New test may measure muscle mass in older adults better than current scans

The age-related decline in muscle mass and strength are collectively referred to as sarcopenia. However, the tools currently employed to assess skeletal muscle mass (SMM) (e.g., Dual-energy Xray Absorptiometry; DXA) have substantial drawbacks, and it is known that DXA-lean soft tissue (LST) is generally not associated with health outcomes of interest. Thus, the investigators propose using a novel, non-invasive, stable isotope-labelled probe (Deuterium (D)-labelled creatine (D3-creatine; D3-Cr)) to measure skeletal muscle mass in a large cohort of older individuals. The development and employment of new methods to accurately quantify the biological substrate of sarcopenia, skeletal muscle, are critical for the measure to remain clinically relevant. The plan is to measure 350 persons from the recently established (M3) prospective cohort. There will be measurement of lean soft tissue LST and appendicular LST (aLST) using DXA and compared to D3-Cr-measured SMM (D3-Cr-SMM) at baseline, 12mo, and 24mo (2yr) of follow-up. Physical mobility will also be measured (using various instruments).