Refalo, MCHelms, ERRobinson, ZPHamilton, DLFyfe, JJ2024-11-122024-11-122024-02-23Journal of Sports Sciences, ISSN: 0264-0414 (Print); 1466-447X (Online), Informa UK Limited, 42(1), 85-101. doi: 10.1080/02640414.2024.23210210264-04141466-447Xhttp://hdl.handle.net/10292/18295This study examined the influence of resistance training (RT) proximity-to-failure, determined by repetitions-in-reserve (RIR), on quadriceps hypertrophy and neuromuscular fatigue. Resistance-trained males (n = 12) and females (n = 6) completed an 8-week intervention involving two RT sessions per week. Lower limbs were randomised to perform the leg press and leg extension exercises either to i) momentary muscular failure (FAIL), or ii) a perceived 2-RIR and 1-RIR, respectively (RIR). Muscle thickness of the quadriceps [rectus femoris (RF) and vastus lateralis (VL)] and acute neuromuscular fatigue (i.e., repetition and lifting velocity loss) were assessed. Data was analysed with Bayesian linear mixed-effect models. Increases in quadriceps thickness (average of RF and VL) from pre- to post-intervention were similar for FAIL [0.181 cm (HDI: 0.119 to 0.243)] and RIR [0.182 cm (HDI: 0.115 to 0.247)]. Between-protocol differences in RF thickness slightly favoured RIR [−0.036 cm (HDI: −0.113 to 0.047)], but VL thickness slightly favoured FAIL [0.033 cm (HDI: −0.046 to 0.116)]. Mean volume was similar across the RT intervention between FAIL and RIR. Lifting velocity and repetition loss were consistently greater for FAIL versus RIR, with the magnitude of difference influenced by the exercise and the stage of the RT intervention.© 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent.http://creativecommons.org/licenses/by-nc-nd/4.0/Resistance trainingfatiguemuscle hypertrophyproximity-to-failurerepetitions-in-reserve32 Biomedical and Clinical Sciences42 Health Sciences3202 Clinical Sciences4207 Sports Science and Exercise6.7 Physical1106 Human Movement and Sports Sciences1302 Curriculum and PedagogySport Sciences3202 Clinical sciences4207 Sports science and exercise5201 Applied and developmental psychologyMaleFemaleHumansResistance TrainingBayes TheoremMuscle StrengthAdaptation, PhysiologicalQuadriceps MuscleHypertrophyMuscle, SkeletalMuscle, SkeletalHumansHypertrophyBayes TheoremAdaptation, PhysiologicalFemaleMaleQuadriceps MuscleMuscle StrengthResistance TrainingMaleFemaleHumansResistance TrainingBayes TheoremMuscle StrengthAdaptation, PhysiologicalQuadriceps MuscleHypertrophyMuscle, SkeletalJournal ArticleOpenAccess10.1080/02640414.2024.2321021