The magnitude oi the GRF vector during the first part of the support phase was not significantly different between pre- and post intervention. Moreover, the ratio post- to pre-intervention in external knee adduction moment showed a high correlation with the ratio post- to pre-intervention in lever arm of the GRF acting A about the knee joint in the frontal plane (correlation coefficient up to 0.99). Therefore, the reduction of the external knee adduction moment in the elderly was associated with changes in the lever arms