**3. Muscle injuries in soccer during Ramadan period**

Investigations describing muscle injury risk and muscle injury patterns in soccer are usually conducted over seasons of European or American Leagues (Andersen et al., 2004; Ekstrand et al., 2011; Dupont et al., 2011). To our knowledge, only one study (Chamari et al., 2012) has focused on the injury-rates of muslim soccer players during the holy month of Ramadan. In this context, to our knowledge this is the only scientific publication having studied the effect of Ramadan fasting on sports' injuries.

#### **3.1. Ramadan characteristics**

**Time (minutes)**

312 Muscle Injuries in Sport Medicine

sessions adapted from Hawkins et al., (2001).

0 – 15 8

>15 – 30 14.5

>30 – 45 22.5

>45 – 60 10

>60 – 75 19

>75 – 90 26

Total 100

**Table 6.** Timing of occurrence of injuries in matches with 91 English professional soccer clubs during two consecutive

There is evidence to suggest that fatigue is associated with muscle injury. Indeed, empirical observations have shown that fatigued individuals are susceptible to muscle injury [See for review (Schlabach, 1994)]. Fatigue may not be the only cause of muscle injury, but rather a contributing factor. After reviewing the literature regarding the etiology of muscle injuries, Worrell and Perrin (1992) reported that fatigue was one of several factors that may contribute

Since muscle glycogen depletion is associated with fatigue and possibly injury, it should also be treated as a potential risk factor. Muscle glycogen stores are almost entirely derived from carbohydrate intake. Both indirect and direct evidence support the notion that depleted muscle glycogen stores contribute to muscle injury. Indirectly, it is quite clear that depleted muscle glycogen stores coincide with fatigue, and fatigue in turn is associated with muscle injury as mentioned above. Although most of the evidence involves relationships rather than showing cause, many of the investigations strongly suggest a cause-and-effect relationship between low muscle glycogen stores and injury risks [See for review (Schlabach, 1994)]. Depletion up to 84-90% of intramuscular glycogen stores has been observed in soccer players at the end of a soccer match (Jacobs et al., 1982). Soccer players with low glycogen stores at the start of a match had almost no glycogen left in their working muscle and physical performance of these players decreased in the second half in comparison to those players with higher pre-game and halftime glycogen muscle levels (Jacobs et al., 1982). Because there is a limited capacity to store muscle glycogen, and because muscle glycogen is the predominant fuel in exercise of moderate to severe intensity, the nutritional focus should be on carbohydrate consumption [See for review (Schlabach, 1994)]. The absolute amount of carbohydrates in the diet may be an important factor for the recovery of muscle and liver glycogen stores after training and competition (Ivy, 2001). In this context, it is important to mention that an inadequate nutrient intake and hypo-

to frequency of hamstring strains (one of the common muscle injuries in soccer).

**Injuries (%)**

> During the wholly month of Ramadan, fasting Muslims do not eat, drink, smoke, or have sexual activities daily from dawn to sunset. Since the Islamic Calendar is based on the lunar cycle, which advances 11-days compared with the seasonal year, Ramadan occurs at different times of the seasonal year over a 33‐year cycle (Chaouachi et al., 2009a). This implies that Ramadan occurs at different environmental conditions between years in the same country (Leiper et al., 2003; Leiper et al., 2008). It is supposed that most Muslim soccer players fast during Ramadan, even if some exceptions are observed. Ramadan fasting is intermittent in nature, and there is no restriction to the amount of food or fluid that can be consumed after dusk and before dawn. Therefore, since the international sporting calendar is not adapted for religious observances, and Muslim soccer players continue to compete and train during Ramadan, various studies have determined whether this religious fast has any effect on athletic

performance (Chaouachi et al., 2009a) and cognitive functions (Maughan et al., 2010; Water‐ house, 2010). These have suggested that only few aspects of physical fitness are negatively affected, and only modest decrements are observed when physical performance is considered on the basis of fitness testing (Chaouachi et al., 2009a). The evidence to date indicates that highlevel athletes can maintain most of the performance measures during Ramadan if physical training, diet, and sleep are well controlled. Nevertheless, despite this, fasting athletes report higher fatigue feelings at the end of Ramadan (Chaouachi et al., 2009a; Güvenç, 2011). This could have a possible effect on performance of injury during or at the end of the month of Ramadan.

