1 RM muscle strength and leg power:
The 1 repetition maximum (1 RM) for seated knee extension, and leg extension are determined with the baseline 1 RM test repeated twice separated by one week74. Strength and power measurements will be performed unilaterally for the knee extensors and bilaterally for the leg press. The baseline 1 RM is established as the best value from the two trials due to the well-established learning effect of this measure. Peak power is assessed for both knee extensors and leg extensors. We have recently validated this method of testing power against our previous methods of assessing muscle power69. Following the measurement of the baseline 1 RM, each subject will perform 5 repetitions as fast as possible at 40% 1 RM and 70% 1RM. The highest power output achieved during each of these 5 repetitions is determined to be their peak power. The reliability of these measurements in older subjects in our hands is excellent (leg extensor ICC = 0.95). Both the Tufts and Spaulding facilities have identical equipment (Keiser Pneumatic resistance training apparatus) and testing protocols, for the 1 RM and power measures, thus ensuring appropriate standardization across institutions.