A refined view of the determinants of gait: significance of heel rise.

OBJECTIVES: Although the major determinants of gait described by Saunders and colleagues have been accepted for more than 40 years, recent investigations raise the question of whether the reduction in center of mass (COM) displacement compared with a compass gait model indeed results from the factors originally described. We tested the hypothesis that heel rise at the end of stance is a true determinant that can explain a considerable portion of the reduction in COM vertical displacement during walking. DESIGN: Stereophotogrammetric data during walking were collected. A modified compass gait model incorporating the effect of heel rise, as compared with predictions based on a standard compass model, were used to estimate the isolated effect of heel rise on reducing the vertical displacement of COM. SETTING: A gait laboratory. PARTICIPANTS: Thirty able-bodied subjects. MAIN OUTCOME MEASURE: The estimated reduction in COM displacement due to heel rise was compared with the actual reduction in displacement. RESULTS: The estimated effect of heel rise on reduction in COM displacement was 23.4+/-7.6mm, whereas the actual reduction in COM displacement was 21.2+/-6.5mm (difference not significant, paired p = .185). CONCLUSION: During normal walking, heel rise from foot flat has a considerable role in raising the height of the COM when it is at its lowest, thus reducing its overall displacement. Insofar as reduction of COM vertical displacement may have important energy implications, appreciating the specific gait parameter of heel rise is key in rehabilitative approaches to improve gait disability.