Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.
J Exp Biol. 2011 Nov 1;214(Pt 21):3588-95. doi: 10.1242/jeb.055087.
Attenuation of locomotor function is common in many species of animals as they age. Dysfunctions may emerge from a constellation of age-related impairments, including increased joint stiffness, reduced ability to repair muscle tissue, and decreasing fine motor control capabilities. Any or all of these factors may contribute to gait abnormalities and substantially limit an animal's speed and mobility. In this study we examined the effects of aging on whole-animal locomotor performance and hindlimb muscle mechanics in young adult rats aged 6-8 months and 'early aged' 24-month-old rats (Rattus norvegicus, Fischer 344 × Brown Norway crosses). Analyses of gaits and kinematics demonstrated that aged rats moved significantly more slowly, sustained longer hindlimb support durations, moved with a greater proportion of asymmetrical gaits, were more plantigrade, and moved with a more kyphotic spinal posture than the young rats. Additionally, the external mechanical energy profiles of the aged animals were variable across trials, whereas the younger rats moved predominantly with bouncing mechanics. In situ analyses of the ankle extensor/plantar flexor muscle group (soleus, plantaris, and medial and lateral gastrocnemii) revealed reduced maximum force generation with aging, despite minimal changes in muscle mass. The weakened muscles were implicated in the degradation of hindfoot posture, as well as variability in center-of-mass mechanics. These results demonstrate that the early stages of aging have consequences for whole-body performance, even before age-related loss of muscle mass begins.
随着动物年龄的增长，运动功能的衰减在许多物种中都很常见。功能障碍可能源于一系列与年龄相关的损伤，包括关节僵硬增加、修复肌肉组织的能力降低以及精细运动控制能力下降。这些因素中的任何一个或多个都可能导致步态异常，并极大地限制动物的速度和活动能力。在这项研究中，我们研究了年龄对年轻成年大鼠（6-8 个月）和“早期老年”24 个月大大鼠（挪威褐鼠×布朗挪威杂交）整体运动表现和后肢肌肉力学的影响。步态和运动学分析表明，老年大鼠移动速度明显较慢，后肢支撑时间更长，不对称步态比例更大，跖行性更强，脊柱后凸姿势更明显，与年轻大鼠相比。此外，老年动物的外部机械能谱在试验中变化不定，而年轻大鼠主要以弹跳力学运动。对踝关节伸肌/跖屈肌（比目鱼肌、跖肌、内侧和外侧腓肠肌）的原位分析表明，随着年龄的增长，最大力量生成减少，尽管肌肉质量变化很小。这些虚弱的肌肉与后足姿势的退化以及质心力学的变化有关。这些结果表明，即使在与年龄相关的肌肉质量丧失开始之前，衰老的早期阶段也会对全身性能产生影响。
