Ramadan and its effect on fuel selection during exercise and following exercise training

Fasting induces short-term physiological adaptations which spare the body's remaining carbohydrate stores and mobilize lipid stores to provide a substitute fuel for many tissues and organs, especially skeletal muscle. Rodent studies show that regular occurrence of fasting then refeeding, stimulates adaptations in muscle which make the animal better placed to withstand a further period of fasting by possessing a better ability to oxidise lipid. This review explores the research describing these adaptations, with an emphasis on Ramadan, a human model of repeated fasting/refeeding. Separately, a single bout of endurance exercise places similar metabolic stress on the body as fasting since the exercising muscle must reduce its use of carbohydrate and utilize lipid more readily as exercise progresses. Not surprisingly therefore, adaptations in muscle to repeated bouts of endurance exercise [endurance training] are similar to those seen with repeated fasting/refeeding. Superimposing the stressors of repeated fasting/refeeding and exercise training, and subsequent adaptations to the muscle and exercise response, are examined by describing the published research which has investigated the situation where athletes continue their training whilst participating in Ramadan

Effects of Ramadan fasting on biochemical and anthropometric parameters in physically active men

The aim of this study was to assess the effects of Ramadan fasting on several biochemical and anthropometric parameters in physically active men by comparing fasters and nonfasters before, during, and after Ramadan. Eighteen physically active men [10 fasters and 8 nonfasters] participated in this study. Subjects visited the laboratory for a total of four sessions on the following occasions: three days before Ramadan [Bef-R], the 15th day of Ramadan [Mid-R], the 29th day of Ramadan [End-R], and 21 days after Ramadan [Post-R]. During each session, subjects underwent anthropometric measurements, completed a dietary questionnaire and provided a fasting blood sample. Body weight and body fat percentage decreased in fasters by 1.9% [P<0.001] and 6.2% [P=0.003], respectively, but increased in nonfasters by 2.2% [P<0.001] and 10.2% [P=0.001], respectively, from Bef-R to End-R. Fasters' hematocrit and hemoglobin increased by 5.3% [P<0.001] and 6.3% [P=0.01], respectively, from Bef-R to End-R, while neither of these parameters changed in nonfasters. Fasters experienced an increase in the following parameters from Bef-R to End-R: urea [8.7%; P<0.001], creatinine [7.5%; P<0.001], uric acid [12.7%; P<0.001], serum sodium [1.9%; P<0.001], serum chloride [2.6%; P<0.001] and high-density lipoprotein cholesterol [27.3%; P<0.001]. Of these parameters, only creatinine increased [4.4%; P=0.01] in nonfasters. We conclude that Ramadan fasting lowers body weight and body fat percentage and can elevate high-density lipoprotein cholesterol in physically active men. However, practicing aerobic exercise during a hot and humid Ramadan month can induce a state of dehydration marked by an increase in some renal function markers and serum electrolytes

Effect of Ramadan fasting on body water status markers after a rugby sevens match

To evaluate the effect of Ramadan fasting on body water status markers of rugby players at basal condition and following a simulation of rugby sevens match. Twelve recreational rugby sevens players played three matches: one day before Ramadan [before Ramadan], at the end of the first week of Ramadan [Beg-R] and at the end of Ramadan [End-R]. Before and immediately after each match, body weight was determined and blood samples were taken for the measurement of body water status markers. Total body water was measured with an impedancemeter only before matches. At rest, an increase in hematocrit [+4.4%, P=0.03], hemoglobin [+3.4%, P=0.01] and plasma osmolarity [+2.8%, P<0.001] was noticed at End-R compared to before Ramadan. Total body water measured before Ramadan did not differ significantly from that of Ramadan. After the match, values of hematocrit and plasma osmolarity increased significantly at End-R [+1.4%, P=0.02;+3.1%, P<0.001 respectively] compared to before Ramadan. Although, hemoglobin measured after matches occurring during Ramadan did not differ from those of before Ramadan. In response to matches, the change of percentage of body water status markers did not differ during each period of the investigation. The present results show that Ramadan fasting induces dehydration at basal conditions. Also, rugby sevens match played during Ramadan did not exacerbate the magnitude of responses to matches of blood and body water status markers