**Year**

Ramadan and After Ramadan, reported by Chamari et al., (2012).

after-Ramadan periods for the fasting players (Table 8).

0 (-1.3-1.3)

0.6 (-1.1-2.2)

+ each period consisted of 4 weeks respectively in each of the two studied seasons.

0 (-1.3-1.3)

0.6 (-1.1-2.2)

b significantly higher than before and after-Ramadan. Note: values in bracket are 95% confidence intervals.

**Before Ramadan**

**Ramadan**

**After Ramadan**

Values are mean (SD)

*Rate of muscle injury during matches*

*Rate of muscle injury during training*

Chamari et al., 2012).

**Ambient Temperature (C°)**

**Table 7.** Ambient Temperature, Atmospheric Pressure and Relative Humidity for the months of Ramadan, Before

Chamari et al., (2012) have shown that muscle injuries were lower during the months prior toand after-Ramadan with only 22.22% of total muscle injuries in both cases, while this type of injury (i.e., muscle injury) dramatically increased during Ramadan with 84.21% out of total injuries observed for the two months of Ramadan monitored. For these two periods of Ramadan (Chamari et al., 2012), the muscle injuries were distributed as follows: muscle spasms (contractures) 43.75%, tendinopathy 43.75%, and muscle strains (one tear at the hamstrings and one strain at the thigh-adductors) 12.5%. The 7 contractures were located at the hamstrings (42.86%), calf muscles (28.57%), thigh-adductors (14.29%), and knee extensors (14.29%). The tendinopathy injuries were located at the thigh-adductors (42.86%) and foot quadriceps (14.29%), with the remaining tendinopathy injuries (42.86%) located at the abdomen and pelvis. The foremost result of the study of Chamari et al., (2012) was the absence of significant difference between non-fasting and fasting players with regard to general injury rates, while the training muscle injury rates were significantly higher during Ramadan than before and

**Atmospheric Pressure (mmHg)**

Muscle Injuries in Professional Soccer Players During the Month of Ramadan

2010 28.83 (1.72) 1012.33 (2.25) 44.00 (5.02) 2011 31.31 (5.38) 1011.38 (3.10) 39.15 (13.61)

2010 27.60 (4.04) 1014.20 (2.05) 55.80 (8.44) 2011 24.50 (1.29) 1014.50 (2.65) 64.50 (6.56)

2010 25.25 (2.06) 1014.00 (3.83) 61.50 (8.66) 2011 28.50 (1.29) 1013.25 (3.10) 63.25 (8.54)

**Before Ramadan + Ramadan + After Ramadan + Fasting Non-Fasting Fasting Non-Fasting Fasting Non-Fasting**

> 0 (-1.3-1.3)

3.2 (1.5-4.8)

0.5 (-0.7-1.8)

0.5 (-1.1-2.2)

0 (-1.3-1.3)

0 (-1.6-1.6)

1.2 (-0.1-2.4)

5.6 b (4.0-7.2)

**Table 8.** Comparisons of muscle injury rates in fasters and non-fasters for the two monitored seasons ( adapted from

**Relative Humidity (%)**

315

http://dx.doi.org/10.5772/56292

The increased perception of fatigue reported at the end of Ramadan fasting and the combination of intense training with altered carbohydrate intake, hydration-status, and sleeping pattern may place fasting Muslim athletes at greater risk of overreaching or overtraining (Chaouachi et al., 2009b; Chaouachi et al., 2009c) which could result in physical injury specifically overuse injuries (Johnson and Thiese, 1992). Most previous studies determined whether the holy month of Ramadan has any detrimental effect on performance and cognitive functions, but to our knowledge, only the study of Chamari et al., (2012) has examined the impact of the month of Ramadan and its specific sociocultural and religious environment on the injury rates of professional elite soccer players. This pilot study presented some results on the injury rates between fasting and nonfasting players within a team before, during, and after the month of Ramadan in a professional football team during two consecutive seasons.

