How close to failure? Muscle swelling and EMG responses to resistance training with different proximities to muscle failure
DOI:
https://doi.org/10.47197/retos.v81.118964Keywords:
Cross-sectional area, Muscle activation, Repetition number, Resistance trainingAbstract
Introduction: Muscle swelling and electromyography (EMG) are non-invasive markers of peripheral and neuromuscular responses to resistance training. However, no study has examined how graded proximity to muscle failure modulates these responses in trained individuals.
Objective: This study compared the acute responses of EMG and muscle swelling across six protocols differing in proximity to muscle failure in trained men.
Methodology: Fourteen trained men performed the bilateral knee extension exercise with four sets at 60% of one-repetition maximum. Protocols included training to muscle failure (MF) and five non-failure (NMF) conditions with 10%, 20%, 30%, 40%, and 50% fewer repetitions than MF. Cross-sectional area (ultrasound) and normalized EMG (surface electrodes) of the rectus femoris and vastus lateralis were assessed pre- and post-training.
Results: Muscle swelling differed significantly between all protocols for both muscles (p<0.05), increasing progressively as repetitions approached failure. For EMG, MF produced the highest activation; however, NMF protocols with small repetition reductions (−10% to −30%) did not differ significantly from each other. Muscle swelling was more sensitive to small changes in repetition volume than EMG amplitude.
Conclusion: These findings indicate that proximity to failure modulates peripheral and neuromuscular responses in a dose-dependent manner, with distinct sensitivity thresholds between variables, providing practical guidance for resistance training prescription.
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Copyright (c) 2026 Bruno de Freitas Rodrigues, Marcelo Danillo Matos dos Santos, Eduardo Mendonça Pimenta, Lucas Túlio Lacerda, Marcel Bahia Lanza, Gustavo Ferreira Pedrosa, Fernando Vitor Lima, Mauro Heleno Chagas, Rodrigo César Ribeiro Diniz
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