WHY WE WALK THE WAY WE DO

By using inverse dynamics and forceplate recordings, this study establ ished the principle of oscillating systems and the influence of gravit y and body parameters on the programming of the gait parameters, step frequency and length. Calculation of the ratio of the amplitude of the center of mass (CM) and the center of foot pressure (CP) oscillations yielded an equation and established a biomechanical constant, the nat ural body frequency (NBF). NBF appears to be an absolute invariant par ameter, specific to human standing posture and gait in terrestrial gra vity, which influences the relative positions of CM and CP and whose v alue separates the frequency bands of standing posture from those for gait. This equation was tested by using the experimental paradigm of s tepping in place and then used in calculating the magnitude of CM osci llations during gait. The biomechanical analysis of the experimental o bservations allows one to establish the relationships between body par ameters and gravity and the central programming of locomotor parameter s.