Intake of whey isolate supplement and muscle mass gains in young healthy adults when combined with resistance training: a blinded randomized clinical trial (pilot study)

Whey protein is consumed worldwide by athletes due to its alleged benefits on muscle mass and strength. Because of its rich branched chain amino acids content, namely leucine, whey appears to favor muscle protein synthesis through the mTOR pathway in combination with resistance training, when taken...

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Bibliographic Details
Published in:	Journal of sports medicine and physical fitness Vol. 60; no. 1; p. 75
Main Authors:	Duarte, Nuno M, Cruz, Agostinho L, Silva, Diogo C, Cruz, Graça M
Format:	Journal Article
Language:	English
Published:	Italy Edizioni Minerva Medica 01-01-2020
Subjects:	Adolescent Adult Body composition Body Composition - drug effects Body fat Body mass Clinical trials Dietary Supplements Double-Blind Method Elbow Female Humans Lean body mass Leucine Male Muscle function Muscle strength Muscle Strength - drug effects Muscle, Skeletal - drug effects Muscles Muscular Strength Physical Fitness Physical training Pilot Projects Protein biosynthesis Proteins Quadriceps muscle Resistance Training - methods Strength training Supplements TOR protein Torque Ultrasound Whey protein Whey Proteins - administration & dosage Whey Proteins - pharmacology Young Adult
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Summary:	Whey protein is consumed worldwide by athletes due to its alleged benefits on muscle mass and strength. Because of its rich branched chain amino acids content, namely leucine, whey appears to favor muscle protein synthesis through the mTOR pathway in combination with resistance training, when taken after exercise in sufficient amounts. In the present study resistance trained (≥3 months) participants (men and women) between the age of 18 and 30 years old were randomized in a blinded fashion to whey protein isolate (N.=4) and an isocaloric placebo (N.=4) groups. Both groups were subjected to a 12-week RT protocol designed to increase muscle mass and strength. Muscle thickness of the biceps brachii (BB) at 67% of its length and quadriceps muscles, vastus lateralis (VL); vastus intermidius (VI) and rectus femoris (R.F.) at 30% and 50% of its length were assessed using ultrasound technique. Muscle strength was assessed using an isokinetic protocol at angular velocities of 60º.s-1 (5 repetitions) and 180º.s-1 (10 repetitions) with a range of motion of 0º to 100º on a dynamometer to determine peak torque (PT). Lean body mass (LBM) and body fat percentage (%BF) were assessed using a body composition analyzer through segmental multi-frequency bioelectrical impedance method. All variables were assessed before and after interventions. Results show an increase in muscle thickness of all muscles from RT except for V.L. and RF at 30% (P>0.05) with an increase in VI at 50% (P=0.045) and a trend in VI at 30% (P=0.075) related to whey protein intake. PT increased with RT for all knee flexors/extensors (P<0.05) and for elbow flexors/extensors at 60º extension and 180º flexion (P<0.05) with no effect from whey. LBM increased with RT (P=0.015) and %BF was maintained during the trial (P>0.05). No interactions were found between training and supplementation. Supplementation with whey protein, combined with RT can increase muscle mass with no effects on muscle strength. Whey protein supplementation may alter body composition in favor of additional fat free mass with no significant changes in body fat.
ISSN:	0022-4707 1827-1928
DOI:	10.23736/S0022-4707.19.09741-X