Sport Sciences for Health, cilt.22, sa.1, 2026 (ESCI, Scopus)
Background: Inter-set rest intervals in resistance training have been shown to affect muscle growth and strength gains. However, limited evidence indicates that its influence seems to be offset when training volume-load is matched between training schemes. The present study compared the effects of volume-load-equated resistance-training programs with very-short (SHORT) and long (LONG) inter-set rest intervals on changes in muscle size and maximum strength. Methods: In a within-subject design, 17 untrained young men (25.3 ± 2.8 years) completed unilateral knee-extension resistance training twice a week for 10 weeks with either LONG (10RM, 3–4 sets to failure; 2-min rest) or SHORT rests (10RM, multiple sets to failure until matching the volume of repetitions done in LONG; 20-s rest). Quadriceps regional hypertrophy was evaluated via MRI, and changes in strength were assessed through unilateral knee-extension 1RM testing. Results: No significant differences were observed between conditions for the changes in cross-sectional area of the rectus femoris (SHORT = 14.3%; LONG = 16.7%; diff: 0.30 cm2 [95% CI − 0.77, 1.37]; P = 0.587) and the vastii (SHORT = 7.2%; LONG = 6.4%; diff: − 1.34 cm2 [95% CI − 5.56, 2.89]; P = 0.541), as well as in maximum strength (SHORT = 42.4%; LONG = 41.5%; diff: − 0.59 kg [95% CI − 8.36, 7.18]; P = 0.883). Conclusion: Changes in quadriceps cross-sectional area and unilateral knee-extension 1RM performance do not seem to differ between 10-week training programs comprising 20-s and 2-min inter-set rest intervals with volume-load-equated conditions in untrained young men.