No Difference between Spray Dried Milk and Native Whey Supplementation with Strength Training

Abstract

Background: A rapid digestibility and high leucine content are considered important for maximal stimulation of muscle protein synthesis. Consequently, with these properties, native whey may hold greater anabolic potential than milk, when supplemented in combination with strength training. Our aim was to compare the effects of supplementation with milk or native whey, during a 12-wk strength training period, on gains in muscle mass and strength in young adults.

Methods: In this double-blinded, randomized, controlled study a total of 40 untrained young men and women received two daily servings of either milk or native whey containing 20 g of protein, during a 12-wk strength training intervention. Muscle strength, lean mass, thigh muscle cross-sectional area, m. vastus lateralis thickness and muscle fiber cross-sectional area were assessed before and after the training period. In addition, the acute phosphorylation of the anabolic kinases p70S6K, 4E-BP1 and eEF-2 in response to a standardized workout and supplementation was investigated before and after the 12-wk training period.

Results: Muscle mass and strength increased, by all measures applied (5%-16%, P < 0.001), with no differences between groups (P > 0.25). p70S6K phosphorylation increased (~1000%, P < 0.02) 2 h after exercise in the untrained and trained state, but no differences in anabolic signaling were observed between supplements (P > 0.40). No correlation between these acute measures and changes in muscle mass or strength were observed.

Conclusion: Supplementation with milk or native whey during a 12-wk strength training period did not differentially affect muscle mass and strength in young untrained individuals.

FIGURE 1

Timeline of the study.

FIGURE 2

Blood concentrations of essential amino acids (A), branched chain amino acids (B) and leucine (C) following intake of 20 g of milk protein, or native whey immediately after a bout of resistance exercise. Arrow indicates time point of protein supplement ingestion. Values are mean ± SD (only shown for highest and lowest values). n = 12 and 10 in the milk group and native whey group, respectively. Data were analyzed with a two-way repeated measures ANOVA (time–supplement). Multiple comparisons tests were used as post hoc tests to specify the significant differences between groups (Tukey) and within groups (Dunnett). Black data points indicate difference form resting values, gray data points indicate no significant difference from resting levels. *Milk difference between pre and post, §native whey difference between pre and post, †milk and native whey different at pre, ‡milk and native whey different at post, P < 0.05.

FIGURE 3

Phospho/total ratio of P70S6K (A), 4E-BP1 (B) and eEF-2 (C) after intake of milk or native whey immediately after a bout of resistance exercise. Values are mean ± SD. n = 12 and 10 in the milk group and native whey group, respectively. Data were analyzed with a two-way repeated-measures ANOVA (time–supplement). Multiple-comparisons tests were used as post hoc tests to specify the significant differences between groups (Tukey) and within groups (Sidak). *Different from pre within group, §Relative difference from pre, difference between untrained and trained state (P < 0.05).