387 Motor Control, 2009, 13, 387-411 © 2009 Human Kinetics, Inc. Muscle Activation Patterns and Postural Control Following Stroke S. Jayne Garland, Vicki L. Gray, and Svetlana Knorr Many stroke survivors have residual sensorimotor defcits that impact negatively on balance and quality of life. The purpose of this review is to provide an overview of the impairments in motor control following stroke and the impact of those impairments on muscle activation patterns during postural control in stroke. Motor control impair- ments following stroke result in force production that is slow, weak and lacking in precision making it diffcult to produce a fast rate of force development with suffcient magnitude to be effective for postural responses. Whether postural perturbations require feedback or feedforward responses, there is impairment to the timing, magni- tude and sequencing of muscle activation following stroke. The impairment in muscle activation is dependent on the extent of the motor control impairments and strategies used by the individuals following stroke to compensate for the impairments. The cen- tral nervous system uses a variety of mechanisms to improve the muscle activation patterns needed for the recovery of postural responses following stroke. Keywords: electromyography, force, balance, movement Many stroke survivors have residual sensorimotor defcits that impact nega- tively on balance and quality of life. Indeed, it has been reported that 83% of patients 2–4 weeks poststroke had a balance disability and practicing balance and walking activities comprised 34% of physiotherapy treatment (Tyson & Selley, 2006). The impact of standing balance on activities of daily living can be signif- cant, in that standing balance is associated with ambulatory ability and indepen- dence in gross motor function (Berg, Wood-Dauphinee, & Williams, 1995; Pat- terson et al., 2007; Piotrowski & Cole, 1994; Tyson, Hanley, Chillala, Selley, & Tallis, 2007). The ability to stand and walk infuences hospital length of stay (Wee, Bagg, & Palepu, 1999) and discharge disposition (Wee & Hopman, 2005). Thus, regaining independent standing balance and ambulation is of paramount impor- tance for patients recovering from stroke. The purpose of this review is to provide an overview of the impairments in motor control following stroke and the impact of those motor control impairments on muscle activation patterns during postural control in stroke. Garland is with the Dept. of Physical Therapy, University of British Columbia, Vancouver, British Columbia. Gray and Knorr are with the School of Physical Therapy, University of Western Ontario, London, Ontario.