Progress against the field
Sem Zonderwijk has gained 6:31 on the field from Amsterdam 2023 to Amsterdam 2026.
The clock says 21:29 faster, but the races themselves got 14:58 quicker for everyone.
341 days between Amsterdam 2023 and Amsterdam 2024 is the longest gap compared here, and the second race was 3:10 better than the field.
How this is worked out ⓘ
A finish time moves for two reasons: the athlete, and the race — its course, its floor, its day. For each pair of races in a row in one category, we take everyone who raced both and use the middle of how much they moved (the median) as "the race". Whatever is left is the athlete. Doubles are compared only when the same two people raced both, and told as the pair's; relays are left out. A pair with fewer than 15 athletes in common is not shown. The summary above covers Individual Pro · Men, the one raced most; every comparison is in the list below.
Every race
13 races · 11 events
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Maastricht19 Sep 2026Doubles Pro · Men1:00:5370/316Beat 78%
↑ 93 days after Stockholm 2026, with Joost Huisman 2:35 worse than the field Why ↓Close ↑
1:09 slower on the clock in a race that was 1:26 faster for everyone: 2:35 lost to the field.
The fieldCompare these two →1:26 faster This pair1:09 slower -
Stockholm18 Jun 2026Doubles Pro · Men59:44354/704Beat 50%
↑ 84 days after Mechelen 2026, with Joost Huisman 0:56 better than the field Slower on the clock, ahead of the field Why ↓Close ↑
0:36 slower on the clock, but the race was 1:32 slower for everyone, so this was 0:56 better than the field.
The fieldCompare these two →1:32 slower This pair0:36 slower -
Mechelen26 Mar 2026Doubles Pro · Men59:08 PB102/493Beat 79%
↑ 64 days after Amsterdam 2026, with Joost Huisman 0:16 worse than the field Faster on the clock, behind the field Why ↓Close ↑
0:27 faster on the clock looks better than it was: the race was 0:43 faster for everyone, which leaves this 0:16 behind the field.
The fieldCompare these two →0:43 faster This pair0:27 faster -
Amsterdam21 Jan 2026Doubles Pro · Men59:3511/94Beat 88%
↑ 124 days after Maastricht 2025, with Joost Huisman 1:41 worse than the field Faster on the clock, behind the field Why ↓Close ↑
2:30 faster on the clock looks better than it was: the race was 4:11 faster for everyone, which leaves this 1:41 behind the field.
The fieldCompare these two →4:11 faster This pair2:30 faster -
Amsterdam21 Jan 2026Individual Pro · Men1:12:09 PB89/243Beat 63%
↑ 54 days after Utrecht 2025 0:14 worse than the field Faster on the clock, behind the field Why ↓Close ↑
4:22 faster on the clock, yet the race was 4:36 faster for everyone, so 0:14 was lost on the field.
The fieldCompare these two →4:36 faster This athlete4:22 faster -
Utrecht28 Nov 2025Relay · Men57:0012/38Beat 68%
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Utrecht28 Nov 2025Individual Pro · Men1:16:3131/102Beat 70%
↑ 203 days after Heerenveen 2025 0:10 worse than the field Why ↓Close ↑
0:10 behind the field: 1:46 slower on the clock, against 1:36 slower for everyone.
The fieldCompare these two →1:36 slower This athlete1:46 slower -
Maastricht19 Sep 2025Doubles Pro · Men1:02:0523/131Beat 82%
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Heerenveen9 May 2025Individual Pro · Men1:14:4552/216Beat 76%
↑ 211 days after Amsterdam 2024 3:45 better than the field Why ↓Close ↑
8:21 faster on the clock, and the race was 4:36 faster for everyone, so 3:45 of it was this athlete.
The fieldCompare these two →4:36 faster This athlete8:21 faster -
Belgium5 Apr 2025Doubles Open · Men58:48 PB29/898Beat 97%
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Rotterdam27 Feb 2025Individual Open · Men1:09:42 PB34/600Beat 94%
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Amsterdam10 Oct 2024Individual Pro · Men1:23:0693/177Beat 48%
↑ 341 days after Amsterdam 2023 3:10 better than the field Why ↓Close ↑
10:32 faster on the clock, and the race was 7:22 faster for everyone, so 3:10 of it was this athlete.
The fieldCompare these two →7:22 faster This athlete10:32 faster -
Amsterdam4 Nov 2023Individual Pro · Men1:33:3870/102Beat 31%