The purpose of this study was to evaluate body-sway characteristics during anticipatory and reactive postural compensation. Mechanisms of postural control were studied during self-initiated rapid arm movements (RAMs) and unexpected @entity572 ( @entity572 ). Ten healthy subjects, 5 @entity1 and 5 @entity1 with a mean age of 28 years, were blindfolded and stood symmetrically on a moveable force platform or with weight shifted right (R) or left (L). Averaged electromyographs were obtained from L anterior deltoid, L ipsilateral biceps femoris (BFi), R contralateral biceps femoris (BFc), R quadriceps (Q), R medial gastrocnemius (G), and R tibialis anterior (TA) muscles. During @entity15838 , the relative timing of distal-proximal synergists was altered during all biased postures. In L biased standing, functional pairs, TA-Q and G-BF, discharged at their shortest latencies. Anterior deltoid onset times during RAM were most preparatory during R weight shift. Sway latencies were shorter also in biased standing. Absolute sway latency, peak sway, and time-to-peak sway were significantly longer in @entity15838 conditions in comparison with RAM. When disturbances in balance cannot be predicted, lower extremity preloading facilitates contralateral muscle-discharge patterns at shorter latencies. In some neurological conditions that result in incorrect body alignment, the mechanical effects of postural bias rather than the abnormal control mechanisms may at least contribute to alterations in the postural response. These results provide a basis for evaluating balance in @entity1 with @entity51 .

Effects of postural bias during XXXX and rapid arm movements.

@entity1 :: ('9606', 'Species') :: ['women', 'patients', 'men'] @entity51 :: ('MESH:D009461', 'Disease') :: ['neurological deficit'] @entity572 :: ('MESH:D006617', 'Disease') :: ['SSDs', 'support surface displacements'] @entity15838 :: ('MESH:C563928', 'Disease') :: ['SSD']
@entity572 :: (MESH:D006617,Disease) :: ['support surface displacements']
