He came in third place at the world championships in London, losing to two Americans, Justin Gatlin who took the gold and Chris Coleman who took the silver.

　　Bolt, still the world record holder, said this would be his last competition.

　　For more context about the Bolt effect, earlier I spoke with Christopher Clarey of "The New York Times" who joined me via Skype from London.

　　Chris, is it possible to overestimate the as a matter of impact of Usain Bolt on track and field and sports?

　　You know, he has been the face and the soul of the sport for almost a decade now, and it's extraordinary.

　　It really is. He has been the one global figure that they've had,

　　and also he's been pretty good news for the sport, instead of a lot of bad news. So, definitely, a seminal figure.

　　It's a bit like Michael Phelps is to swimming, or Tiger Woods as to golf.

　　When you think of track and field, you have that, you know, million watts smile and the guy doing the lightning bolt dance at the end of his races.

　　No, it's true. He and Phelps are a good comparison. I mean, they've just been the kings of their sports in the same period of time.

　　They kind of broke through in Beijing and dominated that Olympics at the same time. Very similar. Dominant figures, huge appetite for success, and really enduring.

　　You know, even if track and field -- as track and field had these sort of repeated, high-profile doping incidents,

　　Usain Bolt was able to just kind of glide above it all, winning match -- or meet after meet.

　　In a way, that's been maybe his greatest accomplishment in some way, greatest act he's pulled up in a sense that he's been able to really remain above that fray.

　　It's been quite a fray. A lot of scandals in track and field, a lot of credibility crises, and Bolt really has been able to stay above that.

　　There have been things that have affected him. He's lost a medal in the relay because one of his teammates was involved in a doping infraction.

　　There have been, you know, fellow Jamaicans who tested positive for banned substances as well, including Asafa Powell.

　　But Usain has never tested positive, never been sanctioned. So, that's a bit of good news for the sport.

　　Is there a reason he chose to retire now? I mean, you can see that his times have been slowing, and -- but this is a guy who loves the competition, who loves to get in there and win.

　　I mean, I don't think, at least in the interviews that I've read, I don't think he particularly likes to train and put the work in, but he does it because he loves to win.

　　I think that's it. I think that's -- you put your finger on it. I mean, he's had injury problems throughout his career.

　　He's got to come in to major championships for the last five years fighting injuries almost every time. So, I think he's tired of that.

　　And, really, I mean, he did a great documentary last year which was a lot of fun to watch called "I Am Bolt," and you can see him complaining about the training in almost every scene.

　　I mean, I think he really enjoys the competition, enjoys that magnetic moment when he's out there and the crowd is communing with him and racing and beating everybody.

　　But when it comes to the day-to-day drudgery of being a sprinter, I think he would be happy to leave that behind, and I think, also, he's really done all there is to do in this sport.

　　And this is a guy, when you look at him, he doesn't look like a sprinter that has been the archetype that we've had, especially in the 100 meters.

　　This short, super, stocky, muscular guys that explode out of the blocks. He's literally, at times a foot taller than his competition.

　　Yes, it's true. When he lines up to race and get in a set position, you can see he's already higher than everybody else even with his head down. He's a much taller person, about 6'5.

　　You look back in the past of track and field, Carl Lewis obviously wasn't as tall as Usain, but he was the same sort of -- same sort of lines.

　　You know, a tall -- a tall sprinter by those standards of that day.

　　And I think now what Bolt has really done is being able to combine the two of being a tall sprinter but he also has a very quick turnover,

　　able to explode off the track and really produce tremendous power in each of his strides.

　　And also, he has long strides so he's able to cover the whole race, 100 meters in about 41 strides whereas a lot of his competitors are 44, 45, 46.

　　So, that's all been a big factor and many will try to replicate it in the years to come.

　　Do you ever wonder what that world record time could have been in Beijing or other places where it almost seemed like in the last 10 meters,

　　he's looking up at the big screen, and he's almost coasting in?

　　I mean, there wasn't anybody just kind of breathing down his neck, and if he'd just given us that last extra 10 percent.

　　Yes, you're right. I mean, that was the first breakthrough globally at the Beijing Olympics when he did let up in the 100 when he got to the finish line.

　　But a year later in Berlin, when he set the world record that still exist, 9.58 seconds, he ran through the tape, and you saw what happened, a world record.

　　But he's been unable to touch, maybe nobody will touch for many, many years to come.

　　And he himself was quite young at the time, we figured he'd be able to go on, maybe get into the 9.4s, never did for a variety of reasons,

　　but he did run through the tape and that record is there to prove it.

　　All right. Christopher Clarey of "The New York Times," thanks so much for joining us. My pleasure. undefined