I factor in the level of competition on the day, the level of competition that's attempted the world or course record at any point in history, weather (where applicable, like at Western States where it can vary significantly) and knowledge of the tactics and skill used to get such a great performance. I was lucky enough to see some of these performances in person or at least meet most of the runners mentioned below.
I include only one performance per race, unless the race has more than one format or direction (like Comrades with its Up and Down runs or the clockwise/anti-clockwise directions at Hardrock 100). Also, how well these records stand the test of time is important, so a very well-challenged record from longer ago is deemed to be especially impressive.
I also work off the assumption that if a runner hasn't been caught doping then their results are legitimate, since unfounded accusations are spiteful. Anyone who is a confirmed doper is not part of this list (that I'm aware of).
No photo available of Tomoe Abe - anyone got one?
1. Tomoe Abe, Japan - 100k World Record at Lake Saroma, Japan (6:33:11, 2000)
She set the fastest 100k time for women by a long margin (nobody else has broken 7hrs and Ann Trason is one of the closest with a 7:00:47 best). I've heard that this record was set with a tailwind, but it's still so far ahead of any of the other road or track marks set by women at any ultra distance that it really stands out. To give an idea of Abe's caliber, she won the bronze medal in the marathon at the 1993 World Championships and her personal best time is 2:26:09. In addition, she ran a 2:28:01 in the same year as her 100k record and a 2:27:01 the following year so was very much at her peak at that point. This is equivalent to 5:16 for 50 miles (compared to the 5:40 world record by Ann Trason), or even quicker if she slowed towards the end of the 100k. Also, this record is surprisingly close to the men's record by Don Ritchie of 6:10:20 (number five on the top 10 all time ultra men's list).
|Frith van der Merle. Photo: Sport.co.za|
van der Merwe destroyed the Comrades down run record in 1989 and nobody's come very close since, with just two other women breaking 6hrs - Ann Trason with a 5:58:24 in 1997 and Tatyana Zhirkova with 5:58:50 in 2005. van der Merwe's average pace was 6:23/mile, working out as around 5:19:30 through 50 miles with hills. The down run is usually won in a time around 6:10:00 and the record looks safe for the moment.
However, the up run course record of 6:09:24 (Elena Nurgalieva, 2006) isn't quite as comparably fast and doesn't make the top 10 list. It's 15 mins off the down run record while the men's up run record is only four minutes slower than the down run record (see the top 10 all time ultra men's list).
|Rory Bosio. Photo: Tim Kemple|
The top ranked trail performance is by Rory Bosio, who decimated the Ultra-Trail du Mont Blanc field two years in a row (2013 and 2014 wins), taking over two hours off the course record and finishing seventh overall in 22:37:26, well ahead of the female competition. On top of that she made it look easy, smiling and playing in the mountains throughout the race. This is arguably the most competitive trail ultra in the world and Rory was so dominant that this could easily have been number one in the list.
|Ann Trason. Photo: Running Times|
No woman dominated ultra running like Ann Trason. 14 wins at Western States 100, including the former course record, plus wins at Comrades, the 100k World Cup and just about every major ultra you can think of in the 1990s. She also holds American and World Records at numerous distances, most of which still stand today. She generally raced the men since no women could keep up with her and the fact she has several spots in this top 10 reflects that her times are just as competitive today.
However, I judge the top-rated performance of her career as her Grand Slam of Ultra Running record, the combined time for the Western States 100, Vermont Trail 100, Leadville Trail 100 and Wasatch Front 100, all over one summer in a period of 10-11 weeks. The next best female time was nine hours back by Krissy Moehl! Ann was the female winner in each of those races, which wasn't unexpected for such a talented runner, but it speaks to her ability to not just perform well for a single target race but to manage so many other factors within ultra running to stay strong and fast through each of these races. If there was an award for the best female ultra runner of all time, it would be hard to argue against Ann as the clear winner, especially with her breadth of dominance.
