(SportsNetwork.com) - Michael Phelps could be mulling a return to competitive swimming.
Data released Thursday by the U.S. Anti-Doping Agency shows Phelps was tested twice in the most recent quarter this year, an indication he might make a run at qualifying for the 2016 Rio Olympics.
The most decorated Olympian of all time retired after winning six medals at last year's London Games, saying he had accomplished all he ever wanted to and longed to see more of the world than its hotels and pools.
But his inclusion in USADA testing numbers for the third quarter, along with a report by Swimming World saying Phelps took part in warmup activities at the Arena Grand Prix in Minneapolis, fueled new speculation that he may return.
Phelps told The Associated Press "nothing is set in stone" but that he enjoyed being around his old swim team in Baltimore. His longtime coach, Bob Bowman, told the AP Phelps would be eligible to compete again in March.
A swimmer looking to come out of retirement must subject themselves to nine months of out-of-competition doping control before competing in a sanctioned meet. Third quarter testing ended Sept. 30, but the AP said Phelps rejoined the anti-doping testing program near the end of the second quarter.
Since London, Phelps has denied -- or at least shrugged off -- the idea he was thinking about swimming competitively again.
In May, a television station in Fort Myers, Fla., reported Phelps was planning a return. The report was written by an anchor at the station who is also the son of USA Swimming's national team director.
"Why do I keep getting texts about coming back?" Phelps tweeted at the time. "Do (people) really believe everything they hear or read? There are too many (people) in the world that think they have a 'story.'"
Phelps, 28, has won 22 Olympic medals and 18 golds -- both records. After winning eight gold medals at the 2008 Beijing Olympics to break Mark Spitz's record, he won six medals in seven races in London, including four more golds and his first two silvers.
"I've been very fortunate to look back over my career and say I've been able to accomplish every goal that I've ever wanted to. And I think at that point in your career, it's just time to move on," the four-time Olympian said after his last race in London.
"There are other things that I want to do in my life and I'm not sure staring at a black line for four hours a day is one of those."
11/14 17:35:49 ET