Vienna laboratory Humanplasma hit back on Tuesday at claims that it stood at the centre of a massive doping network, naming instead several well-known coaches for the first time. Banned Austrian biathlon and cross-country coach Walter Mayer, Stefan Matschiner, the former manager of disgraced cyclist Bernhard Kohl, and Martin Kessler, a rowing coach, were those at the heart of the doping network that used Humanplasma's facilities between 2003 and 2006, the laboratory said in a statement.