Effect of ramadan fasting on the sympathovagal balance through a study of heart rate variability

Academic year 2011- 12

Republic of Tunisia

Ministry of Higher Ministry of youth and sports

Education and Scientific Research

UNIVERSITY OF SFAX

High Institute of Sport and Physical Education of Sfax

Master degree in Sciences and technique of physical and sport activities. (Specialty: Biological Sciences)

MASTER'S THESIS

EFFECT OF RAMADAN FASTING ON THE SYMPATHOVAGAL BALANCE THROUGH A STUDY OF HEART RATE VARIABILITY

By:

Mohamed EL Amine FANNANI

Supervisors:

Dr. Imed LATIRI

Dr. Mohamed Ali SAAFI

THANKS

This work has been completed thanks to many people whom I cannot list here exhaustively. I am, however, deeply grateful to all those who have supported, helped, encouraged and mentored me.

I want to express my gratitude to Mr. Imed LATIRI, Assistant Professor of Higher Education at the Faculty of Medicine of Sousse, for having accepted the charge of my direction. I thank him very sincerely for his kindness, patience and invaluable help.

I would like to thank Dr. Mohamed Ali SAAFI, a university hospital assistant at Sahloul Hospital in Sousse, who helped and directed me a lot. May he find in this work the expression of my deep gratitude and deep respect.

I would also like to thank Professor Zouhaïer TABKA for the welcome he has given me in his research unit. Without his support, this work would never have succeeded.

My compliments to all my teachers of the High Institute of Sport and Physical Education of Sfax.

Thank you very much to the members of the jury who were kind enough to have accepted to evaluate this work.

Finally a big thank to all the volunteers who participated in this study.

DEDICATION

To my dear parents Hedi and Najet Nabiha

For their great affections and their sacrifices approved throughout my university studies. May they find in this work the expression of my eternal love and my infinite gratitude.

To my sisters Wafa and Wiem and her husband Riadh

For their encouragement, their support, their affection, with all my wishes of happiness and success.

To all the members of my family and all my friends.

That they find in this work, my recognitions for their patience, their kindness and their pleasant company.

Table of Contents

Introduction 10

Part I : literature review 13

I- Ramadan, change of habits and sports performances 14

I.1. Changing of style of life during the month of Ramadan 14

I.2. Effect of fasting Ramadan on body weight 16

I.3. Effects of Ramadan Fasting on Sports Performance 16

II - The heart rate variability 20

II.1. Autonomic nervous system 20

II.1.1. The sympathetic nervous system 22

II.2. Influence of autonomic nervous system on heart rate 23

II.3. Cardiac variability study 23

Part II : Material and Methodes 29

I. Participants 30

II. Experimental procedures 30

II.1. The Wingate test 31

II.2 Recording of heart variability 31

III. Statistical analysis 33

Part III : Results 34

I. Anthropometric characteristics of the sample 35

II. The Wingate test 35

II.1. Average power (P ave) 35

II.2 Peak power (Ppic) 36

III. Effect of fasting Ramadan on the autonomic nervous system 37

III.1. Effect of Ramadan fasting on the sympathetic system 39

III.2Effect of Ramadan fasting on the parasympathetic system 41

III.3. Effect of Ramadan fasting on sympathovagal balance 45

III.4. Effect of fasting Ramadan on the durations RR (ms) 46

Part IV : Discussion 48

I. The effects of fasting Ramadan on body weight 49

II. The effects of Ramadan fasting on Wingate test performances 49

III. The effect of fasting Ramadan on the heart rate variability 51

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Conclusion 55

Bibliography 57

Figure 10: Average(#177; SD) of the RRs (ms) recorded during the second, fourth week and before

Ramadan (n = 9) 46

List of Figures

Figure 1: Average (#177; SD) mean wingate power (W) values recorded during the second, fourth week

and before Ramadan (n = 9) 36

Figure 2: Average (#177; SD) of the Peak (W) Wingate ratings recorded during the second, fourth week

and before Ramadan (n = 9) 36

Figure 3: Average (#177; SD) LF (ms²) values recorded during the second, fourth week and before

Ramadan (n = 9) 39

Figure 4: Average (#177; SD) LF (nu) values recorded during the second, fourth week and before Ramadan

(n = 9) 40

Figure 5: Average (#177; SD) of RMSSDs (ms) recorded during the second, fourth, and before Ramadan (n

= 9) 41

Figure 6: Average(#177; SD) of PNN50 (%) recorded during the second, fourth week and before Ramadan

(n = 9) 42

Figure 7: Average(#177; SD) of the HF (ms²) values recorded during the second, fourth week and before

Ramadan (n = 9) 43

Figure 8: Average(#177; SD) of the HF (nu) values recorded during the second, fourth week and before

Ramadan (n = 9) 44

Figure 9: Average(#177; SD) values (LF / HF) recorded during the second, fourth week and before

Ramadan (n = 9) 45

List of Tables

Table I: Index of human heart rate variability in the frequency and time domains and their

approximate matches of 24-hour records 26

Table II: Average #177; SD of anthropometric characteristics of subjects during the second week, the

fourth week and before Ramadan (n = 9) 35

Table III: Average #177; SD of wingate test parameters during the second and fourth week of Ramadan

and after Ramadan (n = 9) 35

Table IV: Average (#177; SD) of parameters of analysis of cardiac variability in the supine position 37

Table V: Average (#177; SD) of parameters of analysis of cardiac variability while standing 37

Table VI: Average (#177; SD) of the parameters of the analysis of the cardiac variability during the

effort 38

Table VII: Heart rate averages (bpm) recorded before, in the middle and at the end of the month of

Ramadan (n = 9). 47

List of Photos

Photo 1: Achievement of the Wingate test 31

Photo 2 and 3: Recording resting heart rate variability 32

List of Abbreviations

B R: Before Ramadan

CMJ: Countermovement jump

Cm: Centimetres

ECG: Electrocardiogram

MVF: Maximum voluntary isometric force

R 4: End Ramadan

G: Grams

Hz: Hertz

HF: High frequency

Kg: Kilograms

LF: Low frequency

M: Meters

Ms: Milliseconds

R1: Second week of Ramadan

R2: Fourth week of Ramadan RF: Ramadan fasting

RR: Time interval between the two successive peaks of the R-waves of the ECG

NN50: Number of successive RR intervals greater than 50 ms

Nu: Normalized

PNN50: Percentage of successive RR interval differences greater than 50 ms

RMSSD: Square root of squared differences of successive RR intervals

Ppic: Peak power

Pave: Average power

Pmax: Maximum power

SNA: Autonomic Nervous System

SDNN: Standard deviation of the RR interval over the entire recording period

SNV: Vegetative nervous system

ULF: Ultra low frequency

VLF: Very low frequency

HRV: heart rate Variability

VO2 max: maximal oxygen consumption

Introduction

T

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this holy month, Muslims who reached the required age (puberty) should not eat, drink, smoke or engage into sexual intercourse, from dawn to sunset. As the lunar Muslim calendar counts eleven to twelve days shorter than the solar calendar and no intercalation, Ramadan shifts each year and gradually changes from one season to another (kadri et al., 2000).

During the last two decades, numerous studies tried to evaluate the effects of Ramadan fasting (RF) on both physiological level and clinical level. Their results showed that during this holy month, people change their daily habits, promoting a more sedentary lifestyle because they tend to stay up late, watching TV, praying or reading the holy Coran (Afifi et al., 1997). There is also a tendency to eat, at night, food and beverages that are higher in calories than those consumed during other months (Ziaee et al., 2006).

It was also revealed that the occurrence of irritability, headaches, and lack of sleep were distinguishably highlighted while fasting, in addition of an increased fatigue during the whole month. General exhaustion, reduced vigilance, low sense of well-being and weakened cognitive functions are the results of changes in eating habits and sleep deprivation (Kadri et al., 2000, Leiper et al., 2003, Roky et al., 2004). This may as well explain the increase of vehicle accidents and the inflow of Muslims to medical services during this month (Langford et al., 1994, Shanks et al., 1994).

The physiological and clinical effects of Ramadan have been the subject of many studies for many years (Zinker et al., 1990, Ramadan et al., 1999, Bouhlel et al., 2006). Body weight reduction was confirmed in some studies (Husain and al., 1987, Hallak & Nomani 1988, Ramadan and al., 1999), other work founded weight gain during this month (Frost and Pirani, 1987, Yucel and al., 2004, Siddiqui et al., 2005), while other authors note no significant changes in body weight during this month (El Ati et al., 1995, Finch et al. 1998, Ramadan 2002).

According to some studies, results showed an increase in fat oxidation during sub-maximal exercise, which becomes moderate towards the end of Ramadan (Bouhlel and al., 2006, Stannard and Thompson 2007). Only an increase of urea and uric acid in serum was frequently reported which could be attributed to dehydration during this month (Ramadan et al., 2002, Roky et al., 2004).

The interest of cardiac function has been addressed by some studies. The effect of fasting on the increase in heart rate caused by exercise remains ambiguous. Indeed, some authors have

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reported no effect of fasting on heart rate (Whitley et al., 1998, Montain et al., 1991); while other authors have reported a decrease in heart rate during fasting even during exercise (Husain R et al., 1987, Nieman et al., 1987, Lam et al., 1996, Zoladz et al., 2005).

It is obvious that the influence of Ramadan in various clinical and physiological areas has aroused the interest of scientists these last decades. Therefore, we propose to study the effects of fasting Ramadan on Heart Rate Variability before and during the wingate test done by young footballers aged from 15 to 16 years. The aim of this study is to:

· Recognize the effect of RF on anaerobic sports performance through a laboratory test (the Wingate test).

