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PEOPLE naturally opt for the gait that makes walking most efficient—so
long as it’s safe, says Rodger Kram of the University of Colorado in Boulder.
His team measured the metabolic rates of 10 adult volunteers as they walked on a
treadmill with their feet wide apart, close together or normally spaced. The
most efficient gait—and the one adults usually choose—was when feet
were about the width of a foot apart (Proceedings of the Royal Society
B, vol 268, p 1985). Children and elderly people tend to walk with their
feet wide apart, however. Kram thinks they trade efficiency for balance, because
wide steps help stop them falling over.