Alberto Salazar: Galen Rupp says he is '100% behind' his coach

US distance runner Galen Rupp backs his coach Alberto Salazar "100%" despite allegations he practised doping techniques on him as a teenager.

Rupp spoke after winning his seventh consecutive 10,000m national title, which secured his place at the World Championships in Beijing in August.

The athlete admitted it had been "difficult to focus" following allegations - made in a BBC documentary in collaboration with US journalism website ProPublica - that Salazar violated various anti-doping rules and used testosterone medication on a 16-year-old Rupp in 2002.

Both Salazar and Rupp, 29, deny all the allegations.