· Identify the effects of RF on the activity of the autonomic nervous system through the analysis of heart rate variability.

Part I : literature review

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I- Ramadan, change of habits and sports performances I.1. Changing of style of life during the month of Ramadan

The major changes in the rhythm of life in Ramadan essentially affect the time of food intake and sleep (Chaouachi et al., 2008, Maughan etal., 2008a, Leiper et al., 2008). This is associated with a change in the total amount of energy consumed (Angel & Schwartz. 1975). Indeed, two or three meals (usually two), are taken between dawn to sunset but, Since Ramadan is a lunar month, it is not fixed to a specific Gregorian month. Thus, the period of time during which food and water intake is permitted is variable, long in winter and short in summer in the northern hemisphere of the terrestrial globe (Sobhani et al., 1997). Indeed, the usual dietary practice is to consume a large meal just after sunset and a lighter meal before dawn (the Shour) (Roky et al., 2001, Ibrahim et al., 2008). It has been reported, moreover, a greater variety of food consumed during Ramadan compared to the rest of the year (Hallak & Nomani, 1988). Frost and Pirani (1987) showed that energy intake was higher during Ramadan compared to post Ramadan (3680 kcal / day versus 2425 kcal / day). In contrast, other studies (Ziaee et al., 2006, Bouhlel et al., 2008, Chennaoui et al., 2009) have shown a decrease in daily calorie intake during the month of Ramadan. The calorie deficit negatively influences aerobic performance (Aragon & Vargas, 1993). As for anaerobic performance, they are negatively affected by caloric deficits (Mc Murray et al., 1991). In contrast, other studies have shown that the total food intake over a 24-hour period during Ramadan remains the same compared to the control period despite the decrease in the frequency of food intake in the nycthemeron (El Ati et al. 1995, Afifi, 1997, Taoudi et al., 1999, Beltaifa et al., 2002, Souissi et al., 2007b, Meckel et al., 2008). The large amount of food consumed in the evening is likely to prevent the onset of falling asleep (Waterhouse, 2010). In fact, the rat experiment found a significant correlation between the number of calories consumed during the meal and the duration of the next sleep (Danguir & Nicolaidis, 1979).

However, for Reilly and Waterhouse (2007), this relationship is less obvious in humans. To say that sleep during this month is also disturbed by the change in daily habits is banal. Muslims do indeed tend to watch later by spending their time watching television, praying or reading (Afifi, 1997 ; BaHammam, 2005), which delays sleep and reduces its duration (Bogdan et al., 2001).These changes in rhythm imposed by Ramadan thus affect the circadian system. If daytime fast times are interrupted by periods of sleep (such as naps), the normal (sleep / wake) cycle will be disrupted (Reilly & Waterhouse, 2007).

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It should be noted that most studies that looked at sleep during Ramadan used questionnaires to evaluate the characteristics of sleep of individuals who work, study, or train themselves to fast during the month of Ramadan. Some of them have shown that the number of hours of sleep decreases during the month of fasting (Chennaoui et al., 2009). On the other hand, other studies (Zerguini et al., 2007, Meckel et al., 2008, BaHammam et al., 2010) have not reported a reduction in the number of hours of sleep per day during Ramadan compared to before Ramadan. A study by Roky et al. (2001) on sleep architecture during Ramadan using polysomnography showed a delay in sleep and a reduction in sleep duration, which can induce partial sleep deprivation (Roky et al 2001, Leiper et al., 2008, Chennaoui et al., 2009). It has been shown, too,an increase in daytime sleepiness during the fasting month, which was associated with changes in circadian rhythm, central temperature, and fasting metabolic changes (Roky et al., 2003). Vigilance decreases between 10^h:00 am and 12^h:00 am during this month of Ramadan especially during the last week. It increases, however, around 14^h:00, probably because of the absence of lunch which usually leads to falling asleep (El Kalifi, 1998). Recall that sleep is initiated by the drop in central temperature (Murphy & Campbell, 1997). So-called thermogenic factors such as nocturnal food intake (Smith et al., 1994), pre-sleep light exposure (Dijk et al., 1991), and nocturnal sport (Mizuno et al. 1998) are likely to delay sleep. The delay in sleep and the reduction in sleep duration observed during Ramadan can lead to partial sleep deprivation (Roky et al., 2001), which can influence athletic performance.

Few studies have investigated the effects of total sleep deprivation on aerobic performance (VanHelder & Radomski, 1989). The latter authors claim that the most recent studies support the effect of sleep deprivation on aerobic performance. As for the literature on the impact of partial sleep deprivation on anaerobic performance is very rich .Symons et al., (1988) found that 60 hours of sleep deprivation had no effect on Peak Power (PP), mean power (MP),fatigue index, and blood lactate concentrations measured during a Wingate test.

In addition, Souissi et al., (2008) found that peak power (Ppic) and mean power (MP) were lower due to sleep deprivation at the end of the night compared with sleep deprivation at the beginning of the night compared to a reference night. In the same study, the authors noted that the anaerobic powers recorded in the morning following sleep deprivation at the beginning or end of the night, and those recorded at night following the sleep deprivation at the beginning of the night were not modified by compared to the reference night.

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In another study based on sleep limitation (imposed bedtime and wake-up time respectively at 3:00 am and 7:00 am), Mougin et al., (1996) did not observe any variations in maximum speed, peak and and mean powers and blood lactate concentrations measured in a 30 sec Wingate test against a reference night. In short, partial sleep deprivation does not seem to affect muscle power. Forcibly, muscle strength seems to be little affected by partial sleep deprivation. (Bambaeichi et al., 2005) have shown that the maximum isometric force of knee extensors is not altered by partial sleep deprivation.

However, it should be noted that lack of sleep itself has little direct effect on muscle activity, but it has an indirect effect on physical performance because of changes in mental performance, motivation and coordination (Reilly & Waterhouse, 2009). So, we could say that the reduction of sleep gives rise to a fall in performance when the exercises require sensorimotor coordination or cognitive processes. The risks of this decrease in performance increase both with the strength of sleep deprivation and the importance of the neuronal component of the exercise in question (Mougin et al., 1996). In this vein, it has been shown that motivation is lost in cases where the exercises are repeated or in training sessions where several tasks are repeated to achieve a targeted goal (Waterhouse, 2010).

I.2. Effect of fasting Ramadan on body weight

Experiments on the effect of fasting during the month of Ramadan on body weight have yielded divergent results. In fact, some studies have revealed a decrease in body weight during this month (Husain et al., 1987, Hallak & Nomani, 1988, Ramadan et al., 1999, Roky et al., 2001, Bouhlel et al. 2006, 2008, Ziaee et al., 2006, Chaouachi et al., 2008, Maughan et al., 2008a). Other studies have not reported significant changes in body weight during the fasting period (El Ati et al., 1995, Finch et al., 1998, Ramadan 2002, Souissi et al., 2007, Zerguini et al. 2007, Meckel et al., 2008, Chennaoui et al., 2009). While some studies have shown weight gain during this month (Frost & Pirani, 1987, Yucel et al., 2004, Siddiqui et al., 2005). These divergent conclusions are explained by differences in daily habits (dietary and other), occupations and also in the social and geographical environment that can influence the energy balance (Meckel et al. , 2008).Thus different factors explain the divergence of the conclusions drawn by the researchers.

I.3. Effects of Ramadan Fasting on Sports Performance

The effect of Ramadan fasting on sports performance has been the subject of very varied and diverse studies. The conclusions drawn are, moreover, divergent. However, the exact mechanisms responsible for the declines in these performances are not clearly defined

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(Barret al., 1999, Maughan, 2010). Indeed, multiple and interlocking factors related to the athlete, himself, the nature of the sport, the weather conditions that the athlete faces, the schedule and the duration of the exercise to be performed, influence the effect of fasting on sports performance. Maughan et al (2010) reported that the effect of Ramadan fasting differs from one sporting discipline to another and from one athlete to another. They also noted that there are several difficult situations that the athlete faces when he fasts during Ramadan. These include endurance events in hot or humid weather, multi-day events, or late-night events, or the example of athletes who face challenges during competitions lasting more than 30 minutes at high temperature. As for Armstrong et al., (1985), they put forward the example of the competitions that are scheduled at the end of the day of the month of Ramadan. They note that fasting athletes may be hypo hydrated before the start of competition, which is likely to lead to a loss of performance. Warned, some athletes take before the competition, certain provisions to avoid and limit this hypo hydration. However, the inability to ingest fluids during exercise remains unresolved and the risk of loss of performance remains high (American College of Sports Medicine, 2007).

Burke et al., 2006; Shirreffs et al., 2006 also pose the physiological problem of the inability to replace sweat losses and ingest carbohydrates to begin the process of replenishing muscle glycogen in the immediate recovery period at a competition. That said, other factors that are responsible for the fall in athletic performance among Ramadan athletes have also been identified .In addition, the time of day when the test is performed, the physical condition of the subjects and the measures taken can be determining factors (Reilly and Waterhouse, 2007). In addition, although there is a decrease in athletic performance during Ramadan, it is unclear whether there is a systematic decline in physiological variables related to exercise (Waterhouse, 2010). On the other hand, and to our knowledge, research studies the impact of Ramadan fasting on disciplines where exercise protocols are the most difficult ( Intermittent high intensity exercises requiring physical and cognitive skills such as marathon, high-level football match, tennis matches, road cycling competitions, etc.) especially in hot conditions are very rare or nonexistent (Maughan et al., 2010).

