What Yomif Kejelcha Wore On His Wrists As He Set A New World Record

Yomif Kejelcha ran the fastest half-marathon anyone has managed in record-eligible conditions on Sunday, wearing an Amazfit Cheetah 2 Pro on his left wrist and a Whoop MG on his right, and only one of the two could tell him anything while he ran.

The Ethiopian ran 56:51 at the Media Maratón Ciudad de Buenos Aires, a World Athletics label road race in the Argentine capital, taking 29 seconds off Jacob Kiplimo’s 57:20. Neither mark has been ratified. Kiplimo also ran 56:42 in Barcelona last year, nine seconds quicker than Sunday, in a race whose conditions did not fully comply with World Athletics rules.

The watch on his left wrist is Amazfit’s top running model. The Cheetah 2 Pro is built on a Grade 5 titanium frame under sapphire glass, weighs 45.6 grams without its strap, and carries a 1.32-inch AMOLED display that runs to 3,000 nits, which is what matters when a runner needs to read a split in daylight. It uses dual-band positioning across six satellite systems, holds about 31 hours of accurate GPS tracking, stores offline topographic maps, and reports running power and a lactate threshold estimate. It is also 15.6mm thick, which reviewers have called its main flaw.

The band on his right wrist does none of that. The Whoop MG has no display at all, so it could not show him a pace, a split or an elapsed time at any point in the 21.1K. What it does instead is record: heart rate and the physiological data built on it, sampled 26 times a second, on a screenless band that runs four days between charges and takes a medical-grade ECG when a wearer pinches its clasp.

The Pairing Is New

Kejelcha has not raced this combination before. He ran his sub-two-hour London Marathon debut in April on a Coros Pace 3. That watch weighs 30 grams and sold for less than half the Amazfit’s price. Gadgets & Wearables, which was first to identify what he wore in Buenos Aires, found much the same pattern across the London field in April: the fastest marathoners in the world mostly raced in ordinary running watches rather than the largest multisport flagships.

What It Costs

The Cheetah 2 Pro went on sale April 16 at $449.99, presented alongside Rory Linkletter, an Amazfit ambassador. The Whoop is not sold as hardware at all. It comes with a membership, and the tier carrying the MG’s medical-grade heart screening costs $359 a year. Amazfit’s named runners include Grant Fisher and Morgan Pearson as well as Linkletter, and no public agreement between Kejelcha and either brand could be found.

What he did with the numbers he could read was his own call. He had said before the race that he wanted to run inside 58 minutes, and his two pacemakers were briefed to hold 2:45 per kilometer. His 5K splits were 13:45, 13:34, 13:22 and 13:23, which put him through 20K in 54:04. The last full kilometer took 2:32, or 4:04 mile pace, and the 97.5 meters remaining after it took the other 15 seconds. His average for the distance was 2:42 per kilometer. “I had planned to run conservatively over the early stages, but I felt good and decided to give it my all,” he told World Athletics afterward.

Kejelcha returns to the marathon in Valencia on Dec. 6, a race he spent two years being recruited for, and Fotyen Tesfay, who won the women’s race in Buenos Aires, is in that field too.