Zabala ran his first marathon at the end of October, 1931. Ten days later he ran a new world record in 30 km (1:42:30.4). Later, before the 1936 Summer Olympics, Zabala would run a new world record in 20 km (1:04:00.2).
Zabala's high peak was the Los AngelesOlympics. Zabala ran in the lead group almost the entire distance. With just four kilometres to run, he broke free to finish 20 seconds ahead of Sam Ferris from Great Britain. Zabala also participated at the Berlin Olympics, gaining sixth place at the 10,000 m, but could not defend his Olympic title in the marathon. Zabala took the lead from the start, but abandoned the race after 33 km when the main group caught him.