Steadiness of quadriceps contractions in young and older adults with and without a history of falling |
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Authors: | Serena F Carville Mark C Perry Olga M Rutherford I Christopher H Smith Di J Newham |
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Institution: | (1) Division of Applied Biomedical Research, School of Biomedical and Health Sciences, King’s College London, 3.1 Shepherd’s House, Guy’s Campus, London, SE1 1UL, UK;(2) Present address: Academic Department of Rheumatology, King’s College London, School of Medicine, London, UK;(3) Present address: School of Physiotherapy, Curtin University of Technology, Perth, Australia |
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Abstract: | Decreased steadiness of muscle force may be associated with ageing and could be a cause of falls in older people. We studied
this in isometric and anisometric quadriceps contractions in healthy young and older people. The older group contained people
with and without a history of medically unexplained falls. Forty-four young (aged 18–40 years) and 78 older (aged > 70 years)
subjects participated. In the latter group 34 people had a history of falling (fallers) and 44 did not (non-fallers). Isometric
steadiness was measured by the coefficient of variation (CoV) of force at 10, 25 and 50% maximal voluntary force (MVC). Anisometric
steadiness was measured by the SD of acceleration during concentric and eccentric contractions against two external loads
(1 and 5 kg). There was an overall trend for the younger subjects to be most steady and the fallers the least but the differences
were not consistently significant. Isometric steadiness was unaffected by force in all groups. The fallers were less steady
(P < 0.001) than both the young and non-fallers, who had similar values. During anisometric contractions, steadiness was similar
with both external loads and types of contraction in all groups. During dynamic contractions the older subjects were less
steady (P < 0.002). Only eccentric contractions distinguished between the two older groups, with the fallers being less steady by 31%
(P = 0.013). These data indicate ageing per se is associated with decreased anisometric, but not isometric, steadiness. Greater
unsteadiness during eccentric contractions in the fallers could be an important mechanism of medically unexplained falls. |
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Keywords: | Muscle Seadiness Ageing Falls |
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