Francis Peter, Toomey Clodagh, Mc Cormack William, Lyons Mark, Jakeman Philip
Department of Rehabilitation and Health Science, Leeds Beckett University, Leeds, UK.
Department of Physical Education and Sport Sciences, Faculty of Education and Health Sciences, University of Limerick, Limerick, Ireland.
Clin Physiol Funct Imaging. 2017 Jul;37(4):448-455. doi: 10.1111/cpf.12332. Epub 2016 Jan 7.
Muscle quality is defined as strength per unit muscle mass. The aim of this study was to measure the maximal voluntary isometric torque of the knee extensor and flexor muscle groups in healthy older women and to develop an index of muscle quality based on the combined knee extensor and flexor torque per unit lean tissue mass (LTM) of the upper leg. One hundred and thirty-six healthy 50- to 70-year-old women completed an initial measurement of isometric peak torque of the knee extensors and flexors (Con-Trex MJ; CMV AG, Dubendorf, Switzerland) that was repeated 7 days later. Subsequently, 131 women returned for whole- and regional-body composition analysis (iDXA ; GE Healthcare, Chalfont St Giles, Buckinghamshire, UK). Isometric peak torque demonstrated excellent within-assessment reliability for both the knee extensors and flexors (ICC range: 0·991-1·000). Test-retest reliability was lower (ICC range: 0·777-0·828) with an observed mean increase of 5% in peak torque [6·2 (17·2) N m] on the second day of assessment (P<0·001). The relative mean decrease in combined isometric peak torque (-12·2%; P = 0·001) was double that of the relative, non-significant, median difference in upper leg LTM (-5·3%; P = 0·102) between those in the 5th and 6th decade. The majority of difference in peak isometric torque came from the knee extensors (15·1 N m, P<0·001 versus 2·4 N m, P = 0·234). Isometric peak torque normalized for upper leg LTM (muscle quality) was 8% lower between decades (P = 0·029). These findings suggest strength per unit tissue may provide a better indication of age-related differences in muscle quality prior to change in LTM.
肌肉质量被定义为单位肌肉质量的力量。本研究的目的是测量健康老年女性膝伸肌和屈肌肌群的最大等长自愿收缩扭矩，并基于大腿上部每单位瘦组织质量（LTM）的膝伸肌和屈肌扭矩总和制定一个肌肉质量指数。136名年龄在50至70岁的健康女性完成了膝伸肌和屈肌等长峰值扭矩的初始测量（Con-Trex MJ；CMV AG，瑞士杜本多夫），7天后重复测量。随后，131名女性返回进行全身和局部身体成分分析（iDXA；通用电气医疗集团，英国白金汉郡查尔方特圣贾尔斯）。等长峰值扭矩在膝伸肌和屈肌的评估内均显示出极好的可靠性（组内相关系数范围：0·991 - 1·000）。重测可靠性较低（组内相关系数范围：0·777 - 0·828），在评估的第二天观察到峰值扭矩平均增加5%[6·2（17·2）N·m]（P<0·001）。在50多岁和60多岁的人群中，等长峰值扭矩总和的相对平均下降（-12·2%；P = 0·001）是大腿上部LTM相对的、无显著差异的中位数差异（-5·3%；P = 0·102）的两倍。等长峰值扭矩的大部分差异来自膝伸肌（15·1 N·m，P<0·001，而屈肌为2·4 N·m，P = 0·234）。按大腿上部LTM标准化的等长峰值扭矩（肌肉质量）在不同十年间低8%（P = 0·029）。这些发现表明，在LTM发生变化之前，单位组织的力量可能能更好地反映与年龄相关的肌肉质量差异。
