Jack Rosenfeld
ID 248392
Born : 1979 Cat. M45 Ultrarunner since 2010 USA
35
DUV-index ?Largest integer N such that the runner has at least N credited races of at least N km.
50
DUV-index+ ?Largest integer N such that the race distances provide at least N complete segments of N km in total. A single long race may therefore contribute several segments. See the DUV-Index tab for the detailed calculation. calculation details
1
Countries visited ?USAUnited States
42,2%
Rank quotient ?This runner's calculation uses 35 eligible race(s): Σ(rank − 1) = 2 241; Σ finishers = 5 315. 2 241 / 5 315 × 100 = 42.16%. A win adds 0 to the numerator. Lower is better.

Totals

Ultras completed35
Km — ultra races3 163 km
> 100 km6
> 160 km6
> 200 km3
> 24h2
> 48h1
Longest race321,9 km
2nd Cowboy 200 — 15/9/2023

Km per year (ultra races)

50
1 race
2022
628
3 races
2023
200
3 races
2024
405
2 races
2025
211
2 races
2026

Race types (share of distance)

Road9,4%
Trail90,6%

Wins & podiums (ultra)

🏆 Win0
🏆 Win M0
🏅 Top 30
🏅 Top 3 M1
Longest winning streak0
Current streak0

Records

50 km5h17'41100 km13h54'0050 mi8h13'2112 h66,10 km48 h172,33 km

HISTORY

35 race(s)
DateRacePerf.Rk
2026
13.05 4d USA16th Born to Run Ultra 4 days Marathon 160.934 km31
10.01 50km USA30th Bridle Trails Winter Running Festival 7:02:48 h40
2025
02.08 32h USA12th Hamster Endurance Runs 32 Hour Run 163.187 km9
14.05 4d USA15th Born to Run Ultra 4 days Marathon 241.401 km10
2024
14.12 50km USA13th Deception Pass 50 km 7:10:52 h170
27.10 50km USA14th Cougar Mountain Trail Run 7:41:04 h23
28.06 100km USA4th The Yeti 100 km Endurance Run-Washington 17:40:37 h36
2023
15.09 200mi USA2nd Cowboy 200 3d 09:58:41 h28
29.07 50mi USA17th Burning River 50 Mile Endurance Run 14:17:24 h187
12.04 4d USA13th Born to Run Ultra 4 days Marathon 225.308 km17
2022
17.09 50km USA5th Teanaway Country 50 Race 14:05:00 h57
2018
19.05 30mi USA8th Born to Run Ultra 30 Mile Marathon 5:47:46 h66
14.04 12h USA5th Cottontail 12 Hour Race 59.014 km8
2017
23.07 50km USA2nd West Seattle Beach Run - Summer Edition 5:57:50 h6
03.06 50mi USA15th Rainier to Ruston Rail-Trail 50 Mile Ultra 11:45:12 h36
20.05 30mi USA7th Born to Run Ultra 30 Mile Marathon 10:25:26 h126
2016
26.03 12h USACottontail 12 Hour Race 66.095 km4
2015
06.12 50km USA29th OTHTC High Desert 50K Ultra 6:25:18 h123
16.05 30mi USA5th Born to Run Ultra 30 Mile Marathon 5:07:56 h52
21.02 50mi USA2nd Antelope Canyon 50 Mile Race 11:36:17 h48
07.02 50km USA2nd Sean O'Brien 50 km Trail Race 7:20:28 h103
2014
30.12 48h USA30th Across the Years, 48h 172.328 km14
12.10 50km USA8th Whoo's In El Moro 50k Trail Races - Fall Edition 6:31:33 h52
13.09 50mi USA8th Headlands Hundred 50 Mile Endurance Run 13:31:29 h50
23.08 50km USA23rd Bulldog 50k Ultra Run 5:17:41 h37
17.05 100km USA4th Born to Run Ultra 100 km Marathon 17:20:15 h32
2013
24.08 50km USA22nd Bulldog 50k Ultra Run 5:51:59 h67
13.01 50mi USA33rd Avalon Benefit 50-Mile Run 8:19:05 h27
2012
17.11 50mi USA50th JFK 50 Mile 10:26:44 h517
19.05 100km USA2nd Born to Run Ultra 100 km Marathon 13:54:00 h8
07.04 50mi USA33rd American River 50 Mile Endurance Run 8:13:21 h77
2011
03.12 50mi USA5th Endurance Challenge - California Trail 50 Mile 10:02:50 h130
20.11 50km USA7th Santa Monica Mountains 50 km 5:46:30 h16
27.08 50km USA20th Bulldog 50k Ultra Run 6:01:18 h26
2010
27.11 40mi USA2nd Santa Barbara Red Rock 40 Mile 10:36:00 h43