Anticipatory postural adjustments in the shoulder girdle in the reach movement performed in standing by post-stroke subjects Cl audia F. Silva a , Soraia Pereira b , Cl audia C. Silva b ,S  ılvia Ferreira a , Nuno Oliveira c and Rubim Santos d a Pysiotherapist graduate at the School of Health, Polytechnic Institute of Porto, Porto, Portugal; b Department of Physiotherapy, School of Health, Polytechnic Institute of Porto, Porto, Portugal; c Department of Physics, School of Health, Polytechnic Institute of Porto, Porto, Portugal; d Department of Physics and Activity and Human Movement Study Center (CEMAH), School of Health, Polytechnic Institute of Porto, Porto, Portugal ABSTRACT After a stroke in middle cerebral artery territory, there is a high probability of dysfunction of the ventromedial pathways, mainly related with postural control mechanisms such as the anticipatory pos- tural adjustments (APAs). According to neuroanatomical knowledge, these pathways have a predomin- ant ipsilesional disposition, which justifies a bilateral postural control dysfunction, often neglected in rehabilitation. In order to assess this bilateral postural control dysfunction, electromyography activity was assessed in eight post-stroke and 10 healthy individuals in the anterior deltoids, the superior and lower trapezius, and the latissimus dorsi as they reached for a bottle with both upper limbs separately at a self-selected velocity and fast velocity while standing associated with trunk kinematics analysis. Through this analysis it was possible to compare the timing of APAs in scapular muscles between sides in post-stroke and with healthy individuals, and to verify if there is a relation between the timing and the displacement of the trunk in the temporal window of the APAs. Indeed, post-stroke individu- als show a delayed activation of APAs on scapular girdle muscles on both ipsilesional and contrale- sional sides, which were not reflected in the trunk displacement. KEYWORDS Anticipatory postural adjustments; stroke; reach movement; standing; scapular stabilisers Introduction Reaching while standing is an essential task of daily life that requires spatial and temporal coordination to efficiently inte- grate the intended movement with appropriate postural con- trol (McCombe Waller et al. 2016). This is a unique challenge to the central nervous system (CNS) that has to coordinate anticipatory postural adjustments (APAs) by anticipatory recruitment of the postural muscles, 100 ms to 50 ms prior to muscle activation. Studies about APAs in reaching while standing have high- lighted an initial inhibition of the soleus muscle, followed by the activation of the tibialis anterior (McCombe Waller et al. 2016). On the other hand, prior to the activation of the anterior deltoid (AD), the lateral gastrocnemius, the biceps femoral and the erector of the spine are simultaneously acti- vated with the rotator cuff muscles (Dietz et al. 2000; Tyler and Karst 2004). Although previous studies have only focused on the lower limbs during reaching while standing, the task also demands a modification of the upper trunk orientation (Dickstein et al. 2004), including the scapula. With a better understand of the shoulder and the surrounding structures the scapula role in promoting optimal shoulder complex function with interaction of scapulohumeral anat- omy and biomechanics in order to produce efficient move- ment has become recognized. To allow for the stability of shoulder movement, a coordinated activity of the surrounding musculature must be recruited in an anticipa- tory manner (Kibler et al. 2013) to allow the normal function of the glenohumeral joint (Paine and Voight 2013). After a stroke the anticipatory postural activity (APA) may be compromised. Indeed, unilateral strokes in the territory of the middle cerebral artery (MCA) cause subcortical lesions, resulting in injury of the internal capsule and the corticofugal fibres that connect with the pontomedullary reticular forma- tion, which is responsible for APAs (McCombe Waller et al. 2016). Injury in the corticoreticular connections prompts dys- functions in the ventromedial systems, including the cortico- reticular pathway, which could be associated with impairment of APAs on either the ipsilateral or contralateral side of the injured hemisphere (Matsuyama et al. 2004). In fact, considering the ventromedial system disposal, which, although bilateral, has a predominant ipsilateral projection, the ipsilesional deficits can no longer be ignored by the clin- ical and research community. That dynamic was identified by Pereira et al. (2014), who verified a delayed onset of APAs in the scapular stabilizers on both sides of the body among post-stroke individuals during sitting reach movement. However, standing is a more complex and challenging mech- anical task, given the relatively high location of the centre of mass and the small area of support (Piscitelli et al. 2016). It becomes even more challenging after a stroke, due to larger postural sway and weight-bearing asymmetry