PATTERNS OF MUSCLE ACTIVATION ACCOMPANYING TRANSITIONS IN STANCE DURING RAPID LEG FLEXION

The organization of electromyographic. ground reaction force, and tota l body kinematic responses accompanying dynamic transitions from biped al to unipedal stance during rapid leg flexion movements was examined in healthy human subjects. An impulse-momentum model of motion of the centre of body mass (CM) was used to predict the patterns of muscle ac tivation among bilateral hip abductor-adductor muscles with respect to the primary task muscle. The results indicated an intralimb and inter limb coupling of hip muscle activations which preceded and accompanied the leg flexion response and were compatible with contributing to inc reasing and subsequently reducing momentum of the CM in the frontal pl ane. Overall, the findings suggested that the coordinative interaction of postural and intended movement components may be a reflection of t he mechanical constraints inherent to stance alteration function.