|Anna Frost. Photo: irunfar.com|
Anna's had numerous spectacular performances and is undoubtedly one of the best female mountain runners of all time. Her course record at the hyper competitive Transvulcania ultra on the island of La Palma in the Canary Islands is something that stands out. When Anna's on top form she's like a steam train uphill and most of the very fastest mountain women of the modern era have tackled this course and not come close to this time. Only Anna herself (8:11:31 in 2012) and Skyrunning star, Emelie Forsberg (8:13:22 in 2013), have come close to this performance.
|Ellie Greenwood. Photo: irunfar|
When someone breaks the record by a large margin at the oldest 100-mile trail race in the world and the former record was the result of 14 wins by Ann Trason, you know it's a special performance. Yes, the weather was very mild and that made it quicker, but it was 50 mins faster than Ann's best. It may take another colder year and a group of the quickest women ever in the world to break this record. Several of the other women in this list have tried, many on more than one occasion, but Ann and Ellie are the only women to break 18hrs.
|Nicole Studer. Photo: Jason Bryant|
The 100 mile record for trails has been less tested by the quickest women in history, but is still a very solid mark. Nicole took 35 mins off the course record at Rocky Raccoon 100 in a mind-blowing performance and took 20 mins off the existing world trail best from Tunnel Hill 100, a flatter course that's arguably easier. Nicole started fast and held on for an astounding win that doubled as the USATF National Championship and not far off the 100 mile record for any type of terrain, which stands at 13:47:41 by (you guessed it) Ann Trason, dating back to 1991.
8. Ann Trason, USA - Leadville Trail 100 Record (18:06:24, 1994)
Ann's Western States wins were clearly excellent, as were many of her road and track records, but her 1994 winning time at Leadville is far ahead of any other woman at that race. The high altitude course sits between 9,200ft and 12,600ft, with around 15,000ft of vertical gain and the same descent. It includes a lot of fast, flat running but that altitude slows it significantly and many fast women have raced it, with only a handful breaking 20hrs.
Stick with me for a minute here for some back of the cigarette packet calculations...Using my own rough comparison of the Western States 100 and Leadville Trail 100 courses (from running both numerous times) I'd estimate that the male course record times (14:46 for WS100 and 15:42 for LT100) are roughly equivalent in terms of difficulty, giving the nod to Matt Carpenter's LT100 as being marginally more impressive. So I think of them as having a one hour difference for that pace, meaning around 1:10 at Ann's pace, i.e. her 18:06 at LT100 is equivalent to a sub 17hr WS100. So, pretty damned quick, then.
9. Ann Trason, USA - American River 50 Record (6:09:08, 1993)
You could pick any number of Ann's records as being amongst the best runs in the world, but the only other one I choose for the top 10 is her American River 50 record from 1993 - a race that's been competitive since it's inception in 1980. That older course was quicker than the current course and involved about 50% bike path and 50% rolling trail, but this is a record that's been tested over the years, not least by Ann herself within her five wins. The only other woman under 6:30 is Ellie Greenwood, who's career mimics many of the elements and highlights of Ann's.
10. Anna Frost, New Zealand - The North Face Endurance Challenge 50 San Francisco Record (6:56:07, 2011)
Anna's second appearance in the top 10 is at the season-ending TNFEC50 in the Marin Headlands. The large prize purse and reputation of the race means it's always got a deep field and the aggressive running for the men's record by Zach Miller from 2015 was also spectacular, narrowly missing out on inclusion in the men's top 10. It's often muddy and the rolling hills add up to around 10,000ft of vertical gain, so sub-7hrs is extremely fast and involves beating the quickest women in the world on runnable, hilly trails. In comparison, the similarly difficult Lake Sonoma 50, which also attracts a stellar field and has 10,000ft of vert, has a female course record of 7:08:23 by Steph Howe, which narrowly missed a place in this top 10.