San Francisco 49ers QB Colin Kaepernick (knee, shoulder, thumb) has tried to improve his flexibility this offseason by stretching his back because it would tighten up on him in the past. He is looking to become more limber so he can be a more elusive runner, according to a source. Kaepernick is also wearing contact lenses to help his short-area vision and has a tinted visor on his helmet to protect the contacts and reduce the sunlight in his eyes.