No abstract

The development is described of an equation to predict the energy cost of treadmill walking of adult males. Oxygen consumption during level walking is considered as the product: oxygen consumption per step · number of steps per minute. At any given speed within the domain of the variable, number of steps per minute is then found to be a reciprocal function of height, and oxygen consumption per step a function of body weight. Rearrangement of the mathematical expressions that describe these relationships permits the calculation of oxygen consumption of level walking as the product of two constants, Pw, a constant for the individual; and Ks, a constant for the speed. It is suggested that these constants may have other uses besides the prediction of oxygen consumption of level walking. Oxygen consumption of grade walking is considered as the excess of oxygen consumption over that observed walking on the level at the same speed. This should be, but apparently is not, simply related to body weight. In a test of its predicting power, the equation predicted the oxygen consumption of 84 treadmill walks of 44 subjects, with a correlation coefficient measured: predicted values, γ = + 0.935. Submitted on October 26, 1962

No abstract

No abstract

Twenty years of published experience with the Workman-Armstrong equation for predicting walking VO2 is reviewed. The equation is reexpressed in currently accepted terminology, and it is shown that the equation serves well as a basic model of normal walking. Employing this model to analyze VO2/step leads to the elaboration of a three-compartment model of the metabolic cost of walking. This three-compartment model provides a rational estimate of the fraction of walking's metabolic cost that powers the actual walking movement. Doubt is expressed that "comfortable speed of walking" is definable in energy terms. It is suggested that the requirements of maintaining balance while walking may determine both the comfortable speed of walking and the curvilinearity of the relationship between ground-speed and freely chosen step frequency of walking.

These data demonstrate that oxygenation is primarily a function of mean airway pressure, and that longer inspiratory times can be used as an alternative to applied PEEP to increase this oxygenation. If no air trapping develops, lung inflation pressures and delivered volumes remain constant with this approach. Because the technique was used only in patients refractory to conventional techniques, the poor outcome is not surprising.

No abstract

No abstract