Abstract
Ghrelin is an important stomach hormone that influences several metabolic activities and influences growth hormone (GH) release in response to change in energy homeostasis. The aim of this study was to investigate the effect of Ramadan fasting on acylated ghrelin and GH concentrations during a short-term maximal exercise. Eleven male soccer players (age, 22.11 +/- 1.3 years; height, 1.76 +/- 0.2m; body mass, 75.3 +/- 2.2; mean +/- SD) were asked to perform a 30-s Wingate test, during which we recorded the peak (PP) and mean (MP) powers and fatigue index. Measurements were performed in the afternoon at 18:00h, after three different occasions: (i) one week before Ramadan (BR), (ii) the first week of Ramadan (FWR), and (iii) the fourth week of Ramadan (ER). Blood samples were taken before, immediately and 60min after the exercise. Our results show that PP and MP were affected by Ramadan fasting with a significant decrease during Ramadan (i.e. FWR and ER) in comparison with ER (p<0.05). However, no significant difference was observed between BR and FWR (p>0.05). Also, a significant decrease in body weight and body fat percentage was observed during Ramadan in comparison with ER. From diet record analysis, protein, fat, and carbohydrate decreased significantly during FWR (p<0.01), often with further decreases by ER. A significant increase in plasma concentrations of ghrelin was observed during the ER (p<0.001) compared with BR and FWR, and GH levels were significantly higher during ER (p<0.01) in comparison with BR and FWR. However, the 30-s Wingate tests had no significant effect on plasma concentrations of ghrelin before or during Ramadan. Our study shows that the concentrations of ghrelin and GH change in the last week of Ramadan fasting, though it is unclear if these changes are related to the changes in body composition during Ramadan, or if they are responsible for the change in performance at the short-duration anaerobic test.