Faulkner J A, Brooks S V, Zerba E
Institute of Gerontology, University of Michigan, Ann Arbor, USA.
J Gerontol A Biol Sci Med Sci. 1995 Nov;50 Spec No:124-9. doi: 10.1093/gerona/50a.special_issue.124.
In old compared with young animals, muscle mass is decreased by 30% to 40%, and maximum force and power are decreased to an even greater extent. The age-related declines in muscle mass and muscle function are similar to those that occur with decreased physical activity. Despite the similarities, we conclude that the losses in muscle mass, force, and power are not due solely to old animals being less active, but rather accrue from intrinsic age-related changes in muscles and in muscle fibers that appear to be immutable and irreversible. The intrinsic changes are associated with denervation of fast fatigable fibers and motor units and motor unit remodeling, which may be initiated by contraction-induced injury. The mechanisms remain unresolved for the weakness, the fatigability, the high susceptibility to contraction-induced injury, and the impaired recovery from injury demonstrated by the skeletal muscles of old animals.
与年轻动物相比，老年动物的肌肉质量减少了30%至40%，最大力量和功率下降的幅度更大。与年龄相关的肌肉质量和肌肉功能下降与体力活动减少时出现的情况相似。尽管存在相似之处，但我们得出的结论是，肌肉质量、力量和功率的损失并非仅仅是因为老年动物活动较少，而是源于肌肉和肌纤维中与年龄相关的内在变化，这些变化似乎是不可改变和不可逆的。内在变化与快速疲劳纤维和运动单位的去神经支配以及运动单位重塑有关，这可能是由收缩诱导的损伤引发的。老年动物骨骼肌所表现出的虚弱、易疲劳、对收缩诱导损伤的高度易感性以及损伤恢复受损的机制仍未得到解决。
