Learning about gravity: segmental assessment of upright control as infants develop independent sitting

Abstract

The question of how infants attain upright sitting is at the core of understanding the development of most functional abilities. Our simple, practical method of securing the hips and different trunk segments while evaluating the infant's ability to vertically align and stabilize the trunk in space contributes a useful method and new insights into the development of upright control. Previous studies have considered the trunk to develop as a single segment. The goal of the present study was to examine how postural control changes across multiple trunk segments during typical development (TD) of sitting balance. For this purpose, electromyography (EMG) and kinematic data were collected at four levels of trunk support (axillae, midribs, waist, hips), in a longitudinal study of eight TD infants (3-9 mo of age). We found that developmental changes in stability were specific to the region of the trunk being investigated, changes in antagonistic muscle activity differed for the anterior-posterior versus the medial-lateral axis, and the relationship between muscle activation and movement changed from erratic attempts to gain upright position to anticipatory graded responses as infants developed upright control through a four-stage behavioral process. This information can be used by researchers to further refine hypotheses regarding this developmental process and by clinicians who wish to develop and test more specific treatment programs for children with postural dysfunction.

Versão brasileira da Segmental Assessment of Trunk Control (SATCo)

“…The ability to maintain balance in sitting posture gradually emerges in children with typical development at around six months of age. It begins with the development of the head control, followed by the progressive development of trunk control 3,4 . In children with neuromotor disabilities, motor control may be altered and, depending on the severity of the disorder, it can present restrictions of balance in sitting posture throughout life, without ever acquiring the independent control of the trunk movement 5 .…”

Segmental Contributions to Trunk Control in Children With Moderate-to-Severe Cerebral Palsy

“…We previously used a segmental approach to evaluate changes in trunk control in TD infants prior to acquisition of sitting 11 . Our simple, practical method of securing the hips and different trunk segments while evaluating the infant’s ability to vertically align and stabilize the trunk in space showed that developmental changes in stability were specific to the region of the trunk being investigated.…”

Trunk and respiratory motor control in typically developing children and its implications in children with chronic spinal cord injury.

“…The test has been used in pediatric clinics to measure precise control of sitting balance at various levels of support (P. B. Butler et al, 2010;MB, 1943;Rachwani et al, 2013;Sandra L. Saavedra, 2012). During reactive control, the external perturbation is provided in all four directions (front, back, right and left) using two fingers.…”

“…During typical development, posture control of trunk is different for different trunk segments (Curtis et al, 2015;Rachwani et al, 2013;Sandra L. Saavedra, 2012). …”

“…During typical development, posture control of trunk is different for different segments of trunk (Curtis et al, 2015;Rachwani et al, 2013;Sandra L. Saavedra, 2012). SCI at the cervical or thoracic level causes impaired trunk control due to paresis or paralysis or spasticity of major trunk muscles, hence, inability to sit without support (Bjerkefors, Carpenter, Cresswell, & Thorstensson, 2009;Bolin, Bodin, & Kreuter, 2000;Potten, Seelen, Drukker, Reulen, & Drost, 1999) Muscles of the trunk have the dual function of maintaining trunk posture and respiration (Paul W. Hodges & Gandevia, 2000;P.…”