Training sitting: principles and assumptions

Importance of independent sitting 

"Sitting is one of the key motor milestones in the first year of life, which changes the way infants interact with the world." Dinkel 2017

"From the sitting position, looking, reaching, and interacting become functional and allows exploration that supports learning and further development of motor skills." Dinkel 2017

Sitting development is related to gesture and babble onset (LeBarton 2016).

TOMT training activities follow the natural progression of sitting development

The development of sitting involves increasing control over the segments involved in sitting erect and maintaining balance nl head, upper torso, lower torso and pelvis (Butler et al 2010,  Rachwani et al 2015). 

The development of sitting starts with the infant first learning to hold the head erect and steady when supported around the upper chest in an upright position. 

will 6w sitting.jpg   Will4m2w sitting with caregiver support 14.jpg

Over time and with practice the infant learns to stabilize the head and trunk when supported around the waist, and later with support around the pelvis. 

At this stage typically developing infants are usually more interested in reaching and an grabbing interesting toy than maintaining balance. 

Will 11w sitting.jpg       Will 5m sitting.jpg

This increasing level of control of the trunk on the pelvis is promoted by frequent opportunities to sit with support during everyday routines and handling. 

Will4m2w sitting with caregiver support 14.jpg   Sitting on my lap 3.jpg

Once the infant can stabilize the trunk on the pelvis, and sit briefly without arm or external support, typically developing infants start to pay attention to maintaining their balance as they reach out to connect with people and objects in their environment  (Harbourne et al 2013).

will 7m2w sitting reach side 2.jpg   will 7m2w sitting reach side 8.jpg

Postural stability and balance depend on integration of multiple sources of information

From birth infants make use of multiple sources of information regarding the position of the body in space: visual, tactile, vestibular.

A reliable and adaptive relationship between action and perception is necessary for postural control (Chen et al 2016).

"Newly sitting infants, however, show variable postural behavior and do not systemically respond to the visual stimulus. Our results suggest that visual-postural entrainment and sensory re-weighting are fundamental processes that are present after a few months post sitting. Sensorimotor refinement during early postural development may result from the interactions of improved self-motion control and enhanced perceptual abilities." (Chen et al 2016).

Postural stability and  balance are learned through repeated perception-action cycles 

Infant development is a process that involves the interaction of multiple systems within an environment. All spatially and temporally coordinated behaviors are organized as action systems involving the coupling of perception and action.

Perception-action theory proposes that movement (action) provides perceptual information that, in turn, influences movement and interaction with the environment. This perception-action cycle enhances motivation to move and promotes cognitive development. (Berthenthal)  BB (Downloaded 28 May 2017)

"The Russian physiologist, Nikolai Aleksandroich Bernstein (1896-1966) was one of the first to recognize that spatially coordinated behaviors involved more than simply programming muscular responses, because other factors such as inertia of the limbs, reactive forces from the support surface, and initial postural conditions always combine with active muscle forces in producing complex chains of multi-segment movements. All of these factors, or degrees of freedom, necessitate that active muscle forces are modulated by perceptual information to insure a functionally organized and goal-directed response. As actions continue to change over time so will the modulation of the perceptual information. In essence, perception and action form a continuous loop in which, according to James Gibson (1904-1979), “we must perceive in order to move, but we must also move in order to perceive.” All spatially and temporally coordinated behaviors require the coupling of perception and action. For example, reaching for an object is guided by perceptual information specifying the relation between the self and the environment which changes as the reach progresses. These perceptual changes produce adjustments to hand and arm movements to insure that a reach is successful, which, in turn, modify the perceived relation between the reach and the target.

Similarly, perceptual information is necessary to maintain a balanced posture during the reach, but again the perceptual information changes as the posture is adjusted to that information. This cycle of perceptual changes and motor responses is dynamic and continuous. Neither perception nor action alone is sufficient to simultaneously maintain postural stability and perform goal-directed actions. Moreover, each time the same action is performed (e.g., reaching for a glass), the initial conditions between the actor and the goal (e.g., distance and size of the glass, posture, inertia of the limbs) will differ requiring variations in the movements and the response." (Bertenthal: Perception and Action  page 4)

Sitting development is influenced by child rearing practices

Sitting development is influenced by cultural differences in child rearing practices, with infants sitting independently with good balance at 5 months in  cultures promoting early sitting (Karalik 2016).

Infants learn when they actively engage in goal directed actions 

Intention and goals inform the choices infants make regarding the the actions that are needed to achieve their goals. Infants who are motivated to move, who have a strong interest in exploring objects and opportunities, will actively seek to achieve their goals. 

Infants will quickly refuse to continue cooperating with adult lead activities when they are thwarted or when an activity does not interest them. Other infants give up easily if they feel they cannot achieve a goal, or an activity appears to involve effort or challenges their balance. 

References 

Bertenthal, BB. Perception and Action.   (Downloaded 28 May 2017) https://pdfs.semanticscholar.org/eb4f/74f6546943442a1a0eb3340a6d249db501...

Butler, P., Saavedra, S., Sofranac, M., Jarvis, S., & Woollacott, M. (2010). Refinement, Reliability and Validity of the Segmental Assessment of Trunk Control (SATCo). Pediatric Physical Therapy : The Official Publication of the Section on Pediatrics of the American Physical Therapy Association, 22(3), 246–257.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2927393/#APP1

Dinkel D, Snyder K, Molfese V, Kyvelidou A. Postural control strategies differ in normal weight and overweight infants. Gait Posture. 2017 Apr 13;55:167-171. doi: 10.1016/j.gaitpost.2017.04.017. [Epub ahead of print] PubMed PMID: 28458148.

Harbourne RT, Lobo MA, Karst GM, Galloway JC. Sit happens: Does sitting development perturb reaching development, or vice versa? Infant Behav Dev. 2013 Jun;36(3):438-50.

Karasik LB, Tamis-LeMonda CS, Adolph KE, Bornstein MH. Places and postures: A cross-cultural comparison of sitting in 5-month-olds. J Cross Cult Psychol. 2015 Sep;46(8):1023-1038. Epub 2015 Jul 13. PubMed PMID: 26924852; PubMed Central https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4767024/

LeBarton ES, Iverson JM. Associations between gross motor and communicative development in at-risk infants. Infant Behav Dev. 2016 Aug;44:59-67. doi: 10.1016/j.infbeh.2016.05.003. Epub 2016 Jun 14. PubMed PMID: 27314943; PubMed Central PMCID: PMC4992626.

Rachwani, J., Santamaria, V., Saavedra, S. L., & Woollacott, M. H. (2015). The development of trunk control and its relation to reaching in infancy: a longitudinal study. Frontiers in Human Neuroscience, 9, 94. http://doi.org/10.3389/fnhum.2015.00094

Bibliography