#### **3.2. Muscle injury rates during Ramadan**

The study of Chamari et al., (2012) presented some results on the muscle injury rate between fasting and non-fasting players within a professional soccer team during the month of Ramadan during two consecutive seasons. Ramadan occurred from 10 August to 11 September 2010 and from 1 to 30 August 2011, respectively, where the daily fast occurred from ~04 h to ~19.15 h, for a total duration of ~15h15min fasting duration. In this study, training loads (using the RPE-method), Hooper index (Hooper and Mackinnon, 1995a) {i.e., Sum of well-being subjective ratings relative to fatigue, stress, delayed onset muscle soreness (especially "heavy" legs), and sleep quality/disorders} and muscle injury were monitored in 42 professional soccer players (Age, 24 ± 4 years; height, 185 ± 8 cm; body mass, 78 ± 4 kg) a month before Ramadan, the month of Ramadan, and the month after Ramadan during each season. Injury data were considered when a player was unable to take full part in future soccer training sessions or matches owing to physical complaints (Fuller et al., 2006). Information about mechanism of injury (traumatic or muscle injury) and circumstances (training or match injury) were docu‐ mented. Before and after Ramadan the sessions and matches were scheduled in the afternoon (starting at 15 or 16h) and sometimes in the morning for training (for the days in which 2 training sessions were scheduled, starting at 09.30 h) while during Ramadan, training sessions and matches were performed after dusk (starting at 22h). Ambient temperature, atmospheric pressure and relative humidity were measured for each training session and are presented in Table 7.


**Table 7.** Ambient Temperature, Atmospheric Pressure and Relative Humidity for the months of Ramadan, Before Ramadan and After Ramadan, reported by Chamari et al., (2012).

Chamari et al., (2012) have shown that muscle injuries were lower during the months prior toand after-Ramadan with only 22.22% of total muscle injuries in both cases, while this type of injury (i.e., muscle injury) dramatically increased during Ramadan with 84.21% out of total injuries observed for the two months of Ramadan monitored. For these two periods of Ramadan (Chamari et al., 2012), the muscle injuries were distributed as follows: muscle spasms (contractures) 43.75%, tendinopathy 43.75%, and muscle strains (one tear at the hamstrings and one strain at the thigh-adductors) 12.5%. The 7 contractures were located at the hamstrings (42.86%), calf muscles (28.57%), thigh-adductors (14.29%), and knee extensors (14.29%). The tendinopathy injuries were located at the thigh-adductors (42.86%) and foot quadriceps (14.29%), with the remaining tendinopathy injuries (42.86%) located at the abdomen and pelvis. The foremost result of the study of Chamari et al., (2012) was the absence of significant difference between non-fasting and fasting players with regard to general injury rates, while the training muscle injury rates were significantly higher during Ramadan than before and after-Ramadan periods for the fasting players (Table 8).


+ each period consisted of 4 weeks respectively in each of the two studied seasons.

b significantly higher than before and after-Ramadan.

performance (Chaouachi et al., 2009a) and cognitive functions (Maughan et al., 2010; Water‐ house, 2010). These have suggested that only few aspects of physical fitness are negatively affected, and only modest decrements are observed when physical performance is considered on the basis of fitness testing (Chaouachi et al., 2009a). The evidence to date indicates that highlevel athletes can maintain most of the performance measures during Ramadan if physical training, diet, and sleep are well controlled. Nevertheless, despite this, fasting athletes report higher fatigue feelings at the end of Ramadan (Chaouachi et al., 2009a; Güvenç, 2011). This could have a possible effect on performance of injury during or at the end of the month of

The increased perception of fatigue reported at the end of Ramadan fasting and the combination of intense training with altered carbohydrate intake, hydration-status, and sleeping pattern may place fasting Muslim athletes at greater risk of overreaching or overtraining (Chaouachi et al., 2009b; Chaouachi et al., 2009c) which could result in physical injury specifically overuse injuries (Johnson and Thiese, 1992). Most previous studies determined whether the holy month of Ramadan has any detrimental effect on performance and cognitive functions, but to our knowledge, only the study of Chamari et al., (2012) has examined the impact of the month of Ramadan and its specific sociocultural and religious environment on the injury rates of professional elite soccer players. This pilot study presented some results on the injury rates between fasting and nonfasting players within a team before, during, and after the month of Ramadan in a

