Double-Blind Controlled Trial
Author information The University of Tampa, Tampa FL Sharp M, Shields K, Lowery R, Lane J, Partl J, Holmer C, Minevich J, Souza E, Wilson J
The purpose of this study was to determine the effects of post-exercise consumption of two servings of whey isolate, compared to a maltodextrin control on lean mass and strength during 8 weeks of resistance training.
Thirty college-aged, resistance-trained males and females were randomly assigned to one of the treatment groups. Subjects consumed two servings (46g) of whey protein isolate or maltodextrin. Subjects trained 5 days per week (3 resistance training, 2 cardio) for 8 weeks as a part of a daily undulating periodized resistance-training program. Two servings of protein were consumed immediately following exercise or at a similar time of day on off days. Dual-emission x-ray absorptiometry (DXA) was used to determine changes in body composition. Maximum strength was assessed by one-rep-max (1RM) for bench press (upper body) and deadlift (lower body). A two-way ANOVA with repeated measures model was used to identify the group, time, and group by time interactions. The significance level was set at p < 0.05
Whey protein isolate lead to a significant increase in lean body mass (4.7%) compared with baseline (p < 0.0001). Fat loss was also significantly decreased at 8 weeks compared to baseline for whey isolate at 8.3% respectively (p < 0.0001). 1RM both deadlift and bench-press were both significantly increased for all treatment groups when compared to baseline. Therefore whey protein isolate can help with optimizing body composition.
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