Muscle hypertrophy is one of the most extensively studied adaptations in the fields of sport science and resistance training. Nevertheless, for many years, knowledge regarding the training variables influencing hypertrophy has largely been shaped by simplified assumptions and single-variable approaches. Contemporary scientific evidence, however, clearly demonstrates that muscle hypertrophy is a complex, multifactorial, and context-dependent process that cannot be explained by any single training parameter.

This book systematically examines the primary resistance training variables that influence muscle hypertrophy, including training frequency, volume, intensity, rest intervals between sets, proximity to failure, range of motion, repetition duration, and contraction phases, in light of current experimental studies, systematic reviews, and meta-analyses. Each variable is discussed not only in terms of its isolated effects but also within the context of its interaction with other training components, providing a comprehensive scientific framework for understanding hypertrophic adaptations.

Rather than offering universal or rigid prescriptions for hypertrophy-oriented training, the primary aim of this book is to clarify the role, limitations, and practical applicability of individual training variables within resistance training program design. Particular emphasis is placed on the importance of individual differences, recovery capacity, training experience, and programmatic demands. The evidence presented highlights that hypertrophy-focused training should be guided not by the question of “what should be done,” but rather by “for whom, under which conditions, and to what extent.”

This work is intended to serve as an evidence-based, up-to-date, and integrative reference for academics in sport sciences, graduate students, strength and conditioning professionals, and practitioners who seek to design resistance training programs grounded in scientific principles.