While there is much information on selected health, sociological, and physical responses to the Ramadan fasting, there is relatively little information in the literature about exercise in general and athletic
performance in particular. The aim of this investigation was to examine the effect of Ramadan fasting on aerobic and anaerobic performances in young fasting Muslim soccer players. The present results demonstrated that Ramadan fasting affects performance during the Yo-Yo and RSA tests at the end of Ramadan with no changes in the middle of that month. However, performances during the Wingate test decreased at the two periods of testing during Ramadan in comparison with before Ramadan.
To date, there are only a few studies that have examined the effects of Ramadan fasting on physical performance and the results have been inconclusive [1,2,5,15]
. The discrepancies between data might be due to several factors such as the duration of fasting, subjects’ fitness levels, environment, motivation, changes in sleep patterns and the time-of-day of measurement.
Concerning aerobic performances, in agreement with results of the present study, Sweileh et al 
reported that VO2
(oxygen uptake) may decrease significantly over the month of Ramadan and there may be a substantial reduction in maximal oxygen uptake (VO2max
) within the first week in sedentary subjects. Bigard et al 
showed that muscle endurance at 35% and 55% of maximal voluntary contraction (MVC) decreased by 28% and 22%, respectively, by the end of Ramadan in healthy subjects. However, Ramadan
reported no adverse effects on sedentary subjects exercising at about 70% of VO2max under thermo-neutral conditions. In athletes, Meckel et al
showed that the fast resulted in a significant reduction in aerobic capacity (3000 m run). Likewise, Chennaoui et al 
showed that maximum aerobic velocity, as determined by the Montreal Track Test Velocity, decreased by 3-4% during Ramadan. However, Chaouachi et al 
showed that estimated values for maximal aerobic velocity (vVO2max), and VO2max during the Multistage Fitness Test were relatively unchanged during Ramadan in elite judo athletes. Recently, Hamouda et al 
showed a significant reduced performance during the Yo-Yo intermittent recovery test during Ramadan in young football players.
Fasting prior to exercise may result in greater mobilization of liver glycogen, increased gluconeogenesis and increased use of free fatty acids for fuel during exercise 
. Although these adjustments may act against a potential reduction in performance by maintaining sufficient blood glucose for intense aerobic muscular activity, it was not surprising to find a significant reduction of performances during the Yo-Yo test in the present study during Ramadan. In fact, it is well known that fasting is associated with catecholamine inhibition and reduced venous return, causing a decrease in the sympathetic tone, which leads to a decrease in blood pressure, heart rate, and cardiac output [27,28]
Concerning anaerobic performances, the present study's results showed a significant decrease of performances during the RSA and the Wingate tests. Meckel et al 
showed a decrease in speed endurance measured by 4×10 m run time (i.e. an increased sum of the six sprint times and performance decrement during the RSA test). These authors showed a significant mean performance decrement of 9.5% at the end of Ramadan compared to 9.0% before Ramadan. In the present study, PD increased significantly during the ER in comparison with BR (≈7 vs
. (≈10%). In addition, Meckel et al 
showed that the sum of the six sprint times increased from 46.36 s before the beginning of the Ramadan fast to 46.73 s at the end of the month. Likewise, we showed that Wtotal decreased from ≈44 to ≈42.5 (W · kg−1
) at the end of Ramadan. Moreover, in agreement with our findings, Hamouda et al 
showed a significant decrease in PP during a 5×6 s RSA test during Ramadan. These changes may reflect a decreased glycolytic capacity, as well as a slower replenishment of muscle creatine phosphate (CP) stores during the short recovery period between the sprints during the month of Ramadan. During the Wingate test, the results of the present study are in agreement with those of a previous research which showed that Ppeak
decreased significantly during Ramadan 
. However, Karli et al 
showed that power output during the Wingate test didn't change throughout this month. It is possible that the decrease in power during Ramadan may occur because participants are less motivated and less aroused. In fact, individuals tend to prepare for the period of fasting during Ramadan by rising earlier and eating a meal before sunrise 
. As a result of these, participants would have been suffering from the effects of partial sleep deprivation. Sleep deprivation primarily affects the higher cognitive centers of the central nervous system 
, and motivation is a key factor in the validity of tests of anaerobic power and capacity during the Wingate test
Sleep patterns may also influence athletic performance [32,33]
and negatively affect mood and mental performance 
. However, in agreement with Chennaoui et al 
, in the present study there were no differences in tension, depression, anger, vigor, and confusion estimated by the POMS questionnaire. Only fatigue was higher at the end of Ramadan. It has been shown that mood, psychomotor and cognitive functions deteriorate more quickly than physical capabilities and the complexity, duration, and boredom produced by the task can also accelerate this decline 
. The declined mood and mental activity were suggested as the main reasons for the declines in performance [9,16,17]
. In this context, Waterhouse et al
observed that during Ramadan, the daytime hours were associated with more fatigue and less physical and mental activity than on control days but that these changes were reversed after sunset, as individuals broke their fast, often in the company of friends/family. In addition the RPE scores were higher during Ramadan. Thus, the increased muscle fatigue during Ramadan (i.e. FI during the Wingate test and PD during the RSA test) could be due to an increase in perceived exertion. The increased perception of fatigue reported during Ramadan is in agreement with previous research that reported an increased sensation of fatigue 
. The increased RPE score suggests that Ramadan intermittent fast may result in an increased level of fatigue during training and, more seriously, a raised incidence of injury and illness. Indeed, decrements in physical function can lead to an increase in perceived exertion, an earlier onset of fatigue, and hence to an increased risk of injury or illness 
. Regarding these results of POMS and RPE, in practice, coaches might be advised to adjust training plans during Ramadan to alleviate the increased fatigue. However, care must be taken when adopting such an approach because detraining may occur, particularly with high-level athletes 
Studies such as the present one are subject to some limitations. First, all maximal physical tests, such as the Yo-Yo, the repeated sprints, and the Wingate test, require a high level of motivation. However, we have to assume that all soccer players performed at their maximal capacity on all tests. Second, during the present study, soccer players continued to train during Ramadan without calculation of their training load (estimated from RPE scores). In this context, Meckel et al 
suggested that the decrease in performance was due to the significant decrease in the weekly volume of intense physical activity from 6.4±0.2 h/wk before Ramadan to 4.5±0.1 h/wk during Ramadan. However, in the present study both the training volume and intensity were the same before and during Ramadan; the weekly training program included 5 training sessions averaging a total of ≈8 hours. Future studies might consider the weekly training load before and during Ramadan.
In conclusion, the results of the present study suggest that Ramadan negatively affects perceived exertion and physical performances during the Wingate, the Yo-Yo, and the repeated sprint ability tests in young soccer players especially during the last week of fasting. However, for the mood states, only fatigue was higher during Ramadan. Thus from the results of the POMS and RPE, it seems that Muslim soccer players may be at risk of experiencing increased feelings of fatigue during Ramadan which can be an early sign of overreaching or overtraining. For practical consideration, in order to maximize training benefits and avoid overreaching or overtraining during Ramadan, coaches must be advised to properly handle the training program variables (e.g. intensity, frequency, volume) when planning training sessions in the evening. In other words, when planning training sessions later in the day during Ramadan (i.e. in the evening), coaches should reduce the training volume to avoid overreaching or overtraining and to allow their athletes to cope better with the training while following their religious demands. However, it is clear that the detailed nature of the problems involved with training during Ramadan and dealing with them in a manner based upon a firm body of knowledge requires far more experimental investigations.