Associations between dietary nutrient intake and muscle mass and strength in community-dwelling older adults: the Tasmanian Older Adult Cohort Study

OBJECTIVES: To describe associations between dietary nutrient intake and progression of sarcopenia, the age‐related loss of muscle mass and strength. DESIGN: Prospective cohort study of community‐dwelling older adults. SETTING: Southern Tasmania, Australia. PARTICIPANTS: Seven hundred forty noninstitutionalized older adults (50% female; mean age 62±7) randomly sampled from electoral rolls. MEASUREMENTS: Dietary nutrient intake was examined at baseline and follow‐up (2.6±0.4 years later) using The Cancer Council Victoria's Food Frequency Questionnaire (FFQ). Appendicular lean mass (aLM) was assessed using dual X‐ray absorptiometry and muscle strength of the knee extensors using a dynamometer. RESULTS: Failing to meet the recommended dietary intake for protein was associated with significantly lower aLM at baseline (?0.81 kg, 95% confidence interval (CI)=?1.54 to ?0.08) and follow‐up (?0.79 kg, 95%CI=?1.42 to ?0.17). Energy‐adjusted protein intake was a positive predictor of change in aLM over 2.6 years (β=0.10, P=.003). Energy‐adjusted intake of iron (β=0.07, P=.02), magnesium (β=0.07, P=.02), phosphorus (β=0.07, P=.047), and zinc (β=0.08, P=.02) were positive predictors of change in aLM, whereas retinol (β=?0.09, P=.005) was a negative predictor of change in aLM after adjustment for protein intake. No significant associations were observed between nutrient intake and muscle strength. CONCLUSION: Protein and several other dietary nutrients are associated with muscle mass and rate of muscle loss (but not strength) in older adults, suggesting that multiple dietary components may ameliorate the progression of sarcopenia.     

肌少症的诊疗和防治研究

肌肉是保证人体进行日常生理活动的基础。肌少症是以肌量减少、肌力下降和肌功能减退为特征的综合征,严重影响老年人生活质量,已受到广泛关注。本文就肌少症的概念、诊断以及防治进行综述,旨在更全面的认识肌少症。     

老年髋部骨折患者肌肉减少症与骨密度的关系

目的探讨老年髋部骨折患者肌肉减少症(sarcopenia)及与骨密度下降的关系。方法 113例65岁的老年髋部骨折患者(骨折组)纳入本研究,男性67例,女性46例;同期非髋部骨折老年患者1 321例作为对照组,男性654例,女性667例。所有患者均用双能X线骨密度仪(DXA)检测全身身体组成成分(骨量、肌肉含量,脂肪含量)。肌肉减少症的诊断标准:骨骼肌重量指数(SMI)(肢体骨骼肌重量/身高平方,kg/m2)低于同人种健康成年人1个标准差为1级肌肉减少症(class 1),低于2个标准差为2级肌肉减少症(class 2)。根据以上标准将受试者分为肌量正常组:男性SMI7.01 kg/m2,女性SMI5.42 kg/m2;class 1组:男性SMI 6.09~7.01 kg/m2,女性SMI 4.80~5.42 kg/m2;class2组:男性SMI≤6.08 kg/m2,女性SMI≤4.79 kg/m2。分析不同组老年髋部骨折患者肌肉减少症的检出率。结果老年髋部骨折患者肌肉减少症检出率明显高于同性别类似年龄人群:骨折组男性肌肉减少症检出率(62.6%)与对照组男性肌肉减少症检出率(12.8%)比较差异有统计学意义(P0.001),骨折组女性肌肉减少症检出率(13.0%)与非骨折组女性肌肉减少症检出率(4.1%)比较差异有统计学意义(P0.001);老年女性髋部骨折患者中肌量正常者24例(52.1%),Class 1级者16例(34.7%),Class 2级者6例(13.0%);骨骼肌重量指数与股骨颈骨密度和全身骨密度呈正相关。老年男性髋部骨折患者中肌量正常者9例(13.4%),Class 1级者16例(23.8%),Class 2级者42例(62.6%),骨骼肌重量指数与BMI呈正相关,与年龄呈负相关。结论老年髋部骨折患者肌肉减少症检出率明显高于同龄非骨折者,男性肌少症检出率高于女性。老年女性髋部骨折患者的骨骼肌重量指数与股骨颈和全身骨密度呈正相关,老年男性髋部骨折患者骨骼肌重量指数则与骨密度无明显相关性。应关注骨折患者肌肉减少症的防治。     

