Effects Of Resistance Training Volume And Whey Protein Supplementation On Lower-Body Strength And Muscle Cross-Sectional Area

Abstract

Based on recent studies, it may be possible to use a reduced-volume resistance training program in conjunction with whey protein supplementation to achieve similar increases in strength and hypertrophy compared to traditional-volume resistance training without supplementation. To examine the effects of eight weeks of reduced-volume resistance training with whey protein supplementation versus traditional volume resistance training without supplementation on leg press strength (LPMAX) and thigh muscle cross-sectional area (mCSA) in collegeaged men. Twenty-two healthy, recreationally active men (mean ± SD age: 21.5 ± 3 yrs; height: 180 ± 7.1 cm; weight: 81.6 ± 13.8 kg) volunteered for LPMAX and mCSA testing before and after an 8-week resistance training intervention. LPMAX was determined using a standard one-repetition maximum (1-RM) protocol on a 45° hip sled, and mCSA at mid-thigh was assessed using a peripheral quantitative computed tomography scanner. Participants were randomly assigned to either the whey protein (WP) or control (CON) group. The CON group (n = 10) performed workouts with no supplementation 3 times per week at 80% of their LPMAX for 8 weeks, where week 1 consisted of 3 sets of 6 repetitions, week 2 was 4 sets of 6 repetitions, and weeks 3 - 8 were 5 sets of 6 repetitions. The WP group (n = 12) consumed a whey protein drink (20g polyethylene glycosylated whey protein concentrate, 7g leucine, and 200mg proteases) 30 minutes before and immediately after each training session and completed 1 set of 6 repetitions during week 1, 2 sets of 6 repetitions during week 2, and 3 sets of 6 repetitions during weeks 3 - 8. Resistance training volume was calculated as sets × repetitions × load (kg). An independent-samples t-test indicated that the volume of the CON group (mean ± SD = 144,215 ± 31,332) was 1.9 times greater than (p < 0.001) the volume of the WP group (75,552 ± 17,362). The two-way ANOVAs indicated 28% (WP) and 22% (CON) increases (p < 0.001) from pre- to post-training for LPMAX, while mCSA increased (p < 0.001) by 3.4% (WP) and 4.4% (CON). However, there were no interactions (p > 0.05) and no differences (p > 0.05) between the WP and CON groups at either pre- or post-training. These findings suggested that resistance training with 48% less volume plus whey protein supplementation for 8 weeks resulted in similar increases in leg press strength and thigh mCSA as a higher-volume resistance training program with no supplementation. These results demonstrated the general importance of nutritional strategies (i.e., protein timing) in conjunction with resistance training for increasing muscle strength and size. These findings may be particularly useful when resistance training volume must remain low, such as during injury rehabilitation and in-season resistance training mesocycles.