GETTING ACTIVE: Neiman Marcus is getting into the growing activewear business with a shop-in-shop test concept at several stores including Dallas’ NorthPark Center. Called NM on the Go, the boutique features fashionable workout clothing by Payne, Aryn Glasser, Splits 59, Zobha and Adidas by Stella McCartney as well as casual lifestyle sportswear by Monrow, James Perse and Neiman’s own label. “We are planning to roll the concept out to more stores in the next few months,” a spokesman said, declining to comment further. NM on the Go is demarcated by a textured floor mat and distinctive mobile racks with wooden bases. At the NorthPark store, it occupies space formerly held by DKNY on the second floor, where the contemporary and bridge areas are gradually being renovated and an Elie Tahari shop is currently under construction. Sales of women’s activewear rose 2.6 precent to $30.5 billion for the year ended in March, according to NPD Group. That includes active tops, bottoms and jackets, fleece wear, swimsuits and sports bras, which was the only category that declined.