Quality in Sport · Aug 11, 2026
Preserving Skeletal Muscle and Function During GLP-1 Receptor Agonist Therapy: An Evidence-Informed Exercise Prescription Framework
By Adamczak M, Majewski M, Libura B et al.
Background & Aim: GLP-1 RAs (e.g., semaglutide) and dual GIP/GLP-1 RAs (tirzepatide) induce substantial weight loss, but ~25% derives from fat-free mass (FFM). Whether this threatens skeletal muscle remains contested. Standard guidelines offer generic resistance training advice, ignoring the drugs' gastrointestinal and behavioral side effects. This narrative review aims to synthesize mechanisms of GLP-1 RA-associated lean mass loss, critique DXA-derived FFM as a clinical endpoint, shift focus to muscle quality/function, and propose a tailored exercise and nutritional framework. Material and Methods: Literature, guidelines, meta-analyses, and clinical trials regarding GLP-1 RA body composition, muscle physiology, training methodology, and sports nutrition were synthesized. Recommendations were graded using a 4-tier hierarchy: direct clinical evidence, indirect evidence, mechanistic rationale, and expert inference. Results: FFM loss (~25%) is heterogeneous and method-dependent. A model of drug-associated anabolic resistance (negative energy balance, protein intake below the per-meal leucine threshold, and reduced NEAT) explains this loss without direct muscle toxicity. DXA-FFM is a biased proxy for muscle; MRI and functional data suggest muscle quality may improve despite mass declines. Four distinct clinical barriers were identified: unreliable self-assessment of gastric motility, chronic nausea/fatigue, severe appetite suppression, and a gap in structured guidance. A framework of 20 tailored recommendations was developed (3 based on direct evidence, 17 on indirect/mechanistic data). Conclusions: GLP-1 RA-associated muscle loss is a real, unevenly distributed risk mitigable via barrier-adapted resistance training and nutritional optimization. The proposed framework is physiologically plausible but requires prospective validation. Intervention is highly indicated for patients with low baseline muscle reserve, advanced age, prior bariatric surgery, CKD, or HFrEF.