The study of Chamari et al., (2012) presented some results on the muscle injury rate between fasting and non-fasting players within a professional soccer team during the month of Ramadan during two consecutive seasons. Ramadan occurred from 10 August to 11 September 2010 and from 1 to 30 August 2011, respectively, where the daily fast occurred from ~04 h to ~19.15 h, for a total duration of ~15h15min fasting duration. In this study, training loads (using the RPE-method), Hooper index (Hooper and Mackinnon, 1995a) {i.e., Sum of well-being subjective ratings relative to fatigue, stress, delayed onset muscle soreness (especially "heavy" legs), and sleep quality/disorders} and muscle injury were monitored in 42 professional soccer players (Age, 24 ± 4 years; height, 185 ± 8 cm; body mass, 78 ± 4 kg) a month before Ramadan, the month of Ramadan, and the month after Ramadan during each season. Injury data were considered when a player was unable to take full part in future soccer training sessions or matches owing to physical complaints (Fuller et al., 2006). Information about mechanism of injury (traumatic or muscle injury) and circumstances (training or match injury) were docu‐ mented. Before and after Ramadan the sessions and matches were scheduled in the afternoon (starting at 15 or 16h) and sometimes in the morning for training (for the days in which 2 training sessions were scheduled, starting at 09.30 h) while during Ramadan, training sessions and matches were performed after dusk (starting at 22h). Ambient temperature, atmospheric pressure and relative humidity were measured for each training session and are presented in

professional football team during two consecutive seasons.

**3.2. Muscle injury rates during Ramadan**

Ramadan.

314 Muscle Injuries in Sport Medicine

Table 7.

Note: values in bracket are 95% confidence intervals.

**Table 8.** Comparisons of muscle injury rates in fasters and non-fasters for the two monitored seasons ( adapted from Chamari et al., 2012).

The rates reported during the month of Ramadan (Chamari et al., 2012) were consistent with data found in Union of European Football Associations {UEFA} (Ekstrand et al., 2011), English Premier League (Hawkins et al., 2001), Swedish Premier League (Hagglund et al., 2006), Scottish league (Dupont et al., 2011), and Norwegian league (Andersen et al., 2004). Never‐ theless, the muscle injury rate of the study of Chamari et al., (2012) outside the month of Ramadan is lower than what is typically reported in the literature. It has to be stressed by the authors that this muscle injury rate concerns pre-season and the start of the season and this might explain these lower rates. Indeed, pre-season is characterized by a high prevalence of endurance training and fitness training which were performed in a progressive manner. The low frequency of matches at these stages might be the cause of the low overall injury rates of the studied periods (Chamari et al., 2012). Indeed, it has been well demonstrated (as mentioned above in the present book chapter) that the match injury rates are always much higher than the training injury rates (Ekstrand et al., 2011). In this context, Koutedakis and Sharp (1998) showed that the preparation phase of the season is accompanied with fewer injuries than the competition phase. Despite a higher mean overall injury rate during the Ramadan months of the 2 studied seasons (Chamari et al., 2012), i.e. 12.3 injuries/1000-h exposure, vs 4.9 for the month's before-Ramadan and 6.7 for the month's after-Ramadan, the difference between nonfasting and fasting players being not significant, while the rate of muscle injuries during training was significantly higher during Ramadan than before- and after-Ramadan in fasting players (Table 8). Nevertheless, these groups showed differences for the Hooper's Index and perceived stress (Hooper and Mackinnon, 1995b) with fasting players having lower Hooper's Index and stress during Ramadan and after Ramadan than non-fasting players. Moreover, no difference was observed between fasting and non-fasting players for the reported quality of sleep, and quantity of delayed onset muscle soreness and fatigue during Ramadan, before, and after-Ramadan (Figure 1).

