• Roy J Shephard.
• Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada, royjshep@shaw.ca.
• Sports Med. 2013 Dec 1; 43 (12): 1217-41.

AbstractThe intermittent fasting of Ramadan could affect various aspects of body physiology and biochemistry important to athletic success. Much of the available information on this subject has been collected from sedentary subjects or low-level competitors, often without well matched controls. Other issues requiring clearer definition include the duration of fasting, the local environment, the timing of observations, and changes in training, diet and sleep patterns. Sleep may be shortened or made good with daytime naps. Circadian rhythms of temperature, metabolism, hormonal secretions and physical performance may be disrupted and incidental activities curtailed. Disturbances of psychomotor performance include daytime sleepiness, impaired vigilance and slower reactions. Food intake is limited to night-time meals. Sedentary individuals sometimes exploit Ramadan to reduce body fat stores. Well disciplined athletes usually maintain energy balance unless daily energy expenditures are very high. Protein intake must allow for gluconeogenesis, and provide quality protein ingested around training times. Blood sugar levels are likely to fall over a long and active day, even if morning glycogen reserves are maximized. Metabolism of fat should be encouraged, beginning prior to Ramadan; inclusion of fat in the pre-dawn meal also slows gastric emptying. Daytime fluid depletion is inevitable if athletes exercise in the heat, but the immediate deficit can usually be made good at night. Some studies show an initial fluid depletion, with recovery as Ramadan continues, possibly reflecting changes in urine and sweat production. Top athletes can maintain training throughout Ramadan, although coaches sometimes reduce demands through a pre-competitive tapering of effort. Late night or early morning training requires negotiation with players who are not observing Ramadan, and dietary adjustments to maintain optimal plasma amino acid levels when training. Performance of repeated anaerobic exercise is impaired, but aerobic power and muscular strength show little change during Ramadan. Ratings of fatigue are increased, and vigilance and reaction times are impaired, particularly during the afternoon. Medical issues during Ramadan are few. Athletes with diabetes mellitus should seek a medical exemption from fasting, and prescribed drug schedules should be carefully maintained. There is no major increase of injury rates, but competitors may have difficulty in producing urine for doping controls. Logical measures to minimize the effects of Ramadan include the optimization of mood state, maintenance of training, minimization of sleep loss, appropriate adjustments of diet, and the monitoring of competitors for chronic dehydration. Future research should concentrate on the changes observed in top athletes, particularly women, with data collected in the late afternoon after a known period of fasting in a well defined environment. It will be important to ensure that the lifestyle of those studied has been optimized. Implications of chronic dehydration for doping control also merit further investigation. Current data suggest that the impact of Ramadan upon athletic performance is small relative to the precision of test procedures, although it may be sufficient to cause a loss of medals. Negative effects vary widely with the type of sport, the season when fasting is observed, the local culture and the discipline exercised by the athlete.

15 keywords...

hide…