On aerobic-dominated performance, Sweileh et al. (1992) showed that maximum oxygen uptake (VO2 max) decreases during the first week of Ramadan, then returns to values before Ramadan at the last week of this month. This can be explained by a physiological adaptation linked to fasting. In addition, Sweileh et al. (1992) also found a lower resting VO2 in the afternoon during Ramadan. This indicates, according to Meckel et al., (2008) a strategy for

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conserving energy reserves. It should be noted that fasting has also been associated with decreased venous return, resulting in lower sympathetic tone, leading to a reduction in blood pressure, heart rate and cardiac output (Stokholm et al., 1991; Al Suwaidi et al., 2006). These physiological changes can negatively influence the ability of physical work and promote the deterioration of sports performance (Meckel et al., 2008).Similarly, Meckel et al., (2008) observed that Ramadan fasting leads to a reduction in aerobic endurance performance (3000m run) in young footballers (14-16 years old). These authors did not indicate the time of day or the season during which the tests were performed. Chennaoui et al., (2009) also noted, in middle-aged runners who train 6 to 10 times a week, a decrease in maximum aerobic speed on the first and the third week of Ramadan in September compared with before Ramadan. The duration of fasting was around 13 hours a day. These authors explained the drop in performance observed by maintaining the same volume of training during Ramadan despite the constraints associated with it (sleep deprivation, caloric restriction and fatigue).

Similarly, Kirkendall et al., (2008) noted that the endurance of young footballers assessed by the shuttle run test established by Léger and Lambert, 1982, was affected during the second week of Ramadan but this capacity is restored towards the end of month of fasting. The authors explain the divergence of their results with the previous results (Zerguini et al., 2007, Meckel et al., 2008) by the change of the living conditions during Ramadan since in their study, the young footballers resided together and were under control throughout the investigation, which is not the case for the other two studies. In addition, the intensity and duration of the training sessions and the quality of sleep were not changed during Ramadan. In contrast, Chaouachi et al., (2009) found no change in maximal oxygen uptake or heart rate peak recorded in high-level judokas that maintained high training intensity and volume during Ramadan. These researchers explained their results by the fact that Ramadan fasting-induced metabolic constraints, concomitant with maintaining a high training intensity, have little effect on the performance of high-level athletes.

In terms of anaerobic performance, Bigard et al., (1998) showed that the month of Ramadan affects muscular strength and endurance. Indeed, the maximum voluntary isometric force (MVF) of the elbow flexors decreases as of the first week of Ramadan. In addition, the MVF of knee extensors and muscular endurance at 35% and 70% of the MVF of the knee extensors and elbow flexors decreased at the end of the month. Similarly, Souissi et al., (2007) showed that maximum muscle powers (Pmax) recorded during the strength / velocity test were lower

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during Ramadan than before Ramadan (for tests conducted in the afternoon). On the other hand, during the Wingate test, Souissi et al. (2007) found that the peak powers (Ppic) recorded around 17^h:00 and around 21^h:00 were lower during the month of fasting and during the second week compared to before Ramadan. Moreover, the average powers recorded around 17^h:00 and 21^h:00 during the same test were lower during the fourth week of Ramadan than before Ramadan, while they were unchanged during the second week of the month of fasting compared to the control session Ramadan.

In addition, Meckel et al., (2008) observed that Ramadan fasting in results in a reduction in speed endurance (6 x 40m) and countermovement jump (CMJ) performance in young footballers (14-16 years). On the other hand, performances in sprint (40m) and agility (4x10m shuttle race) were not affected during this month. The experiments made by Zerguini et al. (2007) showed that the performances recorded during the vertical Jump tests were not affected while those recorded during the 20 m sprint test, the dribbling speed test and the agility test were altered during the test during the fourth week of Ramadan compared to before Ramadan. These authors mentioned that the decrease observed was not related to fasting but rather to environmental and motivational factors since the tests performed are not of sufficient duration to be influenced by the availability or not of the energy substrates. Thus the tests are unlikely to be affected by the low caloric intake associated with the month of Ramadan. In addition, Kirkendall et al., (2008) reported performance in sprint (7 x 30 m), dribbling (McGregor et al., 2002), CMJ, pass testing (Ali et al., 2007) and agility 4-line agility test(Rösch et al., 2000) were not affected in footballers continuing their training during Ramadan. The authors explained the stability or sometimes the improvement in performance observed during the month of fasting by the effect of maintaining the same intensity and duration of the training sessions and by the fact that the players live together during the period of investigation. Similarly, Chaouachi et al. (2009) did not report a change in performance in sprint (5 m, 10 m, 30 m), squat jump and CMJ recorded at high level judokas who maintained a high intensity and high training volume during Ramadan.

However, the average power recorded during the 30-second repetitive jump test decreased towards the end of Ramadan. Chaouachi et al., (2009) explain this decline by the effects of reduced carbohydrate consumption and lower body mass, which results in decreased buffering capacity during intense muscle contractions. On the other hand, Girard and Farooq (2011) studied the impact of fasting during the month of Ramadan on the ability to repeat sprints in children aged between 10 and 14 years and they showed that the performance during repeated

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sprints had deteriorated at the end of Ramadan and this effect persisted for at least two weeks while the fatigue resistance was preserved.

II - The heart rate variability

This part is devoted to the heart rate variability (H.R.V). We will successively present the following points:

· The branches of the autonomic nervous system that innervate the heart and influence its rhythm and contractions.

· Study of the cardiac variability on the two analysis plans (temporal and frequency) and the parameters measured.

· Physiological interpretation of different parameters of heart rate variability II.1. Autonomic nervous system

The autonomic nervous system (ANS), also called vegetative nervous system (VNS) or neurovegetative intervenes in the regulation of many functions of the body. It can be considered as a common final pathway, stretched between the neural axis and effectors organs, and subject to the double influence of peripheral afference and supra segmental centres of the central nervous system. Its involvement does not lead to paralysis but dysfunction of the organ that innervates, which organ most often has a specific functional autonomy that the vegetative system adapts incessantly to the conditions of the environment (Mathias &Bannister, 2002).

The ANS thus has a role of modulator and regulator of the unconscious vegetative life while fine-tuning the activities of the organs, with respect to the environment and respecting their independence (Appenzeller & Oribe, 1997, Mathias, 2000). It acts on metabolism and electrolyte balances, blood pressure, body temperature, blood composition and is involved in the functioning of the cardiovascular, respiratory and digestive systems (Guyton, 2006).

ANS effectors are the tissues and organs responsible for maintaining homeostasis, mainly the myocardium, the smooth muscles of the vessels and hollow viscera, such as the bronchi, the digestive tract and the bladder, as well as the glands and secretory cells. Its functioning is reflex, unconscious and autonomous (Spalding, 1969) but is under control of other parts of the nervous system.

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ANS reactions are fast, of the order of a second, and are distributed in the body, whereas the somatic nervous system has reactions of the order of a millisecond and are local. Moreover, the ANS can also solicit the somatic nervous system to feel sensations, such as thirst, hunger, urge to urinate, or pain. The involvement of the ANS means a dysfunction of the organ and not a stop. The organs have functional autonomy that the SNV only adapts. If it is no longer active, the organs continue to function but their activities are no longer maintained in homeostasis and in the reaction to aggression (Langley, 1921, Cannon, 1929). While an attack of the somatic nervous system will cause a loss of function, identical to anaesthesia or paralysis.

The ANS is composed of two subsystems: sympathetic and parasympathetic. At the level of an effectors, there is a double innervations by the two sub-systems whose effects are conjugated, opposed or succeed one another. However, sweat glands, piloerector muscles, and some subcutaneous vessels do not exhibit parasympathetic innervations. These two subsystems are composed of afferents, specific centres located in the central nervous system and an efferent pathway, formed by two neurons within the SNA. There are also relays in the ANS outside the central nervous system, in cell clusters called ganglia, between centres and effectors. We then distinguish Pre-ganglion neurons, which have cell bodies located in the central nervous system (spinal cord), and postganglionic neurons, so-called effectors, located in the ganglia (Pruvost, 2007).

Many organs, such as the heart, have a double innervations; sympathetic and parasympathetic. Now, the effects of the two branches of the autonomic nervous system are antagonistic. Their actions interact constantly: the parasympathetic influence is restricted by sympathetic influence and vice versa. Nerve modulation on the heart causes a change in heart rate, called a chronotropic effect. It should also be noted that the heart rate is also influenced by hormonal control mediated through the bloodstream, but hormonal control is less rapid and less powerful than direct nerve control (Pocock & Richards, 2004). It has been suggested that abnormal regulation of the autonomic nervous system is a biological process leading to arrhythmias and cardiovascular events during stress (Bhattacharyya & Steptoe, 2007). For example, an increase in cardiovascular events has already been reported following earthquakes and major sports competitions (Wilbert-Lampen et al., 2008).

It is therefore clear that the autonomic nervous system can be divided into two major parts: the sympathetic nervous system and the parasympathetic nervous system. Their origins are

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found at different levels of the spinal cord and at the base of the brain. The effects of these two systems are often antagonistic, but they always work together, although for more methodological reasons we have to study them separately.

II.1.1. The sympathetic nervous system

The sympathetic nervous system or orthosympathetic nervous system is one of the three parts of the efferent autonomic nervous system. The other two parts are the enteric nervous system and the parasympathetic nervous system. The sympathetic nervous system is our system of action and struggle. It prepares the body for stress situations. It is responsible for controlling a large number of unconscious activities of the body, such as heart rate or contraction of smooth muscles. It exerts its effects on target cells and organs mainly via neurotransmitters called catecholamines (noradrenaline and, to a lesser extent, adrenaline). Yet the sympathetic nervous system is not quite superimposed on the adrenergic nervous system, its action sometimes passing (some vessels, sweat glands) by a secretion of acetylcholine. For this, it produces a massive discharge throughout the body and prepares it for action. A violent and unexpected noise, a situation of fear or the last few seconds before the start of a sports competition are all examples of the moment when this massive discharge takes place. The effects of sympathetic stimulation are important for the athlete.

