In the past week, a few companies with wristworn activity tracking devices, Withings, Xiaomi, Jawbone, and Misfit, have announced new features or accessories for their trackers.

Last week, Jawbone announced that the UP4, which was first announced in April, is now available and shipping in the US from the company's website. The UP4, which costs $199, has an American Express NFC-enabled payment feature that enables users to make payments directly from the device, similar to Apple Pay. 

That same week, Jawbone also announced a partnership with recipe site Yummly. People who are members of both communities will be able to see the UP Food Score on every Yummly recipe, and, with a click, log meals from Yummly.com directly to the UP App. After a meal is logged from Yummly, users can adjust the day and time that they actually ate the meal.

Withings recently added automatic swim detection to its wristworn activity trackers, Activite and Activite Pop. The company announced Activite in June 2014 and Activite Pop, the less expensive version, in January. Both watches track all the same activities, including steps taken, swimming, and sleep, but the Activite Pop is made with a PVD-coated watchcase and a silicone strap while the Activite has a Swiss-made stainless steel watch case, sapphire scratch-proof glass, and French calf leather straps.

The watches, which are water-resistant to 50 meters, will now automatically detect when a user starts their swim workout and will display calories burned as well as total time of the swim once they finish.

Almost a year after first announcing its fitness device, the Mi Band, Xiaomi said it will update the device with a new feature -- heart rate tracking, according to a report over at Engadget. The new device with heart rate tracking, which will be called Mi Band 1S, will look similar to Xiaomi's current wristworn wearable. While the price for Xiaomi's updated device is not yet available, the Mi Band retails for $13, which is much less expensive than most activity trackers on the market. One of the closest contenders in the direct to consumer space, Fitbug, still charges $49.99 for its Orb device.

Recently, a report from research firm IDC found that Xiaomi was gaining on Fitbit in worldwide wearable marketshare, even though Xiaomi just started shipping devices during the second half of 2014. While Fitbit has a number of wristworn wearable offerings, the most recent additions include two devices that offer heart rate tracking, the Charge HR and Surge. With Xiaomi's heart rate tracking update, the Mi Band's feature set will be even more similar to Fitbit's.

About a month ago, Misfit announced that it's partnering with Coca-Cola and will.i.am to release another accessory for Misfit Shine, called the Ekocycle Field Band, which is a rugged wristband made of recycled material. This is not Misfit's first partnership with Coke. In the summer of 2014, Misfit introduced a Coca Cola Red Shine tracker. The soda company also integrated Shine into its wellness program for employees. Notably, Misfit co-founder John Sculley is a former CEO of Pepsi.