Minimal energetic expenditure of women walking burdened on gradients in urban environments.

ABSTRACT

OBJECTIVES: The objective is to understand the walking energy expenditure of women in urban environments (i.e., over-ground), using mass, velocity, gradient (incline and decline), and burden as predictors. In addition, we use an equation to determine the gradient associated with the minimum energy expenditure of walking. METHODS: To do this, we assessed the volumetric consumption of oxygen (VO2 ) of ten females (ages 22-40 years) with a portable Cosmed K4b2 device. Participants walked at three self-selected, over-ground velocities (slow, normal, and fast) on five gradients (0%, +/-7.5%, +/- 12.4%) in different urban community settings burdened (10 kg) and unburdened. We performed a multilinear regression controlling for repeated measures to determine the best predictive equation for VO2 . The first derivative of our equation was used to find the gradient for minimal VO2 . RESULTS: Our equation explains 79% of the variation in VO2 and indicates that over-ground walking is similar to treadmill walking, except that the gradient associated with the minimal energy expenditure of walking is steeper (-11% to -20%) than that established from treadmill walking. CONCLUSIONS: Although our overall equation is an accurate predictor of VO2 for all velocities, burden, incline, and decline in this group, further research needs to be conducted to examine kinetic, kinematic, and velocity interactions in over-ground walking.