wake time.

So, what of the ability to place the tracker elsewhere on the body?

Whoop 4.0 will track your activity and recovery from your wrist and your clothes photo 2
Whoop

Well, debuting alongside Whoop 4.0 is Whoop Body, which is essentially bespoke exercise apparel for the device.

The 'Training Collection' comprises sports bras, compression tops, leggings, shorts, and athletic boxers, while the 'Intimates Collection' includes bralettes and everyday boxers.

Through what the company called Any-Wear Detection, the tracker is able to identify if the tracker is working from the torso, waist, calf or wrist.

The introduction of Whoop Body may be seen as a slightly cynical move into smart clothing, but it also makes a lot of sense on paper, seeing as though wrist-based trackers aren't always convenient and the most accurate place for an optical-based tracker to sit. 

Given our own issues with the accuracy of Whoop Strap 3.0, as well, and the new features to the tracker's core should finally help the tech match up the comprehensive and excellent app experience. 

We'll be testing the Whoop 4.0 over the next few weeks, so stick around for our full review. And if you're interested in picking one up, know that the 4.0 comes included with a Whoop membership, which runs as low as $18 per month.