ASSOCIATIONS BETWEEN WEIGHT LOSS ASSOCIATED CHANGE IN TOTAL BODY MUSCLE MASS AS ASSESSED BY THE NOVEL D3Cr DILUTION METHOD AND TRADITIONAL SARCOPENIA ASSESSMENT TOOLS: PRELIMINARY RESULTS FROM THE INVEST IN BONE HEALTH TRIAL

Abstract

The purpose of this project was to derive estimates of change and variability in D3Cr-derived muscle mass within a geriatric weight loss trial and examine how change in D3Cr-muscle mass correlates with body weight, composition, and muscle function/strength changes. At baseline and six-months, 24 participants were weighed, ingested a D3Cr tracer dose and provided a urine sample, underwent a DXA scan, and performed measures of muscle function/strength (400-meter walk, stair climb, knee extensor strength, and grip strength). Participants included in this study were older (68.0±4.4 years), mostly white (75.0%), predominantly female (66.7%) and living with obesity (BMI: 33.8±2.7 kg/m2). Six-month weight loss was -10.3 (95% CI: -12.7, -7.9) kg, primarily from fat [-8.4 (95% CI: -10.5, -6.3) kg]. DXA-acquired lean body mass and appendicular mass were observed to decrease significantly [-0.7 (95% CI: -1.2, -0.1) kg] and [-0.9 (95% CI): -1.4, -0.4) kg]; no change was observed in D3Cr muscle mass [+0.5 (95% CI: -2.0, 3.0)] or measures of muscle function/strength. Changes in D3Cr muscle mass were modestly correlated with changes in DXA appendicular lean mass (r=0.46; p=0.03). Among older adults experiencing significant weight loss, DXA-derived lean mass measures decreased significantly, while D3Cr muscle mass and muscle function/strength did not.