Is there a volume saturation point for muscle hypertrophy in resistance-trained individuals? A narrative review

Resistance training (RT) volume is recognized as a key variable driving skeletal muscle hypertrophy. Meta-analyses have supported a positive dose-response relationship, with greater volumes resulting in more pronounced hypertrophic adaptations. However, more recent studies conducted in trained individuals have reported conflicting findings, raising the question of whether a saturation point, defined here as a theoretical threshold beyond which additional training volume no longer yields benefits, might exist, or whether the inconsistencies are better explained by methodological limitations and individual variability. In this narrative review, we explore physiological and methodological factors that may explain such discrepancies. Mechanistically, higher RT volumes are associated with greater anabolic signaling, myofibrillar protein synthesis, ribosomal biogenesis, and satellite cell activation, although these results are not universal. Moreover, excessive training volumes may elevate muscle protein breakdown via activation of catabolic pathways. Methodological factors such as the muscle group and exercises selected, lack of control for prior training volume, overestimation of effect sizes in power calculations, and between-subject variability challenge the interpretation of dose-response relationships. Collectively, these physiological mechanisms and methodological challenges highlight the complexity of establishing a clear and consistent relationship between RT volume and muscle hypertrophy. Expanding our knowledge of the RT dose-response relationship will require rigorous experimental designs, integration of molecular and morphological outcomes, and a greater focus on inter-individual variability. These elements may help clarify whether a true saturation point in RT volume exists for anabolic signaling and muscle hypertrophy.