肌肉力量和力对残疾老年男性和女性步态速度的影响。
Impact of muscle power and force on gait speed in disabled older men and women.
作者信息
Cuoco Anthony, Callahan Damien M, Sayers Stephen, Frontera Walter R, Bean Jonathan, Fielding Roger A
机构信息
Human Physiology Laboratory, Department of Health Sciences, Sargent College of Health and Rehabilitation Science, Boston University, 635 Commonwealth Ave., Boston, MA 02215, USA.
出版信息
J Gerontol A Biol Sci Med Sci. 2004 Nov;59(11):1200-6. doi: 10.1093/gerona/59.11.1200.
BACKGROUND
The purpose of this study was to explore the relationship between muscle power output at different external resistances and performance of functional tasks. The authors hypothesized that power at 40% skeletal muscle 1 repetition maximum (1RM), in which contraction velocity is high, would explain more of the variability in tasks such as level walking than would peak power or 1RM strength, in which contraction velocity is lower.
METHODS
Participants were men and women (n = 48; ages 65-91 years) with physical disability as evidenced by 2 or more deficits on the Medical Outcomes Study Short Form physical function subscale or a score of 9 or less on the Established Populations for the Epidemiologic Studies of the Elderly short physical performance battery. Muscle strength (1RM) was measured using a bilateral leg press exercise, and power output was determined by selecting the highest power output from 6 different contraction velocities: 40%, 50%, 60%, 70%, 80%, and 90% 1RM. Functional performance tasks consisted of habitual gait velocity (HGV) and stair climb (SC) and chair rise (CR) performance. Separate linear regression models were fit for each of the 3 dependent variables (SC, CR, HGV) using 1RM strength, power at 70% 1RM, and power at 40% 1RM as independent variables. All models were adjusted for age, body mass, and sex.
RESULTS
Lower extremity power at 70% and 40% 1RM demonstrated greater associations with SC and HGV than did 1RM strength, whereas power at 40% 1RM demonstrated similar or stronger associations with all functional tasks compared with 1RM strength. Power at 40% 1RM explained the same or more of the variability in SC (R(2) = .42 [regression coefficient = -.169 +/- .06] vs .43 [-.206 +/- .071]), CR (R(2) = .28 [-.154 +/- .057] vs .24 [-.152 + .070]) and HGV (R(2) = .59 [.214 + .37] vs .51 [.223 +/- .049]) compared with power at 70% 1RM. Power at 40% 1RM explained more of the variability in the lower intensity (HGV) compared with the higher intensity (SC or CR) functions.
CONCLUSIONS
Power output at 40% of 1RM explained more of the variability in HGV than did power at 70% 1RM, suggesting that measures such as HGV that require a lower percentage of maximal strength to perform might be more sensitive to differences in contraction velocity. Because HGV is highly predictive of subsequent disability, future studies should evaluate the determinants of muscle power output at low external resistances.
背景
本研究旨在探讨不同外部阻力下的肌肉力量输出与功能性任务表现之间的关系。作者假设，在收缩速度较高的40%骨骼肌1次重复最大值（1RM）时的力量，相比收缩速度较低的峰值力量或1RM力量，能更好地解释诸如平地行走等任务中的变异性。
方法
参与者为男性和女性（n = 48；年龄65 - 91岁），根据医学结局研究简短体能量表中存在2项或更多缺陷，或老年流行病学研究既定人群简短体能测试得分9分及以下，证明存在身体残疾。使用双侧腿举运动测量肌肉力量（1RM），并通过从6种不同收缩速度（40%、50%、60%、70%、80%和90% 1RM）中选择最高力量输出，来确定力量输出。功能性任务表现包括习惯性步态速度（HGV）、爬楼梯（SC）和从椅子上起身（CR）表现。使用1RM力量、70% 1RM时的力量和40% 1RM时的力量作为自变量，分别为3个因变量（SC、CR、HGV）拟合单独的线性回归模型。所有模型均对年龄、体重和性别进行了调整。
结果
70%和40% 1RM时的下肢力量与SC和HGV的相关性比1RM力量更强，而40% 1RM时的力量与所有功能性任务的相关性与1RM力量相比相似或更强。40% 1RM时的力量解释了SC（R² = 0.42 [回归系数 = -0.169 ± 0.06] 对 0.43 [-0.206 ± 0.071]）、CR（R² = 0.28 [-0.154 ± 0.057] 对 0.24 [-0.152 + 0.070]）和HGV（R² = 0.59 [0.214 + 0.37] 对 0.51 [0.223 ± 0.049]）中更多的变异性，与70% 1RM时的力量相比。与高强度（SC或CR）功能相比，40% 1RM时的力量解释了低强度（HGV）功能中更多的变异性。
结论
40% 1RM时的力量输出比70% 1RM时的力量解释了HGV中更多的变异性，这表明诸如HGV等需要较低百分比最大力量来执行的测量指标，可能对收缩速度差异更敏感。由于HGV对后续残疾具有高度预测性，未来研究应评估低外部阻力下肌肉力量输出的决定因素。
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