High- and low-load resistance training to failure result in similar muscular adaptations in untrained young males: a randomised trial

Low-load resistance training (LLRT) to failure may be an alternative to high-load resistance training (HLRT), but their comparative effects remain unclear when training volume load is considered. This study compared the effects of LLRT and HLRT on muscle hypertrophy and estimated one-repetition maximum strength (1RM). Twenty-two healthy untrained young males (21.1 ± 2.6 years) were randomly assigned to a LLRT group ( n = 11) or HLRT group ( n = 11). Participants completed supervised knee-extension training to volitional failure three times per week for 6 weeks. Pre- and post-intervention assessments included estimated 1RM and ultrasound-derived muscle thickness (MT) and cross-sectional area (CSA) of the rectus femoris (RF) and vastus intermedius (VI). Total training volume load (repetitions × load) was calculated across all sessions. A two-way mixed-model ANOVA was used for analysis. Estimated 1RM increased in both groups [+ 35.9 kg in LLRT; +32.5 kg in HLRT], with no between-group differences. RF MT increased by 0.46 cm and 0.34 cm, and CSA by 2.07 cm² and 2.36 cm² in the LLRT and HLRT, respectively. Similar increases were observed for VI MT and CSA, with no between-group differences. Total training volume was greater in the LLRT (58,119 ± 12,439 kg) than in the HLRT (45,598 ± 7,963 kg). LLRT and HLRT performed to failure elicited similar muscle hypertrophy and estimated 1RM in untrained young males. The observed equivalence in both hypertrophy and strength likely reflects the rapid neural and morphological responses characteristic of early-phase adaptations in sedentary individuals. The trial was retrospectively registered at ClinicalTrials.gov (Identifier: NCT07412600) on February 14, 2026.