Segmental trunk control acquisition and reaching in typically developing infants

Abstract

This study explored the influence of an external support at the thoracic and pelvic level of the trunk on the success of reaching, postural stability and reaching kinematics while infants reached for a toy. Seventeen infants (4–6 months) were clustered into two groups according to their trunk control assessed with the Segmental Assessment of Trunk Control (SATCo). Major differences were seen between groups with pelvic support, whereas with thoracic support, all infants showed similar quality reaching behaviours. With the external pelvic support, infants who had acquired trunk control in the lumbar region were more accurate in their reaching movements (less movement time, improved straightness of reach, less movement units and path length per movement unit) and were more stable (decreased trunk and head displacement) during a reach than infants that had only acquired trunk control in the thoracic region. These results support the hypothesis that trunk control influences the quality of reaching behaviour.

Behavioral flexibility in learning to sit

“…More experienced sitters are better able to distinguish possible from impossible actions (Adolph, 2000; Yonas & Hartman, 1993). They show more vertical trunk posture (Saavedra et al, 2012), a narrower sway region (Harbourne & Stergiou, 2003; Kyvelidou et al, 2009), more coordinated reaching actions (Rachwani et al, 2013; Rochat & Goubet, 1995), increased ability to turn and look around the room (Bertenthal & von Hofsten, 1998), and so on. Eventually, children are so adept at keeping balance in a sitting posture that they can ride a sled down a steep, snowy hill and balance on a swing and seesaw.…”

“…In the laboratory, infants show directionally-specific muscle responses when experimenters unexpectedly jerk the floor forward or backward (Hedberg, Carlberg, Forssberg, & Hadders-Algra, 2005; Woollacott, Debu, & Mowatt, 1987) or suddenly tilt the floor 4° up and down and then quickly back to horizontal (Hirschfeld & Forssberg, 1994). Indeed, infants show evidence of these aspects of flexibility—anticipatory muscle actions, postural adjustments, and reactive muscle responses—around the time that they pass criterion for independent sitting (Bertenthal & von Hofsten, 1998; Hopkins & Ronnqvist, 2002; Rachwani et al, 2013; Rachwani et al, 2015; Rochat & Goubet, 1995; Yonas & Hartman, 1993). However, new sitters still have much to learn.…”

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.…”