Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
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©Journal of Sports Science and Medicine (2007) 06, 85 - 92

Research article
Effects of Protein Supplementation on Muscular Performance and Resting Hormonal Changes in College Football Players
Jay R. Hoffman , Nicholas A. Ratamess, Jie Kang, Michael J. Falvo, Avery D. Faigenbaum
Author Information
Department of Health and Exercise Science, The College of New Jersey, Ewing, New Jersey, USA

Jay R. Hoffman
✉ Department of Health and Exercise Science, The College of New Jersey, PO Box 7718, Ewing, New Jersey 08628, USA
Email: hoffmanj@tcnj.edu
Publish Date
Received: 10-11-2006
Accepted: 22-12-2006
Published (online): 01-03-2007
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ABSTRACT

The effect of protein supplementation on athletic performance and hormonal changes was examined in 21 experienced collegiate strength/power athletes participating in a 12-week resistance training program. Subjects were randomly assigned to either a protein supplement (PR; n = 11) or a placebo (PL; n = 10) group. During each testing session subjects were assessed for strength (one repetition maximum [1-RM] bench press and squat), power (Wingate anaerobic power test) and body composition. Resting blood samples were analyzed at weeks 0 (PRE), 6 (MID) and 12 (POST) for total testosterone, cortisol, growth hormone, and IGF-1. No difference was seen in energy intake between PR and PL (3034 ± 209 kcal and 3130 ± 266 kcal, respectively), but a significant difference in daily protein intake was seen between PR (2.00 g·kg body mass[BM]-1·d-1) and PL (1.24 g·kgBM-1·d-1). A greater change (p < 0.05) in the ∆ 1-RM squat was seen in PR (23.5 ± 13.6 kg) compared to PL (9.1 ± 11.9 kg). No other significant strength or power differences were seen between the groups. Cortisol concentrations were significantly lower at MID for PL and this difference was significantly different than PR. No significant changes were noted in resting growth hormone or IGF-1 concentrations in either group. Although protein supplementation appeared to augment lower body strength development, similar upper body strength, anaerobic power and lean tissue changes do not provide clear evidence supporting the efficacy of a 12-week protein supplementation period in experienced resistance trained athletes.

Key words: Sport nutrition, resistance training, endocrine, testosterone


           Key Points
  • Collegiate strength/power athletes may not meet daily recommended energy or protein needs.
  • When athletes are provided a protein supplement they appear to meet the recommended daily protein intake for strength/power athletes.
  • Protein supplementation did augment lower body strength development in experienced strength/power athletes.
  • Results of upper body strength, anaerobic power and lean tissue changes did not support the efficacy of a 12-week protein supplementation period in experienced resistance trained athletes.
 
 
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