Ivan Poddubny was one of the greatest of the Russian Strongman /Wrestlers (of which there were many). He was born in a small village and worked hard jobs even from a young age.
After some training, he joined the Russian circus, performing feats of strength and wrestling all comers. The sash he is wearing in this picture is most likely from the 1908 World Championship, which he won by defeating his friend Ivan Zaikin. This was his fifth World Championship title. Even to this day, Poddubny is still a well-known sports hero in Russia and several big wrestling tournaments bare his name.