Department of Physical Therapy, University of British Columbia, Vancouver, Canada.
Exp Gerontol. 2010 Jun;45(6):400-9. doi: 10.1016/j.exger.2010.03.008. Epub 2010 Mar 18.
Overall reductions in muscle strength typically accompany the aging process. However, older adults show a relatively preserved capacity of producing eccentric strength. The preservation of eccentric strength in older adults is a well-established phenomenon, occurring indiscriminately across different muscle groups, independent of age-related architectural changes in muscle structure and velocity of movement. The mechanisms for the preservation of eccentric strength appear to be mechanical and cellular in origin and include both passive and active elements regulating muscle stiffness. The age-related accumulation of non-contractile material in the muscle-tendon unit increases passive stiffness, which might offer mechanical advantage during eccentric contractions. In addition, the preserved muscle tension and increased instantaneous stiffness of old muscle fibers during stretch increase active stiffness, which might enhance eccentric strength. The fact that the preservation of eccentric strength is present in people with chronic conditions when compared to age-matched healthy controls indicates that the aging process per se does not exclusively mediate the preservation of eccentric strength. Physical inactivity, which is common in elderly and people with chronic conditions, is a potential factor regulating the preservation of eccentric strength. When compared to concentric strength, the magnitude of preservation of eccentric strength in older adults ranges from 2% to 48% with a mean value of 21.6% from all studies. This functional reserve of eccentric strength might be clinically relevant, especially to initiate resistance training and rehabilitation programs in individuals with low levels of strength.
随着年龄的增长，肌肉力量通常会整体下降。然而，老年人在产生离心力量方面具有相对保留的能力。老年人离心力量的保留是一个已被证实的现象，它在不同的肌肉群中普遍存在，与肌肉结构的年龄相关变化和运动速度无关。离心力量保留的机制似乎源于机械和细胞，包括调节肌肉硬度的被动和主动元素。在肌肉-肌腱单元中，与年龄相关的非收缩性物质的积累增加了被动硬度，这可能在离心收缩时提供机械优势。此外，在伸展过程中，老年肌肉纤维保持的肌肉张力和增加的瞬时硬度增加了主动硬度，这可能增强了离心力量。与年龄匹配的健康对照组相比，患有慢性疾病的人也存在离心力量保留的事实表明，衰老过程本身并不能完全介导离心力量的保留。身体不活动在老年人和患有慢性疾病的人中很常见，是调节离心力量保留的一个潜在因素。与向心力量相比，老年人离心力量保留的幅度从所有研究的 2%到 48%不等，平均值为 21.6%。这种离心力量的功能储备可能具有临床意义，特别是在启动低力量水平个体的阻力训练和康复计划时。
