[1] He is a two-time Olympian (2000 and 2004), and a three-time medalist at the FINA World Cup.

[2][3] At the 2004 Summer Olympics in Athens, Lagoun qualified as an individual swimmer for the men's 100 m butterfly.

He cleared a FINA B-standard entry time of 53.66 from the European Championships in Madrid, Spain.

[4][5] He challenged seven other swimmers on the fifth heat, including top medal favorite Milorad Čavić of Serbia and Montenegro.

Lagoun failed to advance into the semifinals, as he placed twenty-sixth overall in the preliminaries.