Department of Aging and Geriatric Research, University of Florida, Gainesville, FL 32607, USA.
Exp Gerontol. 2012 Jan;47(1):38-44. doi: 10.1016/j.exger.2011.10.001. Epub 2011 Oct 12.
The lower extremities are important to performing physical activities of daily life. This study investigated lower extremity tissue composition, i.e. muscle and fat volumes, in young and older adults and the relative importance of individual tissue compartments to the physical function of older adults. A total of 43 older (age 78.3±5.6 years) and 20 younger (age 23.8±3.9 years) healthy men and women participated in the study. Older participants were further classified as either high- (HF) or low-functioning (LF) according to the Short Physical Performance Battery (SPPB). Magnetic resonance images were used to determine the volumes of skeletal muscle, subcutaneous fat (SAT), and intermuscular fat (IMAT) in the thigh (femoral) and calf (tibiofibular) regions. After adjusting for the sex of participants, younger participants had more femoral muscle mass than older adults (p<0.001 for between group differences) as well as less femoral IMAT (p=0.008) and tibiofibular IMAT (p<0.001). Femoral muscle was the only tissue compartment demonstrating a significant difference between the two older groups, with HF participants having 31% more femoral muscle mass than LF participants (mean difference=103.0±34.0 cm(3); p=0.011). In subsequent multiple regression models including tissue compartments and demographic confounders, femoral muscle was the primary compartment associated with both SPPB score (r(2)=0.264, p=0.001) and 4-meter gait speed (r(2)=0.187, p=0.007). These data suggest that aging affects all lower extremity compartments, but femoral muscle mass is the major compartment associated with physical function in older adults.
下肢对于进行日常生活中的身体活动很重要。本研究调查了年轻人和老年人下肢组织成分，即肌肉和脂肪体积，以及各组织隔室对老年人身体功能的相对重要性。共有 43 名老年人（年龄 78.3±5.6 岁）和 20 名年轻人（年龄 23.8±3.9 岁）健康男性和女性参加了这项研究。根据简短体能测试电池（SPPB），将老年人进一步分为高功能（HF）或低功能（LF）组。磁共振成像用于确定大腿（股骨）和小腿（胫腓骨）区域的骨骼肌、皮下脂肪（SAT）和肌肉间脂肪（IMAT）体积。调整参与者的性别后，年轻参与者的股骨肌肉质量比老年人多（组间差异 p<0.001），股骨 IMAT（p=0.008）和胫腓骨 IMAT（p<0.001）少。只有股骨肌肉是两个老年组之间存在显著差异的组织隔室，HF 参与者的股骨肌肉质量比 LF 参与者多 31%（平均差异=103.0±34.0 cm³；p=0.011）。在包括组织隔室和人口统计学混杂因素的后续多元回归模型中，股骨肌肉是与 SPPB 评分（r²=0.264，p=0.001）和 4 米步行速度（r²=0.187，p=0.007）均显著相关的主要隔室。这些数据表明，衰老会影响所有下肢隔室，但股骨肌肉质量是与老年人身体功能最相关的主要隔室。
