Growth hormone receptor antagonist treatment reduces exercise performance in young males.
BACKGROUND
The effects of GH on exercise performance remain unclear.


OBJECTIVE
The aim of the study was to examine the effects of GH receptor (GHR) antagonist treatment on exercise performance.


METHODS
Subjects were treated with the GHR antagonist pegvisomant or placebo for 16 d. After the treatment period, they exercised to determine exercise performance and hormonal and metabolic responses.


METHODS
Twenty healthy males participated in the study.


METHODS
Subjects were treated with the GHR antagonist (n = 10; 10 mg/d) or placebo (n = 10). After the treatment period, they performed a maximal oxygen uptake (VO(2 max)) test and a prolonged exercise test, consisting of 60 min of submaximal cycling followed by exercise to fatigue at 90% of VO(2 max).


METHODS
VO(2 max) was measured before and after the treatment period. Hormonal and metabolic responses and time to exhaustion during prolonged exercise were determined.


RESULTS
Resting serum IGF-I concentration decreased by 20% in the GHR antagonist-treated group (P < 0.05), whereas no change was observed in the placebo group. Conversely, resting serum GH concentration was significantly higher in the treatment group compared with the placebo group (P < 0.01). VO(2 max) did not change significantly in either group after the treatment period. Time to exhaustion at 90% of VO(2 max) was significantly shorter in the treatment group (P < 0.05). No significant differences were observed between the groups in terms of changes in serum free fatty acids, glycerol, VO(2), or relative fat oxidation.


CONCLUSIONS
GH might be an important determinant of exercise capacity during prolonged exercise, but GHR antagonist did not alter fat metabolism during exercise.
Goto
Kazushige
K
Institute of Sports Medicine, Bispebjerg Hospital, DK-2400 Copenhagen, Denmark. kgoto@aoni.waseda.jp
Doessing
Simon
S
Nielsen
Rie Harboe
RH
Flyvbjerg
Allan
A
Kjaer
Michael
M
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D004311:Double-Blind Method; D015444:Exercise; D005230:Fatty Acids, Nonesterified / Q000097:blood; D019382:Human Growth Hormone / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D011986:Receptors, Somatotropin / Q000037:antagonists & inhibitors*
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D018972:Insulin-Like Growth Factor Binding Protein 3; D011986:Receptors, Somatotropin; D019382:Human Growth Hormone; D019344:Lactic Acid; D007334:Insulin-Like Growth Factor I; C406545:pegvisomant