Muscle loss with age is considered to be an important cause of disability in older adults. However, current tools frequently used and recommended to measure muscle mass in trials have limitations: For example, DEXA (Dual-energy X-ray absorptiometry) and BIA (Bioelectrical impedance analysis)- both widely used in clinical trials cannot distinguish muscle tissue from non-muscle elements such as subcutaneous and intramuscular fat, skin, water and connective tissue.~Deuterated creatine (D3Cr) dilution is a novel promising method that provides an accurate measure of the functional contractile tissue, without including the non-contractile elements, by measuring total body creatine. Our preliminary cross-sectional results in men aged >65 years show functional muscle mass (FMM) assessed by D3-Cr to be significantly associated with performance outcomes and long-term outcomes, while DEXA showed no associations. However, these are observational data and cannot determine a causative role of muscle per se on functional outcomes.~Hence, the objective of the pilot study is to assess the feasibility of our proposed future study to evaluate the role of muscle mass on functional outcomes. Specifically, the pilot study will randomize moderate to low-functioning older adults to a resistance training program or successful aging health education program to assess recruitment yields, participant adherence, retention, training program design aspects, sample size, and the cost of the main trial. Further, the impact of these changes in FMM on short-term performance outcomes, such as strength, walking speed, SPPB, self-reported measures, and balance will be examined.
The pilot study is to assess the feasibility of using a new method to measure muscle mass called Deuterated Creatine (D3Cr) method and thereby understand the role of muscle mass on functional outcomes in older adults.