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Risk of falling: Predictors based on reduced strength in persons previously affected by polio,☆☆,,★★,,♢♢

https://doi.org/10.1053/apmr.2002.32827Get rights and content

Abstract

Lord SR, Allen GM, Williams P, Gandevia SC. Risk of falling: predictors based on reduced strength in persons previously affected by polio. Arch Phys Med Rehabil 2002;83:757-63. Objectives: To examine the contributions of sensorimotor factors to postural control and falling in people with prior polio and to determine whether these contributions differ from those found in normal populations. Design: Survey and case-control study. Setting: A falls and balance laboratory in Australia. Participants: Forty persons with prior polio (age range, 28-71y) and 38 age- and sex-matched control subjects. Interventions: Not applicable. Main Outcome Measures: Lower-limb muscle strength, sway, vision, lower-limb sensation, reaction time, foot-tapping speed, and falls. Results: Compared with the control subjects, the prior polio subjects performed similarly in sensory tests but worse in tests that involved a motor component. Within the prior polio group, lower-limb strength was strongly associated with postural sway on a compliant surface and explained more of the variance in sway than in control subjects. Prior polio subjects who fell multiple times had reduced lower-limb strength, slower reaction time, lower foot-tapping speed, and increased sway compared with those who fell less often. However, the rate of decline in lower-limb strength within the prior polio group did not exceed normal, age-related changes. Conclusions: This investigation of prior polio subjects provides an appropriate model for studying muscle weakness as a falls risk factor. Weakness was directly associated with falls, and had an indirect effect mediated through increased sway. © 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Section snippets

Participants

A convenience sample of prior polio subjects was recruited from members of the Post-Polio Network and attendees of the Post-Polio Clinic, Prince Henry Hospital, Sydney, Australia.12 All were living independently in the community at the time of assessment. The sample comprised 21 men and 19 women with a mean age ± standard deviation (SD) of 50.7±10.6 years (range, 28-71y). Mean age of polio onset was 8.1±6.6 years (range, 1-31y), and the period since initial infection was 43.6±9.5 years (range,

Comparisons between the prior polio and control subjects

Table 1 shows the mean and SDs for the physiologic measures for the men and women with prior polio and the control women.

Table 1: Performances in the sensorimotor tests: Polio-control comparisons

Empty CellPrior Polio Men (n=21)Prior Polio Women (n=19)Control Women (n=38)
Vision
 Visual acuity (min).93±.37.88±.22.92±.31
 Contrast sensitivity (dB)21.0±2.221.6±2.122.4±1.1
Peripheral sensation
 Proprioception (deg difference)2.8±3.41.2±0.91.5±1.5
 Touch (log100.1mm pressure)4.31±.374.28±.61*3.93±.44
Strength (Nm/weight

Discussion

As anticipated, the prior polio subjects showed significant weakness in muscle groups of the lower limb. The female prior polio subjects had less than half the knee extension and ankle dorsiflexion strength of age-matched controls. The muscle groups in the lower limb of the male prior polio subjects were also weak, with knee and ankle strength levels only slightly and insignificantly higher than the levels found in the women with prior polio. This finding further shows the striking effects of

Conclusion

The present investigation of a group patients who had prior polio provides an appropriate model for studying the importance of muscle weakness as a risk factor for falling. Weakness was identified as having both a direct association with falls and an indirect effect mediated through increased postural sway.

Acknowledgements

We thank Dr. Jill Middleton for assistance with subject recruitment. The assistance of the Post-Polio Network and the Australian National Health and Medical Research Council is greatly appreciated.

References (28)

  • SR Lord et al.

    The effect of a physical activity program on balance, strength, neuromuscular control and reaction time in older persons

    Arch Phys Med Rehabil

    (1994)
  • AJ Campbell et al.

    Risk factors for falls in a community-based prospective study of people 70 years and older

    J Gerontol

    (1989)
  • SR Lord et al.

    Physiological factors associated with falls in an elderly population

    J Am Geriatr Soc

    (1991)
  • SR Lord et al.

    Physiological factors associated with falls in older community-dwelling women

    J Am Geriatr Soc

    (1994)
  • M Nevitt et al.

    Risk factors for recurrent non-syncopal falls

    JAMA

    (1989)
  • A Gabell et al.

    Falls in healthy elderly: predisposing causes

    Ergonomics

    (1985)
  • LA Lipsitz et al.

    Causes and correlates of recurrent falls in ambulatory frail elderly

    J Gerontol

    (1991)
  • ME Tinetti et al.

    Risk factors for falls among elderly people living in the community

    N Engl J Med

    (1988)
  • MB Pearson et al.

    Muscle strength and anthropometric indices in elderly men and women

    Age Ageing

    (1985)
  • SR Lord et al.

    Postural stability and associated physiological factors in a population of aged persons

    J Gerontol

    (1991)
  • SR Lord et al.

    Age-related changes in sensori-motor function and balance in community dwelling women

    Age Ageing

    (1994)
  • AJ Windebank et al.

    Late effects of paralytic poliomyelitis in Olmsted County, Minnesota

    Neurology

    (1991)
  • SC Gandevia et al.

    Post-polio syndrome: assessments, pathophysiology and progression

    Disabil Rehabil

    (2000)
  • JL Cosgrove et al.

    Late effects of poliomyelitis

    Arch Phys Med Rehabil

    (1987)
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    Supported by the Australian National Health and Medical Research Council.

    ☆☆

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the author are associated.

    Reprint requests to Stephen Lord, PhD, Prince of Wales Medical Research Institute, Barker St, Randwick, NSW 2031, Australia, e-mail: [email protected].

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