How fast was Emily Sisson’s American record? 2022 Chicago Marathon breakdown 

Emily Sisson made history on Sunday 9 October when she smashed the American women's marathon record at the Chicago Marathon.

Just five months after claiming the American half marathon record in a time of 1:07:11 at the 500Festival Mini-Marathon in Indianapolis, the 30-year-old Olympian put in a hugely impressive display to come home second in the Chicago Marathon in a time of 2:18:29, shaving a full 43 seconds off the previous US best set by Keira D’Amato in January 2022.

Sisson has long been identified as a top marathon prospect and it hasn’t taken long for her potential to turn into record-breaking results. The 2022 Chicago Marathon was only the third time she has raced the 42.195km format and she showed she is more than capable of mixing it with the best over the distance.

Sunday’s race saw her finish second to Kenya’s Ruth Chepngetich, who crossed the finish line in 2:14:18 - the second-fastest time in history and just 14 seconds slower than the world record.

And while Sisson's run was over four minutes down on that mark, she showed why she is one of the most exciting runners in US history by finishing in a time that puts her 22nd on the all-time list.

Sisson’s average pace per hour at the Chicago Marathon was 18.81 km/h which translates to an average pace per kilometre of 3 minutes and 12 seconds.

“I actually didn’t know what pace I was on the whole time,” Sisson admitted after the race. “I was just given instructions to go off my pacers and not think about time so I had no clue about what pace I was running until I think like a mile to go.

“A few people had told me to pick it up, so I knew I must be close to either breaking 2:20 or the American record, but I didn’t know which one. So when I crossed the finish line I was really surprised with the time and the pace. I’m just really, really happy.”

Emily Sisson’s American record vs. Keira D’Amato’s previous American record

The American women’s marathon record has changed hands twice this year, with D’Amato the first to break it when she finished in a time of 2:19:12 in January’s Houston Marathon. Before that, the record had stood for a full 15 years with Athens 2004 marathon bronze medallist Deena Kastor becoming the first American woman to post a sub-2:20 time when she crossed the line in 2:19:36 at the 2006 London Marathon.

On Sunday, Sisson set off on American record pace with her first 5k completed in 16:23, two seconds faster than D’Amato’s run in January.

From kilometres five to 10, Sisson slipped below D’Amato’s pace at the same stage, registering a time of 32:54 compared to D’Amato’s 32:45, and she continued to be just off the pace through 15km with a time of 49:17 compared to the 49:14 of D’Amato.

However, it was at the half-marathon point that Sisson really began to streak ahead. Her time of 1:09:26 was already 14 seconds up on D’Amato, with the lead extended by 25km as Sisson posted a time of 1:22:09 compared to D’Amato’s 1:22:35.

Sisson crossed the 30km mark in 1:38:37, some 37 seconds ahead of the pace of D’Amato, with the gap lowering at the 35km mark as she posted a split time of 1:55:10 to D’Amato’s 1:55:42.

However, Sisson’s split between 35km and 40km was the fastest of her race, as she reached the latter mark at 2:11:29 compared to D’Amato’s 2:12:08 while averaging 3:16 per km.

By the end of the race, a new American record of 2:18:29 had been set, 43 seconds faster than D’Amato’s January time of 2:19:12.

Emily Sisson's splits compared to Keira D'Amato's splits