Biomechanics and Kinesiology Fundamentals
Core concepts
Candidates must apply anatomical and mechanical principles to movement. Understand planes and axes: sagittal plane with frontal axis (flexion/extension), frontal plane with sagittal axis (abduction/adduction), and transverse plane with longitudinal axis (rotation). Know joint types and their movement capabilities, muscle actions (concentric, eccentric, isometric), and the roles of agonist, antagonist, synergist, and stabilizer. Grasp levers: first class (fulcrum between load and effort), second class (load between fulcrum and effort), and third class (effort between fulcrum and load, the most common in the body). Also understand force-velocity and length-tension relationships, moment arms, and how posture and alignment affect load.
Traps in questions
A frequent trap is confusing the plane of motion with the axis of rotation. Another is misidentifying muscle action: lowering a weight under control is eccentric, not concentric. Questions may ask which muscle is the prime mover versus a stabilizer, so read carefully. Watch for lever-class errors; most human limbs are third-class levers, which favor speed and range over force. Also beware of assuming a muscle's action is fixed regardless of joint position.
Worked example
A biceps curl: the elbow flexes in the sagittal plane about a frontal axis. Lifting the dumbbell is concentric biceps action; lowering it slowly is eccentric. The elbow acts as a third-class lever because the effort (biceps insertion) lies between the fulcrum (elbow joint) and the load (hand).
Rule of thumb
Identify plane and axis first, then muscle action, then lever class; this sequence resolves most biomechanics items.