How do lane assignments and starting spots work in track?

On Sunday night, South Africa's Wayde van Niekerk won the gold medal in the 400 meters with an astonishing world record run of 43.03 seconds. He took a whopping 0.15 seconds off Michael Johnson's record from 1999 in a stunning display of speed and strength. Perhaps most impressive of all: he did it from lane 8. No one had ever won a 400 title at the Olympic Games from the track's outermost lane.

For the casual track and field fan who watches track every four years when the Olympics come around, it might not seem like a big deal -- heck, it might not even make sense that runners are starting the 200 or 400 in different lanes. Here's a look at why athletes are starting races in a stagger and why van Niekerk's historic run might have even been aided by being in the eighth lane:

The answer to why races have staggered starts is simple: Math. If you're running in one of the outside lanes, you're running around a bigger oval -- the farther out you go, the longer you'd have to run if you were running a full lap. Races have staggered starts so that everyone is running the same distance.

Theory says that being in one of the middle lanes is the marquee position -- a runner will be able to chase his or her opponents down throughout the race, just like a dog race with a fake rabbit leading the hounds around a track.

When Michael Johnson ran to his 43.18 world record at the 1999 world championships, he was in lane 5. He had nearly caught up to the runner in lane 6 by the time he reached the second turn, then ate up the entire field around the turn before unleashing into a furious kick in the home stretch.

The lanes for the 400 on Sunday were drawn based on the semifinal results. Grenada's Kirani James and Team USA's LaShawn Merritt had the two fastest times from the semifinal, so were given lanes 6 and 5, respectively. Van Niekerk had only the fifth-fastest time, so ended up in the eighth lane.

The new world record holder wasn't thrilled about drawing lane 8, but he didn't dwell on it. "I don't think any athlete really wants to be in lane 8," van Niekerk told reporters after the race. "But the moment I had it, I knew it has its advantages and it has its disadvantages. You have the perfect opportunity to [go out there and run as hard as you can]."

That's exactly what van Niekerk did to defeat James and Merritt, who won silver and bronze, respectively. Van Niekerk ran hard from the opening gun, unaware of the athletes starting in a stagger behind him. He jumped out of his blocks like a bullet, running his first 100 in 10.8 seconds around the turn, per NBC announcer Ato Boldon -- then he really turned on the jets on the back stretch.

James and Merritt had the advantage of chasing van Niekerk while the South African had to run within himself. But van Niekerk flew during the second 100, running an absurd 9.8 seconds.

James and Merritt were clear of the runners they were staggered behind, but they couldn't catch up to van Niekerk, who had gone out in about 20.6 seconds. They would begin to reel him in around the turn, however.

At 100 meters to go, with the stagger finally even, James and Merritt had nearly pulled even with van Niekerk -- but it was the closest they would get. Van Niekerk powered away down the stretch, never trailing for any moment and running to a shocking world record.

While van Niekerk wasn't thrilled to be in lane 8, there were some advantages, too. First, he ran his race without a worry of anyone else's. He wasn't chasing anyone; he was simply running as hard as he could. Second, wider turns make for faster running. Van Niekerk had less time on the first turn because he started nearly halfway into it, and he had a more gradual turn to run around while the athletes on the inside lanes had a tighter turn to manage.

Lane 8 might not turn into the premiere lane, but van Niekerk's run should make it more desirable.

Starting in lanes makes a big difference for the athletes -- chaos would reign if lanes weren't assigned. The 400 is the longest event in which runners stay in the same lane for the entire race, but 800-meter races usually have a one turn stagger, meaning they'll run the first turn of the race in a lane before cutting into lane 1 on the back stretch. At the recent U.S. Olympic Trials, the 800 had a waterfall start, meaning all the athletes would start on the same line, but could cut in as soon as the gun went off. It wasn't necessarily fair.

Here's the start:

With five runners trying to get to the inside, someone is bound to get stuck on the outside.

The athletes who drew a starting spot on the outside of the line ended up running farther than those on the inside because they didn't have their own lane around the first turn.

That's why lanes are important -- they make the race as evenly matched as possible.

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Wayde Van Niekerk's coach is a great grandmother