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Updated: Jul 4, 2026
10:40
Measuring Neuromuscular Junction Functionality
Published on: August 6, 2017
High frequency tendon reflexes in the human soleus muscle
Maria Carolina Dos Santos Fornari1, André Fabio Kohn
1Neuroscience Program and Biomedical Engineering Laboratory, Universidade de Sao Paulo, Brazil.
Neuroscience Letters
|June 17, 2008
Summary
High-frequency vibration bursts applied to the Achilles tendon elicit rapid, sequential soleus muscle reflexes. This suggests distinct motoneuron pools activate phasically during vibratory stimulation of human tendon reflexes.
Area of Science:
- Neuroscience
- Human Physiology
- Motor Control
Background:
- Tendon reflexes are crucial for studying the human nervous system in both healthy and diseased states.
- Previous research has primarily investigated reflexes using single taps or prolonged vibrations.
Purpose of the Study:
- To investigate soleus muscle responses to high-frequency vibration bursts applied to the Achilles tendon.
- To determine if tendon reflexes can occur in rapid succession.
Main Methods:
- Subjects stood in quiet stance or a forward-leaning posture.
- A high-frequency vibration burst (3 cycles of a 100 Hz sine wave) was applied to the Achilles tendon.
- Electromyogram (EMG) activity of the soleus muscle was recorded.
Main Results:
- The soleus EMG typically displayed three distinct components, separated by 10 ms.
- These components were interpreted as three individual reflexes, each triggered by a cycle of the vibration burst.
- This rapid, phasic response occurred despite potential synaptic depression and motoneuron hyperpolarization.
Conclusions:
- Soleus tendon reflexes can respond in quick succession to brief, high-frequency vibratory stimuli.
- The findings suggest that different subsets of motoneurons may respond to individual cycles within the vibratory burst.
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