Size matters in running and swimming: some data


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It’s not just Usain Bolt — elite athletes have been getting bigger for the past century at a faster rate than the general population, according to researchers from Duke University in North Carolina. Yeah, I think we already knew that. But…

Futhermore, the researchers said, this pattern of growth can be predicted by the constructal theory, a Duke-inspired theory of design in nature that explains such diverse phenomena as river basin formation and the capillary structure of tree branches and roots. (

Apparently, the size of athletes illustrates some deep underlying truths about patterns in nature, as described in this Journal of Experimental Biology paper. Maybe, maybe not — it didn’t make a lot of sense to me. What I did find interesting was the data set they dug up for 100-metre world-record setters in swimming and running:

Specifically, while the average human has gained about 1.9 inches in height since 1900, Charles’ research showed that the fastest swimmers have grown 4.5 inches and the swiftest runners have grown 6.4 inches.

There’s been a lot of talk about how Usain Bolt’s otherworldly sprint times might be explained by the fact that he’s one of the first very tall men (6’5″, according to the JEP paper) to master sprinting. The second-tallest world-record holder is, not coincidentally, the second-fastest man, Asafa Powell, at 6’3″. This paper makes some interesting arguments about why this should be so, based on the scaling of horizontal and vertical forces in locomotion. It’s obvious to everyone why basketball players are almost all enormously tall — but the same forces appear to be in play, though less obviously, for runners and swimmers.

The authors also suggest that we may need to introduce size classifications, as in boxing and wrestling, to other sports. It’s an interesting idea — but I’m not sure that the genetic advantage of height is really any different from the genetic advantage of having a huge oxygen capacity or lots of fast-twitch muscle fibres.