In 1920 he was part of the Swiss boat, which won the gold medal in the coxed fours event. He was also a member of the Swiss eights which was eliminated in the first round of the eights competition.
Four years later he won the gold medal as part of the Swiss boat in the coxed fours competition again. He also competed with the Swiss team in the coxless fours event and won the bronze medal.
Rix has been working on the evolution of galaxies. His doctoral thesis was titled Disk Components in Early Type Galaxies and he has, as of 2011, published 290 papers in peer-reviewed journals. He has made important contributions to the structure and dynamics of galaxies, to the evolution of galaxies since the early epochs of the Universe, and the formation of our own Milky Way and its satellites.