Is Progressive Overload Necessary? The Time Course of Muscle Hypertrophy in Resistance Training Protocols With and Without Progression

• Grant number: 25/09806-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2025
• End date: August 31, 2026
• Field of knowledge: Health Sciences - Physical Education
• Principal Investigator: Cleiton Augusto Libardi
• Grantee: Otavio Ferrari Netto
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 23/04739-2 - RESISTANCE TRAINING PROGRESSION: EFFECTS ON THE REMODELING OF THE EXTRACELLULAR MATRIX IN HUMANS, AP.R

Abstract

Progressive overload is widely regarded as a fundamental principle of resistance training (RT) and is systematically included in international exercise prescription guidelines. Nevertheless, there is no direct evidence that its absence compromises the magnitude of muscle hypertrophy. No randomized controlled trial has demonstrated that individuals following a protocol without overload progression fail to achieve hypertrophic gains or experience inferior adaptations. This gap is particularly relevant for untrained individuals, in whom submaximal and non-progressive stimuli may be sufficient to induce initial increases in muscle mass while imposing lower physiological stress, an aspect that may enhance training adherence. Still, it is plausible that, as training status improves, progressive overload becomes necessary, although the exact timing for its implementation remains unclear. This project aims to investigate the time course of muscle hypertrophy in protocols with and without load progression, both performed within the same repetition range (10 to 12 RM), using a within-subject design and ultrasound-based assessments of the cross-sectional area of the vastus lateralis every three weeks. Additionally, total training volume progression, perceived exertion, and repetitions in reserve (RIR) will be analyzed. The results may provide novel evidence regarding the actual necessity of progressive overload in RT programs and help identify the most appropriate timing for its implementation. (AU)