Complex sentence: The Soviet Union came out of international isolation by eschewing the Spartakiad and participating in the 1952 Summer Olympics in Helsinki, and continued by making their Winter Olympics debut at the Cortina Games.
Split into simpler sentences: The Soviet Union started to come out of international isolation by eschewing the Spartakiad and participating in the 1952 Summer Olympics in Helsinki. They continued these efforts by making their Winter Olympics debut at the Cortina Games.