During the 1950s, leisure opportunities greatly expanded, and children and adolescents began to wear sneakers as school dress codes relaxed. Sneaker sales rose so high, they began to adversely affect the sales of conventional leather shoes, leading to a fierce advertising war for market share in the late '50s. In the 1970s, jogging for exercise became increasingly popular, and trainers designed specifically for comfort while jogging sold well. Companies also started to target some of their products at the casual fashion market. Soon, shoes were available for football, jogging, basketball, running, etc. Many sports had their relevant shoe, made possible by podiatrist development of athletic shoe technology.