Adidas by Stella McCartney's ability to blend functional sportswear and laidback style has proved a hit with active fashionistas everywhere. The Brit designer joined up with Adidas in 2004 to create performance collections. Running, gym and yoga, tennis, dance or wintersports; it's the chicest sportswear around. "Each season we are able to merge more and more performance products with style," says McCartney, whose sporty signatures include hooded sweaters, parkas, jersey tops and pants.