Effect of Ramadan Fasting on Physical Performance, Blood and Body Composition

Abstract

In order to understand the physiological adaptations during Ramadan fasting (RF), we studied the body composition, electrolyte balance, hematological response and physical performance in 15 healthy male Kuwaitis (mean age 37 years). Body composition, biochemical analysis, hematological count and exercise performance were evaluated on four occasions: 1 week before RF, 2 weeks during RF, during the last 4 days of RF, and 1 week to 10 days after RF. Cardiopulmonary exercise was performed on a Monark bicycle ergometer at 100 W for 6–8 min. Body composition was obtained using the skin-fold technique, and biochemical and hematological analyses were done using established standard techniques. Subjects lost 1.2% of their total body weight and 5 % of their body fat weight within 2 weeks of RF (p < 0.05). Total serum proteins, albumin and osmolarity significantly increased (p < 0.05) at the end of RF. White blood cells, platelets and serum iron were significantly decreased at the end of RF (p < 0.05). There was no significant change in red blood cell count and hematocrit during RF. Submaximal heart rate was significantly decreased (p < 0.05) by 5.4% whereas submaximal oxygen uptake increased by 12.7% at the end of RF. There was no significant difference in submaximal minute ventilation during the study period. It is concluded that RF is associated with metabolic, hematologic and cardiopulmonary adaptations which are of paramount importance in this period of restricted fluid, mineral and food intake.

Does Fasting during Ramadan Alter Body Composition, Blood Constituents and Physical Performance?

“…An increase in stroke volume during exercise may be secondary to a positive inotropic effect of hormones such as angiotensin II [7] and glucagon [8], which increase in plasma concentration during dehydration [9] and fasting [10]. Alternatively it may be secondary to increases in central blood volume due to redistribution of blood from the periphery to central reservoirs [11] during the prolonged period of consecutive daytime abstentions from fluids, salt and other foods. Hormonal changes (e.g.…”

“…There are no significant changes in maximal exercise capacity, in body composition, nor in the efficiency of treadmill walking at a defined grade and speed during the Ramadan testing period. We have previously shown that there are no differences in the physiological responses to moderate submaximal aerobic exercise between sedentary and physically active subjects and thus that no training effects are involved [11,14].…”

Physiological and Chronobiological Changes during Ramadan Intermittent Fasting

“…Concerning serum protein levels, an increase was demonstrated for total proteins [16,28,29,42] , albumin [5,16,29,42,43] , creatinine [5,16,31,[42][43][44] , bilirubin [16] and hematocrit [5] . The most important change observed during Ramadan was the increase of serum uric acid [13,18,24,42,[44][45][46][47] , urea [32,40,48,49] and serum osmolarity [42,50] .…”

“…The most important change observed during Ramadan was the increase of serum uric acid [13,18,24,42,[44][45][46][47] , urea [32,40,48,49] and serum osmolarity [42,50] . These changes were attributed to dehydration.…”

“…Electrolyte changes were also seen during Ramadan as there was a decrease in calcium, iron and magnesium [14,42,44,50,51] and an increase in phosphate blood levels [14,16,29] . In physically active subjects, serum osmolarity did not increase and serum iron and calcium levels did not decrease in comparison to sedentary subjects [50] .…”