How Alex Yee unlocked his 2:06 marathon breakthrough

At Sunday’s Valencia Marathon, just the second 42.2K of his career, Olympic triathlon champion Alex Yee delivered one of the fastest performances ever by a British athlete. The 27-year-old clocked a blistering two hours, six minutes and 38 seconds, making him Great Britain’s second-fastest marathoner of all time and slicing more than four minutes off his debut from London earlier this year (2:11:08). So what changed between London and Valencia? According to post-race data from COROS, the biggest difference wasn’t Yee’s fitness–it was his stride length.

London vs. Valencia

In his London debut, Yee’s race data (captured by his Coros Pace Pro) showed that fatigue affected his stride length first, and in the final 10 km of the race, his steps shortened considerably. His stride length, which hovered around 189 cm for the first 30 km, dropped to 177 cm between 30-40 km and continued to drop to 173 cm in the final two km. Because speed is directly impacted by stride length and cadence (stride frequency), Yee’s pace slowed significantly in the final stretch.

Through his 12-week Valencia training block, Yee focused on improving his stride length under fatigue, and the work paid off. In Sunday’s race, not only did his stride length not slip in the final 10K, it actually increased from his average of 189 cm to 192 cm. His cadence throughout the entire race was also consistently higher than in London.

Despite Valencia’s hot conditions, these changes had a major impact on his finishing time, which fell within 52 seconds of the COROS Race Predictor’s estimate of 2:05:46, based on Yee’s fitness. His pacing remained consistently within five seconds of his average of 3:01/km, and he covered the final 400m in 64 seconds (equalling his 5K pace).

Locked in to marathoning

After winning Olympic gold in Paris last summer, Yee immersed himself in marathon training to switch up his routine and look for different ways to improve. He’s now spent a year away from triathlon, although he continues to cycle for cross-training.

This training block, Yee used the Valencia Half-Marathon six weeks out as a fitness checkpoint and to familiarize himself with the course. During peak week, his mileage hit 170 km, on top of 250 km of cycling. One of his key marathon workouts, Coros reveals, was five by 5 km at race pace with 1 km steady recovery.

Olympic triathlon champ wants 2:07 marathon debut

Yee will now turn his focus back to triathlon in preparation for the L.A. 2028 Olympic Games.