Looking back at Rio 2016, how great was Wayde van Niekerks win in the 400m sprint? Not only running the fastest time ever but doing it from lane 8? How much more extraordinary is the feat seeing as it came from such a lane?
It's difficult to quantify the effect of lane placement in the 200m and 400m (the sprint races which require running bends) because there are competing factors in place. A victory from lane 8, like Van Niekirk's, is indeed extraordinary, but that race was perhaps more extraordinary because he broke a longstanding world record, without apparently planning to do so, and dominated a high-quality field. (That is, the run would have been extraordinary regardless of the assigned lane.)
The bare differences between the lanes are twofold:
- First, because the bends cause a full lap in each lane to be different lengths (i.e. finish-to-finish in lane 2 is longer than lane 1), the 200m and 400m are run with a staggered start (i.e. outer lanes start farther up the track in order to run the same distance). This means until the race reaches the final homestretch, and the stagger is "unwound", runners in inner lanes can see runners outside them without turning their head very much.
- Second, the geometry of the track means the turn on inner lanes are sharper than those in outer lanes. This means the physiology and running mechanics of taking the bend is slightly different for runners in each lane. (The difference is magnified on 200m indoor tracks, which is partly why many such tracks are banked.)
The first difference is generally considered to be an advantage to the runner on the inside, i.e. lane 1 has the most advantage and lane 8 the least. This is generally why people consider Van Niekerk's lane draw remarkable.
The second difference, on the other hand, is mixed. The inner-most lanes (1, 2, and sometimes 3) are considered technically more difficult than the outer lanes, which have gentler turns; the wider sweep of the outer lanes means an athlete can put more energy into moving forward instead of turning their momentum. Individual runners' physiology and form can mitigate this problem; for example, Usain Bolt's long stride would theoretically be hampered by the inside lanes, but Bolt has also compensated for this by apparently developing very good form for the curve. So in theory the inside lane is disadvantaged and the outside advantaged by this, but in practice it varies. (This is why tracks with a full 9 lanes will run sprint races in 2-9 rather than 1-8.)
(This, incidentally, is also why 4x100m relay teams sometimes put their fastest runners on the 1st or 3rd legs rather than the last, "anchor" leg - because starting from the blocks and running the bends are very specialized skills, and teams can pick up some advantage by putting runners who excel at those skills on those legs rather than on the anchor.)
So with Van Niekerk as one "exceptional" lane 8 runner, it's worth also remembering two similarly exceptional lane 1 runners: both Angelo Taylor and John Akii-Bua won gold medals in the 400m hurdles from lane 1, with Akii-Bua, like Van Niekerk, setting a world record.
Regardless of lane, however, it's clear that Van Niekerk is an extraordinary talent with excellent coaching and support to enable such a run. If the 2016 gold-medal run is not the peak of his career, I can't imagine what he will do to top it.
I wouldn't call it that unlikely because you are still running the same distance. But 2 things that work against you is that 1) You were probably in lane 8 because you were the slowest person that qualified for the final race and 2) You aren't really chasing anyone so you have to be able to run all out as soon as the starting gun fires.