You are right in that "strength" isn't the dominating factor for these events or why males go so much faster/farther but rather VO2 max and for peak athletes males normally maintain a good 10% lead due to biological factors.
The male vs female 100 meter:
9.58 vs 10.49 = female record is 9.5% longer to run
Male vs female 200 meter:
19.19 vs 21.34 = female record is 11.2% longer to run
Male vs female 50km
2:38:43 vs 2:59:54 = female record is 13.35% longer to run
The difference also doesn't really change once we start going really long either
6 hour: 98.5km vs 85km male ran 15% farther
12 hour: 177.410 vs 153.600 male 15.5% farther
24 hour: 319.614 vs 278.621 male 14.7% farther
48 hour: 485.099 vs 436.371 male 11.17% farther
6 days: 1045.519 vs 928.577 male 12.6% farther
https://en.wikipedia.org/wiki/Ultramarathon scroll down to the male vs female records.