[4] At the 1920 Summer Olympics in Antwerp he represented Finland in the cross-country race, placing 18th; the race doubled as a team event, which Finland won, but only the results of the best three finishers (Paavo Nurmi, Heikki Liimatainen and Teodor Koskenniemi) counted for the team result.

[1] At the 1924 Olympics in Paris Rastas represented Finland in both the 5000 m and the cross-country race, the latter again doubling as a team competition.

[1] The conditions for the cross-country race were extremely hot and demanding, and the majority of runners failed to finish; this included Rastas, who dropped out shortly after the halfway point.

Two other Finns (Väinö Sipilä and Eero Berg) also dropped out, but Finland still won the team race again.

[5][6] Rastas made a third and final Olympic appearance in 1928, this time in the marathon; he placed fourteenth.