Despite the difference in Hooper Index observed, Chamari et al., (2012) showed that training load, training strain, and training duration were maintained during the 3 periods and between groups for the 2 monitored seasons (Figure 2). The technical staffs of this study (Chamari et al., 2012) had not decrease training load during Ramadan based on the key findings of Chaouachi et al., (2009a) who has suggested that elite athletes could avoid steep decrements in their physical capacities while undergoing the intermittent fast of Ramadan, when they were maintaining their usual training loads; However, although there is no study contrasting the suggestions of Chaouachi et al., (2009a), technical staffs should adapt the training load of their players based on daily observations. The suggestion of Chaouachi et al., (2009a) concerned players from elite Tunisian athletes with different characteristics of training compared to European top-level teams. Indeed, in Tunisia, there are less frequencies of matches than in European top-class teams with games played each 3-4 days almost continuously for about 10 months (about 25 to 40 games vs. 45-62 games, respectively). Another concern with Ramadan in Europe comes from the daylight duration. Indeed, fasters in Europe abstain from food and fluids for 1 to 2 hours longer than Tunisia in summer for example. In summer, with the relative heat, this could be a challenge for Muslim Fasters that are part of a European Team in which technical staffs have objectives of performance and hence, do not even think about managing the training pattern. The study of Chamari et al., (2012) reported data of players that trained at night during Ramadan and avoiding days including two training sessions. Consequently, their conclusions are not adaptable to such specific European Fasting players keeping training during the day (often in the morning and with some double sessions' days) and having to keep off their food and fluid intakes that are one of the pillars of recovery. Ending a high load training session at around 11h00 a.m. and having to keeping on fasting for the remaining hours until the sunset (Iftar) certainly presents a challenge, especially for the long daylight days (i.e., summer). Adding a second training session in the afternoon, is certainly not easy at all. Some recommendations in that regard have been made by Kirkendall et al., (2012) in trying to advise the technical staffs and athletes to deal with training during Ramadan. In this regard, further studies on injuries during Ramadan in different parts of the world, and through the year calendar are needed. Other specific situations should also be investigated as some players chose to fast during the week but not the day of the games. This surely presents another pattern

**Figure 1.** Comparisons of Hooper Index, (sleep, stress, delayed onset muscle soreness, and fatigue) {means of the 2

Muscle Injuries in Professional Soccer Players During the Month of Ramadan

http://dx.doi.org/10.5772/56292

317

of fasting with specific physiological adaptations and therefore injury pattern.

The study Chamari et al., (2012) have shown that the perceived quality of sleep was not significantly different between the months of Ramadan and the months before and after

**3.3. Possible causes of muscle injuries during Ramadan**

+ each period consisted of 4 weeks in each year, respectively.

significant different from non-fasting players at p<0.05.

studied seasons} (Chamari et al., 2012).

a

*3.3.1. Sleep disturbance and consequences*

+ each period consisted of 4 weeks in each year, respectively.

a significant different from non-fasting players at p<0.05.

The rates reported during the month of Ramadan (Chamari et al., 2012) were consistent with data found in Union of European Football Associations {UEFA} (Ekstrand et al., 2011), English Premier League (Hawkins et al., 2001), Swedish Premier League (Hagglund et al., 2006), Scottish league (Dupont et al., 2011), and Norwegian league (Andersen et al., 2004). Never‐ theless, the muscle injury rate of the study of Chamari et al., (2012) outside the month of Ramadan is lower than what is typically reported in the literature. It has to be stressed by the authors that this muscle injury rate concerns pre-season and the start of the season and this might explain these lower rates. Indeed, pre-season is characterized by a high prevalence of endurance training and fitness training which were performed in a progressive manner. The low frequency of matches at these stages might be the cause of the low overall injury rates of the studied periods (Chamari et al., 2012). Indeed, it has been well demonstrated (as mentioned above in the present book chapter) that the match injury rates are always much higher than the training injury rates (Ekstrand et al., 2011). In this context, Koutedakis and Sharp (1998) showed that the preparation phase of the season is accompanied with fewer injuries than the competition phase. Despite a higher mean overall injury rate during the Ramadan months of the 2 studied seasons (Chamari et al., 2012), i.e. 12.3 injuries/1000-h exposure, vs 4.9 for the month's before-Ramadan and 6.7 for the month's after-Ramadan, the difference between nonfasting and fasting players being not significant, while the rate of muscle injuries during training was significantly higher during Ramadan than before- and after-Ramadan in fasting players (Table 8). Nevertheless, these groups showed differences for the Hooper's Index and perceived stress (Hooper and Mackinnon, 1995b) with fasting players having lower Hooper's Index and stress during Ramadan and after Ramadan than non-fasting players. Moreover, no difference was observed between fasting and non-fasting players for the reported quality of sleep, and quantity of delayed onset muscle soreness and fatigue during Ramadan, before, and