· Increased heart rate and contraction force of the heart,

· Dilatation of the coronary vessels and therefore increased cardiac output,

· Muscle vasodilatation to bring more blood to the active muscles,

· Vasoconstriction in other areas, diverting the blood mass to the active muscles,

· Increased blood pressure, which improves muscle perfusion and venous return,

· Increased metabolic level in response to increased needs,

· Stimulation of mental activity that improves perception and concentration,

· Liver release of glucose into the blood,

· Finally, functions that are not directly involved in exercise function at a slower rate (renal function, digestion), which saves the energy needed for movement.

These changes in the basal body function facilitate the motor response. This highlights the importance of the autonomic nervous system to acute stress or physical exercise (Wilmore & Costill, 1998).

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II.1.2. The parasympathetic nervous system

The parasympathetic nervous system or vagal system is our defense system. It is one of three divisions of the autonomic or visceral nervous system, with the orthosympathetic nervous system and the enteric nervous system. The nerve fibers of the parasympathetic system originate in the cranial (nerve III, VII, IX, and X) and sacral parts of the spinal cord. It controls the involuntary activities of the organs, glands, and blood vessels together with one of the other parts of the autonomic nervous system: the sympathetic nervous system (orthosympathetic).

The parasympathetic influence is modulated by the release of acetylcholine, the latter is responsible for the slowing of the heart rate (cardio-moderator). This acetylcholine plays a major role in the digestive and urinary functions; this secretion is more active when one is calm or at rest. Its effects are generally opposed to those of the sympathetic system and leads to:

· a drop in the heart rate,

· an increase in gastric, salivary and intestinal secretions.

· a loosening of most sphincters of the gastrointestinal tract.

II.2. Influence of autonomic nervous system on heart rate

Although the heart has a specific functional autonomy, the autonomic nervous system constantly adapts its frequency and contraction force to different environmental conditions and influences. The parasympathetic nervous system (via the vagus nerve or X) has a general effect on the heart rate. The sympathetic nervous system generally increases cardiac activity. Although these two systems interact continuously, the permanent parasympathetic influence (vagal tone) is often the most intense, making the heart rate largely dependent on vagal stimulation / inhibition.

II.3. Cardiac variability study

Blood pressure and heart rate fluctuate continuously and are under the control of several regulatory systems: short-term regulation represented by the central nervous system, baroreflex and choreflex systems; medium-term regulation thanks to the hormonal systems (renin-angiotensin system, vasopressin, natriuretic atrial factor ...), the tension-relaxation phenomenon and the transfer of interstitial fluid to the plasma sector and vice versa; and finally, a long-term regulation supported especially by the kidneys. Blood pressure and heart

24

rate are therefore not constant phenomena: they vary constantly. This variability can be defined as the set of variations of these parameters around an average reference value and can be broken down into two time scales:

· Variability over a 24-hour period, still termed circadian or long-term.

· Variability over a period of a few minutes (usually 5 minutes), termed short-term variability, including spontaneous and unannounced variations (effort, emotion, positional change ...).

Because of its ability to rapidly modulate blood pressure and heart rate levels through the baroreflex system primarily (short-term regulation), the activity of the autonomic nervous system can be studied by measuring the variability of these two parameters. Over the last twenty years, heart rate variability has become a non-invasive marker of autonomic nervous system activity (Jourdan, 2008). The study of cardiac variability is done on two different temporal and frequency planes (Neto et al, 2005).

II.3.1. In the time domain

Time domain analysis is a simpler analysis than spectral analysis. Measurements in the time domain are produced from arithmetic calculations. There are two classes: on the one hand, the measurements derived directly from the normal-to-normal intervals between two beats and, on the other hand, the measurements derived from the differences of the normal-to-normal intervals themselves, among the parameters which can be measured by the analysis in the field of time:

· NN 50: number of successive RR intervals greater than 50 ms.

· PNN50: NN50 divided by the total number of intervals that expresses the high frequency variability mainly of modulated parasympathetic origin.

· RMSSD: square root of the squared differences of the successive RR intervals (the squared root of the mean of the sum of the squares of differences between adjacent NN intervals) which also expresses the high frequency variability mainly of parasympathetic origin, modulated by the breathing. This measurement is preferable to pNN50 and NN50.

· SDNN: (standard deviation of the RR interval over the entire recording period, standard deviation of all NN intervals) which gives information on the overall variability.

25

These indices are therefore a non-invasive method for studying the cardiac response to stimulation of the autonomic nervous system. They constitute a global approach to the influence of the autonomic nervous system. However, some methodological precautions should be emphasized. Many of these clues depend on the length of the recording. It is therefore necessary to standardize this length in order to be able to compare these different parameters. Consequently, it is imperative to only compare these parameters for an identical recording length (Jourdan.G, 2008).

II.3.2. In the frequency domain

In recent years, the spectral analysis of cardiac variability, based on the analysis of variations of RR intervals, has become the reference tool for the study of the dynamic interactions between parasympathetic and sympathetic controls (Malliani et al. 1991). Spectral analysis then breaks down a complex signal like heart rate into its constituents of frequency and quantifies the relative power of these components (Jourdan.G, 2008).After mathematical processing, a periodic signal of any shape (such as the heart rate, for example) appears in fact as the superposition of a sum of sinusoids or elementary oscillations. The fast Fourier transform allows the mathematical decomposition of a complex record into its constituent or elementary elements without loss of information. Each elementary sinusoid is mathematically defined by its amplitude and frequency. The set of sinusoids then constitutes the spectrum. The resulting graph shows on the abscissa, a frequency scale (in hertz, Hz) and on the y-axis, an amplitude scale. It allows the study of different oscillations of specific frequencies. In humans, the spectrum of the heart rate ranges from 0 to 0.4 Hz and can be divided into 3 areas of interest (on a recording of short duration, 2 to 5 minutes) or in 4 areas of interest (on a long-term recording, 24 hours) (Anonymous, 1996).

The parameters that can be calculated from the spectral analysis:

· Total power (ms²): Normal-to-normal interval variance of the entire record.

· Ultrafast frequencies (ULF): from 0.0001 to 0.003 Hz (only if 24 hours recording).

· Very low frequencies (VLF): from 0.003 to 0.04 Hz.

· Low Frequencies (LF): 0.04 to 0.15 Hz Oscillation in this frequency band is known as Traube-Hering waves.

· High frequencies (HF): 0.15 to 0.4 Hz. The oscillation in this frequency band is known as the Mayer wave.

·

26

VLF (ms²): Power in very low frequencies.

· LF (ms²): Power in the low frequencies.

· HF (ms²): Power in high frequencies.

LF and HF can also be in so-called normalized values, which corresponds to the power of the frequency band considered divided by the total power of the spectrum less VLF:

· HF (normalized): HF nu = 100 X HF / (HF + LF).

· LF (normalized): LF nu = 100 X LF / (HF + LF). The values thus standardized and the LF / HF ratio then make it possible to quantify, albeit in a simplified way, the sympathetic and vagal contribution to the variability of the heart rate (Neto et al., 2005).

II.3.3. Relationship between spectral and temporal study parameters

Neto et al., (2005) showed that in the analysis of cardiac variability, many temporal and frequency domain variables appear strongly correlated. These correlations are in fact a reflection of their mathematical as well as physiological significance and interdependence. Unless performing other analyzes than those commonly used in the frequency domain and which are mentioned above, the variables conventionally used in the frequency domain are therefore equivalent to those of the time domain.

Table I: Indices of human heart rate variability in the frequency and time domains and their approximate matches of 24-hour recordings. (Neto et al.)

Time variable Frequency domain Temporal domain Correspondence

PT Whole frequency scale but approximately <0.4 SDNN

ULF(VLT) 0,0001 à 0,0003 Hz SDNN, SDANN

VLF(VLT) 0,0001 à 0,0003 Hz SDNN Index

LF(VCT) 0,0001 à 0,0003 Hz SDNN Index

HF(VCT) 0,0001 à 0,0003 Hz RMSSD, PNN50

PT: total power of the spectrum; ULF: ultra low frequencies; VLF: very low frequencies; LF: low frequencies; HF: high frequencies; SDNN: standard deviation of the RR interval over the entire recording period; SDANN: standard deviation of the mean RR intervals over 5-minute periods over the entire recording period; SDNN index: mean of standard deviations of the RR interval over 5-minute periods over the entire recording period; RMSSD: square root of

27

squared differences of successive RR intervals; pNN50: this is the NN50 divided by the total number of RR intervals.

II.3.4. Physiological interpretation of different parameters of heart rate variability

The physiological basis for analyzing the short-term variability of heart rate is based on different mechanisms of action and control between the parasympathetic and the orthosympathetic systems. Parasympathetic influences exert a rapid and dynamic control via the release of acetylcholine and its action on the Muscarinic receptors are mainly reflected by the high frequency component of heart rate variability.

Moreover, the orthosympathetic system is reflected by the release of noradrenaline and its action on â-adrenergic receptors, which exerts a slower influence and is manifested in the low frequency component of the variability of the heart rate.

