Complex sentence: Through the 1930s he conducted at the Kirov Ballet and Bolsoi Opera, before taking up in 1938 the post that he would hold until 1982: chief conductor of the Leningrad Philharmonic Orchestra.
Split into simpler sentences: Through the 1930s he conducted at the Kirov Ballet and Bolshoi Opera. In 1938 he took up the post that he would hold until 1982: chief conductor of the Leningrad Philharmonic Orchestra.