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PERSPECTIVE article

Front. Sports Act. Living
Sec. Exercise Physiology
Volume 7 - 2025 | doi: 10.3389/fspor.2025.1517190

Within-individual design for assessing true individual responses in resistance training-induced muscle hypertrophy

Provisionally accepted
Talisson Santos Chaves Talisson Santos Chaves 1Deivid Gomes da SIlva Deivid Gomes da SIlva 1Manoel Lixandrao Manoel Lixandrao 2Cleiton Augusto Libardi Cleiton Augusto Libardi 1*
  • 1 MUSCULAB - Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education (DEFMH), Federal University of São Carlos (UFSCar)., São Carlos, São Paulo, Brazil
  • 2 University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States

The final, formatted version of the article will be published soon.

    Understanding interindividual variability in muscle hypertrophy in response to resistance training (RT) is a key focus of contemporary research. Common aims include identifying determinants of variability and recognizing individuals who do not respond to RT (i.e., non-responders). However, accurately identifying true individual responses (TIR) remains challenging due to the complex nature of muscle hypertrophy assessments. This complexity arises from distinguishing the TIR from natural variation in muscle mass over time and random measurement error in pre- and postintervention assessments. Existing studies have often overlooked this complexity, failing to employ experimental designs capable of isolating the TIR. Additionally, the reliance on random measurement error assessments based on group level data may not adequately capture the biological variation in muscle mass within individuals. In this context, we propose an experimental design based on unilateral, within-subject resistance training, capable of estimating biological variation in muscle mass and identifying TIR to RT-induced muscle hypertrophy. Additionally, we present an approach to effectively identify non-responders.

    Keywords: Non responders, Typical error of measurement, experimental design, Biological vailability, Random error analysis

    Received: 25 Oct 2024; Accepted: 13 Jan 2025.

    Copyright: © 2025 Chaves, da SIlva, Lixandrao and Libardi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Cleiton Augusto Libardi, MUSCULAB - Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education (DEFMH), Federal University of São Carlos (UFSCar)., São Carlos, São Paulo, Brazil

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.