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Electromyography (EMG) : Hear and See Muscles in Action
  • Human
  • Grade 4+

Electromyography (EMG) of Motor Movements

How does your brain make your body move? This experiment dives into the fascinating world of motor control, showing how neurons in your motor cortex communicate with muscles to generate movement. Let’s explore the electrical signals behind every step, jump, and dance!

Devices and Accessories7Related Experiments1

About the Experiment

What Will You Learn?

What Will You Learn?

  • How the motor cortex sends electrical signals to control movement.
  • How to record and analyze muscle action potentials using a SpikerBox.
  • The difference between neural and muscle action potentials.
Background

Background

Movement lets us explore the world, but how does your brain tell your body what to do? Neurons in the motor cortex fire, signals zip down the spinal cord, and motor neurons activate muscle fibers. In this experiment, you’ll record those signals—called motor-unit action potentials—to see how they translate into force.

Experiment

  1. Biceps EMG Recording

    Biceps EMG Recording

    Materials:

    • Human SpikerBox (or Muscle SpikerBox)
    • Orange electrode cable
    • Patch electrodes (3)
    • Smartphone, tablet, or computer with SpikeRecorder

    Setup:

    • Place two patch electrodes on your biceps, spaced a few centimeters apart but over the same muscle.
    • Attach the red recording clips to the patch electrodes. Clip the black ground lead to the back of your hand or to metal jewelry.
    • Connect the orange cable to the SpikerBox and power it on.
    • Launch SpikeRecorder and confirm the device is recognized.

    Procedure:

    • Relax your arm and record a 10-second baseline.
    • Slowly flex your biceps. Listen for the popping sound of motor units firing and watch the spikes on the screen.
    • Hold the contraction for 5 seconds, then relax.
    • Repeat the flex-and-relax cycle five times, logging the data for later analysis.
Results & Analysis

Results & Analysis

Compare spike shapes during contraction versus relaxation. Muscle spikes are broader than neural spikes—measure their widths in SpikeRecorder. Does spike frequency rise with stronger flexion? Plot your data and discuss how motor-unit recruitment scales force.

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