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 (2010) 09, 262 - 269

Research article
Caffeine Attenuates Acute Growth Hormone Response to a Single Bout of Resistance Exercise
Bo-Han Wu1, , Jung-Chang Lin2
Author Information
1 Department of Sports & Recreation Management, Chang Jung Christian University, Tainan, Taiwan
2 Graduate Institute Sport Coaching Science, Chinese Culture University, Taipei, Taiwan

Bo-Han Wu
✉ Department of Sports & Recreation Management, Chang Jung Christian University, 396 Chang Jung Rd., Sec.1, Kway Jen, Tainan 71101, Taiwan, R.O.C
Email: licar1980@hotmail.com
Publish Date
Received: 22-10-2009
Accepted: 22-03-2010
Published (online): 01-06-2010
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ABSTRACT

The purpose of this study was to investigate the effects of caffeine consume on substrate metabolism and acute hormonal responses to a single bout of resistance exercise (RE). Ten resistance-trained men participated in this study. All subjects performed one repetition maximum (1RM) test and then performed two protocols: caffeine (CAF, 6 mg·kg-1) and control (CON) in counter balanced order. Subjects performed RE (8 exercises, 3 sets of 10 repetitions at 75% of 1RM) after caffeine or placebo ingestion one hour prior to RE. Blood samples collected prior to treatment ingestion (pre-60), immediately prior to RE (pre-exe), and 0, 15, 30 min post to RE (P0, P15, P30) for analysis of insulin, testosterone, cortisol, growth hormone, glucose, free fatty acid and lactic acid. Each experiment was separated by seven days. In this study, statistical analysis of a two-way analysis of variance (treatment by time) with repeated measures was applied. After ingesting caffeine, the concentrations of free fatty acid (pre- exe, P0, P15, P30) in CAF were significantly higher than CON (p < 0.05). Additionally, the responses of GH (P0, P15, P30) in CAF were significantly lower than CON (p < 0.05), whereas the concentrations of insulin, testosterone and cortisol were not different between CAF and CON (p < 0.05) after RE. The results of this study indicated that caffeine ingestion prior to RE might attenuate the response of GH. This effect might be caused by the elevation in blood FFA concentration at the beginning of RE.

Key words: Nutritional supplementation, growth hormone, free fatty acid, ergogenic aids


           Key Points
  • Caffeine ingestion may attenuate the response of GH to a single bout of resistance exercise.
  • The depression of GH response may be caused by the elevation in serum FFA concentration at the beginning of resistance exercise.
  • Caffeine ingestion before resistance exercise may not alert the concentration of cortisol and testosterone.
 
 
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