Here's a thought provoking article from the Washington Post's Paul Farhi:
World records fell like the Amazon rain at the World Swimming Championships that ended last Sunday in Australia. Led by the indomitable Michael Phelps, who set five records, swimmers in Melbourne cruised to the best times ever in 11 events.
It's a remarkable outburst of history-making performances, but the fact is, world records in swimming tend not to last long. Sixty percent of all the men's and women's world records on the books were set in just the past two years. The oldest men's swimming record has been around for barely seven years.
This constant redefinition of athletic achievement stands in sharp contrast to track and field, another Olympic sport that, like swimming, involves individuals competing against an objective measure (a clock or a tape measure). Track and field performances have improved much more slowly in recent years. Fifteen of the 24 world records in men's track, for example, were established before 2000. And every record in the men's field events — long jump, shot put, etc. — has stood for more than a decade. Some haven't budged in 20 years.
How is it possible that Homo sapiens keeps getting better and better in one measurable physical activity but isn't improving all that much in another?
Some observers say swimmers are evolving so rapidly because training and coaching methods are improving. Swimming is a more technical sport than running, and even slight improvements in stroke technique or training regimes can make huge differences. Phelps' phenomenal performances, for example, came after he began more rigorous weight training.
It may also be that today's swimmers are simply better athletes than their peers of 10 or 20 years ago.
"Swimming is overcoming drag, so you have to have a certain body," says Jon Urbanchek, a former University of Michigan swim coach. " Fifty years ago, it was heavy and pear-shaped. Now it's V-shaped, broad-shouldered, no hips. Now we have better selection, better athletes in the sport."
Underlying this thesis are the relative participation rates of the two sports. Running is a global sport, practically universal, and has been for years. With such a maxed-out talent roster, as well as better methods for detecting illegal performance-enhancing drugs, it has become more difficult to set new track and field records, says Jon Entine, an American Enterprise Institute fellow who has written extensively about race, genetics and sports.
Swimming, on the other hand, still has plenty of room to grow. The sport requires facilities and specialized coaching that are still largely concentrated in a few swimming superpowers, such as the U.S. and Australia. However, "the 'universe' of competitive swimming is always increasing," points out Entine. "More and more countries, and people within those countries, have the opportunity to do it, meaning that better athletes are likely to emerge from this larger base."
Elite swimmers are also older than they were a generation ago, which means they are more experienced and possibly stronger, too. The average age of competitors in the national swimming championships in the late 1960s was around 16; in 2004, the average was 20.
"We're now coming to the realization," Stager says, "that if you can keep a top swimmer motivated after college, if he can keep training and invested in the sport longer, he will get faster."
The X factor in all this may be the psychology of record-breaking, says Jon Hendershott, an editor and historian at Track & Field News. As each new record is set, he says, it redefines what's possible. "Every great athlete believes they can run faster, jump higher, throw farther or swim faster than the people who came before them," Hendershott says.