The effect of resistance training repetition load on muscular hypertrophy and strength in young resistance trained men

Resistance training (RT)-induced skeletal muscle hypertrophy is partly responsible for the RT-induced increase in strength. Previously, we reported that exercise repetition load played a minimal role in the promotion of RT-induced gains in hypertrophy and strength gains in RT-naïve participants performing RE to volitional failure. Thus, the main aim of this study were to determine the effects of 12 weeks of RT on muscle strength and hypertrophy in a trained population. 49 resistance-trained men (mean ± SEM, 23 ± 1 years, 85.9 ± 2.2 kg, 181 ± 1 cm) were randomly allocated into a lower load-high-repetition group (HR, n=24) or a higher load-low-repetition group (LR, n=25). Repetition load was set so that volitional lifting failure was achieved within the repetition ranges of 20-25 (~35-50% of 1RM) for HR or 8-12 for LR (~70-85% of 1RM). Strength as one repetition maximum (1RM) was assessed pre and post. Changes in lean body mass (LBM), appendicular lean mass (ALM) and leg lean mass (LLM) were assessed using dual-energy x-ray absorptiometry (DXA). There were significant increases in strength in all exercises with no differences between groups (p > 0.05) with the exception of bench press where LR showed a greater increase in 1RM than HR (p = 0.012). Similarly, LBM, ALM, and LLM increased significantly following training in the HR group (1.0 ± 0.9kg, p < .001; 0.8 ± 1.1 kg, p < 0.05; 0.7 ± 0.9 kg, p < 0.01 respectively) and the LR group (1.6 ± 1.4 kg, p < .001; 1.0 ± 1.2 kg, p < 0.05; 0.7 ± 1.0 kg, p < 0.01 respectively) with no significant differences between groups (all p > 0.05). These data show that RE performed to volitional failure using either HR or LR induces similar adaptations strength and lean mass accrual in young resistance-trained men.