Investigating the Impact of Less Than or Greater Than 60 Seconds of Inter-Set Rest on Muscle Hypertrophy and Strength Increases in Males with >1 Year of Resistance Training Experience: Systematic Review with Meta-Analysis

Background: Inter-set rest intervals (ISR) influence resistance training adaptations. Shorter intervals (<60s) promote metabolic stress, while longer intervals (>60s) are thought to enhance recovery, mechanical tension, and strength. Aim: This review examined the effects of <60s vs. >60s ISR on hypertrophy, strength, and secondary outcomes in resistance-trained males. Methods: Six studies were included, assessing hypertrophy, strength, motor unit recruitment, power, and hormones. Standardised mean differences (SMDs) and forest plots were used. Results: Longer ISRs provided small improvements in hypertrophy (SMD = 0.08) and strength (SMD = -0.74). Hormonal and power outcomes were inconsistent. Conclusion: Longer ISRs slightly improve strength but show minimal advantage for hypertrophy, highlighting the need for further study in trained populations.