The short-term variability of heart rate is therefore an indirect measure of autonomic nervous system activity. It is a reflection of autonomous influences on the sinoatrial node, more than on the ventricular myocardium. The analysis of heart rate variability, however, provides an insight into the variations in autonomic tone associated with various conditions. Two major components are studied: low frequencies (LF, from 0.04 to 0.15 Hz) and high frequencies (HF, from 0.15 to 0.4 Hz, synchronized with the respiratory rhythm). While the high frequency band is clearly attributed to vagal mechanisms (Akselrod et al., 1981, Malliani et al., 1991, Camm, 1996), several hypotheses have been advanced regarding the low frequency band. The interpretation of this LF component is considered by some to be a sympathetic modulation index (Rimoldi et al., 1990, Malliani 1991, Kamath & Fallen, 1993, Montano et al., 1994) and for others as a parameter. Including both sympathetic and parasympathetic influences (Akselrod et al., 1981, Appel et al., 1989).

Therefore, the low frequency-high frequency ratio can be considered as a mirror of the sympathovagal balance or the influence of the sympathetic system on the heart rate. A circadian rhythm of the sympathovagal balance has been observed in the population: the LF spectral component predominates during the day whereas it is the HF spectral component that is predominant at night. There is therefore a marked decrease in the LF / HF ratio between day and night. This observation reflects the day / night variation in the influences of para- and

28

orthosympathetic systems (sympathetic predominance during the day and vagal at night) (Furlan et al., 1991, Malliani et al., 1991).

Part II : Material and

Methodes

I. 30

Participants

Nine male athletes playing football for at least 5 years in a "professional league II" club aged 16.2 #177; 0.5 years and a size of 176 #177; 5 cm participated in our study after reading the different modalities of the experimental protocol. The weight and height of the subjects were measured using a scale and a height scale. The inclusion criteria consist of keeping standard meal times (breakfast at 07:00: 00 #177; 1:00, lunch at 12:00: 00 #177; 1:00: 00 and dinner at 20:00: 00 #177; 1: 00) and sleep (sleep between 11:00 pm and 7:00 am + 1:00 am) before the start of the study. This criterion allowed to provide a sample of participants having the same bedtime (23h: 00 #177; 00h: 30) and to raise (06h: 30 #177; 00h: 30). The subjects are non-smokers and do not consume caffeine or alcoholic beverages. The first day of the month of Ramadan of the year 1432 of Hegira corresponds to August 1, 2011 while the last day corresponds to August 30, 2011. The time elapsing from the beginning of dawn until sunset was from 05h: 24 to 19h: 27 at the beginning of Ramadan and from 05h: 47 to 18h: 53 at the end of the Holy month. During this month, participants consume their last meal around 1:00 am and since then refrain from eating and drinking until sunset.

II. Experimental procedures

The experimental protocol spanned three periods: two weeks before Ramadan (BR), the end of the second week of Ramadan (R2) and the end of the fourth week of Ramadan (R4). Before the beginning of the protocol, a familiarization session is performed in order to avoid the effects of learning that could occur with the repetition of the test sessions (Pincivero et al., 1997). During this familiarization session, subjects became aware of the nature of the test and the constraints of the experiment. Instructions regarding sleep, diet and physical activity have been provided to the subjects concerned. During the experimental period, subjects were asked not to perform intense sporting activities the day before and during the day they were assessed. During the same experimental period, subjects were reminded that ingestions of caffeine-based foods and beverages are out of the question, as anything that could increase their awakening.

The test sessions were conducted in the biology laboratory of Farhat Hachad Hospital in Sousse at the same time of the day (between 14:00 and 17:00) in order to maintain identical experimental conditions. The subjects are asked to use the same sports shoes at each session.

31

II.1. The Wingate test

The Wingate test was performed on a Monark model 894E (Monark AB, Varberg, Sweden) with pedals fitted with footrests. The athlete performs maximum effort for 30 seconds against a braking force. For each subject the load is determined according to body weight according to the Bar-Or (1987) optimization table (87g / kg of body weight). During the test, subjects were strongly encouraged to motivate them. The test then allows us to record average power and peak power during exercise.

Photo 1: Achievement of the Wingate test II.2 Recording of heart variability

The work begins with a period of stabilization of the autonomous system. The subject being completely isolated from his comrades, he is asked to lie down for ten minutes while being awake (he is asked about not falling asleep, not to talk, and not to change too much their breathing) (Cassirame, 2007).

From this moment, the protocol starts, which consists of recording the heart rate with a Polar S810 watch (in RR mode):

1.

32

Recumbent position: in the supine position for ten minutes without the subject making any movement,

2. Standing position: Follows a second period of ten minutes during which the subject moves to the standing position,

3. During the effort: during the third period, the subject is asked to pass on the cyclo-ergometer where he will pedal for 2'30 " at moderate intensity as a warm-up, then the subject will execute the Wingate test (30 sec of maximum effort) then continue pedalling for 2 min at empty load as active recovery.

Photo 2 and 3: Recording heart variability at rest

The environment is kept stable, with an average temperature and atmospheric pressure of (25 #177; 1° C, 45%), a decrease in noise and no movement around the person. The data was then analyzed using KUBIOS HRV 2.0 software for the study of cardiac variability.

The KUBIOS HRV 2.0. is a software that allows to study the activity of the sympathovagal balance. Indeed, through this software, we can analyze individually the sympathetic and parasympathetic effect on cardiac function. Data obtained by POLAR S810 were transferred to KUBIOS, and analyzed on time and frequency plans. This non-invasive method to study cardiac function and its control by the vegetative nervous system has shown its credibility which according to Gamelin et al. (2005), has achieved the same results as a direct recording of the heart rate (ECG).

33

III. Statistical analysis

Statistical analysis of the data was performed using the Statistica 6.01 software (Stat Soft, France). Values are expressed as mean #177; standard deviation.

Data analysis was performed as follows:

· One-way analysis of variance (ANOVA) (Ramadan: BR, R2, R4) for the Wingate test.

· One-way analysis of variance (ANOVA) (Ramadan: BR, R2, R4) for cardiac variability parameters.

For each analysis, when the ANOVA shows a significant effect, a Tukey post-hoc test is applied to compare the experimental data in pairs. All observed differences are considered statistically significant for a probability threshold of less than 0.05.

Part III : Results

I. 35

Anthropometric characteristics of the sample

Anthropometric parameters are shown in Table II. The analysis of the variance did not show a significant effect for the weight and BMI parameters that were not changed during the three measurement periods.

Table II: Mean #177; SD anthropometric characteristics of the subjects during the second week, the fourth week and before Ramadan (n = 9).

	B R	R 1		R 2
				Weight (KG)
65.78 #177; 5.71	65.55 #177; 5.56	64.74 #177; 6.11
				BMI
21,23 #177; 1.73	21,16#177; 1.76	20.90 #177; 1.81

II. The Wingate test

The parameters calculated from the Wingate test during the second week, the fourth week and before Ramadan are presented in Table 3.

Table III: Mean #177; SD of Wingate test parameters during the second and fourth week of Ramadan and Before Ramadan (n = 9).

	B R	R1	R2
Ppic (W)	623,11#177;75,96	622,58#177;62,02	622,44#177;69,01
Ppic (W/kg)	9,51#177;0,58	9,48#177;0,63	9,62#177;0,59
Pave (W)	495,43#177;49,6	494,75#177;64,3	492,45#177;71,91
Pave (W/kg)	7,57#177;0,62	7,55#177;0,66	7,61#177;0,36

II.1. Average power (P ave)

The analysis of the variance does not show any significant effect of the fast of Ramadan on the average power expressed in Watts. Similarly, the relative average powers (W / Kg) relative to weight do not show any significant difference between the three periods even though the values have slightly decreased during these periods.

P ave (Watt)

450

400

600

550

500

350

300

250

200

BR

A R M R

R2 R3

F R

36

Figure 1: Average (#177; SD) of mean powers (W) of the Wingate test recorded during the
second, fourth week and before Ramadan (n = 9).

II.2 Peak power (Ppic)

Variance analysis does not show a significant effect of Ramadan fasting on Peak power expressed in Watts. Likewise, the relative peak powers (W / Kg) show no significant difference between the different measurement periods (BR, R1 and R2).

P.pic (Watt)

400

700

600

500

300

200

A R M R

R2 R3

F R

BR

Figure 2: Average (#177; SD) of the Peak (W) Wingate ratings recorded during the second, fourth
week and before Ramadan (n = 9).

37

III. Effect of fasting Ramadan on the autonomic nervous system

The parameters calculated from the cardiac variability analysis during the second week, the fourth week and before Ramadan are presented in the following tables:

Table IV: Mean (#177; SD) of the analysis parameters of cardiac variability analysis in supine position

B R R 1 R 2

R R	1001 #177; 105	1054 #177; 83*	1081 #177; 89*
RMSSD	72, 88 #177; 21, 86	81, 91 #177; 14, 58*	90, 16 #177; 15, 55*
PNN50	39, 42 #177; 17, 18	45, 67 #177; 9, 62*	47, 25 #177; 11, 26*
L F (ms^2)	324 #177; 126	304 #177; 101*	298 #177; 112*
H F (ms^2)	1011 #177; 572	1082#177;659*	1181 #177; 623*
L F (nu)	38, 77 #177; 24, 12	31, 56 #177; 22, 3*	29, 44 #177; 20, 4*
H F (nu)	57, 39 #177; 20, 4	69, 33 #177; 32, 3*	75, 66 #177; 29, 12*
LF/HF	1, 69 #177; 0, 90	1, 37 #177; 0, 69 *	1, 24 #177; 0, 70*

RR, Time intervals between two successive RR peaks; RMSSD, square root of squared differences of successive RR intervals: PNN50 percentage of differences in successive RR intervals greater than 50 ms; LF, Power in the low frequencies; HF, power in high frequencies; LF / HF, sympathovagal balance, recorded during the second, fourth week and before Ramadan (n = 9). ** (p <0.01), * (p <0.05): Significant difference from before Ramadan. ££ (p <0.01), £ (p <0.05): Significant difference between the second and fourth week of Ramadan.

