His best performance came in the triple jump, where he placed fourth, while his countryman Mikio Oda won the gold.

In the long jump, he finished ninth, and his 4 × 100 m relay team was eliminated in the heats.

The next year, at the Los Angeles Games, he was one of the favourites for the Olympic titles in both horizontal jumps.

[1] After retiring from competitions Nambu became a sports journalist for Mainichi Shimbun.

He also remained active in sports, being head coach for the Japanese Athletics Association, and acting as manager of the national team at the 1964 Tokyo Olympics.