LONDON, Sept 26 Reuters Adidas39; newest running shoes, worn by Ethiopia39;s Tigist Assefa on Sunday to set a new women39;s marathon world record in Berlin, went on sale on Tuesday with an eyewatering price tag that will test the enthusiasm of amateur runners.

Adidas, its bigger rival Nike and other sports brands, have been locked in a supershoe war for years, since the first running shoes containing a thick, shockabsorbing foam and carbon fibre plate helping athletes run more efficiently, were released.

At 500 a pair, the Adizero Adios Pro Evo 1 cost 225 more than Nike39;s equivalent Alphafly 2, raising the question of how many amateur runners will swallow the extra cost.

The price tag is just insane, said Harry Swinhoe, founder of Grove Lane Runners, an amateur running club in southeast London. People will flock to it, but I wonder whether the average runner will really feel the benefit of the ultrasupershoe, versus the supershoe, or the normal shoe.

Weighing just 138 grams 5 ounces, the shoes are very light, but not durable. They39;re designed to be worn for a single marathondistance race 42 kilometres, or 26 miles and prerace warmup, making the cost per mile at around 19 if, as Adidas says, runners must buy a new pair for each marathon.

This is a shoe optimized for speed, versus durability, Adidas said. The retailer released just 521 pairs of the shoes on Tuesday, with a second drop planned for November.

Adidas is marketing them as world record breakers,…