Editor's note: This report originally appeared at Competitor.com.

In a surprise announcement, two-time Olympian Ryan Hall has said he is retiring from professional running just four weeks ahead of the U.S. Olympic Trials Marathon in Los Angeles.

Hall cited chronically low testosterone levels as the reason in a New York Times story announcing the decision.

The 33-year-old Hall, who nine years ago set a still-standing American record of 59:43 at the Armco Houston Half Marathon, where his wife Sara will compete this Sunday, made the announcement in a New York Times story. The Halls have been sponsored by the shoe and apparel brand Asics since graduating from Stanford University in 2005.

“The last four years certainly have been very trying,” Hall admitted to Competitor last October.

“The last Olympic Trials cost me four years of struggle as I got plantar fasciitis about a month before the trials and ran through the trials with it. Then I trained for the Olympics with plantar fasciitis, which resulted in my stride changing and an endless chain of injury after injury.”

Hall, who won the 2008 U.S. Olympic Trials Marathon in New York in an event-record time of 2:09:02 and finished second to Meb Keflezighi at the 2012 Trials in Houston, dropped out of the 2012 Olympic Marathon with a hamstring injury. Laden with injuries and illness in recent years, Hall hasn’t finished a marathon since placing 20th at Boston in 2014, where he ran 2:17:50.

The Halls live in Redding, Calif., with their four daughters -- Hana, Mia, Jasmine and Lily -- adopted last September from Ethiopia.