Despite the difference in Hooper Index observed, Chamari et al., (2012) showed that training load, training strain, and training duration were maintained during the 3 periods and between groups for the 2 monitored seasons (Figure 2). The technical staffs of this study (Chamari et al., 2012) had not decrease training load during Ramadan based on the key findings of Chaouachi et al., (2009a) who has suggested that elite athletes could avoid steep decrements in their physical capacities while undergoing the intermittent fast of Ramadan, when they were maintaining their usual training loads; However, although there is no study contrasting the suggestions of Chaouachi et al., (2009a), technical staffs should adapt the training load of their players based on daily observations. The suggestion of Chaouachi et al., (2009a) concerned players from elite Tunisian athletes with different characteristics of training compared to European top-level teams. Indeed, in Tunisia, there are less frequencies of matches than in European top-class teams with games played each 3-4 days almost continuously for about 10 months (about 25 to 40 games vs. 45-62 games, respectively). Another concern with Ramadan in Europe comes from the daylight duration. Indeed, fasters in Europe abstain from food and fluids for 1 to 2 hours longer than Tunisia in summer for example. In summer, with the relative heat, this could be a challenge for Muslim Fasters that are part of a European Team in which technical staffs have objectives of performance and hence, do not even think about managing the training pattern. The study of Chamari et al., (2012) reported data of players that trained

after-Ramadan (Figure 1).

316 Muscle Injuries in Sport Medicine

**Figure 1.** Comparisons of Hooper Index, (sleep, stress, delayed onset muscle soreness, and fatigue) {means of the 2 studied seasons} (Chamari et al., 2012).

at night during Ramadan and avoiding days including two training sessions. Consequently, their conclusions are not adaptable to such specific European Fasting players keeping training during the day (often in the morning and with some double sessions' days) and having to keep off their food and fluid intakes that are one of the pillars of recovery. Ending a high load training session at around 11h00 a.m. and having to keeping on fasting for the remaining hours until the sunset (Iftar) certainly presents a challenge, especially for the long daylight days (i.e., summer). Adding a second training session in the afternoon, is certainly not easy at all. Some recommendations in that regard have been made by Kirkendall et al., (2012) in trying to advise the technical staffs and athletes to deal with training during Ramadan. In this regard, further studies on injuries during Ramadan in different parts of the world, and through the year calendar are needed. Other specific situations should also be investigated as some players chose to fast during the week but not the day of the games. This surely presents another pattern of fasting with specific physiological adaptations and therefore injury pattern.

#### **3.3. Possible causes of muscle injuries during Ramadan**

#### *3.3.1. Sleep disturbance and consequences*

The study Chamari et al., (2012) have shown that the perceived quality of sleep was not significantly different between the months of Ramadan and the months before and after

cascade of small biochemical adjustments including hormonal, immunoglobulin, and antiox‐ idant system changes, and an elevated inflammatory response. These variations are close to what is observed in tissue traumatic processes as found in athletes in state of over-reaching or overtraining (Chaouachi et al., 2009c). Although the variations are small and may not be considered clinically relevant, they may still signal physiological stress (Chaouachi et al., 2009c). In this context, the overtraining syndrome has been referred as staleness or chronic fatigue with a mental lassitude along with some associated injuries that are observed in parallel to a significant decline in physical performance (Kenttä and Hassmén, 1998; Halson and Jeukendrup, 2004). Overtraining affects the musculoskeletal system in that sense that serum creatine kinase levels are increased and enzymatic markers of muscle tissue injury significantly elevated the day after high training loads. It is unclear whether the observed over-use injuries observed in the over-trained or over-reached athlete could be the result of excessively high training loads and/or the impaired ability to recover from training. As training load was not different between fasters and non fasters in the study of Chamari et al., (2012), it is possible

Muscle Injuries in Professional Soccer Players During the Month of Ramadan

http://dx.doi.org/10.5772/56292

319

that the recovery processes could be altered by Ramadan intermittent fasting.

