Low Muscle Mass

Childhood cancer survivors experience premature declines in muscle mass, strength, and physical function that contribute to morbidity and early mortality. The biological mechanisms driving these impairments are heterogeneous and poorly understood. This observational study aims to characterize distinct muscle health endotypes in adult survivors of childhood cancer using advanced imaging, neuromuscular testing, and functional assessment. Survivors with reduced muscle health and community controls will undergo multimodal magnetic resonance imaging and spectroscopy, nerve conduction studies, surface electromyography, body composition assessment, and physical performance testing during a single study visit integrated into an ongoing cohort evaluation. Identifying mechanistic endotypes of impaired muscle health will support development of targeted interventions to preserve function and improve long-term outcomes in childhood cancer survivors. Primary Objective: \- Characterize reduced muscle health endotypes in childhood cancer survivors. Secondary Objective: \- Identify specific treatment and lifestyle related risk factors for each reduced muscle health endotype. Exploratory Objective: \- Host germline genetics will be associated with specific muscle endotypes.

The investigators aimed to examine if β-hydroxy-β-methylbutyrate (HMB) supplementation enhances the effects of exercise on muscle mass, physical performance and insulin resistance and observe potential residual effects in older diabetes with low muscle mass, and to find the optimal treatment plan.