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Aging effects on postural responses to self-imposed balance perturbations
Vassilia Hatzitaki1, Ioannis G Amiridis, Fotini Arabatzi
1Motor Control and Learning Laboratory, Department of Physical Education and Sport Sciences, Aristotle University of Thessaloniki, Greece. vaso1@phed.auth.gr
Gait & Posture
|October 11, 2005
Summary
Older adults exhibit weaker postural control during leg swings due to reduced ankle muscle activity and impaired coordination, leading to increased instability. This contrasts with young adults who demonstrate better balance and joint coordination.
Area of Science:
- Biomechanics
- Gerontology
- Motor Control
Background:
- Postural organization is crucial for maintaining balance, especially during dynamic movements.
- Aging is associated with declines in motor control and balance, increasing fall risk.
Purpose of the Study:
- To investigate age-related differences in postural organization during self-induced balance perturbations.
- To analyze the coordination between limb movements, center of gravity (CoG), and center of pressure (CoP) in young and older adults.
Main Methods:
- Participants performed oscillatory hip movements while joint kinematics, CoP, and muscle EMG were recorded.
- Cross-correlation function (CCF) analysis assessed the coupling between swinging limb (SL), CoG, and CoP.
- EMG of tibialis anterior (TA), medial gastrocnemius (MGAS), rectus femoris (RF), and semitendinosus (ST) were analyzed.
Main Results:
- Older adults showed limited anterior/posterior (A/P) motion of SL, CoG, and CoP, with reduced ankle muscle activity.
- Young adults exhibited sufficient ankle muscle activity for stability, with greater joint range of motion from ankle to hip.
- While both groups showed anti-phase CoP-SL correlation, older adults had weaker, non-synchronous CoG-SL and CoG-CoP coupling.
Conclusions:
- Insufficient ankle muscle activity, impaired central integration, and anxiety contribute to weaker postural synergies in older adults.
- Older adults display a 'freezing of degrees of freedom' strategy, limiting movement to maintain stability.
- Age-related deficits in motor control and coordination impact dynamic balance during single limb oscillations.