Complex sentence: Tchachina's first victory was at age 8 at the Omskaya oblast championship; by age 12 she was already on Russia's national team and routinely travelled to Moscow to take part in the training camps.
Split into simpler sentences: Tchachina's first victory was at age eight at the Omskaya oblast championship. By age 12 she was part of Russia's national team and routinely travelled to Moscow to take part in training camps.