The dose-response of weekly resistance training volume on skeletal muscle adaptations in trained males

Purpose: Previous literature is unclear on the dose response relationship between resistance training (RT) volume and skeletal muscle adaptations when weekly sets exceed 10-12. The present study compared the effects of various weekly RT volume on skeletal muscle thickness and strength in young RT trained males over 6 weeks. Methods: RT trained young (aged 18-21) males (n=21) were randomly allocated to a low (LOW, n=7) moderate (MOD,n=7) or high (HIGH,n=7) group. Participants undertook RT of the biceps over a 6- week period. LOW performed 1 RT session per week consisting of 9 sets (9 weekly sets), MOD performed 2 RT sessions per week consisting of 9 sets (18 weekly sets), HIGH performed 2 RT sessions per week consisting of 14 and 13 sets (27 weekly sets). All participants consumed 40g whey protein post RT session, whilst recording dietary intake and external RT volume throughout the 6-week period. Pre and Post training period assessments of muscle thickness (MT; Ultrasound), isometric maximal voluntary contraction and one repetition maximum strength was completed by all groups. Data was analysed using a mixed design ANOVA to examine within and between group pre-post changes. Results: MT significantly increased pre-post in LOW (9.3 ± 5.5%, p<.001) and MOD (14.3 ± 10.4%, p<.001) but not in HIGH (5.59 ± 4.0%, p=.054). All groups experienced significant increases in 1RM strength but no significant increase in isometric strength. There were no significant differences between groups for MT, 1RM and isometric strength. Conclusion: The findings of this study suggest that moderate and high weekly RT volumes, performed twice per week, provide minimal further benefit to skeletal muscle adaptations over lower weekly RT volumes performed once per week for 6 weeks