Motor Control, Mobility, and Stability Concepts
This domain tests the concepts behind the screen: mobility, stability, motor control, and strength are related but not interchangeable. FMS Level 2 questions often ask you to decide which concept a pattern is actually testing, then choose an intervention that matches it.
Definitions that matter
- Mobility is usable range of motion at a joint or region.
- Stability is the ability to control motion and maintain position under load or during movement.
- Motor control is the nervous system’s planning and coordination of posture and movement.
- Strength is the capacity to produce force; it can support stability but does not define it.
A pattern can fail because range is insufficient, because available range cannot be controlled, or because pain changes the strategy. Mobility without control becomes uncontrolled motion; stability without mobility forces compensation elsewhere. The screen samples both, but it does not isolate a single joint or muscle.
Applying the concepts
A deep squat requires ankle dorsiflexion, hip flexion, thoracic extension, and trunk control. A score of 2 with heels elevated may reflect limited ankle dorsiflexion, but do not assume that until a knee-to-wall or similar check supports it. If ankle range is adequate and the squat still fails, examine motor control of the squatting pattern, including foot pressure, pelvic position, and trunk strategy.
Worked example
A client’s deep squat scores 2 because the heels lift. The knee-to-wall check shows clearly limited ankle dorsiflexion on both sides. The priority is ankle mobility, not core strengthening. After range improves, retest the squat. If the heels now stay down but the torso still collapses forward, the next target is motor control and thoracic position, not more ankle stretching. This reasoning shows the exam that you can separate mobility from control and avoid treating a range problem with stability exercises.
Traps that cost marks
Stretching a region that needs stability; calling stability strength; assuming a tight muscle is a short muscle; ignoring the thoracic spine in overhead and squat patterns; and using core stability as a generic answer for every compensation.