When performing trunk extension from a flexed position, around which axis does the movement occur?

When performing trunk extension from a flexed position, the movement occurs around the X axis, which runs horizontally through the body from side to side. In biomechanical terms, trunk extension involves moving the torso backward, lifting it into an upright position from a flexed state (where the torso leans forward).

This backward movement is characterized as occurring in the negative direction along this axis, meaning that the angle between the torso and the thighs increases. The X axis is considered in a negative direction during this action since the movement is typically observed as an extension (moving away from the flexed position) rather than a further flexion or any lateral movements.

Understanding this axis and the direction of movement is crucial in clinical biomechanics, as it helps practitioners analyze movement patterns, identify any abnormalities, and develop appropriate interventions or exercises aimed at enhancing trunk stability and mobility.