A deficit in central activation ratio (CAR) indicates?

A deficit in central activation ratio (CAR) indicates?

• A. Increased voluntary activation
• B. No change in CNS activation
• C. Central activation deficit
• D. Improved motor unit recruitment

Answer: (C)

Central activation ratio reflects how completely the brain and spinal pathways can drive the muscle during a maximal effort. When CAR is deficient, it means the CNS isn’t fully activating all the motor units even at maximal effort, revealing a central activation deficit. In testing, a supramaximal stimulus is applied during a maximal voluntary contraction; if the stimulus adds little force, CAR is high and CNS drive is near complete. If there’s a deficit, the stimulus elicits a noticeable additional force, indicating that not all motor units were being activated by the CNS. So a deficit in CAR points to central activation problems rather than issues with muscle or peripheral recruitment.

Central activation ratio reflects how completely the brain and spinal pathways can drive the muscle during a maximal effort. When CAR is deficient, it means the CNS isn’t fully activating all the motor units even at maximal effort, revealing a central activation deficit. In testing, a supramaximal stimulus is applied during a maximal voluntary contraction; if the stimulus adds little force, CAR is high and CNS drive is near complete. If there’s a deficit, the stimulus elicits a noticeable additional force, indicating that not all motor units were being activated by the CNS. So a deficit in CAR points to central activation problems rather than issues with muscle or peripheral recruitment.