Random House:

obstacle race

Summary:

a foot race in which the contestants are prevented in a specific way from covering the full course at top speed, as by having hurdles to jump, sacks ...  (28 of 38 words)

Link:

http://dictionary.infoplease.com/obstacle-race  [cite]

Encarta:

obstacle race | obstacle races [plural]

Summary:

a race in which competitors have to get past a range of obstacles  (13 of 25 words)

Link:

http://encarta.msn.com/dictionary 1861696797/definition.html  [cite]

Wikipedia:

Running

Summary:

a means of terrestrial locomotion allowing a human or an animal to move rapidly on foot. It's defined in human sporting terms as a gait in which at some point all feet are off the ground at the same time. This is in contrast to walking, where one ...  (48 of 4857 words, 2 images)

Link:

http://en.wikipedia.org/wiki/Running  [cite]

Merriam-Webster:

footrace

Summary:

a race run by humans on foot  (7 of 16 words, pronunciation)

Link:

http://www.merriam-webster.com/dictionary/footrace  [cite]

Wiktionary:

footrace | footraces [plural]

Summary:

A race run on foot  (5 of 6 words, 1 image)

Link:

http://en.wiktionary.org/wiki/footrace  [cite]