Why Do Astronauts On The Moon Bounce When They Walk?

Zero gravity

Most animals adopt gaits that get them where they want to go with the least expenditure of energy consistent with the chosen speed of travel. A man on the moon is no exception. The bouncy walk works well in the low gravity, giving the appropriate amount of control of speed and direction with no more energy use than would be normal on Earth. Besides, flexing the space suit requires work, so the less often the astronaut has to do it, the less tired s/he gets.