Fear of falling modifies anticipatory postural control

This study investigated the influence of fear of falling or postural threat on the control of posture and movement during a voluntary rise to toes task for 12 healthy young adults. Postural threat was modified through alterations to the surface height at which individuals stood (low or high platform) and changes in step restriction (away from or at the edge of the platform) creating four levels of postural threat: LOW AWAY, LOW EDGE, HIGH AWAY and HIGH EDGE. To rise to the toes, an initial postural adjustment must destabilise the body so that it can be moved forward and elevated to a new position of support over the toes. Centre of pressure and centre of mass profiles, as well as tibialis anterior (TA), soleus (SO) and gastrocnemius (GA) muscle activity patterns were used to describe this behaviour. The results showed that the performance of the rise to toes task was significantly modified when positioned at the edge of the high platform. In this situation, the central nervous system reduced the magnitude and rate of the postural adjustments and subsequent voluntary movement. Although the duration of the movement was lengthened for this most threatening condition, the sequencing and relative timing of TA, SO and GA muscle activity was preserved. These changes in rise to toes behaviour were accompanied by evidence of increased physiological arousal and participant reports of decreased confidence, increased anxiety and decreased stability. Evidence of fear of falling effects on anticipatory postural control is clinically relevant as it may explain deficits in this control observed in individuals with balance disorders. For example, individuals with Parkinson’s disease or cerebellar dysfunction demonstrate impaired performance on the rise to toes task as reflected in alterations of both the timing and magnitude of their anticipatory postural adjustments. Our findings suggest alterations in the magnitude of postural adjustments may be magnified by fear of falling while changes in the timing of postural adjustments may reflect underlying pathology.

[1]  M. E. Anderson,et al.  The effects of movement velocity, mass displaced, and task certainty on associated postural adjustments made by normal and hemiplegic individuals. , 1984, Journal of neurology, neurosurgery, and psychiatry.

[2]  J P Miller,et al.  The prevalence and correlates of fear of falling in elderly persons living in the community. , 1994, American journal of public health.

[3]  W. E. McIlroy,et al.  Task constraints on foot movement and the incidence of compensatory stepping following perturbation of upright stance , 1993, Brain Research.

[4]  J. Massion Movement, posture and equilibrium: Interaction and coordination , 1992, Progress in Neurobiology.

[5]  R. Baumgartner,et al.  Fear of falling and restriction of mobility in elderly fallers. , 1997, Age and ageing.

[6]  M. Tinetti,et al.  Fear of falling and fall-related efficacy in relationship to functioning among community-living elders. , 1994, Journal of gerontology.

[7]  J Howland,et al.  Falls and fear of falling among elderly persons living in the community: occupational therapy interventions. , 1991, The American journal of occupational therapy : official publication of the American Occupational Therapy Association.

[8]  M G Carpenter,et al.  Postural control is scaled to level of postural threat. , 2000, Gait & posture.

[9]  J. Downton,et al.  Postural disturbance and psychological symptoms amongst elderly people living at home , 1990 .

[10]  K E Popov,et al.  Quantitative analysis of anticipatory postural components of a complex voluntary movement. , 1981, Human physiology.

[11]  D. Winter,et al.  Stiffness control of balance in quiet standing. , 1998, Journal of neurophysiology.

[12]  A. Takahashi,et al.  Reaction times of movement preparation in patients with Parkinson's disease , 1989, Neurology.

[13]  M L Latash,et al.  Anticipatory postural adjustments in conditions of postural instability. , 1998, Electroencephalography and clinical neurophysiology.

[14]  L. Nashner,et al.  Properties of postural adjustments associated with rapid arm movements. , 1982, Journal of neurophysiology.

[15]  B. E. Maki,et al.  A prospective study of postural balance and risk of falling in an ambulatory and independent elderly population. , 1994, Journal of gerontology.

[16]  B. E. Maki,et al.  Fear of falling and postural performance in the elderly. , 1991, Journal of gerontology.

[17]  L. E. Powell,et al.  The Activities-specific Balance Confidence (ABC) Scale. , 1995, The journals of gerontology. Series A, Biological sciences and medical sciences.

[18]  B E Maki,et al.  Influence of arousal and attention on the control of postural sway. , 1996, Journal of vestibular research : equilibrium & orientation.

[19]  M. Tinetti,et al.  Risk factors for falls among elderly persons living in the community. , 1988, The New England journal of medicine.

[20]  J. Frank,et al.  Surface height effects on postural control: a hypothesis for a stiffness strategy for stance. , 1999, Journal of vestibular research : equilibrium & orientation.

[21]  Thomas Brandt,et al.  Increased body sway at 3.5–8 Hz in patients with phobic postural vertigo , 1999, Neuroscience Letters.

[22]  M. Tinetti,et al.  Falls efficacy as a measure of fear of falling. , 1990, Journal of gerontology.

[23]  J. Dichgans,et al.  The coordination of posture and voluntary movement in patients with cerebellar dysfunction , 1992, Movement disorders : official journal of the Movement Disorder Society.

[24]  S Corna,et al.  Subjective perception of body sway , 1999, Journal of neurology, neurosurgery, and psychiatry.

[25]  H. Diener,et al.  Associated postural adjustments with body movement in normal subjects and patients with parkinsonism and cerebellar disease. , 1990, Revue neurologique.

[26]  Mark G. Carpenter,et al.  The influence of postural threat on the control of upright stance , 2001, Experimental Brain Research.

[27]  F. Horak,et al.  Step initiation in Parkinson's disease: Influence of levodopa and external sensory triggers , 1997, Movement disorders : official journal of the Movement Disorder Society.

[28]  J. Preisser,et al.  Predictors of fear of falling in dizzy and nondizzy elderly. , 1995, Psychology and aging.

[29]  Jaap H. van Dieën,et al.  Scaling anticipatory postural adjustments dependent on confidence of load estimation in a bi-manual whole-body lifting task , 1998, Experimental Brain Research.

[30]  Smith RonaldE.,et al.  Measurement and correlates of sport-specific cognitive and somatic trait anxiety: The sport anxiety scale , 1990 .

[31]  A. Berthoz,et al.  Balance control and posture differences in the anxious BALB/cByJ mice compared to the non anxious C57BL/6J mice , 2000, Behavioural Brain Research.

[32]  J. Frank,et al.  Postural compensations to the potential consequences of instability: kinematics , 1997 .

[33]  F B Horak,et al.  Centrally initiated postural adjustments in parkinsonian patients on and off levodopa. , 2000, Journal of neurophysiology.