Gustavo F. Pedrosa, Arthur B.G. Bischoff, Antony K. Luchese, Maria E. C. Rigo, Douglas G.D. Silva, Leonardo R. Marques, Tiago D. L. Nunes, Lorenzo I. Laporta, Fábio J. Lanferdini

SUMMARY
Background. Previous studies suggest training to failure may not yield superior muscle responses compared to non-failure training, leaving the combined use unexplored.
Objective. To compare the number of repetitions, volume-load, time under tension (TUT), rate of perceived exertion (RPE), and muscle swelling between two protocols: one involving four sets to failure (TFAS) and the other involving only the final set reaching failure (TFLS).
Methods. Fourteen trained adults completed both conditions in four sessions, with the first two sessions dedicated to determining the one-repetition maximum (1RM) for the barbell preacher curl exercise. In the third session, participants completed TFAS, maxing repetitions across four sets at 70% of 1RM. In the fourth session (TFLS), they fixed repetition in the first three sets (mean achieved during TFAS), with the final set to failure. In both sessions, repetitions, volume-load, RPE, and TUT were recorded postset.
Before and immediately after both TFAS and TFLS, participants’ biceps brachii cross-sectional area at 50% of humerus length was measured using ultrasound imaging to assess muscle swelling. Comparisons used ANOVA and paired t-tests.
Results. TFAS had higher RPE across sets (TFLS = 32 ± 4; TFAL = 37 ± 4) and a greater total TUT compared to TFLS (TFLS = 168 ± 44s; TFAL = 178 ± 41s). TFLS achieved more repetitions (TFLS = 38.93 ± 6.51; TFAL = 37.36 ± 5.24) and volumeload (TFLS = 918.55 ± 235.38 kg; TFAL = 888.77 ± 241.46 kg). Both protocols showed similar muscle swelling (TFLS = 23.90 ± 5.27 cm2; TFAL = 20.73 ± 10.71 m2).
Conclusions. TFLS allowed for more repetitions with lower RPE, with no difference
in swelling.

Keywords: Failure, muscle swelling, non-failure, rate of perceived exertion, repetitions,