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Muscle Performance, Size, and Safety Responses After Eight Weeks of Resistance Training and Protein Supplementation: A Randomized, Double-Blinded, Placebo-Controlled Clinical Trial

Herda, Ashley A.1; Herda, Trent J.2; Costa, Pablo B.3; Ryan, Eric D.4; Stout, Jeffrey R.5; Cramer, Joel T.6

Journal of Strength & Conditioning Research: November 2013 - Volume 27 - Issue 11 - p 3091–3100
doi: 10.1519/JSC.0b013e31828c289f
Original Research

Abstract: Herda, AA, Herda, TJ, Costa, PB, Ryan, ED, Stout, JR, and Cramer, JT. Muscle performance, size, and safety responses after eight weeks of resistance training and protein supplementation: A randomized, double-blinded, placebo-controlled clinical trial. J Strength Cond Res 27(11): 3091–3100, 2013—The purpose of this study was to examine the effects of 2 different types of protein supplementation on thigh muscle cross-sectional area (CSA), blood markers, muscular strength, endurance, and body composition after 8 weeks of low- or moderate-volume resistance training in healthy, recreationally trained, college-aged men. One hundred and six men were randomized into 5 groups: low-volume resistance training with bioenhanced whey protein (BWPLV; n = 22), moderate-volume resistance training with BWP (BWPMV; n = 20), moderate-volume resistance training with standard whey protein (SWPMV; n = 22), moderate-volume resistance training with a placebo (PLA; n = 21), or moderate-volume resistance training with no supplementation (CON; n = 21). Except for CON, all groups consumed 1 shake before and after each exercise session and one each on the nontraining day. The BWPLV, BWPMV, and SWPMV groups received approximately 20 g of whey protein per shake, whereas the BWP groups received 5 g of additional polyethylene glycosylated (PEG) leucine. Resistance training sessions were performed 3 times per week for 8 weeks. There were no interactions (p > 0.05) for muscle strength and endurance variables, body composition, muscle CSA, and safety blood markers, but the main effects for training were observed (p ≤ 0.05). However, the Albumin:Globulin ratio for SWPMV was lower (p = 0.037) than BWPLV and BWPMV. Relative protein intake (PROREL) indicated a significant interaction (p < 0.001) with no differences across groups at pre; however, BWPLV, BWPMV, and SWPMV had a greater intake than did PLA or CON at post (p < 0.001). This study indicated that 8 weeks of resistance training improved muscle performance and size similarly among groups regardless of supplementation.

1Department of Ophthalmology, KU Eye, University of Kansas Medical Center, Prairie Village, Kansas;

2Department of Health, Sport, and Exercise Sciences, Biomechanics Laboratory, University of Kansas, Lawrence, Kansas;

3Department of Kinesiology, Human Performance Laboratory, California State University-San Bernardino, San Bernardino, California;

4Department of Exercise and Sport Science, Neuromuscular Research Laboratory, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina;

5Department of Sport and Exercise Science, University of Central Florida, Orlando, Florida; and

6Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska

Address correspondence to Joel T. Cramer,

Copyright © 2013 by the National Strength & Conditioning Association.