What is the typical pulse duration range used for motor recruitment?

What is the typical pulse duration range used for motor recruitment?

• A. 50-150 microseconds
• B. 200-600 microseconds
• C. 600-1000 microseconds
• D. 10-50 microseconds

Answer: (B)

To recruit motor units with NMES, the pulse duration must be long enough to depolarize the thicker motor axons. Short pulses mainly activate sensory fibers and often produce little or no visible contraction, while longer pulses deliver more charge per pulse, reliably triggering motor unit action potentials. The mid-range duration of about 200 to 600 microseconds provides enough stimulus to evoke a strong but tolerable muscle contraction across many muscles, balancing effectiveness with comfort. Durations much shorter than this tend to be ineffective for motor recruitment, while durations much longer can increase discomfort and fatigue without always adding benefit.

To recruit motor units with NMES, the pulse duration must be long enough to depolarize the thicker motor axons. Short pulses mainly activate sensory fibers and often produce little or no visible contraction, while longer pulses deliver more charge per pulse, reliably triggering motor unit action potentials. The mid-range duration of about 200 to 600 microseconds provides enough stimulus to evoke a strong but tolerable muscle contraction across many muscles, balancing effectiveness with comfort. Durations much shorter than this tend to be ineffective for motor recruitment, while durations much longer can increase discomfort and fatigue without always adding benefit.