AUTHOR=Huschtscha Zoya , Parr Alexandra , Porter Judi , Costa Ricardo J. S. 

TITLE=The Effects of a High-Protein Dairy Milk Beverage With or Without Progressive Resistance Training on Fat-Free Mass, Skeletal Muscle Strength and Power, and Functional Performance in Healthy Active Older Adults: A 12-Week Randomized Controlled Trial

JOURNAL=Frontiers in Nutrition

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.644865

DOI=10.3389/fnut.2021.644865

ISSN=2296-861X

ABSTRACT=<p>The study aimed to investigate the independent and combined effects of consuming a high-protein dairy milk beverage, twice daily, with or without a progressive resistance training (PRT) program on outcomes of age-related sarcopenia, in healthy active older (≥50 years) adults. In this 12-week, 2 × 2 factorial study, participants were randomly allocated into one of four groups: dairy milk beverage (DM), exercise and dairy milk beverage (EX+DM), exercise alone (EX), and control (CON). The EX group underwent a 12-week whole-body PRT schedule (three sessions/week) and a high-protein dairy milk beverage (DM) was consumed twice daily (30 g protein/day). At weeks 0, 6, and 12, body composition (iDXA), strength [one-repetition maximum (1RM): leg press, chest press, lateral (<italic>lat</italic>) pull-down, and handgrip], power (countermovement jump), cardiorespiratory fitness (<italic>V</italic>O<sub>2</sub>), and physical performance (gait speed) were measured. Before measurements, blood samples were collected to determine the immune (i.e., leukocyte trafficking and inflammatory cytokines) and hormonal (i.e., insulin, cortisol, IGF-1, testosterone, and estradiol) profiles. Participants (<italic>n</italic> = 37) completed the study within the controlled experimental conditions. Protein intake increased in the EX+DM [mean ± SD, 1.2 ± 0.2 to 1.8 ± 0.4 g/kg body mass (BM) per day<sup>−1</sup>] and DM (1.3 ± 0.5 to 1.8 ± 0.6 g kg<sup>−1</sup> BM day<sup>−1</sup>) groups during the intervention. Absolute fat-free mass increased in the EX+DM [mean (95% confidence interval) = 0.65 (0.25–1.0) kg] and EX [0.49 (−0.44 to 1.40) kg] groups (<italic>P</italic> &lt; 0.001) compared to DM [−0.54 (−1.6 to 0.05) kg]. Relative fat mass decreased (group<sup>*</sup>time, <italic>P</italic> = 0.018) in DM [−1.8% (−3.3 to −0.35%)] and EX+DM [−1.3% (−2.3 to −0.31%)], which was a greater reduction than that in the CON [0.10% (−0.80 to 1.0%)] group (P &lt; 0.01). Relative maximal strength increased in both the EX and EX+DM (≥35%, <italic>P</italic> &lt; 0.05) groups, but not in the DM and CON groups. The change in 1RM strength outcomes was higher in EX+DM compared to all other groups (53–78%, <italic>P</italic> &lt; 0.01). There was an increase in resting plasma IL-10 concentration in EX+DM (88%), compared to all the other groups (<italic>P</italic> = 0.016). No other differences in systemic inflammatory cytokines were observed. There were no significant changes in all hormone concentrations measured among all groups. In conclusion, a high-protein dairy milk beverage providing additional protein did not further enhance the effects of PRT on outcomes of fat-free mass, power, or physical performance. However, there was a significant augmentative effect for high-protein dairy milk consumption on changes to maximal strength outcomes during PRT in healthy active older adults.</p>