Biomechanics of sit-to-stand and stand-to-sit in typical children aged 4 - 12 years and young adults

The aim of study is to investigate the biomechanical pattern of sit-to-stand and stand-to-sit movement in children aged 4 to 12 years and young adults. Seventy-six participants were separated into 4 groups as following: (1) 18 children aged 4-6 years; (2) 19 children aged 7-9 years; (3) 20 children aged 10-12 years; (4) 19 adults aged 18-25 years. All participants performed their preferred pattern of sit-to-stand and stand-to-sit movement. The results showed that two patterns of sit-to-stand movement were found including sit-to-stand with and without feet moving backward. Children performed sit-to-stand with and without feet moving backward while adults only performed sit-to-stand with feet moving backward. The proportion of children who did sit-to-stand with feet moving increased as the children were older. For sit-to-stand movement, children aged 4 to 9 years completed the task faster than children aged 10 to 12 years and adults. Children aged 4 to 9 years moved trunk forward faster and had more hip flexion than children aged 10 to 12 years and adults. Moreover, the maximum knee extension moments in children aged 4 to 9 years were less than adults. For stand-to-sit movement, children aged 4 to 9 years showed less knee flexion than adults. In addition, the children aged 4 to 9 years showed lower maximum knee extension and ankle dorsiflexion moments as compared to adults.  Therefore, the children aged 10 years and older would perform sit-to-stand and stand-to-sit movement like adults. This information was useful to help the clinicians to assess and interpret the sit-to-stand and stand–to-sit capability of the children to see how their performance deviated from the typical children. Moreover, this information can be used as the supporting document for clinical decision making in order to apply an appropriate treatment.