From Tokyo Olympiad, which is one of the very best sports documentaries ever made. Great footage of Abebe Bikila's second consecutive Olympic marathon win on an apparently muggy day in 1964, when leather or canvas shoes were still the state-of-the-art and nylon in running shoes was still a ways off. Essentially no narration or dialogue, simply superb cinematography and a perfect soundtrack. Results from the race (note Billy Mills doubling back from his 10,000m win with a 2:22:55 in 14th) are here: http://en.wikipedia.org/wiki/Athletics_at_the_1964_Summer_Olympics_%E2%80%93_Men's_marathon
Marathon start is near the 7:30 mark of the first video clip.