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Fear of falling modifies anticipatory postural control
Allan L Adkin1, James S Frank, Mark G Carpenter
1Gait and Posture Laboratory, Department of Kinesiology, 200 University Avenue West, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1. aladkin@healthy.uwaterloo.ca
Experimental Brain Research
|March 7, 2002
Summary
Fear of falling significantly alters voluntary movement control, reducing movement speed and magnitude during a rise to toes task under high threat conditions. This impacts anticipatory postural adjustments, potentially explaining balance deficits in neurological disorders.
Area of Science:
- Biomechanics
- Neuroscience
- Human Movement Science
Background:
- Fear of falling (FoF) and postural threat significantly impact motor control.
- The rise to toes task is a sensitive measure of anticipatory postural adjustments (APAs).
- Understanding FoF effects on APAs is crucial for explaining balance deficits in clinical populations.
Purpose of the Study:
- To investigate how fear of falling (postural threat) influences posture and movement control during a voluntary rise to toes task.
- To examine the effects of varying surface height and step restriction on APAs and muscle activity.
- To correlate behavioral changes with physiological arousal and self-reported confidence.
Main Methods:
- 12 healthy young adults performed a rise to toes task under four postural threat conditions (LOW AWAY, LOW EDGE, HIGH AWAY, HIGH EDGE).
- Kinematic data (center of pressure, center of mass) and muscle activity (tibialis anterior, soleus, gastrocnemius) were recorded.
- Physiological arousal and self-reported measures of anxiety and stability were assessed.
Main Results:
- The rise to toes task performance was significantly altered under high postural threat (HIGH EDGE condition).
- Reduced magnitude and rate of APAs and voluntary movement were observed under high threat.
- Movement duration increased, but muscle activation sequencing (TA, SO, GA) remained intact.
- Increased physiological arousal, anxiety, and decreased stability were reported.
Conclusions:
- Fear of falling significantly modifies anticipatory postural control, primarily affecting the magnitude of adjustments.
- Altered APAs due to FoF may exacerbate balance deficits seen in individuals with neurological conditions like Parkinson's disease.
- Changes in APA timing may indicate underlying neuropathology, distinct from FoF effects.