THE World Anti-Doping Agency on Monday described allegations made in an al-Jazeera report that U.S. National Football League (NFL) team Denver Broncos’ quarterback Peyton Manning took human growth hormone as “very concerning” and has urged “increased collaboration” with sports leagues in the United States.

    Though Manning has vehemently denied the allegations and the source of the al-Jazeera report has since recanted the claims he was shown making in the film, WADA says that it expects a careful investigation by the relevant authorities.

    The Sunday investigative documentary ‘The dark side: The secret world of sports doping,’ linked well known players from the National Football League and Major League Baseball with performance enhancing drugs.

    Green Bay Packers linebackers Clay Matthews, Julius Peppers and Mike Neal, who the report said have used either banned hormone supplement Delta-2 or powerful anti-inflammatory drugs, also denied any wrongdoing.

    David Howman, WADA director general, said he was nevertheless taking the report seriously and took aim at the NFL.

    “Al-Jazeera’s allegations are very concerning, particularly as it relates to the NFL’s and MLB’s testing programs,” Howman said in a statement.

    While the documentary’s makers and its critics have clashed over the validity of the claims, the report has nevertheless pushed concerns of illegal performance enhancements in popular U.S. sports leagues into the spotlight once again.

    Athletics, cycling and baseball have all suffered huge embarrassment over doping in the past decade and al-Jazeera’s report at the very least has highlighted long-running differences between WADA and NFL in their anti-doping strategy.

    (SD-Agencies)