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Postural coordination patterns associated with the swinging frequency of arms
1Laboratory of Human Movement Sciences, Graduate School of Education, Hokkaido University, Sapporo, Japan. abe@edu.hokudai.ac.jp
Experimental Brain Research
|August 3, 2001
Summary
Body posture control shifts coordination modes between hip-shoulder and ankle-shoulder coupling based on arm swing frequency. These changes align with the arm's natural resonant frequency, influencing joint torques.
Area of Science:
- Biomechanics
- Human Motor Control
- Postural Stability
Background:
- Voluntary arm movements significantly disrupt upright body equilibrium.
- Maintaining balance requires coordinated leg joint movements that adapt to arm motion, potentially altering postural patterns.
Purpose of the Study:
- To investigate if arm swinging frequency influences the kinematic generation of upright posture.
- To determine if postural pattern generation correlates with changes in shoulder joint torque.
Main Methods:
- Four male subjects performed voluntary arm swings at various frequencies (35%-65% of maximum).
- Kinematic and kinetic analyses were conducted on shoulder, hip, and ankle joint rotations.
- Joint torques were analyzed to assess kinetic responses.
Main Results:
- Lower arm swing frequencies (<40-45% max) showed tight coupling between shoulder and hip joint movements.
- Higher frequencies (>40-45% max) demonstrated tight coupling between shoulder and ankle joint movements.
- Joint torque patterns at the shoulder and hip changed around 40-45% max frequency, near the arm's eigenfrequency.
Conclusions:
- Upright postural patterns exhibit two distinct coordination modes (hip-shoulder and ankle-shoulder in-phase) based on arm swing frequency.
- The transition between these postural coordination modes appears to be related to the arm's eigenfrequency.