[Postural adjustments to voluntary movements. Electrical activity of muscles and biomechanics of the human body in an upright position].

Involuntary movements of the pelvis and legs which accompany voluntary arm flexion and correct the orthograde posture start in most trials in normal subjects simultaneously with the voluntary arm movement or later was demonstrated. At the same time bursts of legs and trunk muscles activity anticipate the burst of m.deltoideus activity. In this situation the electromechanical delay (EMD) of m.deltoideus is significantly shorter (13-18 ms) than EMD of legs and trunk muscles (70-80 ms). Perhaps more long EMD of legs and trunk muscles in orthograde posture "impels" anticipation of its activity for economic control of the body position in initial period of a fast voluntary movement.