High-frequency resistance training does not promote greater muscular adaptations compared to low frequencies in young untrained men.

The aim of the study was to compare the effect of resistance training (RT) frequencies of five times (RT5), thrice- (RT3) or twice- (RT2) weekly in muscle strength and hypertrophy in young men. Were used a within-subjects design in which 20 participants had one leg randomly assigned to RT5 and the other to RT3 or to RT2. 1 RM and muscle cross-sectional area (CSA) were assessed at baseline, after four (W4) and eight (W8) RT weeks. RT5 resulted in greater total training volume (TTV) than RT3 and RT2 (P = .001). 1 RM increased similarly between protocols at W4 (RT5: 55 ± 9 Kg, effect size (ES): 1.18; RT3: 51 ± 11 Kg, ES: 0.80; RT2: 54 ± 7 Kg, ES: 1.13; P < .0001) and W8 (RT5: 62 ± 11 Kg, ES: 1.81; RT3: 57 ± 11 Kg, ES: 1.40; RT2: 60 ± 8 Kg, ES: 1.98; P < .0001) vs. baseline (RT5: 45 ± 9 Kg; RT3: 42 ± 11 Kg; RT2: 46 ± 7 Kg). CSA increased similarly between protocols at W4 (RT5: 24.6 ± 3.9 cm, ES: 0.54; RT3: 22.0 ± 4.6 cm, ES: 0.19; RT2: ES: 0.25; 23.8 ± 3.8 cm; P < .001), and W8 (RT5: 25.3 ± 4.3 cm; ES: 0.69; RT3: 23.6 ± 4.2 cm, ES: 0.58; RT2: 25.5 ± 3.7 cm; ES: 0.70; P < .0001) vs. baseline (RT5: 22.5 ± 3.8 cm; RT3: 21.2 ± 4.0 cm; RT2: 22.9 ± 3.8 cm). Performing RT5, RT3 and RT2 a week result in similar muscle strength increase and hypertrophy, despite higher TTV for RT5.