Yomif Kejelcha breaks half marathon world record wearing two fitness trackers

Yomif Kejelcha has smashed the half marathon world record with a 56:51 run in Buenos Aires, and he did it wearing a fitness tracker on each wrist.

Kejelcha won the Media Maratón Ciudad de Buenos Aires on Sunday, August 23, taking 29 seconds off the 57:20 mark Jacob Kiplimo ran in Lisbon earlier this year. The new record is still subject to the usual World Athletics ratification process, but it makes Kejelcha the first man to go below 57 minutes in record-eligible conditions.

It was not exactly a cautious race either. Kejelcha initially planned to run at around 2:45 per kilometre, but gradually picked things up before reaching 15km in about 40:41 and 20km in 54:04. World Athletics’ race report also specifically notes that Kejelcha was checking his watch regularly as he started increasing the pace.

Two devices, two different jobs

Footage from Buenos Aires show Kejelcha once again racing with two wearables. On his left wrist is what appears to be the Amazfit Cheetah 2 Pro, while his right wrist appears to carry a Whoop MG.

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That is a new combination for him. Kejelcha used the Whoop along with Coros Pace 3 at the London Marathon earlier this year.

At first glance, running a half marathon with a tracker on each wrist might seem unnecessary. In reality, the two devices potentially serve very different purposes.

A running watch such as the Amazfit can provide something Kejelcha clearly used during the race: information he can actually see. Pace, elapsed time, distance and lap data can all sit directly on the wrist, which becomes rather useful when you are trying to average roughly 2:41 per kilometre for an entire half marathon.

WHOOP takes almost the opposite approach. It has no display and is designed around continuous physiological tracking, strain, sleep and recovery rather than giving a runner a screen full of live race metrics.

That combination actually makes quite a lot of sense. One device can handle the immediate job of pacing and recording the run, while the other continues collecting the data that feeds into longer-term recovery and training analysis.

A pretty good advert for keeping things simple

A pretty good advert for specialised gear

There is another interesting part to all of this. Kejelcha was not racing with some enormous top-end adventure watch packed with every possible feature, but with a purpose-built running watch alongside a screenless tracker.

The Cheetah 2 Pro is very much aimed at runners, with dual-band GPS, offline maps and training metrics rather than the bulk and outdoor extras found on larger multisport watches. Pairing it with what appears to be a WHOOP also suggests Kejelcha prefers separate devices for separate jobs, one for live race information and another for continuous physiological tracking.

We saw much the same thing in our look at the watches used by the leading runners at the 2026 London Marathon. Several of the fastest athletes in the world were racing with relatively straightforward running watches rather than the biggest flagship models.

Whatever Kejelcha was getting from the two devices, the setup certainly did not get in his way. He averaged roughly 2:41 per kilometre across 21.1km and crossed the line in 56:51, becoming the first man to officially break 57 minutes and putting the half marathon world record back in his hands.