Kinesiology and Functional Anatomy
This domain tests functional anatomy: how muscles produce and control force across joints, and how the nervous system coordinates movement. Items often ask you to identify the muscle action, the limiting factor at a joint angle, or the consequence of a weak link in a kinetic chain.
Core rules
- Concentric: muscle shortens while producing force; eccentric: lengthens under tension; isometric: no change in length.
- Length-tension: active force is highest near mid-range; passive tension rises at end range. Force-velocity: concentric force falls as shortening velocity rises; eccentric can exceed isometric.
- Pennate muscles pack more fibers and produce greater force; parallel/fusiform muscles favor speed and range.
- Agonist, antagonist, synergist, and stabilizer roles are task-dependent.
- Active insufficiency: a two-joint muscle cannot produce force at both joints simultaneously. Passive insufficiency: it cannot lengthen enough to allow full range at both joints.
- The kinetic chain transfers force through linked segments; proximal stability supports distal mobility.
Worked example
In a back squat, the gluteus maximus and quadriceps act eccentrically during descent, then concentrically during ascent. At the bottom, hip extensor length is shortened relative to standing, so their active force potential is reduced; the hamstrings also cross both hip and knee, so knee flexion shortens them at the hip while hip flexion lengthens them at the knee-joint positions change their effective length. A lifter who shifts excessively to the toes increases knee extensor demand and reduces hip extensor contribution.
Traps
- Calling every lengthening action "eccentric" even when no tension is produced.
- Assuming a muscle is equally strong through the whole range.
- Naming a muscle's role without considering the joint angle and load.
- Ignoring two-joint muscles when explaining range limitations.