Related Experiment Videos
Patterns of muscle activation in human hopping
K Funase1, T Higashi, A Sakakibara
1School of Allied Medical Sciences, Nagasaki University, Japan. funase@net.nagasaki-u.ac.jp
European Journal of Applied Physiology
|August 3, 2001
Summary
Human hopping relies on short-latency reflexes in the soleus muscle for landing and voluntary activation for propulsion. Researchers found no evidence of long-latency stretch reflexes during this natural movement.
Area of Science:
- Biomechanics
- Human Movement Science
- Neurophysiology
Background:
- Rhythmical hopping is a natural human movement.
- Understanding muscle activation and reflex contributions is crucial for analyzing locomotion.
Purpose of the Study:
- To investigate the electromyogram (EMG) patterns of soleus and medial gastrocnemius (MG) muscles during two-legged hopping.
- To determine the roles of short- and long-latency stretch reflexes in human hopping.
Main Methods:
- Electromyogram (EMG) analysis of soleus and medial gastrocnemius (MG) muscles.
- Subjects performed rhythmical, two-legged hopping at preferred frequencies.
Main Results:
- Soleus muscle showed reflex activation at near-monosynaptic latency upon landing and voluntary activation for propulsion.
- Medial gastrocnemius (MG) exhibited initial activity for stiffening, with superimposed monosynaptic reflex responses.
- No evidence of long-latency stretch reflexes was observed during hopping.
- Preferred hopping frequency was approximately 2 Hz, balancing landing and propulsion.
Conclusions:
- Hopping involves a combination of short-latency reflexes and voluntary muscle activation.
- The nervous system optimizes muscle activity patterns around 2 Hz for efficient hopping.
- Long-latency stretch reflexes do not appear to contribute significantly to this natural human movement.