I just asked Claude to give me a list of records for male runners in different distances, to see how the curve would look like.

• 100m — 9.58s — Usain Bolt — 1:36/km
• 200m — 19.19s — Usain Bolt — 1:36/km
• 400m — 43.03s — Wayde van Niekerk — 1:48/km
• 800m — 1:40.91 — David Rudisha — 2:06/km
• 1500m — 3:26.00 — Hicham El Guerrouj — 2:17/km
• 3000m — 7:17.55 — Daniel Komen — 2:26/km
• 5000m — 12:35.36 — Joshua Cheptegei — 2:31/km
• 10,000m — 26:11.00 — Joshua Cheptegei — 2:37/km
• Half Marathon — 57:30 — Jacob Kiplimo — 2:43/km
• Marathon — 2:00:35 — Kelvin Kiptum — 2:51/km
• 50km — 2:40:13 — Thompson Magawana — 3:12/km
• 100km — 6:09:14 — Nao Kazami — 3:42/km
• 100 miles — 10:51:39 — Aleksandr Sorokin — 4:03/km

For women:

• 100m — 10.49s — Florence Griffith-Joyner — 1:45/km
• 200m — 21.34s — Florence Griffith-Joyner — 1:47/km
• 400m — 47.60s — Marita Koch — 1:59/km
• 800m — 1:53.28 — Jarmila Kratochvílová — 2:22/km
• 1500m — 3:49.04 — Faith Kipyegon — 2:33/km
• 3000m — 8:06.11 — Wang Junxia — 2:42/km
• 5000m — 14:05.20 — Faith Kipyegon — 2:49/km
• 10,000m — 28:54.14 — Almaz Ayana — 2:53/km
• Half Marathon — 1:02:52 — Letesenbet Gidey — 2:59/km
• Marathon — 2:09:56 — Ruth Chepngetich — 3:05/km
• 50km — 3:07:20 — Alyson Dixon — 3:45/km
• 100km — 6:33:11 — Tomoe Abe — 3:56/km
• 100 miles — 12:42:40 — Camille Herron — 4:44/km

The pattern is the same: speed falls down logarithmically with distance.

For recreational runners that finish the distance, the curve looks much flatter in the middle:

• 5k — ~30-35 min — ~6:30/km
• 10k — ~60-65 min — ~6:15/km
• Half Marathon — ~2:05-2:10 — ~6:00/km
• Marathon — ~4:20-4:30 — ~6:15/km
• 50km — ~6:00-6:30 — ~7:30/km
• 100km — ~12:00-13:00 — ~7:30/km
• 100 miles — ~26:00-30:00 — ~10:00/km