The development of sit-to-stand in typically developing children aged 4 to 12 years: Movement time, trunk and lower extremity joint angles, and joint moments.

Background: Sit-to-stand (STS) movement is an important transition movement for daily life. STS movement is typically seen in children aged 1 year and older. According to the motor development process, the ability of children in different age groups to perform STS movement would be different before they meet the mutuality. However, it is still unclear whether there are changes in the STS movement of growing children and adults.

Research Question: Are there any differences in the movement time, joint angles, and peak joint moments of STS in typically developing (TD) children?

Methods: Motion analysis and the force plate system were used to analyze the STS movement in 77 healthy participants. All participants were asked to perform the STS movement using an adjustable bench with a self-selected pattern. Statistical analysis was done with respect to age (4-6, 7-9, 10-12, 18-25 years) and body height (1.00-1.20, 1.20-1.40, 1.40-1.60, 1.60-1.80 meters).

Results: Children aged 4-6 years (or 1.0-1.20 m height) took less time to accomplish STS movement than adults (or 1.60-1.80 m height). Children aged 4-9 years performed STS movement by using more trunk and hip flexion and anterior pelvic tilt, but less knee flexion and ankle dorsiflexion than children aged 10-12 years and adults. At the final standing position, children aged 4-12 years exhibited more knee extension and more ankle plantar flexion than adults. In addition, children aged 4-12 years had more peak trunk-pelvic extension and less peak knee extension moments than adults.

Significance: Different strategies to achieve the STS task were found among children aged 4-12 years in terms of total movement time, joint angle, and joint moments. Adult-like kinematic and kinetic STS patterns were not seen in children up to 12 years old.