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.