Related Experiment Videos
Principles underlying the organization of movement initiation from quiet stance
1Department of Physical Therapy, University of Florida, Gainesville, FL 100154, USA.
Gait & Posture
|September 30, 1999
Summary
Movement initiation, like gait and stepping, uses two coordinated motor programs. The timing between muscle activity and ground forces is consistent across different speeds and tasks, suggesting shared control mechanisms.
Area of Science:
- Biomechanics
- Motor Control
- Human Movement Science
Background:
- Understanding the fundamental principles of movement initiation is crucial for rehabilitation and performance enhancement.
- Gait initiation and stepping tasks involve complex neuromuscular coordination.
Purpose of the Study:
- To identify common principles governing movement initiation from a quiet stance.
- To compare motor programming across different initiation conditions and speeds.
Main Methods:
- Subjects performed gait initiation, ruler stepping, and obstacle stepping at self-paced and fast speeds.
- Measured electromyography (EMG) of soleus (S1, S2) and tibialis anterior (TA) muscles.
- Analyzed ground reaction forces (Fx) and timing events like heel-off.
Main Results:
- The latency between soleus inhibition and tibialis anterior onset was invariant across all conditions.
- Tibialis anterior duration increased with speed, while soleus activity decreased; durations were similar across initiation types.
- Time to heel-off was invariant; pre-heel-off forces increased with speed but were similar across conditions.
Conclusions:
- Movement initiation involves two distinct, coordinated motor programs, with heel-off marking the transition.
- Gait initiation and stepping tasks appear to be governed by shared underlying motor programs.