When Erik Soderstrom, a seventh-grader at Inman Middle School in Atlanta, did his back-to-school shopping last month, there were three sartorial imperatives on his list: a pair of black baggy jeans, all-white sneakers and Nike wristbands. "I wear them around my wrists for sports," says the basketball-and football-loving 13-year-old. "But during the school day I wear them close to my elbow."
Sweatbands are just part of an athletic-wear invasion that is one of this year's biggest themes in back-to-school fashion. "Music stars 50 Cent, Blink 182 and Avril Lavigne contributed to this trend," says bicoastal fashion stylist Darshan Gress, whose clients...