Carville Serena F, Perry Mark C, Rutherford Olga M, Smith I Christopher H, Newham Di J
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.
Eur J Appl Physiol. 2007 Jul;100(5):527-33. doi: 10.1007/s00421-006-0245-2. Epub 2006 Sep 16.
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.
肌肉力量稳定性下降可能与衰老有关，并且可能是老年人跌倒的一个原因。我们在健康的年轻人和老年人的等长和非等长股四头肌收缩中对此进行了研究。老年组包括有和没有医学上无法解释的跌倒史的人。44名年轻人（年龄在18 - 40岁之间）和78名老年人（年龄大于70岁）参与了研究。在后一组中，34人有跌倒史（跌倒者），44人没有（非跌倒者）。等长稳定性通过在最大自主收缩力（MVC）的10%、25%和50%时力量的变异系数（CoV）来测量。非等长稳定性通过在对抗两个外部负荷（1千克和5千克）的向心和离心收缩过程中的加速度标准差来测量。总体趋势是年轻受试者最稳定，跌倒者最不稳定，但差异并不始终显著。等长稳定性在所有组中不受力量影响。跌倒者比年轻受试者和非跌倒者都更不稳定（P < 0.001），后两者的值相似。在非等长收缩过程中，所有组在两种外部负荷和收缩类型下的稳定性相似。在动态收缩过程中，老年受试者更不稳定（P < 0.002）。只有离心收缩能区分两个老年组，跌倒者的稳定性低31%（P = 0.013）。这些数据表明衰老本身与非等长稳定性下降有关，但与等长稳定性无关。跌倒者在离心收缩过程中更大的不稳定性可能是医学上无法解释的跌倒的一个重要机制。
