The development of trunk control and its relation to reaching in infancy: a longitudinal study

Abstract

The development of reaching is crucially dependent on the progressive control of the trunk, yet their interrelation has not been addressed in detail. Previous studies on seated reaching evaluated infants during fully supported or unsupported conditions; however, trunk control is progressively developed, starting from the cervical/thoracic followed by the lumbar/pelvic regions for the acquisition of independent sitting. Providing external trunk support at different levels to test the effects of controlling the upper and lower regions of the trunk on reaching provides insight into the mechanisms by which trunk control impacts reaching in infants. Ten healthy infants were recruited at 2.5 months of age and tested longitudinally, until 8 months. During the reaching test, infants were placed in an upright seated position and an adjustable support device provided trunk fixation at pelvic and thoracic levels. Kinematic and electromyographic data were collected. Results showed that prior to independent sitting, postural instability was higher when infants were provided with pelvic compared to thoracic support. Associated reaches were more circuitous, less smooth and less efficient. In response to the instability, there was increased postural muscle activity and arm muscle co-activation. Differences between levels of support were not observed once infants acquired independent sitting. These results suggest that trunk control is acquired in a segmental sequence across the development of upright sitting, and it is tightly correlated with reaching performance.

Effect of Segmental Trunk Support on Posture and Reaching in Children With Cerebral Palsy

“…We recently explored reaching performance across development of segmental trunk control. 16 Infants who had not acquired control of the lumbar region demonstrated significant postural and reaching impairments with pelvic compared to mid-ribs support. However, once infants had acquired lumbar control, and thus, had the ability to sit independently, reaching differences between levels of support disappeared.…”

“…16,17 Postural control and reaching performance are dependent on the extent of segmental trunk control acquired during sitting development. 16 Children with CP (GMFCS III–V), without the ability to sit, display segmental deficits of the trunk, comparable to those observed during sitting development in typical infants. In fact, the extent of segmental trunk control acquired, measured with the Segmental Assessment of Trunk Control (SATCo), is related to the child’s functional disability.…”

Versão brasileira da Segmental Assessment of Trunk Control (SATCo)

“…A good evaluation instrument must address what is desired to investigate, be trustful to the investigated population, present validity, be of easy applicability and sensitive to changes 10 . SATCo showed high correlation with Alberta Infant Motor Scale (r=0.86), Bayley Scales of Infant and Toddler Development Test (r=0.83) and age (r=0.90) 4 . However, there are studies that confirm the instrument validity.…”

“…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 .…”

Infants plan prehension while pivoting

“…Fast and efficient visual and manual actions are rooted in improvements in postural control (Bertenthal & von Hofsten, 1998;Rachwani et al, 2013;Rachwani, Santamaria, Saavedra, & Woollacott, 2015;Reed, 1989). Postural control sets up the prerequisites for looking around, orienting eyes, head, and trunk to the target location.…”