recruitment pattern
EMG assessment of how motor units are activated with increasing voluntary muscle contraction, indicating the integrity of motor neuron pools.
Full Definition
Recruitment pattern refers to the orderly activation and frequency modulation of motor units during voluntary muscle contraction as assessed by electromyography. Normal recruitment follows the size principle, where smaller motor units are recruited before larger ones, and firing frequency increases in a predictable manner. Abnormal recruitment patterns include decreased recruitment (fewer motor units firing at higher frequencies, seen in motor neuron disease), increased recruitment (more motor units firing at lower frequencies, seen in myopathy), and early recruitment (motor units recruited at low force levels, typical of primary muscle disorders). This assessment is fundamental to EMG interpretation and neuromuscular diagnosis.
Usage
Usage note: Key component of EMG interpretation requiring assessment at varying contraction levels.
In Context
- "The recruitment pattern was reduced with high-frequency firing, suggesting lower motor neuron dysfunction." — EMG interpretation
- "Early recruitment with low-amplitude potentials indicated a primary myopathic process." — Muscle disease evaluation