Which two motor response types are produced by NMES?

• A. Direct motor response via peripheral pathways and reflex motor response via spinal reflexes
• B. Voluntary motor response and involuntary motor response
• C. Cortical motor response and brainstem response
• D. Autonomic response and somatic response

Answer: (A)

NMES can produce muscle activity through two mechanisms, giving two types of motor responses: a direct motor response and a reflex motor response.

The direct motor response happens when the electrical current directly depolarizes motor nerves or the axons within peripheral pathways. That forces the muscle to contract without needing any processing by the brain—essentially a straightforward, stimulus-driven contraction of the stimulated muscle.

The reflex motor response arises when the stimulation also activates sensory afferent fibers that enter the spinal cord and engage reflex circuits. This produces a contraction via a spinal reflex pathway, which can involve the same or neighboring muscles and may have a different timing or recruitment pattern than the direct response.

These two types reflect how NMES can trigger muscle activity either by directly exciting motor elements or by engaging spinal reflexes. NMES targets the somatic peripheral system, not voluntary brain commands or autonomic responses, which is why options emphasizing voluntary, cortical/brainstem, or autonomic responses don’t fit.