The measurement of muscle quality (strength per unit tissue) of the major muscle groups in the appendages can contribute to the diagnosis of sarcopenia and be used in the evaluation of therapeutic intervention to reduce physical frailty. Maximal voluntary contraction (MVC) and dual energy x-ray absorptiometry (DXA) are criterion measures of muscle strength and lean tissue 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 LTM of the upper leg. Following habituation to the test protocol one hundred and thirty six healthy 50 – 70y 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 (iDXATM; GE Healthcare, Chalfont St Giles, Bucks., 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<.001). The observed learning effect in the measurement of MVC is almost 50% of the cross-sectional change in isometric strength (-12.2%) between the 5th and 6th decade. Therefore, it is recommended that the measurement of MVC in healthy older women require a minimum of two testing sessions. Though cross-sectional in nature, the relative mean decrease in combined isometric peak torque (-12.2%; p=.001) was double that of the relative, non-significant, median change in upper leg LTM (-5.3%; p=.102) (Table 1). Isometric peak torque normalised for upper leg LTM (muscle quality) was 8% lower for those in the 6th decade of life compared with those in the 5th. This suggests that muscle strength may provide an earlier indicator of changes in muscle quality than LTM.