Contradictory with many studies [see for review (Chaouachi et al., 2009a] showing that Ramadan induces additional stress on the athlete, the perceived mental stress assessed by the Hooper scale during Ramadan in the study of Chamari et al., (2012) was not different from stress measured before and after Ramadan for non-fasting players. Rather, the fasting players reported decreased stress for Ramadan and for the month after-Ramadan compared to pre-Ramadan month. It could be speculated that the religious beliefs and the well-being of living and practicing a holy month, could have led to a lower perception of stress in the latter players. The possible habituation process in the fasting players has also to be considered, as they reported that they had fasted and trained simultaneously for a mean period of seven years and thus the absence of total injury risk with respect to the non-fasting players relates to habituated fasters. Newly fasting players' data are not available from the study of Chamari et al., (2012).

The period of the year and changing climate has to be considered with respect to the effect of Ramadan on the incidence of sporting injuries. Indeed, the study of Chamari et al., (2012) was conducted over the 2010 and 2011 years with the months of Ramadan occurring in August/ September in Tunisia where daily fasting lasted about 15h15min and the temperature was relatively high. Different fasting periods and environmental conditions have to be experi‐ mented with respect to their effects on professional soccer players' injury rates. It has also to be noted that in the latter study the training sessions occurred during the nights (22h00, i.e. about 3 hours after the ''iftar'' / fasting break). In that sense, the injury rates reported concern therefore ''Fasting'' players that were not in a fasting state, as they did break the fast about three hours earlier and were allowed to drink ad-libitum before and during the training sessions and games. Unfortunately, no data is yet available for any injury rate occurring in

*3.3.3. Psychological alteration and general fatigue*

*3.3.4. Contextual conditions*

fasting players during training or matches.

+ each period consisted of 4 weeks respectively in each season. A.U.: arbitrary units

**Figure 2.** Comparisons of weekly training load, strain, and duration {mean of the 2 studied seasons} (Chamari et al., 2012).

Ramadan. Even if the reported quality of overall sleep was not altered during Ramadan, the sleeping scheduling was greatly modified with players not going to bed before 03.00-h a.m. (Chamari et al., 2012). Recently, Luke et al., (2011) showed that sleeping less than 6-h the night before the injury occurrence was associated with increased fatigue-related injuries. The results of the study of Chamari et al., (2012) show no influence of Ramadan on the perceived sleep quality of the participants. As the Hooper's index is a simple general index aiming to assess sleep quality, the absence of change does not necessary mean that sleep architecture was not altered. Even if the participants were generally satisfied about their whole 24-h sleeping quality, it may be that the time spent in the different sleeping phases was modified. In this context, it has been well established that sleeping architecture is characterized by different phases at the beginning and the end of the night (Czeisler et al., 1980; Duffy et al., 1996). The change in the sleeping and nutritional habits during Ramadan (i.e. much less night-sleep and more afternoon naps for fasters and non-fasters and major changes in eating patterns for the fasting players) may have altered the players' physiological status during Ramadan, probably leading to the observed higher over-use injury rate during the fasting month (Bogdan et al., 2001; Montelpare et al., 1992; Reilly and Waterhouse, 2007).

#### *3.3.2. Physiological and hormonal disturbances*

After sleeping architecture disturbances, an additional probable cause of higher overuse injuries could also be the end-of-Ramadan state of the fasting players. In this context, Chaoua‐ chi et al., (2009c) have clearly shown that elite athletes continuing to complete high training loads during Ramadan might endure higher levels of fatigue and are likely to experience a cascade of small biochemical adjustments including hormonal, immunoglobulin, and antiox‐ idant system changes, and an elevated inflammatory response. These variations are close to what is observed in tissue traumatic processes as found in athletes in state of over-reaching or overtraining (Chaouachi et al., 2009c). Although the variations are small and may not be considered clinically relevant, they may still signal physiological stress (Chaouachi et al., 2009c). In this context, the overtraining syndrome has been referred as staleness or chronic fatigue with a mental lassitude along with some associated injuries that are observed in parallel to a significant decline in physical performance (Kenttä and Hassmén, 1998; Halson and Jeukendrup, 2004). Overtraining affects the musculoskeletal system in that sense that serum creatine kinase levels are increased and enzymatic markers of muscle tissue injury significantly elevated the day after high training loads. It is unclear whether the observed over-use injuries observed in the over-trained or over-reached athlete could be the result of excessively high training loads and/or the impaired ability to recover from training. As training load was not different between fasters and non fasters in the study of Chamari et al., (2012), it is possible that the recovery processes could be altered by Ramadan intermittent fasting.