Table V: Mean (#177; SD) of the analysis parameters of cardiac variability in standing position.

	B R	R 1	R 2
R R	822 #177;93	872#177;77 a	883#177;82 a
RMSSD	31,93#177;13,96	39,37 #177;7,43 a	41,94#177;9,38 a
PNN50	7,01#177;5,15	12,75 #177;3,24 a	14,52#177;4,80 a
L F (ms^2)	376 #177; 111	333 #177;93 a	321 #177;88 a
H F (ms^2)	239#177; 144	276 #177;155 a	298#177;84 a
L F (nu)	69,33#177; 21,2	62,3 #177;19,2 a	59,88 #177;17,7 a
H F (nu)	32,11#177; 21,2	44,12 #177;22,2 a	51,22 #177;21,7 a
LF/HF	2,93#177;0,93	2,65 #177;0,89 a	2,31#177;0,93 a

RR, Time intervals between two successive RR peaks; RMSSD, square root of squared differences of successive RR intervals: PNN50 percentage of differences in successive RR intervals greater than 50 ms; LF, Power in the low frequencies; HF, power in high frequencies; LF / HF, sympathovagal balance, recorded during the second, fourth week and before Ramadan (n = 9). aa (p <0.01), a (p <0.05): Significant difference from before Ramadan; ££ (p <0.01), £ (p <0.05): Significant difference between the second and fourth week of Ramadan.

38

Table VI: Mean (#177; SD) of the analysis parameters of the cardiac variability during the effort.

B R R 1 R 2

R R		491 #177; 99	521 #177; 71 b		533 #177; 68 b
RMSSD		9,77 #177; 3,96	16,57 #177; 2,91 bb		18,21 #177; 2,92 bb
PNN50		0 #177; 0	0 #177; 0,1		0 #177; 0
LF (ms^2)		25 #177; 18	19 #177; 9 b		17 #177; 13 b
HF (ms^2)		7 #177; 2	9 #177; 3		9 #177; 2
L F (nu)	79,33 #177; 12,33			69,22 #177; 12,44 b		66,33 #177; 13,55 b
H F (nu)	21,33 #177; 12,33			28,64 #177; 12,44 b		31,42 #177; 13,55 b
LF/HF	5,59 #177; 3,95			5,01#177; 3,81 b		4,91 #177; 2,79 b

RR, Time interval between two successive RR peaks; RMSSD, square root of squared differences of successive RR intervals: PNN50 percentage of differences in successive RR intervals greater than 50 ms; LF, Power in the low frequencies; HF, power in high frequencies; LF / HF, sympathovagal balance; recorded during the second, fourth week and before Ramadan (n = 9). bb (p <0.01), b (p <0.05): Significant difference from before Ramadan; ££ (p <0.01), £ (p <0.05): Significant difference between the second and fourth week of the month of Ramadan

39

III.1. Effect of Ramadan fasting on the sympathetic system III.1.1. LF (ms2)

LF (ms2)

400

600 Supine Standing Effort

P.cou P.debou P.l'effo

500

300

200

100

0

*

a

b

*

a

b

Figure 3: Mean (#177; SD) LF (ms²) values recorded during the second, fourth week and before Ramadan (n = 9).

* (p <0.05) Significant difference from before Ramadan (supine position);

a (p <0.05) Significant difference from before Ramadan (standing position); b (p <0.05) Significant difference from before Ramadan (During effort).

· Supine position: the analysis of the variance shows a significant effect F (2) = 12.67; p <0.05 Ramadan fasting on the mean values LF (ms²) (Figure 3).

The post hoc analysis shows that the LF values recorded before Ramadan are significantly higher than those measured in the middle and at the end of the month of fasting P <0.05.

· Standing position: The analysis of the variance shows a significant effect F (2) = 12.22, p <0.05 Ramadan fasting on the mean values LF (ms²) (Figure 3).

The post hoc analysis shows that the LF values recorded before Ramadan, when standing, are significantly higher than those measured in the middle and at the end of the month of fasting p <0.05.

· 40

During effort: The analysis of the variance shows a significant effect F (2) = 11,52; p <0.05 Ramadan fasting on mean values LF (ms2) after exercise (Figure 3).

The post hoc analysis shows that the LF values recorded before Ramadan, during exercise, are significantly higher than those measured in the middle and at the end of the month of fasting (P <0.05).

III.1.2. LF (nu)

LF (nu)

100

40

90

80

70

60

50

30

20

10

0

a b

b

Figure 4: Mean (#177; SD) LF (nu) values recorded during the second, fourth week and before Ramadan (n = 9).

* (p <0.05) Significant difference compared to before Ramadan (supine position); a (p <0.05) Significant difference compared to before Ramadan (standing position); b (p <0.05) Significant difference compared to before Ramadan (During effort).

· Supine position: The Analysis of the variance shows a significant effect F (2) = 11.66; P <0.05 Ramadan fasting on mean values LF (nu) (Figure 4).

The post hoc analysis shows that the LF values recorded before Ramadan, in supine position are significantly higher than those measured in the middle and at the end of Ramadan (P <0.05).

· Standing position: The analysis of the variance shows a significant effect F (2) = 11,23; P <0.05 of Ramadan fasting on the mean LF values (Figure 4).

41

The post hoc analysis shows that the LF values recorded before Ramadan, while standing, are significantly higher than those measured in the middle and at the end of the month of Ramadan (P <0.05).

· During effort: The analysis of the variance shows a significant effect F (2) = 10.55; P <0.05 of Ramadan fasting on mean values LF (nu) (Figure 4).

The post hoc analysis shows that the LF values recorded before Ramadan, during the effort, are significantly higher than those measured in the middle and at the end of the month of Ramadan (P <0.05).

III.2. Effect of Ramadan fasting on the parasympathetic system III.2.1. RMSSD (ms)

RMSSD (ms)

120

100

40

80

60

20

0

*

a

bb

a

bb

Figure 5: Mean (#177; SD) RMSSD(ms) values recorded during the second, fourth week and before Ramadan (n =

9).

* (p <0.05) Significant difference compared to before Ramadan (supine position);

a (p <0.05) Significant difference compared to before Ramadan (standing position);

bb (p <0.05) Significant difference compared to before Ramadan (During effort).

· Supine position: the Analysis of the variance shows a significant effect F(2) = 11,52; P <0.05 Ramadan fasting on mean values RMSSD (ms) (Figure 5).

42

The post hoc analysis shows that RMSSD values recorded before Ramadan are significantly lower than those measured in the middle and end of Ramadan (p <0.05).

· Standing position :The analysis of the variance shows a significant effect F (2) = 11.88;(p <0.05) of Ramadan fasting on mean values RMSSD recorded(ms) (Figure 5).

Post hoc analysis shows that standing RMSSD values before Ramadan are significantly lower than those measured in the middle and at the end of Ramadan (p<0, 05).

· During effort: The analysis of the variance shows a significant effect F (2) = 16,62; (p <0.01) of Ramadan fasting on mean RMSSD values recorded during effort (Figure 5).

The post hoc analysis shows that the RMSSD values recorded during the effort, before Ramadan, are significantly lower than those measured in the middle and at the end of the month of Ramadan (p <0.01).

III.2.2. PNN50 (%)

70

*

60

50

PNN50 (%)

40

30

a

20

10

0

*

a

Figure 6: Mean (#177; SD) of PNN50 (%) recorded during the second, fourth week and before Ramadan (n
= 9).
* (p <0.05) Significant difference compared to before Ramadan (supine position);
a (p <0.05) Significant difference compared to before Ramadan (standing position).

· Supine position: The analysis of the variance shows a significant effect F (2) = 10.89 (p <0.05) of Ramadan fasting on mean values PNN50, expressed in% (Figure 6).

43

Post hoc analysis shows that PNN50 percentages in supine position before Ramadan are significantly lower than those measured in the middle and end of Ramadan (p <0.05).

· Standing position: The analysis of the variance shows a significant effect F (2) = 9.84 (p <0.05) of Ramadan fasting on the values PNN50, expressed in% (Figure 6).

The post hoc analysis shows that the PNN50 percentages recorded, while standing, before Ramadan are significantly lower than those measured in the middle and at the end of the month of Ramadan (p <0.05).

· During effort: the analysis of the variance does not show a significant effect of of Ramadan fasting on the PNN50 expressed in% (Figure 6).

III.2.3. HF (ms2)

Supine Standing Effort

¹⁰

1600

1400

1200

1000

800

600

HF (ms2)

a

a

400

200

0

Figure 7: Mean (#177; SD) of the HF (ms2) values recorded during the second, fourth week and before

Ramadan (n = 9).

* (p <0.05) Significant difference compared to before Ramadan (supine position);
a (p <0.05) Significant difference compared to before Ramadan (standing position).

· Supine position: The analysis of variance shows a significant effect F (2) = 9.67 (p <0.05) of Ramadan fasting on mean HF (ms²) values (Figure 7).

44

The post hoc analysis shows that the HF (ms²) values recorded before Ramadan are significantly lower than those measured in the middle and at the end of the month of Ramadan p <0.05.

· Standing position: Variance analysis shows a significant effect F (2) = 10.22; (p <0.05) of Ramadan fasting on the average values HF (ms²) (Figure 7).

The post hoc analysis shows that the HF values recorded before Ramadan, while standing, are significantly higher than those measured in the middle and at the end of the month of Ramadan P <0.05.

· During the effort: Variance analysis does not show a significant effect of Ramadan fasting on mean LF values during exercise (Figure 7).

