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Anticipatory postural adjustments depend on final equilibrium and task complexity in vertical high jump movements
1Armande Le Pellec, Bernard Maton, Laboratoire de Physiologie du Mouvement, Universit¿e de Paris Sud, Bât 441, 91405, Cedex, Orsay, France. armande.lepellec@lpm.u-psud.fr
Summary
Anticipatory postural adjustments (APA) enable high vertical jumps by preparing muscles and balance before movement. The central nervous system anticipates sequential jumps, utilizing ankle synergy for efficient postural control.
Area of Science:
- Biomechanics
- Human Motor Control
- Neuroscience
Background:
- Anticipatory postural adjustments (APA) are crucial for maintaining equilibrium during voluntary movements.
- Understanding APA in complex tasks like vertical jumping provides insights into motor control strategies.
Purpose of the Study:
- To investigate the characteristics of APA during single versus repetitive high vertical jumps.
- To determine how task complexity (single vs. repetitive jumps) influences APA.
Main Methods:
- Five healthy males performed single and repetitive vertical jumps on a force platform.
- Surface electromyography (EMG) of leg muscles (Soleus, Tibialis anterior, Vastus lateralis, Biceps femoris) and ground reaction forces were recorded.
- Analysis focused on pre-movement muscle activity and center of pressure shifts.
Main Results:
- APA, including Soleus deactivation and Tibialis anterior activation, preceded jumps by hundreds of milliseconds.
- Repetitive jumps showed delayed Soleus deactivation but earlier, longer, and larger center of pressure shifts compared to single jumps.
- Movement initiation was delayed in repetitive jumps.
Conclusions:
- The central nervous system anticipates the postural disturbances of entire movement sequences, not just initial movements.
- APA in vertical jumping heavily relies on a unified functional ankle synergy.
- These findings advance our understanding of predictive motor control and postural stabilization.