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Unexpected Fascicle Length Changes In Denervated Feline Soleus Muscle During Stance Phase Of Walking
Ricky Mehta1, Huub Maas2, Robert J Gregor1,3
1School of Applied Physiology, Center for Human Movement Studies, Georgia Institute of Technology, Atlanta, GA, USA.
Scientific Reports
|December 5, 2015
Summary
Even after nerve injury, paralyzed feline soleus (SO) muscle fascicles change length during walking. This suggests connected muscles influence paralyzed limb movement.
Area of Science:
- Biomechanics
- Neuroscience
- Muscle Physiology
Background:
- Peripheral nerve injuries often result in temporary muscle paralysis, impacting motor function.
- Understanding fascicle dynamics in paralyzed muscles during locomotion is crucial for rehabilitation strategies.
- Limited knowledge exists regarding muscle fascicle length changes in denervated muscles during active movement of synergists.
Purpose of the Study:
- To investigate fascicle length changes in denervated feline soleus (SO) muscles during walking stance.
- To determine the influence of active synergist muscle contraction on paralyzed SO fascicle dynamics.
- To quantify these changes across different walking conditions (level, upslope).
Main Methods:
- Measurements of hindlimb kinematics, fascicle length, muscle-tendon unit (MTU) length, and electromyography (EMG) in adult cats.
- Data collected during level and slope walking before and 1-2 weeks after SO and lateral gastrocnemius (LG) denervation.
- Analysis of SO, LG, and medial gastrocnemius (MG) EMG activity and muscle length dynamics.
Main Results:
- Denervated SO fascicles exhibited both lengthening and shortening during walking stance, contrary to expectations.
- Greatest fascicle shortening (17.3%) and least lengthening (1.5%) occurred during upslope walking.
- Significant discrepancies between post-denervation SO fascicle and MTU length changes were observed, particularly during upslope walking with high MG activity.
Conclusions:
- Paralyzed SO fascicle length changes during locomotion are influenced by factors beyond direct neural activation.
- Myofascial linkages between denervated muscles and their active synergists may play a significant role.
- Further research is necessary to elucidate the mechanisms of these inter-muscular interactions in paralyzed limbs.
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