[Two dimensional analysis of floor reaction force in normal gait (author's transl)].

In order to estimate the gait with force plate, two dimensional analysis with Lisajou's figure composed of two of the three components of floor reaction force was attempted. In normal gait, sagittal component (alpha-diagram) appears as an inverted heart pattern, frontal component (beta-diagram) as a S-shaped pattern and horizontal component (gamma-diagram) as a Gourd-shaped pattern. The most important external force which acts on the body during progression is the sagittal component of floor reaction force, so that the author used the alpha-diagram which was composed of vertical and fore and aft forces for the purpose of gait analysis in normal adults. This study was conducted on 100 normal adults, 50 males and 50 females ranging in age from eighteen to thirty-five years. alpha-diagram was classified into 6 types in males and 5 types in females based on the shape of alpha-diagram and discriminant functions and there were some difference depending on the individual, sex and side was noted. Male differed from female mostly during the heel strike phase. Propulsion forces of dominant side was smaller than that of the other side.