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PURPOSE: To investigate the effect of low glycemic index (LGI) carbohydrate meal on subjective, metabolic and physiological responses, and endurance performance in the Ramadan fasted state. METHODS: During Ramadan, 12 Muslim men, in a randomized and crossover design, ingested for the sahur meal (i.e., last meal before commencement of the day's fast), either LGI (glycemic index = 37) or mixed (CON; ∼57) meal of equivalent macro-nutrient. At ∼12 h post-prandial, subjects completed a 60 min continuous run. RESULTS: There were no significant differences between the two meals for ratings in perceived satiety, fullness, appetite and mood states. During steady-state exercise, there were no significant differences in metabolic and physiological measures. In the time-trial, distance ran was significantly lower in LGI versus CON meal trial, but with a corresponding lower perceived exertion in the LGI trial. CONCLUSION: Compared to CON, ingesting LGI as the sahur meal did not provide any metabolic, physiological or performance benefits during endurance run performed 12 h post-prandial in Ramadan fasted state.

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This study examines the effects of Ramadan fasting on performance during an intense exercise session performed at three different times of the day, i.e., 08:00, 18:00, and 21:00 h. The purpose was to determine the optimal time of the day to perform an acute high-intensity interval exercise during the Ramadan fasting month. After familiarization, nine trained athletes performed six 30-s Wingate anaerobic test (WAnT) cycle bouts followed by a time-to-exhaustion (T(exh)) cycle on six separate randomized and counterbalanced occasions. The three time-of-day nonfasting (control, CON) exercise sessions were performed before the Ramadan month, and the three corresponding time-of-day Ramadan fasting (RAM) exercise sessions were performed during the Ramadan month. Note that the 21:00 h session during Ramadan month was conducted in the nonfasted state after the breaking of the day's fast. Total work (TW) completed during the six WAnT bouts was significantly lower during RAM compared to CON for the 08:00 and 18:00 h (p < .017; effect size [d] = .55 [small] and .39 [small], respectively) sessions, but not for the 21:00 h (p = .03, d = .18 [trivial]) session. The T(exh) cycle duration was significantly shorter during RAM than CON in the 18:00 (p < .017, d = .93 [moderate]) session, but not in the 08:00 (p = .03, d = .57 [small]) and 21:00 h (p = .96, d = .02 [trivial]) sessions. In conclusion, Ramadan fasting had a small to moderate, negative impact on quality of performance during an acute high-intensity exercise session, particularly during the period of the daytime fast. The optimal time to conduct an acute high-intensity exercise session during the Ramadan fasting month is in the evening, after the breaking of the day's fast.

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PURPOSE: Our study aimed to profile the effect of fasting during the Ramadan month on cognitive function in a group of healthy Muslim athletes. METHODS: Eighteen male athletes underwent computerized neuropsychological testing during (fasting) and after (non-fasting) Ramadan. Diet was standardized, and tests were performed at 0900h and 1600h to characterize potential time-of-day (TOD) interactions. Psychomotor function (processing speed), vigilance (visual attention), visual learning and memory, working memory (executive function), verbal learning and memory were examined. Capillary glucose, body temperature, urine specific gravity, and sleep volume were also recorded. RESULTS: Fasting effects were observed for psychomotor function (Cohen's d=1.3, P=0.01) and vigilance (d=0.6, P=0.004), with improved performance at 0900h during fasting; verbal learning and memory was poorer at 1600h (d=-0.8, P=0.03). A TOD effect was present for psychomotor function (d=-0.4, P<0.001), visual learning (d=-0.5, P=0.04), verbal learning and memory (d=-1.3, P=0.001), with poorer performances at 1600h. There was no significant fasting effect on visual learning and working memory. CONCLUSIONS: Our results show that the effect of fasting on cognition is heterogeneous and domain-specific. Performance in functions requiring sustained rapid responses was better in the morning, declining in the late afternoon, whereas performance in non-speed dependent accuracy measures was more resilient.

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OBJECTIVE: This study examines the effects of Ramadan fasting on endurance performance. METHOD: Using a crossover design, 10 moderately trained, active Muslim men performed 60 min runs on a treadmill in the fasted (Ramadan, RAM) and non-fasted (Control, CON) state on two separate counterbalanced occasions. After familiarization, four subjects performed their CON trial 1 week before Ramadan, while the other six subjects performed their CON trial 1 week after the Ramadan month. The subjects' last meals were standardised before their exercise trials. The 60 min continuous endurance running criteria test consisted of 30 min preloading run at 65% maximum oxygen consumption (Vo(2max)) intensity speed, followed by another 30 min time trial (TT) where subjects manually adjusted their speeds so as to cover the greatest possible distance. RESULTS: Subjects ran significantly further during the 30 min TT run in the CON compared to RAM condition (5649+/-715 vs 5448+/-847 m, p=0.023). Blood glucose concentration was significantly lower (4.5+/-0.3 vs 4.9+/-0.4 mmol/l, p=0.003) and urine specific gravity was significantly higher (1.018+/-0.006 vs 1.006+/-0.004, p=0.001) at the start of exercise in the RAM condition than in CON. Physiological responses during the 30 min TT run (mean heart rate, blood lactate and ratings of perceived exertion) were, however, not significantly different between the two conditions (all p>0.05). There were also no significant differences in the subjects' daytime sleepiness or mood profile between the RAM and CON conditions (all p>0.05). CONCLUSION: Ramadan fasting has a small yet significant negative impact on endurance running performance, although the impact varies across individuals.

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