By Andrew Mooney, Boston.com Correspondent

The 2008 Summer Olympics in Beijing were remarkable for many reasons—the opening ceremonies, the human rights controversies, the Redeem Team—but the signature moments many Americans will remember came in the Water Cube, during the swimming events. Who could forget Michael Phelps out-touching Milorad Cavic by 0.01 seconds in the 100m butterfly, or Jason Lezak’s heroic charge in the 4x100m freestyle relay to overtake France’s Alain Bernard and keep Phelps’ pursuit of eight gold medals alive?

Of course, the asterisk with which those events will be tagged by history was the technology: the polyurethane Speedo LZR Racer suit. The space-age, NASA wind tunnel-tested garment increased buoyancy and allowed its wearer to glide through the water with significantly diminished drag. With a life span of only a dozen races and a small army of assistants needed to even put it on, the suit certainly didn’t seem like just a piece of clothing, and the performance it generated in the pool reinforced that impression. A combined 140 world records fell at the hands of swimmers wearing the new suits between February 2008 and July 2009. Finally, in January 2010, the international swimming federation FINA prohibited the wearing of non-textile suits like the LZR and its successor, the Arena X-Glide, in competition.

The results of the suits still stand, however, in the world records they produced. So just how much did they contribute to the swimmers’ successes over this two-year period? I set out to find the answer by isolating the effects of the suit and analyzing the distortions they created on record swimming times.

To start, I examined the progression of world record times in men’s swimming from the last 50 years—a more modern era of swimming, which includes the introduction of the flip turn and half body suits for men—and looked at how frequently, and by how much, world records fell over time. I focused on the freestyle, a stroke that has remained mostly consistent stylistically over this time span, in five different distances: the 50m, 100m, 200m, 400m, and 800m. As an example, here's the world record progression for the last 20 years of the 200m, which is pretty typical of the general trend.

The rate at which the world record times fell was remarkably consistent across the five events. Since 1962, all five world records dropped at between 0.26 and 0.36 percent per year, which I treated as the baseline rate at which all swimming times improve, due to average advances in technique, athletic development, pool design, etc. One way to separate the effects of the polyurethane suits, then, is to compare the rate at which world records fell in 2008-09 to the average up to that time for each event.

As shown by the table, world record times for most of the events fell at a rate about two to five times greater than the average, with the exception of the 400m, which was curiously immune to the effects of the polyurethane suits. This last example says less about the effects of the swimsuit than it does about the greatness of Australian swimmer Ian Thorpe, the previous world record holder in the 400m. At this distance, the Thorpedo was a Speedo LZR unto himself, carving 3.7 seconds (1.7 percent) off the world record time between 1999 and 2002, during which he broke his own world record four separate times. It’s surprising that any equipment, outside of a speedboat, could allow someone to better Thorpe’s time.

Overall, the world records fell by, on average, 1.06 percent in excess of the average rate during the two-year polyurethane reign, which I believe to be mostly attributable to the change in equipment. This, then, is the magnitude of the swimsuits' effects; a one percent drop in time may mean only one or two seconds, but that can be the difference between a very good race and a world record time. If the progression of records resumes its average rate after the ban on polyurethane suits, many of these won’t fall for another five or ten years. Only two world records have been set in men’s swimming since January 2010: the 1500m freestyle, a distance event in which the effects of the suit aren’t as pronounced, and the 200m individual medley, set by Ryan Lochte, perhaps the candidate most likely to produce a record-setting time. I limited my analysis to freestyle, but, as this summary of the 2009 world championships shows, the fact that so many records in other events were broken with the use of these suits suggests that the pattern is fairly uniform.

While the swimsuit may be the most obvious explanation for this spate of world records, a couple other factors might introduce error into my estimates. The first is the evolution of swimming pools over the last half-century, the designs of which have worked to reduce drag on swimmers, with changes in depth, width, and the effects of currents—certainly a contributing factor in the drop in times, though it’s difficult to say to what degree. However, I think the effect of pool improvements, which have come steadily over the past fifty years, would be mostly accounted for by the average rate of world record progression.

The other is that, by dealing with the progression of world record times rather than average times, I've allowed the possibility of the distorting influence of outliers to creep into the analysis. It could be that a few special athletes swam incredible times, independent of their equipment, and the presence of the suits merely disguised this fact. But the rise of relatively unheralded swimmers, like German Paul Biedermann, who bested Thorpe’s record in the 400m by 0.01 seconds in 2009, leads me to believe the suits deserve most of the credit for the flood of record times. As Biedermann himself admitted, the suit was "worth about two seconds" to his times.

In London, I anticipate that we’ll see swimming times more like those at the FINA World Championships in 2011 than at the Olympics in Beijing: impressive, but not record-breaking. Still, the accomplishment of a gold-medal winning race shouldn’t be reduced just because it isn’t done in a historic time. At least now we know that, equipment-wise, the playing field is a little more level, and the champions have achieved their status without rocket fuel in their suits.