肌肉丢失、运动干预及肌肉重建

背景：肌肉丢失是老年人肌肉质量随增龄而减少的现象,它与老年人肌肉功能退化有着密切的关系。近年来,对于肌肉丢失的机制及其运动干预效果研究有了许多新进展。目的：就肌肉丢失细胞水平的机制研究及其运动干预效果进行综述。方法：应用计算机检索 CNKI 期刊全文数据库（2000 年 1 月至 2012 年 12 月）和 PubMed 数据库（2010 年 1月至 2012 年 12 月） 有关肌肉丢失及老年抗阻训练的文献,检索词分别为＂肌肉丢失,肌肉蛋白质代谢,肌细胞,衰老,抗阻训练＂和＂sarcopenia,muscle,resistance training,aging,portein motablism。纳入与肌肉丢失、蛋白质代谢、抗阻训练相关的研究,排除陈旧、重复以及缺乏可信度的文献,最终纳入 58 篇文献进行分析。结果与结论：抗阻训练可以在一定程度上抑制肌肉丢失,使老年人肌肉质量增加,促进运动单位重组,但重组仅限于Ⅱa型和Ⅱb型纤维之间的相互转化;抗阻训练结合蛋白质补充可以有效促进老年人肌肉重建;老年人抗阻训练后的肌肉合成代谢反应较年轻人迟缓,但炎性反应较年轻人剧烈,而 Omega-3 对于消除这种炎性反应具有较好的作用。     

Effects of ultra-low-dose estrogen therapy on muscle and physical function in older women

OBJECTIVES: To determine the effects of ultra-low-dose hormone therapy on muscle mass and physical function in community-dwelling women. DESIGN: Double-blind, placebo-controlled trial. SETTING: Clinical research center in Connecticut. PARTICIPANTS: Healthy, community-dwelling women aged 65 and older (n=167). INTERVENTION: Eligible women were randomly assigned to treatment with 0.25 mg 17-beta estradiol or placebo for 36 months. All women (estradiol or placebo) with an intact uterus received micronized progesterone 100 mg/d for 2 weeks every 6 months. All participants received 1,300 mg elemental calcium with 1,000 IU vitamin D per day. MEASUREMENTS: Appendicular skeletal muscle mass (ASM), lean body mass (LBM), and percentage body fat were measured using dual x-ray absorptiometry. Sarcopenia was defined as skeletal muscle mass (ASM/height2) 2 standard deviations or less than young, healthy reference population mean. Physical activity (Physical Activity Scale in the Elderly (PASE)) and performance were measured. Serum estrone, estradiol, and sex hormone-binding globulin were measured. RESULTS: The prevalence of sarcopenia at baseline was 13%. There were no baseline differences between groups except for PASE score and chair rise time, in which the estrogen group had better performance. No changes in ASM, LBM, percentage of body fat, or physical performance were found after 3 years of estrogen therapy. CONCLUSION: Sarcopenia was present in 13% of this group of community-dwelling, postmenopausal older women. Ultra-low-dose estrogen therapy neither improves nor harms ASM. Similarly, no changes in body fat or physical performance were detected.     

Sarcopenia,calf circumference,and physical function of elderly women: a cross-sectional study

OBJECTIVES: To determine whether calf circumference (CC), related to appendicular skeletal muscle mass, can be used as a measure of sarcopenia and is related to physical function. DESIGN: Retrospective analysis of data from 1992 to 1994 of the European Patient Information and Documentation Systems Study. SETTING: Community setting in France. PARTICIPANTS: One thousand four hundred fifty-eight French women aged 70 and older without previous history of hip fracture were recruited from the electoral lists. MEASUREMENTS: Muscular mass was assessed using dual-energy x-ray absorptiometry (DEXA). CC was measured using a tape measure. Anthropometric measurements (height; weight; and waist, hip, and calf circumference), strength markers (grip strength), and self-reported physical function were also determined. Sarcopenia was defined (using DEXA) as appendicular skeletal muscle mass (weight (kg)/height (m2)) less than two standard deviations below the mean of a young female reference group. RESULTS: The prevalence of sarcopenia was 9.5%. CC was correlated with appendicular skeletal muscle mass (r = 0.63). CC under 31 cm was the best clinical indicator of sarcopenia (sensitivity = 44.3%, specificity = 91.4%). CC under 31 cm was associated with disability and self-reported physical function but not sarcopenia (defined using DEXA), independent of age, comorbidity, obesity, income, health behavior, and visual impairment. CONCLUSION: CC cannot be used to predict sarcopenia defined using DEXA but provides valuable information on muscle-related disability and physical function.     

"肌少-骨质疏松症"的共同发病机制

"肌少-骨质疏松症"(sarco-osteopenia)的提出是基于两者共同的病理生理学基础,其中涉及八类主要影响因素.简要概括为机械因素作用于骨细胞构成的机械支架和肌管;肌肉-骨骼系统相互影响彼此化学因子的释放;甲基转移酶样蛋白21C(METTL21C)和肌肉生长抑制素(myostatin,MSTN,简称肌抑素)以及硬骨抑素(sclerostin,SOST)作为共同的遗传因素调控肌肉-骨骼系统;肌肉和骨骼在旁分泌和内分泌水平上的串扰、脂肪浸润因素导致肌力的下降和骨折发生率增加;炎性反应、糖尿病和糖皮质激素过量影响肌肉的丢失以及骨丢失;营养缺乏加速骨丢失和肌肉蛋白质合成减少;个体运动量的减少和神经-肌肉功能减弱间接影响肌肉和骨骼的合成代谢.深入研究"肌少-骨质疏松症"共同的致病机制,以推动生物检测特异性指标的确定、临床疾病的评估和诊断以及有效治疗药物和设备开发工作,最终目标是有效地治疗和预防"肌少-骨质疏松症".本文对"肌少-骨质疏松症"共同病理生理学机制研究现状与进展进行系统综述.