When humans arrived on the Moon during Apollo, they found that they could not walk around in the reduced gravity environment using the strategies they would have on Earth. This was for two main reasons: the spacesuits the astronauts wore restricted their motions, and the 0.17 G environment had a huge effect on the energy transfer mechanism involved in typical Earth gaits such as walking or running.
Dr. Chris Carr, a recent PhD. recipient, conducted research that examined running, walking, and the run-walk transition in lunar, martian, and terran gravity levels. Results showed that the energetics of walking were negatively impacted by reduced gravity to a much greater extent than for running. Current research is examining loping, a skipping-type gait involving no foot exchange that was adopted by some Apollo astronauts. The objective is to determine if there is an energetic benefit (probably stability-driven) inherent in this gait in reduced gravity, or if it is simply a product of motion restrictions imposed by a gas-pressure spacesuit. This research uses a treadmill, the Moonwalker, a structure that uses a climbing harness attached to springs to partially suspend subjects, and a VO2000 oxygen and carbon dioxide flow meter to measure energy consumption while subjects are locomoting. An exoskeleton, composed of stiff springs in parallel with a subject's legs are used to simulate the stiffness of a gas pressure space suit.