Mayer excelled in combined events from a young age and won the octathlon gold medal at the 2009 World Youth Championships and the decathlon gold medal at the 2010 World Junior Championships.
Mayer excelled in combined events from a young age. Mayer won the octathlon gold medal at the 2009 World Youth Championships at the 2010 World Junior Championships. Mayer won the octathlon gold medal at the decathlon gold medal at the 2010 World Junior Championships.