NEW YORK- Function and fashion must blend seamlessly in modern workout clothes, which have come a long way from the bulky gray cotton sweatshirts and canvas sneakers of years past, fitness experts say.

From sophisticated sweat-absorbing synthetics to cycling pants with strategically placed padding, today's exercise apparel must be durable enough to withstand a hardcore workout, stylish enough to meet friends or run errands, and distinct enough to let the world know who you are.

Chris Froio, head of training for Reebok International Ltd, the running shoe and apparel company, said consumers of both sexes are expecting their clothes not only perform but express the fitness lifestyle of the wearer.

"What you see is: 'Yes, I need my functional clothing, but I also need to look good going to and from the gym and picking up the kids," said Froio. "'I need the style and comfort that's going to let me wear it all day.'"

Froio said customers aren't looking just for function or just for style, they are demanding a blend.

The world sports apparel industry is expected to exceed $126 billion in sales by 2015, according to a 2013 report by Global Industry Analysts, a market research firm.

Froio cites the ubiquity of running shoes being worn by non-runners and notes that teenagers appear to be favoring leggings, yoga pants and other athletic styles.

Bold colors, prints and graphics have gone from the periphery to a fashionable mainstay, Froio said, as exercisers look for clothes that communicate as well as perform.

"People want something that conveys the attitude of the wearer, that allows them to express themselves, whether through a colorful headband or by revealing their tattoos," he said.

Functionality, starting with lightweight, durable, breathable fabrics with enough stretch to cover the exerciser's full range of motion, has evolved with the help of technology imported from other industries.