Complex sentence: A combination of injuries ruled him out for most of the 2008 and 2009 seasons, but he returned to action in 2010, becoming the Italian champion and competing at the 2010 European Athletics Championships.
Split into simpler sentences: A combination of injuries ruled him out for most of the 2008 and 2009 seasons. He returned to action in 2010 and became the Italian champion, representing his country at the 2010 European Athletics Championships.