IB Sports, Exercise and Health Science: Biomechanics practice questions

Question 1

A footballer swings the kicking leg forward from the hip with the knee extending, driving the ball straight ahead. In which plane and about which axis does this leg action occur?

Accepted Answer

Sagittal plane about the frontal (mediolateral) axis — Forward and backward movements such as hip flexion divide the body into left and right, so they occur in the sagittal plane, and the axis is always perpendicular to the plane, which makes it the frontal or mediolateral axis. Pairing the sagittal plane with a sagittal axis is the single most common error in this topic.

Question 2

A gymnast performs a cartwheel, travelling sideways with the trunk and limbs moving away from and back towards the midline. In which plane and about which axis does the whole-body rotation occur?

Accepted Answer

Frontal plane about the sagittal (anteroposterior) axis — Sideways movement divides the body into front and back, which defines the frontal plane, and the perpendicular axis runs front to back, giving the sagittal or anteroposterior axis. A cartwheel is the standard example because the body rotates as a whole in that plane.

Question 3

A swimmer starting a butterfly recovery lifts the straight arm sideways away from the midline of the body with the palm facing down. Which joint action at the shoulder is described?

Accepted Answer

Abduction at the shoulder — Movement of a segment away from the midline in the frontal plane is abduction, and the joint is named because the same term is used at the hip and at the fingers. Horizontal adduction would need the arm to be already at shoulder height and to travel across the body in the transverse plane, adduction returns the arm towards the midline in the frontal plane, and lateral rotation turns the humerus about its own long axis without carrying the arm away from the body.

Question 4

Which description matches the anatomical position used as the reference for describing human movement?

Accepted Answer

Standing erect, feet together and forwards, palms facing forwards — The forward-facing palms are what distinguish the anatomical position from the relaxed standing posture, and every directional term is defined against it. Describing a movement without that fixed reference makes terms such as medial rotation ambiguous.

Question 5

During a lateral cutting movement a basketball player turns the sole of the foot to face the midline of the body. Which joint action is described?

Accepted Answer

Inversion at the subtalar joint — Inversion turns the sole towards the midline and eversion turns it away, and both take place at the subtalar joint rather than at the talocrural hinge, which gives dorsiflexion and plantar flexion. Excessive inversion under load is the mechanism behind the common lateral ankle sprain.

Question 6

A netball player ruptures the anterior cruciate ligament while landing from a jump. Which structures does this tissue join, and what is its main mechanical role?

Accepted Answer

Bone to bone, restraining excessive movement at the joint — A ligament runs from bone to bone and its collagen fibres limit joint movement to a safe range, whereas a tendon joins muscle to bone and transmits contractile force. Ligaments have a poor blood supply, which is why a complete rupture heals slowly.

Biomechanics practice questions.

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