In Pursuit of the Perfect Running Shoe

DICK DeCOST's job is finding a balance: Make a running shoe that's lightweight and comfortable - as well as stable and durable. ``No one has come up with a shoe that's going to work and last,'' says Mr. DeCost, operations manager for research and development at New Balance Athletic Shoe Inc. Lightweight materials that are flexible and resilient don't remain so for long - unless you pair them with long-lasting materials, which tend to be heavier and harder.

In the early '70s, when the running craze started, there was a demand for shoes to suit individual needs. ``Obviously, someone who weighed 200 pounds would want to have a lot more stability and cushioning than someone who weighed 120 pounds - they'd want a lighter, more bouncy shoe,'' DeCost says. The search began for a durable, comfortable shoe that was also fashionable and affordable.

Eighty percent of today's running-shoe technology goes into the midsole, the layer in between what's on the road (outsole) and what's under your socks (insole). The midsole is the ``backbone'' of the shoe, says DeCost. Of course, the insole is important for comfort and the outsole for traction and support, but the midsole is where most of the ``energy return'' (the latest industry buzzwords) comes from.

Manufacturers are always looking for new technology, new materials to improve the midsole - foam, air, gel, rubberlike compounds, even springs. New Balance keeps up with the latest synthetic materials, to see if some new goo is good for shoes. Currently they are experimenting with a substance which, for the record, DeCost will only identify as a ``space-age material.''

Shoe prototypes undergo extensive testing. DeCost pulls out several typewritten pages of description. Computers analyze endurance, impact, and motion control; other machines tug, tear, scrape, and squash new models. Studies of runners in action and other companies' shoes are also part of the process.

New Balance also prides itself on its human testing: World-class racers, employees, and ordinary runners try out the shoes. Strewn about his office, in fact, are the 15 pairs DeCost himself is testing this month.