Martinez was optioned to Triple-A Sugar Land on Friday, Chandler Rome of the Houston Chronicle reports.
Martinez was called up by the Astros in late August, and he allowed five hits and a walk while striking out seven in six scoreless innings over six relief appearances in the majors. In spite of his effectiveness, the right-hander will return to Sugar Land after Justin Verlander (calf) was reinstated from the 15-day injured list Friday.