The endorsement and advertising claims of a running shoe may be the least important criteria in a consumer's decision on which footwear to purchase, a national runners' magazine concluded from an annual performance test.

Running Times magazine's third performance ratings indicated that the AAU Marathon, endorsed by the Amateur Union, had the worst performance in shock absorption and foot-motion control among 51 men's training shoes tested. Last year a J. C. Penney's model finished last despite an official, paid-for endorsement by the U.S. Olympic Committee.

Another shoe poorly rated in the tests, the Fayva "Olympian," is involved in an Olympic Committee suit, which claims the maker does not have the right to use the name, the magazine editors noted.

The best way to buy a shoe "is to seek out a salesperson who knows about running and ask about a good training shoe and rely heavily on the salesperson's advice," Running Times Associate Publisher Jeff Darman said. "I'd suggest going to a store that specializes in running gear."

Running Times Editor and Publisher Ed Ayres explained what to look for in a shoe and how to achieve a desirable fit.

"A good training shoe has a fairly thick midsole (between the foot and the outer sole) that absorbs much of the shock," he said. "The shoe should have good flexibility about one-third of the way back from the toe so it bends easily.

"Beyond that, the fit is all important. The toes should be able to wiggle freely, with about a finger's (width) space at the tip. The heel should be very snug, almost tight. The heel counter that wraps around the back of the shoe should be firm."

Darman and Ayres stressed the results of their testing, which rated 100 men's and women's training and racing shoes. It dealt only with the performance of the shoes in safety and injury prevention and not in durability or other factors that might determine the value of a shoe.

"There are trade-offs. You have to decide whether you want a shoe for safety or durability.People with different builds need different shoes . . . and there's a lot of difference between a racing shoe and a training shoe. A racing shoe should be lighter, have less support and less shock absorption because you're only going to use it for the race.

"If you're interested in durability, you should inquire about the rate of return on a particular shoe."

Darman also suggested the price difference between the cheaper models and more expensive ones might be minimal in terms of performance benefits. He said a runner should expect to pay a minimum of $30-40 for a good shoe.

"The price difference between the reputable shoes and, for example, the $21.99 Penney's shoes is only $8 or $10," Darman said."When you talk about affordable, it's also questionable whether there are additional doctor bills or if you wind up not running (because of ailments)."

Seventeen shoes earned the magazine's "gold shoe" rating in blind tests conducted by Dr. Joseph Ellis of La Jolla, Calif., in which specially wired shoes measured motion and shock on runners.

The gold-shoe winners for men among training shoes were the Brooks Nighthawk, New Balance 420, Saucony Jazz, Nike Tailwind, and Brooks Vantage. The racing elite were the Nike Eagle, Adidas Marathon 80 and Tiger Ultimate.

The New Balance 420, Brooks Lady Nighthawk, Nike Tempest, Saucony Lady Jazz and Adidas Trainer were the women's training gold-shoe winners and the Adidas Marathon 80 was the only female racing shoe winner.