Symmetry and limb dominance in able-bodied gait: a review

As one of the most universal of all human activities, gait in the able-bodied has received considerable attention, but many aspects still need to be clarified. Symmetry or asymmetry in the actions of the lower extremities during walking and the possible effect of laterality on gait are two prevalent and controversial issues. The purpose of this study was to review the work done over the last few decades in demonstrating: (a) whether or not the lower limbs behave symmetrically during able-bodied gait; and (b) how limb dominance affects the symmetrical or asymmetrical behavior of the lower extremities. The literature reviewed shows that gait symmetry has often been assumed, to simplify data collection and analysis. In contrast, asymmetrical behavior of the lower limbs during able-bodied ambulation was addressed in numerous investigations and was found to reflect natural functional differences between the lower extremities. These functional differences were probably related to the contribution of each limb in carrying out the tasks of propulsion and control during able-bodied walking. In current debates on gait symmetry in able-bodied subjects, laterality has been cited as an explanation for the existence of functional differences between the lower extremities, although a number of studies do not support the hypothesis of a relationship between gait symmetry and laterality. Further investigation is needed to demonstrate functional gait asymmetry and its relationship to laterality, taking into consideration the biomechanical aspects of gait.