Collecting Data for Motor Unit Decomposition

Overview

This article outlines the setup and data collection requirements for motor unit decomposition using the Trigno System. It covers sensor requirements; skin preparation and sensor placement; trial length and format; and muscle contraction recommendations necessary to ensure successful motor unit decomposition. Following these guidelines will help you capture high-quality EMG data in order to maximize motor unit yield.

Important

• Not all EMG data can be decomposed into motor units. Read this article to learn how to collect data that is compatible with our decomposition algorithm.

System Requirements

Step-by-Step Instructions

Step 1: Sensor Requirements for Motor Unit Decomposition

The only sensor that is compatible with NeuroMap for motor unit decomposition is the Trigno Galileo Sensor. To record valid data for motor unit decomposition, the Trigno Galileo Sensor must be configured with the following settings:

Important

• Only data from Trigno Galileo sensors can be decomposed

• At least 1 Trigno Galileo sensor is required for decomposition

1. Configuring your Trigno Galileo sensor

   1. Refer to our article Trigno Discover Getting Started Series: Trial Set-Up for more information on how to configure your sensor

   2. The following sensor configuration settings are required for decomposition

      1. EMG Sampling Frequency: 2000 Hz or 2222 Hz

      2. EMG Range: 11 mV

      3. EMG Bandwidth: 20–450 Hz

2. Compatible Sensor Modes:

   1. EMG Only

   2. EMG & IMU

   3. EMG & Orientation

3. If the sensor configuration is compatible with NeuroMap, a compatible indicator appears

   

   

4. If the sensor configuration is not compatible with NeuroMap, a warning will appear

   

   

Important

• Data must be collected in Trigno Discover or EMGworks in order to be compatible with NeuroMap for motor unit decomposition.

Step 2: Advanced Skin Preparation and Sensor Placement

Important

• High-quality EMG signal is crucial for accurate motor unit decomposition. Thorough skin preparation and sensor placement are strongly recommended and will directly influence the motor unit yield.

Skin Preparation

1. Full skin preparation must be done at the EMG sensor head site and at the reference site. This would typically include:

• Shaving the location to remove any excess hair

• Light abrasion of the skin at the chosen location

• Clean the location with a 70% isopropyl wipe

Sensor Placement

1. Place the EMG sensor head on the belly of the muscle.

2. Place the reference on a nearby location. Ensure that the four reference contacts are well-adhered and that the sensor lead has some slack. The reference does not have to be placed on a bony landmark.

3. Allow sensors to fully adhere to the skin before beginning data collection.

Once the skin has been prepared and the sensor has been placed, check the signal quality to ensure baseline noise is low.

Recommendation

• A low baseline noise level (< 0.03 mV) is recommended to achieve high-quality decomposition results.

Step 3: Trial Length and Format

1. Trial length is recommended to be between 30 seconds to 5 minutes. This is to give the algorithm enough data to get an accurate and reliable yield, but not too much data as that will cause elongated decomposition processing time.

2. Motor unit decomposition takes approximately 1 minute per second of data for each sensor (i.e. a 30-second trial may take ~30 minutes to decompose from a single sensor). A trial length of 5 minutes is our recommended maximum duration to avoid elongated processing times.

3. Data must be exported in .HPF format. NeuroMap can only decompose raw, unedited .hpf files.

Information

• Motor unit decomposition takes approximately one minute per second of data for each sensor (i.e. a 30-second trial with 2 sensors would take ~1 hour to decompose)

Summary Checklist

Before collecting data for decomposition using the Trigno system, ensure:

• You are using Trigno Galileo sensors

• EMG sampling frequency is 2000 Hz or 2222 Hz

• EMG range is 11 mV with 20–450 Hz bandwidth

• Data is collected in EMGworks or Trigno Discover

• Skin prep (shave, abrade, and clean) is done at the EMG and reference sites

• Your signal has a low baseline noise level (< 0.03 mV)

• Trial length is between 30 seconds and 5 minutes long

• Data files are exported in .HPF format

By following these guidelines, the data will be suitable for decomposition in NeuroMap and the output motor unit data and accuracy will be maximized for accuracy.

For further guidance on using NeuroMap (See Installing Neuromap and Decomposing Data)

For further guidance on interpreting decomposition results (See Analyzing Decomposed Data)

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