Iso-Hollo was one of the last "Flying Finns", who dominated distance running between the World Wars.

As a youth, Iso-Hollo did skiing, gymnastics and boxing, and took up running when he joined the army.

He was denied a chance at the world record because the officials lost count of the number of laps – the lap-counter was looking the wrong way, being absorbed in the decathlon pole vault.

He also won the silver in the 10,000 m.[1] In 1933, Iso-Hollo broke the 3000 m steeplechase world record, running 9.09.4 in Lahti and won the British AAA Championships title in the steeplechase event at the British 1933 AAA Championships.

He won the steeplechase by three seconds, finishing with a new world record of 9:03.8, and earned a bronze medal over the 10,000 m. After the Olympics, Iso-Hollo fell ill with rheumatism but kept on competing until 1945.