Ramadan fasting and the GH/IGF-1 axis of trained men during submaximal exercise.
OBJECTIVE
The aim of this study was to explore possible changes in body composition, blood glucose regulation, plasma growth hormone (GH), insulin-like growth factor 1 (IGF-1), insulin-like growth factor-binding protein-3 (IGFBP-3), and insulin concentrations of trained athletes in response to the intermittent fasting and dehydration of Ramadan observance.


METHODS
Nine trained male rugby players (age 19 +/- 2 years, height 1.78 +/- 0.74 m) were tested 3 times: before Ramadan (C), at the end of the first week (R1), and during the fourth week (R2). They performed a progressive cycle ergometer test at each visit. The work rate was increased in 6-min stages corresponding to 20, 30, 40, 50 and 60% of W max. Substrate oxidation was evaluated by indirect calorimetry. On each occasion, substrate and plasma hormone concentrations were measured at rest and at the end of the exercise.


RESULTS
Ramadan fasting induced a significant decrease in body mass and body fat (R2 vs. C, p < 0.001). Plasma concentrations of glucose, insulin, GH, IGF-1 and IGFBP-3 did not change significantly between C and R2, either at rest or following exercise.


CONCLUSIONS
Ramadan fasting induces positive changes in body composition without disturbing glucose regulation or activity of the GH/IGF-1 system.
Bouhlel
Ezzedine
E
Institut Supérieur du Sport et de l'Education Physique, Gafsa, Tunisia. ezebouhlel@yahoo.fr
Zaouali
Monia
M
Miled
Abdelhedi
A
Tabka
Zouhair
Z
Bigard
Xavier
X
Shephard
Roy
R
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D001823:Body Composition / Q000502:physiology*; D002153:Calorimetry, Indirect; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005215:Fasting / Q000502:physiology*; D005538:Football; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007514:Islam; D008297:Male; D014416:Tunisia
D001786:Blood Glucose; D007328:Insulin; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone