For centuries shoes have been designed and made from the inside out. Almost all footwear is still made on lasts, a form used to shape a particular shoe style and size around the form of a human foot and ankle. A cordwainer (or cordovan) is the term of art for somebody who makes shoes from fine soft leather by stretching and shaping material around the last, which is not removed until the sole is attached. Top fashion shoe designers like Manolo Blahnik still painstakingly carve lasts from wood.

Athletic shoe manufacturers design walking shoe lasts on computers and shape them on numerically controlled lathes and milling machines. Anatomists, biomechanical engineers, and the athletes who use the shoes provide the input to model the effect of even the most minute variations in toe shape, heel curve and toe spring. 3D computers model the thickness and composition of different combinations of uppers, lowers, interiors and soles on the lasts until the designers achieve exactly the desired specifications for that model walking shoe. All walking shoes are purpose made but not all walking shoes are created equal. People with high arches, in particular, have a serious risk of injury by not wearing impact control walking shoes.

There was a time when the only buying choice for sneakers was white or black. Today's athletic shoes are the product of sophisticated science and engineering. The distinctions between walking shoes, running shoes, and cross trainers from the same manufacturer may be small in some cases but they are real differences and not just a marketing gimmick.

Walking shoes have more flexible soles and are specially designed to promote the easy roll of the foot from heel to toe. Cushioning is designed to absorb about 1.5 times body weight for any shoe size. Walking shoes do not have to be as rugged so there is more opportunity for manufacturers to use mesh and other lighter, highly breathable materials. Tread designs are less deep and provide all around grip. The best walking shoe is, in fact, a Walking Shoe, but you could certainly use the other types of athletic shoes in your walking program so long as the fit was right,

Running shoes are designed to absorb impacts up to three times your body weight and provide sufficient lateral stability to control pronation. Heels are higher and more heavily cushioned. Treads and sides are designed for maximum forward grip. Trail running shoes have impregnated solid guards to prevent bruising from sharp rocks.

Cross-trainers attempt to provide a versatile compromise between walking and basketball, tennis or other court shoes. Generally, cross trainers have more rigid metatarsal support than running shoes, and do not have adequate heel cushioning for long distance running, Cross-trainers work OK if running is limited to a few miles at a time but a cross-trainer shoe would likely break down faster than a purpose made running shoe.