PREVIEW-Olympics-Athletics-Spring effect: Athletics struggles with carbon footprint problem

LONDON, June 28 (Reuters) - When a sport has over a century of meticulous records and gold medals can be decided by a thousandth of a second, times matter, but carbon shoe technology has trampled all over that tradition and left fans unable to quantify what they are seeing.

In the early years of Nike’s carbon-planted, thick-soled Vaporfly revolution, most of the disquiet was about perceived inequality as some athletes had access to shoes that undoubtedly improved performance while others did not.

Predictably, most of the other major manufacturers have now come up with their own version of a carbon shoe, which, although seemingly levelling the playing field at the elite level at least, has now led to concern about how to get any historical perspective of performance.

On one side of the argument are those who see athletics as the purest of all Olympic sports - the simple challenge of who can run fastest over a variety of distances, or throw, leap and jump the furthest or highest.

Every person on the planet can relate to that at some level, which is why the men’s 100 metres, the four-yearly race to find “the fastest human on the planet”, remains the most-watched event at every Olympic Games.

To those purists, the concept of a “spring effect” shoe that is now widely accepted as making people run faster is against everything the sport has stood for for so long.

Conversely, some argue that shoe improvements are just the latest piece of progress, following a long line that includes the introduction of starting blocks, lightweight spikes and, most significant, synthetic tracks.

As equipment, training, nutrition and the appliance of science have improved, times on the track have gradually got quicker. Performance-enhancing drugs skewed that progress enormously, of course, evidenced by the barely credible records still on the books decades on, but fans usually knew that if somebody shaved a few tenths off a track world record, then they were watching the best of the best.

Over the last few years, however, that concept has been torn up. Times set by stars of the sport are being utterly destroyed again and again. Initially it was on the road, where long- distance records tumbled and nobody could win a race without “the shoes” but now track performances are also making a mockery of history.

Long-standing 10,000 and 5,000 metres world records have been obliterated and the impact is now being seen in shorter races. At a low-key meet in Poland in February, Briton Elliot Giles ran 1:43.63, the second-fastest indoor 800m in history - and more than a second quicker than former world record holder Sebastian Coe’s 38-year-old British record.

Governing body World Athletics was too slow to recognise the danger then, under enormous pressure from the shoe companies who effectively finance the sport, and eventually introduced minor restrictions that mean the spring-loaded shoes are here to stay - unlike most of the records.

Reporting by Mitch Phillips, editing by Ed Osmond