Interference Pattern

Interference Pattern Generation

Force Generation	First Recruited Motor Unit	Frequency Modulation
Recruitment of Motor Unit	Interference Pattern Signal	Factors Affecting IP

Models of Disease Processes

Normal Muscle
Neuropathy	Upper Motor Neuron Disease	Myopathy

Assessment Strategies

Methods of Analysis

Our Opinion

Recruitment Frequency

Definition

Example

Recruitment Ratio

Definition

Example

Visual Assessment at Maximal Effort

Definition	Example
The Sound of EMG	Simple Rules

Quantitative Analysis: Turns and Amplitude (TA)

Definition	Minimal Effort	Mild Effort
Moderate Effort	Maximal Effort	Analysis with Normal Cloud
Myopathy	Neuropathy	Comments

Quantitative Analysis: Precision Decomposition

EMG with Increased and Decreased Force

Motor Unit Recruitment and Firing Pattern

IP in Normal Muscle (Biceps)

Recruitment Frequency	Recruitment Ratio
Full IP (Fast Sweep)	Min - Max Effort, 2 Trials

Neuropathy

Typical Findings	Increased Recruitment Frequency (20+ Hz)	Increased Recruitment Ratio (More than 5)
Reduced IP (Slow/Fast Sweep)	Reduced IP (5 Consecutive Sweeps)	Reduced IP, High Amplitude
Discrete IP (Slow/Fast Sweep)	Discrete IP (Single MUP)
Weak Muscle: Reduced IP Normal/Low Amplitude	Irregular MU Firing: UMND

Myopathy

Typical Findings	Normal/Reduced Recruitment Ratio
Early Recruitment (Low Amplitude)	Increased Recruitment Frequency (?)
Full IP, Reduced Amplitude	Full IP, Reduced Amplitude
Low Amplitude at Low Force	Bimodal Amplitude at Higher Force	Bimodal Amplitude, Slow Sweep
Pratical Aspects