Longest time for a robot to perform push-ups

Kengoro – a robot created by professor Inaba and his coworkers from the University of Tokyo’s JSK Lab in Japan – is capable of performing push-ups for a duration of 11 minutes. Kengoro can do this via a cooling mechanism inside its body. Generally, machines such as cars and computers are cooled with fans or with water circulating through them. There wasn't enough space in Kengoro's body to make use of such systems, however, so its creators developed a different mechanism instead: they created small gaps in its frame, allowing water to seep out and evaporate. This evaporation, in turn, cools the areas most likely to overheat – a mechanism similar to the function of human sweating. Kengoro can run for half a day with about one cup of deionised water.

If it is working hard (i.e., performing many push-ups), however, it needs to be rehydrated.