A goal of many physiatric interventions is to improve biomechanical walking efficiency. Thus, a tool that helps assess this efficiency, independent of cardiac, pulmonary, psychologic, or other nonbiomechanical factors, would be useful. Currently used methods to measure efficiency, including comfortable walking speed, are not specific to biomechanical variables. A potential tool, the biomechanical efficiency quotient (BEQ), which uses three variables--average stride length, vertical displacement of the trunk during walking, and sacral height during standing--is proposed and preliminarily tested. This quotient is based on Saunders, Inman, and Eberhart's theories and on a prior study in able-bodied subjects. The BEQ was computed in 20 consecutive patients with neurologically based gait disability referred for gait laboratory evaluation who subjectively reported that one or two ankle-foot-orthoses (AFOs) reduced the effort necessary to walk. The quotient was calculated with and without the AFO(s) by dividing the average vertical displacement of the sacrum, which was measured with an optoelectronic system, and by a predicted displacement, which was based on the patient's sacral height and average stride length. The mean BEQ with the AFO(s) (6.3 +/- 4.4) was significantly less than the mean BEQ without the AFO(s) (9.7 +/- 7.1); P = 0.005. Furthermore, the BEQ was less with the AFO(s) compared with trials without the AFO(s) in all subjects. Percent change in BEQ with the AFO(s) (26.8 +/- 19.6) correlated with percent change in comfortable walking velocity (24.8 +/- 31.8), r = 0.73, P<0.001, across all subjects. The BEQ may be useful in specifically assessing the effect on biomechanical efficiency of physiatric interventions, despite variable nonbiomechnical factors. An instrument to measure vertical trunk displacement during walking outside of the gait laboratory would be extremely useful for further necessary longitudinal studies.

The present study determined the proportion of energy consumption used to lift the center of mass vertically during walking. By assuming that the vertical oscillations of the trunk were identical to those of the center of mass, the complexity of studying the human gait was simplified. The work performed on the center of mass, defined as lift work, was calculated using the subject's mass and the vertical displacement of the trunk. Compensating for the fact that human muscles are approximately 25% efficient in performing external work, the mechanical work was compared with the total energy expenditure, determined using an expired air analysis. At 1.34 and 1.79 m/s, 53.2 +/- 9.3% and 62.8 +/- 8.6%, respectively, of the total energy can be explained by lift work. At 0.45 and 0.90 m/s, the proportions are considerably less, 21.6 +/- 6.6% and 37.6 +/- 8.2%, respectively. These findings provide a rationale for why the metabolic energy cost per unit distance is greater at slower speeds than comfortable or fast speeds of walking. The total energy consumption can be accounted for by changes in the potential and kinetic energies and internal muscular work, defined as the less readily observable work probably needed for balance. The present study demonstrated that the metabolic energy cost of changing the potential energy of the center of mass during walking is significantly less relative to the total energy consumption at slower speeds than at higher speeds. Because kinetic energy is proportional to the square of the velocity, the metabolic energy cost of changing this energy is relatively small at slower speeds. Internal muscular work must therefore play a large role in total energy consumption at slow speeds of walking.

An educational program was developed incorporating people with disabilities (PWDs) as "consumer-trainers" who educate physical medicine and rehabilitation residents about challenges in everyday living and their solutions to these. During the residency postgraduate years 2 and 4, pairs of residents visited trainers in their homes and at their jobs to learn about their lifestyles and adaptations. Residents' described the experience as "excellent, outstanding, invaluable" in more than half of the evaluations. PWDs can educate physical medicine and rehabilitation residents about living with disabilities. This new residency educational strategy encourages residents to value the perspective of PWDs.