Paris - Newly-designed starting blocks to be used at the London Olympics will "enhance" the performance of athletes, according to the sport's world governing body, the IAAF, and not slow them down as claimed by Usain Bolt.
The blocks redesigned by Swiss timekeepers Omega for this season's Diamond League and Olympics came in for criticism last week from none other than Jamaican sprint star Bolt, the world's fastest man whose voice carries considerable weight.
But the IAAF insisted that changes to the starting blocks, which athletes use in the 100m, 200m, 400m, 4x100m and 4x400m relays, as well as the 100, 110 and 400m hurdles, would not affect those using them.
"Visually the starting blocks look very different," an IAAF spokesperson told AFP. "Yes, it is true that Omega has changed a few things.
"Actually they redesigned the starting blocks, but the changes have been introduced in order to enhance the measurement of the athlete's reaction times and to enhance the performance of the athletes."
Bolt, who stands 1.96m (6'5") tall and boasts a whopping UK size 13 shoe size, claimed his feet were just too big for the altered blocks.
"The blocks have changed from last season. They're new models. Personally I think they need to go back to the old blocks," he said, despite storming to victory in the 100m at Thursday's Diamond League meet in Oslo in 9.79sec.
"I'm not very pleased with the new blocks they have, they're a little short for me."
But the IAAF insisted: "The starting blocks haven't been shortened.
"Also, the width of the foot rest has increased from 120mm to 160mm to allow different starting positions and the height has not been adjusted - it remains at 270mm as in the previously-used version."
The re-designed blocks, the spokesman said, were "something certainly much better for all the athletes".
"In other words, it is crystal clear that the new model is an improved edition."
Omega says that the new blocks would also measure athletes' false starts and reaction times more accurately, the latter by determining the force against the back block and not by movement.
"The starting blocks that will be used during the London 2012 Olympic Games have been extensively tested by world-class athletes through 2011," the IAAF spokesperson added.
"Ultimately, the decision for the equipment to be used during the Olympic Games is decided by the governing body of world athletics, the IAAF, months ago.
"First official use was in the test event of the London Olympic Games five weeks ago and they've been used in all Samsung Diamond League meetings so far."