III.2.4. HF (nu)

HF (nu)

120

100

40

80

60

20

0

Supine Standing Effort

a

b

*

a

b

Figure 8: Mean (#177; SD) of the HF (nu) values recorded during the second, fourth week and before Ramadan (n =

9).

* (p <0.05) Significant difference compared to before Ramadan (supine position);

a (p <0.05) Significant difference compared to before Ramadan (standing position);

b (p <0.05) Significant difference compared to before Ramadan (During effort).

· Supine position: The analysis of the variance shows a significant effect F (2) = 9.67; (p <0.05) of Ramadan fasting on mean HF (nu) values (Figure 8).

Post hoc analysis shows that HF values recorded before Ramadan are significantly lower than those measured in the middle and at the end of Ramadan p <0.05.

·

45

Standing position: The analysis of variance shows a significant effect F (2) = 10.29 (p <0.05) of Ramadan fasting on mean HF (nu) values (Figure 8).

Post hoc analysis shows that the HF values recorded before Ramadan, while standing, are significantly lower than those measured in the middle and at the end of the month of Ramadan p <0.05.

· During effort: The analysis of the variance shows a significant effect F (2) = 12.52 (p <0.05) of Ramadan fasting on mean values HF (nu) (Figure 8).

Post hoc analysis shows that HF values recorded prior to Ramadan during exercise are significantly lower than those measured in the middle and end of Ramadan (p <0.05).

III.3. Effect of Ramadan fasting on sympathovagal balance

6

LF / HF

4

Supine Standing Effort

b

8

*

a

A R BR R1 R2

M

2

0

b

12

10

a

*

Figure 9: Mean (#177; SD) values (LF / HF) recorded during the second, fourth week and before Ramadan (n = 9). * (p <0.05) Significant difference compared to before Ramadan (supine position); a (p <0.05) Significant difference compared to before Ramadan (standing position); b (p <0.05) Significant difference compared to before Ramadan (During effort).

· Supine position: Variance analysis shows a significant F (2) = 9.82 (p <0.05) effect of Ramadan fasting on LF / HF ratios (Figure 9).

The post hoc analysis shows that the LF / HF ratios, in supine position, before Ramadan are significantly higher than those measured in the middle of the month and at the end of the month of Ramadan (p <0.05).

·

46

Standing position: The analysis of the variance shows a significant effect F (2) = 8.52; (p <0.05) of Ramadan fasting on the mean values of the LF / HF ratios (Figure 9).

Post hoc analysis shows that LF / HF ratios before Ramadan, in standing position, are significantly higher than those measured in the middle and end of Ramadan (p <0.05).

· During effort: the analysis of the variance shows a significant effect F (2) = 12,32; (p <0.05) of Ramadan fasting on LF / HF ratios (Figure 9).

Post hoc analysis shows that pre-Ramadan LF / HF ratios during exercise are significantly higher than those measured in the middle and end of Ramadan (p <0.05).

III.4. Effect of fasting Ramadan on the durations RR (ms)

R R (ms)

1400

1200

1000

400

800

600

200

0

BR R1 R2

Supine Standing Effort

*

b

*

a

b

Figure 10: Mean (#177; SD) of the RRs (ms) recorded during the second, fourth week and before Ramadan (n

= 9).

* (p <0.05) Significant difference compared to before Ramadan (supine position);

a (p <0.05) Significant difference compared to before Ramadan (standing position);

BR R1 R2

b (p <0.05) Significant difference compared to before Ramadan (During effort).

47

Table VII: Heart rate averages (bpm) recorded before, in the middle and at the end of the month of Ramadan (n = 9).

	B.R	R 1		R 2	F C (bpm) Supine
59,94	56,92	55,50		F C (bpm) Standing
72,99	68,80	67,95		F C (bpm) Effort
122,19	115,16	112,57

· Supine position: the analysis of variance shows a significant effect F (2) = 13.2 (p <0.05) of Ramadan fasting on RR durations (Figure 10).

Post hoc analysis shows that RR durations recorded before Ramadan are significantly lower than those measured in the middle and at the end of Ramadan (p <0.05).

· Standing position: Variance analysis shows a significant effect F (2) = 8.22 (p <0.05) of Ramadan fasting on RR durations (Figure 10).

The post hoc analysis shows that the RR durations recorded in the standing position before Ramadan are significantly lower than those measured in the middle and at the end of the month of Ramadan (p <0.05).

· During effort: the analysis of the variance shows a significant effect F (2) = 17.6 (p <0.05) of Ramadan fasting on the average RR durations (Figure 10).

The post hoc analysis shows that RR durations recorded during the effort before Ramadan are significantly lower than those measured in the middle and at the end of the month of Ramadan (p <0.05).

Part IV : Discussion

49

The objective of this study is to evaluate the effects of Ramadan fasting on:

1. Performances during a Wingate test,

2. The modulation of sympathetic and parasympathetic system activity on cardiovascular function in adolescents who have been playing football for at least 5 years.

Our results showed that Ramadan fasting had no effect on anthropometric parameters and performances during a Wingate test. Moreover, our results revealed a modulation of the autonomic system by the increase of the parasympathetic participation and by the decrease of the sympathetic effect.

I. The effects of fasting Ramadan on body weight

The results of the present study found that the effect of fasting on body weight does not show a significant difference during the month of Ramadan compared to the control period (before Ramadan), this is confirmed by other previous studies (El Ati et al., 1995, Finch et al., 1998, Ramadan 2002, Souissi et al., 2007, Zerguini et al., 2007, Meckel et al., 2008, Chennaoui et al., 2009, Sweileh et al. al., 1992). Moreover, Sweileh et al., (1992) reported that dehydration exists only during the first week of Ramadan as it returns to its pre-Ramadan values during the fourth week of the month of fasting.

Ramadan et al., (1999) also noted a significant increase in osmolarity among sedentarians, which is not the case for athletes who continue to train during Ramadan.

Karli et al., (2007), confirmed the results of Ramadan et al., (1999) in their study of international athletes, where they conclude that the fluid balance has not changed significantly. We can deduce the same conclusions since our subjects are athletes who did not interrupt their sports activities during the holy month.

II. The effects of Ramadan fasting on Wingate test performances

Our results showed that the peak powers and the average powers recorded during the Wingate test do not reveal a significant difference during the second, fourth week of Ramadan compared to the pre-Ramadan control session.

50

This confirms the results of some previous studies that looked for the fasting effect of Ramadan on anaerobic performance especially for the Wingate test. Indeed, Souissi et al., (2007a) showed that the muscle powers recorded during the morning Wingate test are not affected during the month of Ramadan. On the other hand, the muscular powers are diminished during the fourth week compared to before Ramadan for the sessions realized in the afternoon.

In the same vein, Karli et al., (2007) showed that the average powers did not decrease significantly during Ramadan and that the peak powers showed an increase in nine athletes who continued to train normally during Ramadan.

On the other hand, other studies have led to other results. Indeed, Chaouachi et al., (2009) showed that the power recorded during the 30-sec repeated jump test decreased at the end of Ramadan compared to before Ramadan. The study of Abedelmalek (2008) showed that the average powers decreased significantly during the second and fourth week of Ramadan compared to after Ramadan. The same study showed that the Peak powers also declined significantly at the end of Ramadan compared to after Ramadan. In this study, the author explained these decreases in mean powers and peak powers by two essential factors: calorie restriction and sleep deprivation; this is not the case of our study which showed that the peak powers and the average powers were not affected by the fast of the month of Ramadan.

Several factors can explain this stability of performances during Wingate test found in our study. Indeed, the short duration of this test (30s) and its anaerobic nature do not seem to be influenced by the availability or not of the Energetic substrates. Thus, the test is slightly affected by the reduced caloric intake relating to fasting Ramadan (Zerguini et al., 2007).

In addition, our subjects did not stop their training during Ramadan (2 to 4 training sessions per week). This confirms previous studies (Rösch et al., 2000, McGregor et al., 2002, Ali et al., 2007, Kirkendall et al., 2008) which explained the stability or even sometimes the improvement in performance observed during the month of fasting by the effect of maintaining the same intensity and duration of training sessions.

With regard to partial sleep deprivation during Ramadan, data available in the literature have shown that anaerobic performance seems to be little affected by this factor (Mougin et al., 1996, Bambaeichi et al., 2005, Reilly and Waterhouse, 2009). On the other hand,

51

Souissi et al., (2007b) have shown that the effects of total and partial sleep deprivation are mainly related to the time of testing. Indeed, these authors have shown that sleep deprivation has negative effects only during the afternoon and evening, while the average powers were only diminished at the end of Ramadan for sessions performed between 10am and 11am. These results are discordant with ours, despite the fact that we recorded a slight decrease that was not significant during the periods of the test (between 15h and 17h).

In partial conclusion we say that, the performance stability of the peak powers and the average powers during Wingate test during and out of Ramadan can be explained by several factors:

1. the continuity of physical activity practice during Ramadan,

2. the nature of the test itself and its short duration that appears to be little affected by calorie deficit during the month of fasting or sleep / wake rhythm disruption that results in decreased performance when exercises require sensorimotor coordination or cognitive processes (Mougin et al., 1996) which is not the case in our study (purely physical test).

