Voluntary movements of the upper body are accompanied by anticipatory postural adjustments to the lower body in a standing subject. The long-standing hypothesis is that these anticipatory adjustments serve to counteract the perturbation to the body's center of gravity caused by the voluntary arm movement. This paper presents model simulations investigating the possible roles of anticipatory postural activity that accompanies a rapid, upward arm swing. The model encorporates two (idealized) antagonistic muscle pairs controlling the movements of a double-joint system, with a “shoulder joint” between the arm and stiff body links, and an “ankle joint” between the stiff body-leg segment and the ground. Each muscle is represented by a nonlinear viscoelastic element and also includes proprioceptive feedback. Four inputs to the model define the motor control signals for muscle force generation in both the arm and the postural muscle pairs. The neurological component of the model describes consequences of alternate strategies for cocontractions, stretch reflex activity, and anticipatory and synchronous postural activities (or combinations thereof). Simulations with this model show that: (1) none of the postural maintenance schemes considered in these simulations (including varying anticipation) could suppress the initial backward thrust on the body link; (2) the more important destabilizing perturbation is a subsequent forward sway that, left uncountered by postural activity, would eventually leave the body to fall flat on its face; and (3) anticipatory silencing of the postural extensor followed by a brief period of extensor activation (descending control) and synchronous reflex activity (feedback control) appears to be the most likely postural stabilizing strategy that inhibits the continuous forward sway and is consistent with the experimental evidence.
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Bouisset S, Zattara M (1981) A sequence of postural movements precedes voluntary movement. Neurosci Lett 22:263–270
Bouisset S, Zattara M (1987) Biomechanical study of the programming of anticipatory postural adjustments associated with voluntary movement. J Biomech 20:735–742
Clement G, Gurfinkel VS, Lestienne F, Lipshits MI, Popov KE (1984) Adaptation of postural control to weightlessness. Exp Brain Res 57:61–72
Cordo PJ, Nashner LM (1982) Properties of postural adjustments associated with rapid arm movements. J Neurophysiol 47:287–302
Crenna P, Frigo C, Massion J, Pedotti A (1987) Forward and backward axial synergies in man. Exp Brain Res 65:538–548
Debu B, Gahery Y (1988) Postural adjustments to head movements in the cat. Arch Ital Biol 126:75–85
Friedli WG, Hallett M, Simon SR (1984) Postural adjustments associated with rapid voluntary arm movements I. Electromyographic data. J Neurol Neurosurg Psychiatry 47:611–622
Friedli WG, Cohen L, Hallett M, Stanhope S, Simon SR (1988) Postural adjustments associated with rapid voluntary arm movements. II. Biomechanical analysis. J Neurol Neurosurg Psychiatry 51:232–243
Hannaford B, Stark L (1985) Roles of the elements of the triphasic control signal. Exp Neurol 90:619–634
Lee WA, Buchanan TS, Rogers MW (1987) Effects of arm acceleration and behavioral conditions on the organization of postural adjustments during arm flexion. Exp Brain Res 66:257–270
Ramos CF, Stark L (1987) Simulation studies of descending and reflex control of fast movements. J Motor Behav 19:38–62
Ramos CF, Hacisalihzade S, Stark L (1990) The behaviour space of a stretch reflex model and its implications for the neural control of voluntary movements. Med Biol Eng Comp 28:15–23
Wadman WJ, Denier van der Gon JJ, Genze RH, Mol CR (1979) Control of fast goal directed arm movements. J Hum Mov Stud 5:3–17
Woollacott M, Bonnet M, Yabe K (1984) Preparatory process for anticipatory postural adjustments: modulation of leg reflex pathways during preparation for arm movements in standing man. Exp Brain Res 55:263–271
Zangemeister W, Lehman S, Stark L (1981a) Simulation of head movement trajectories: Model to fit main sequence. Biol Cybern 41:19–32
Zangemeister W, Lehman S, Stark L (1981b) Sensitivity analysis and optimization for a head movement model. Biol Cybern 41:33–45
Zatsiorsky V, Selayanov V (1983) The mass and inertia characteristics of the main segments of the human body. In: Matsui H, Kobayashi K, Biomechanics VIII-B. International series on Biomechanics 4B Proceedings of the Eighth International Congress of Biomechanics. Nagoya Japan. Human Kinetics Publishers, Champaign Ill
Zattara M, Bouisset S (1988) Posturo-kinetic organization during the early phase of voluntary upper limb movement. 1. Normal subjects. J Neurol Neurosurg Psychiatry 51:956–965
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Ramos, C.F., Stark, L.W. Postural maintenance during movement: Simulations of a two joint model. Biol. Cybern. 63, 363–375 (1990). https://doi.org/10.1007/BF00202753
- Reflex Activity
- Muscle Pair
- Anticipatory Postural Adjustment
- Extensor Activation
- Postural Maintenance