Complex sentence: Gjerstrøm spent his youth years at Nordstrand IF, and is considered one of the most talented young players in the country, having played for Norway's youth international teams since he was 14.
Split into simpler sentences: Gjerstrøm spent his youth years at Nordstrand IF, and is considered one of the most talented young players in the country. He has played for Norway's youth international teams since he was 14.