#### *3.3.3. Psychological alteration and general fatigue*

Contradictory with many studies [see for review (Chaouachi et al., 2009a] showing that Ramadan induces additional stress on the athlete, the perceived mental stress assessed by the Hooper scale during Ramadan in the study of Chamari et al., (2012) was not different from stress measured before and after Ramadan for non-fasting players. Rather, the fasting players reported decreased stress for Ramadan and for the month after-Ramadan compared to pre-Ramadan month. It could be speculated that the religious beliefs and the well-being of living and practicing a holy month, could have led to a lower perception of stress in the latter players. The possible habituation process in the fasting players has also to be considered, as they reported that they had fasted and trained simultaneously for a mean period of seven years and thus the absence of total injury risk with respect to the non-fasting players relates to habituated fasters. Newly fasting players' data are not available from the study of Chamari et al., (2012).

#### *3.3.4. Contextual conditions*

Ramadan. Even if the reported quality of overall sleep was not altered during Ramadan, the sleeping scheduling was greatly modified with players not going to bed before 03.00-h a.m. (Chamari et al., 2012). Recently, Luke et al., (2011) showed that sleeping less than 6-h the night before the injury occurrence was associated with increased fatigue-related injuries. The results of the study of Chamari et al., (2012) show no influence of Ramadan on the perceived sleep quality of the participants. As the Hooper's index is a simple general index aiming to assess sleep quality, the absence of change does not necessary mean that sleep architecture was not altered. Even if the participants were generally satisfied about their whole 24-h sleeping quality, it may be that the time spent in the different sleeping phases was modified. In this context, it has been well established that sleeping architecture is characterized by different phases at the beginning and the end of the night (Czeisler et al., 1980; Duffy et al., 1996). The change in the sleeping and nutritional habits during Ramadan (i.e. much less night-sleep and more afternoon naps for fasters and non-fasters and major changes in eating patterns for the fasting players) may have altered the players' physiological status during Ramadan, probably leading to the observed higher over-use injury rate during the fasting month (Bogdan et al.,

**Figure 2.** Comparisons of weekly training load, strain, and duration {mean of the 2 studied seasons} (Chamari et al.,

After sleeping architecture disturbances, an additional probable cause of higher overuse injuries could also be the end-of-Ramadan state of the fasting players. In this context, Chaoua‐ chi et al., (2009c) have clearly shown that elite athletes continuing to complete high training loads during Ramadan might endure higher levels of fatigue and are likely to experience a

2001; Montelpare et al., 1992; Reilly and Waterhouse, 2007).

*3.3.2. Physiological and hormonal disturbances*

+ each period consisted of 4 weeks respectively in each season.

A.U.: arbitrary units

318 Muscle Injuries in Sport Medicine

2012).

The period of the year and changing climate has to be considered with respect to the effect of Ramadan on the incidence of sporting injuries. Indeed, the study of Chamari et al., (2012) was conducted over the 2010 and 2011 years with the months of Ramadan occurring in August/ September in Tunisia where daily fasting lasted about 15h15min and the temperature was relatively high. Different fasting periods and environmental conditions have to be experi‐ mented with respect to their effects on professional soccer players' injury rates. It has also to be noted that in the latter study the training sessions occurred during the nights (22h00, i.e. about 3 hours after the ''iftar'' / fasting break). In that sense, the injury rates reported concern therefore ''Fasting'' players that were not in a fasting state, as they did break the fast about three hours earlier and were allowed to drink ad-libitum before and during the training sessions and games. Unfortunately, no data is yet available for any injury rate occurring in fasting players during training or matches.
