IB Syllabus focus: 'Movements occur in planes and rotations occur along axes. Students should describe movement using terms such as flexion, extension, abduction, adduction, pronation, supination and rotation.'
Understanding movement language lets you analyze technique accurately in sport and exercise. To answer IB SEHS questions well, you must link each movement term to the correct plane and the correct axis.
Planes and axes
Human movement is described using planes and axes so that actions can be named precisely. A movement usually occurs in a plane, while the body segment rotates around an axis that is perpendicular to that plane.
Plane: An imaginary flat surface through the body used to classify the direction of movement.
This makes movement analysis more accurate than using everyday words such as “up,” “down,” or “sideways.”
Practice Questions
FAQ
This is because the axis is always perpendicular to the plane of movement.
For example:
movement in the sagittal plane occurs around a transverse axis
movement in the frontal plane occurs around a sagittal axis
movement in the transverse plane occurs around a longitudinal axis
A good memory aid is: the axis “sticks through” the plane at a right angle.
With the elbow bent, the forearm can be seen rotating more clearly without as much movement from the shoulder.
This makes it easier to observe:
the palm turning down for pronation
the palm turning up for supination
When the arm is straight by the side, students sometimes confuse forearm rotation with whole-arm rotation at the shoulder.
Yes. Many real sporting actions are multiplanar, meaning they combine movements from different planes.
For example, a tennis serve may include:
trunk rotation in the transverse plane
elbow extension in the sagittal plane
shoulder abduction earlier in the action in the frontal plane
In analysis, break the skill into parts and identify the main movement at each joint rather than trying to label the whole action with one plane.
A common reason is that the body’s orientation changes during movement, especially in dynamic skills.
If the arm starts at the side and moves outward, that is straightforward abduction. But if the torso leans, rotates, or the arm changes position first, the movement may look different from a simple textbook example.
It helps to:
return mentally to anatomical position
focus on the joint being tested
ask whether the segment is moving away from the midline
Camera angle can make a movement appear to be in the wrong plane. A side view is usually best for flexion and extension, while a front view is often better for abduction and adduction.
If the angle is poor:
depth can be hidden
rotation may be missed
sideways movement can look forward or backward
When analyzing video, try to use the view that is most perpendicular to the plane of movement.
