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Three dimensional preparatory trunk motion precedes asymmetrical upper limb movement.
P W Hodges1, A G Cresswell, K Daggfeldt
1Department of Neuroscience, Karolinska Institute, Stocholm, Sweden. p.hodges@unsw.edu.au
Gait & Posture
|July 19, 2000
Summary
Anticipatory postural adjustments involve three-dimensional trunk movements, not just rigid stabilization. This preparatory trunk motion counteracts reactive moments from voluntary limb actions, challenging previous assumptions.
Area of Science:
- Biomechanics
- Motor Control
- Human Movement Science
Background:
- Voluntary limb movements necessitate anticipatory postural adjustments (APAs) for stability.
- The precise nature of trunk control during APAs, whether movement-based or rigid stabilization, remains debated.
Purpose of the Study:
- To investigate the three-dimensional trunk motion and muscle activation patterns during voluntary unilateral upper limb movements.
- To determine if APAs involve trunk movement or rigid stabilization.
Main Methods:
- Utilized a three-dimensional body model to predict reactive moments.
- Measured three-dimensional trunk motion, trunk muscle electromyography (EMG), and intra-abdominal pressure.
- Analyzed superficial trunk muscle activation patterns.
Main Results:
- Preparatory trunk motion occurred in three dimensions, opposing predicted reactive moments.
- Superficial trunk muscle EMG supported anticipatory trunk movement.
- Transversus abdominis activation was not consistent with controlling direction-specific moments.
Conclusions:
- Anticipatory postural adjustments lead to dynamic trunk movements rather than simple rigidification.
- Trunk motion plays a crucial role in counteracting reactive forces during voluntary limb movements.