III. The effect of fasting Ramadan on the heart rate variability

Ramadan fasting has a significant effect on RR duration (ms) and sympathovagal balance at rest and during exercise. Indeed, under these conditions, there is a lower heart rate (bpm) from one session to another (Table VII); supine (59.94 Versus 56.92 Versus 55.50), standing (72.99 Versus 68.80 Versus 67.95) and during the effort interval (122.19 Versus 115.16 Versus 110,29) associated with an increase in parameter values representing parasympathetic activity (HF« ms²», HF«nu», RMSSD, PNN50) (Tables IV, V, VI): (Akselrod et al., 1981; et al., 1991, Camm, 1996) and the decrease in the values of the parameters representing the sympathetic activity (HF« ms²», HF«nu») (Tables IV, V, VI) (Rimoldi et al., 1990; , 1991, Kamath & Fallen, 1993, Montano et al., 1994), and consequently a decrease in the LF / HF ratio; some authors have adapted this ratio as an indicator of sympathetic activity (Yamamoto et al., 1991), others as an index of sympathovagal balance (Pagani et al., 1986).

This significant increase in RR (ms) duration, which reflects a decrease in mean heart rate, is confirmed with the study by Hussain et al., (1987); these authors found a significant decrease in heart rate at rest throughout the month of fasting in male subjects. Similarly, Karli et al.,

52

(2007) found a nonsignificant decrease heart rate at rest during Ramadan compared to before Ramadan.

In addition, Zoladz et al., (2005) found a decrease in heart rate of 10 beats / min during exercise at each workload that starts at 30 W and ends at 150 W of fasting overnight. Similarly, Ramadan et al., (1999) found a decrease in heart rate at submaximal exercise during the month of Ramadan compared to the control session.

Explanations of this phenomenon differ from one researcher to another. Husain et al., (1987) explained this decrease in heart rateat rest by the decrease in metabolic activity which is under the influence of reduced sympathetic activity; these authors added that the increase in religious devotion during Ramadan results from a solicitation of the mental state which tends to lower metabolic rate and heart rate.

Zoladz et al., (2005) explained the significant decrease in heart rate following a fasting night by increasing the plasma level of noradrenaline leading to an increase in systemic vascular resistance, and thus, the solicitation of arterial baroreceptors leading to vagal stimulation (Schachinge et al., 2001 and Malpas, 2004 cited by Zoladz et al., 2005). It is also known that diet can influence cardiovascular regulation in healthy subjects at rest (Hoost et al., 1996, Karpovich & Sinning, 1980). On the other hand, it has been shown that the effect of diet (abstention or food intake) can influence the cardiorespiratory activity by neuronal or hormonal pathways (Kearney et al., 1996).

Other research has also shown that the secretion of leptin (satiety hormone) and ghrelin (the hormone of hunger) can influence cardiovascular activity (Haynes et al., 1987). According to Matsumura, (2002, 2003) the injection of leptin activates the sympathetic nervous system, and on the contrary, the injection of ghrelin significantly decreases the heart rate in rabbits.

The decrease in resting and exercise heart rate can be explained by increased secretion of ghrelin and a decrease in leptin secretion during Ramadan, so that Zoladz et al.(2005) found no significant difference between the secretion of these two fasting hormones compared to the control session. According to Zoladz, this is probably due to the short duration of fasting (one night) observed during this protocol.

Through the study of cardiac variability, our results reflected a modulation of the autonomic nervous system by the decrease of the parameters reflecting the sympathetic activity on the frequency plane (LF « ms² », LF « nu ») (FIG. 4) and the increase of the parameters

53

reflecting the frequency-domain activity of the parasympathetic system ("HF « ms² », HF « nu ») and their temporal correspondences (PNN50, RMSSD) (FIGS. 5, 6) (Neto et al., 2005) during the month of Ramadan.

We also found a significant decrease in the LF / HF ratio (FIG 9), which reflects sympathovagal activity or also the variation in sympathetic activity, this decrease is explained by the decrease of the LF values (Tables IV, V, VI) and the increase of the HF values (Tables IV, V, VI) during the holy month.

These results may be a good explanation for the decrease in heart rate during Ramadan and confirm the hypotheses of Husain et al., (1987). These authors explained the decrease in heart rate during the holy month by a reduction in sympathetic tone.

These results may be consistent with the explanation given by Zoladz et al., (2005) who attribute the decrease in heart rate observed during exercise during abstinence by increasing systemic vascular resistance and vagal stimulation via the baroreceptors.

We can also add the change in the daily habits of Muslims during Ramadan, favoring sedentarism because Muslims tend to sleep late by watching television, praying or reading (Afifi et al., 1997).

In addition, general fatigue, reduced feeling of well-being, and impaired cognitive function are the result of changes in eating habits and sleep deprivation during Ramadan (Kadri et al., 2000; Leiper et al. 2003, Roky et al., 2004). It has also been shown that the month of fasting is accompanied by a decrease in alertness, probably because of the absence of lunch, which usually leads to falling asleep (El Kalifi, 1998).

The major changes in the rhythm of life in Ramadan, mainly affecting food intake and sleep (Chaouachi et al., 2008, Maughan et al., 2008a, Leiper et al., 2008) can also explain this increase in tone. parasympathetic identified in our results. Indeed, fasting reduces the basic metabolism in the absence of digestion. In addition, it has already been shown that digestion accelerates the heart rate for 2 or 3 hours (Karpovich, Sinning, 1980).

It is known that digestion activates the sympathetic tone (Guyton, 2006) so fasting tilts the sympathovagal balance towards parasympathetic tone which is confirmed by the study of Al-Hazmi et al., (2009) who found a decrease in LF / HF ratio during the holy month compared

54

to the control session according to Ramadan. They also concluded that fasting protects the heart and minimizes the risk of heart attacks.

Nerve modulation on the heart causes a change in heart rate, called a chronotropic effect. It should also be noted that the heart rate is also influenced by hormonal control mediated through the bloodstream, but hormonal control is less rapid and less powerful than direct nerve control (Pocock & Richards, 2004). This may explain the findings found in some studies that show a decrease in heart rate despite the increase in noradrenaline levels (Zoladz et al., 2005).

Indeed, fasting is a phenomenon of long duration; therefore the decrease in heart rate may also be related to the decrease in the secretion of the accelerating hormones of the heart rate during Ramadan; this mechanism remains to be verified.

Our results show a modulation of the autonomic system by the increase of the participation of the parasympathetic system (HF, HF nu, PNN50, NN50) and the decrease of the sympathetic effect (SDNN, LF, LF nu) during the month of fasting on the whole organism, and especially on the heart. The explanation of this phenomenon can be attributed to two essential factors related to the changes of life rhythm during Ramadan:

1. Sleep deprivation observed at night and,

2. The food intake.

There will consequently be a hormonal and nervous response to these two major changes that are accentuated by the psychological factor related to the specific spiritual environment, and the typical religious climate created by the holy month of the Muslims.

Conclusion

56

In this study, we have tried to answer two main objectives:

· Recognize the effect of Ramadan fasting on anaerobic sports performance through a laboratory test (the Wingate test).

· Identify the effect of Ramadan fasting on the activity of the vegetative nervous system including the activity of sympathetic and parasympathetic systems through a study of cardiac variability.

Our results showed that Ramadan fasting did not have any effects:

1. On anthropometric parameters,

2. On performances during a Wingate test,

3. On the other hand, our results revealed a modulation of the autonomous system by the increase of the participation of the parasympathetic system and the decrease of the effect of the sympathetic one.

The stability of performances during the Wingate test during and out of Ramadan concerning essentially the peak powers and the average powers can be explained by the continuity of physical activity practice during Ramadan for our subjects. The nature of the test itself and its short duration appear to be unaffected by caloric deficiency during the fasting month or by sleep / wake disruption which results in decreased performance when exercises require sensorimotor coordination or cognitive processes, which is not the case in our study (purely physical test).

Our study showed that Ramadan fasting causes a decrease in resting and exercise heart rate in response to vegetative nervous system modulation through increased parasympathetic tone and decreased sympathetic tone. This could be explained by the spiritual atmosphere created during the holy month and the abstinence from eating which decreases the basic metabolism in the absence of digestion.

Since this study is descriptive, we plan in the future to continue our experiments in order to define more specifically the precise mechanisms responsible for the modulation of the vegetative nervous system during Ramadan with the different age groups (children, old people) and the different training levels (high level, sedentary).

57

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Abstract

Background

The evaluation of the autonomic nervous system through the analysis of the heart rate variability has been used by a lot of research teams during these last two decades but the effects of Ramadan have always been a matter of controversy, especially, on children and adolescents. And since there were no anterior studies on this specific subject, our protocol tried to establish a connection between RF and the autonomic nervous system.

Aim

Recognize the effects of Ramadan on BMI, on anaerobic sports performance through a laboratory test (the Wingate test) and on the activity of the autonomic nervous system through the analysis of heart rate variability.

Methods

Nine male athletes playing football for at least five years in a professional league club, aged 16.2 #177; 0.5 years, weighing 66 #177; 6 kg and a size of 176 #177; 5 cm, participated in our study. This study took place during the summer of 2011 during the month of Ramadan where the duration of the fast varies between 14h30 and 15h. The measurements were done between 3:00 PM and 5:00 PM. On all sessions these parameters were measured/calculated: Height (cm), Weight (kg), BMI (Kg/m²), Performances during a Wingate test, and the HR beat to beat using a Polar S810 device. The HRV was measured during three maneuvers: supine position, standing position and during the effort. To analyze the results we transferred the data on computer and we used the software (The Biomedical Signal Analysis Group, Applied Physics Department, University of Kuopio, Finland) to process them.

Results

Neither the BMI nor the performances during Wingate test were influenced by RF. The parameter that was significantly lowered during RF was the HR at rest and during the effort. In addition, our results showed a modulation of the vegetative nervous system which leans towards the parasymapatic tone.

Conclusion:

RF did not bring any significant changes on the anthropometric parameters and the anaerobic performances of our subjects but influence the sympathetico-vagal balance.

Keywords

Ramadan fasting - Wingate Test - Autonomic Nervous System - Heart Rate Variability