Optimization of energy expenditure during level walking

Humans prefer to walk at speeds that approximately minimize their metabolic energy expenditure per unit distance (gross cost of transport, COT).

“Further, humans prefer to walk at speeds that approximately minimize their metabolic energy expenditure per unit distance (i.e.gross cost of transport, COT).”

Step frequency, step length, step width and speed are all chosen to minimize energy expenditure.

“For example, it has been shown that step frequency (Zarrugh et al., 1974), step length (Umberger and Martin, 2007), step width (Donelan et al., 2001) and speed (Zarrugh et al., 1974) are all chosen to minimize energy expenditure.”

Humans learn and choose to walk in a way that minimizes their metabolic energy expenditure.

“Further, we learn and choose to walk in a way that minimizes our metabolic energy expenditure (Ralston, 1958;Zarrugh et al., 1974).”

The greater COT values for the rough surface likely reflect shorter step lengths and wider step widths.

“shorter step lengths and wider step widths (Donelan et al., 2001;Zarrugh et al., 1974)”

The function describing the dependence of metabolic rate on speed for the smooth, level floor condition in the present study is similar to prediction equations developed in previous studies.

“The function describing the dependence of metabolic rate on speed for the smooth, level floor condition in the present study is similar to prediction equations developed in previous studies (Givoni and Goldman, 1971;Ralston, 1958;Zarrugh et al., 1974;Pandolf et al., 1977).”

Subjects' preferred speeds on both surfaces were close to the speeds that minimized COT.

“Our results revealed that, similar to past studies that studied COT on smooth, level ground and treadmills (e.g.Ralston, 1958;Zarrugh et al., 1974), the subjects' preferred speeds on both surfaces were close to the speeds that minimized COT.”