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Effects of Ramadan intermittent fastingon postural control in judo athletesNefaa Souissi a , Hamdi Chtourou a , Amira Zouita b , CatherineDziri b & Nizar Souissi a ca Research Laboratory “Sports performance Optimization”,National Center of Medicine and Science in Sports (CNMSS), Tunis,Tunisiab Service de Médecine Physique-Réadaptation Fonctionnelle,Institut Kassab d'Orthopédie, La Manouba, Tunisiec Institut Supérieur de Sport et de l'Education Physique, Ksar Said,Tunisie

Available online: 24 Feb 2012

To cite this article: Nefaa Souissi, Hamdi Chtourou, Amira Zouita, Catherine Dziri & Nizar Souissi(2012): Effects of Ramadan intermittent fasting on postural control in judo athletes, BiologicalRhythm Research, DOI:10.1080/09291016.2012.667980

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Effects of Ramadan intermittent fasting on postural control in judo

athletes

Nefaa Souissia, Hamdi Chtouroua, Amira Zouitab, Catherine Dzirib andNizar Souissia,c*

aResearch Laboratory ‘‘Sports performance Optimization’’, National Center of Medicine andScience in Sports (CNMSS), Tunis, Tunisia; bService de Medecine Physique-ReadaptationFonctionnelle, Institut Kassab d’Orthopedie, La Manouba, Tunisie; cInstitut Superieur de Sportet de l’Education Physique, Ksar Said, Tunisie

(Received 5 January 2012; final version received 8 February 2012)

The present study was designed to evaluate Ramadan intermittent fasting (RIF)effects on postural control in judo athletes. In a counterbalanced order, 11 malejudokas (22.5+ 2.8 yrs, 173.8+ 6.9 cm and 70.3+ 4.4 kg; mean+ standarddeviation) were asked to perform three protocols of postural control one weekbefore and during the second week of RIF. The sway velocity was measuredduring the unipodal (on the right and left foot) and the bipodal (on a firm and anunstable surface) stance with the eyes opened and then with the eyes closed. Inaddition, the percentage of body weight borne during the weight-bearing squattest by each leg was measured with the judoka standing at 08 (erect position), 308,608 and 908 of knee flexion. The results of the present study showed that the swayvelocity during bipodal and unipodal stance and the percentages of the bodyweight were significantly lower during RIF in comparison with that before RIF(p5 0.05). In conclusion, RIF may negatively affect the postural control of judoathletes, which might affect their performances during competitions scheduled inthis month. In fact, equilibrium was worthy during RIF in comparison with thatbefore RIF.

Keywords: equilibrium; Ramadan fasting; Judo

Introduction

Ramadan intermittent fasting (RIF) is a fundamental Islamic rule that requiresMuslims to abstain from eating, drinking, smoking or having sexual relationshipduring the daytime between sunrise and sunset. These changes in eating habits andlifestyle may affect daytime activities and the performance in the mental, physicaland social domains (Waterhouse 2010).

As the month of Ramadan shifts from year to year and the training andcompetition calendar is not modified for religious observances (Chtourou et al. 2011,2012), some elite Muslims athletes have to compete during the RIF period [e.g.,based on the current schedule, the Olympic Games London in 2012 will occur duringRamadan (Chaouachi et al. 2009; Hamouda et al. 2011)]. Thus, it is important todetermine whether this religious fast has any untoward effects on performance.

*Corresponding author. Email: n_souissi@yahoo.fr

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ISSN 0929-1016 print/ISSN 1744-4179 online

� 2012 Taylor & Francis

http://dx.doi.org/10.1080/09291016.2012.667980

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By polysomnographically comparing the nocturnal sleep of Muslims betweenRIF and pre-RIF baselines, BaHammam (2005) and Roky et al. (2003) showed anincrease in the sleep latency and in the proportion of non-rapid eye movement sleep,a modification of the sleep architecture and a reduction in the total sleep time and inthe slow-wave sleep. Thus, the normal sleep-wake cycle is known to be disturbed bythe RIF due to rising earlier and/or retiring later, which can cause partial sleepdeprivation (Waterhouse 2010).

Sleep loss results in a fall in the level of performance of tasks requiringsensorimotor coordination or cognitive processes (Reilly and Waterhouse 2009;Waterhouse 2010). Such deterioration may affect the balance ability of the athlete(Bougard and Davenne 2012). In fact, balance is the process of maintaining theposition of the body’s centre of gravity (COG) vertically over the base of supportand relies on rapid, continuous feedback from visual, vestibular and somatosensorystructures and then executing smooth and coordinated neuromuscular actions(Hrysomallis 2011). In this context, Maki and Mcllory (1996) found that posturalsway increased as the attention load of the cognitive tasks given to the subjectsincreased.

Some studies have investigated the effects of sleep deprivation on posturalcontrol using centre of pressure, centre of pressure area and centre of pressurevelocity as stabilometric indexes (Uimonen et al. 1994; Gribble and Hertel 2004) andshowed that postural control efficiency decreases after one night of sleep deprivationwhile postural sways can be correlated to sleepiness (Liu et al. 2001; Fabbri et al.2006). Recently, Bougard and Davenne (2012) showed that one night of partial sleepdeprivation reduced the ability to maintain balance (i.e., during the stork stand testof the dominant leg) when tests were performed at 18:00 h.

In light of these observations, along with the fact that no previous investigationstudied the relation between RIF and postural control, the aim of the present studywas to determine the effect of RIF on postural control in young judo athletes. Injudo, to move the opponent into a posture from which it is possible to throw downhim, judoka must shift the centre of mass of the opponent, so that the verticalprojection is outside the supporting surface. The attacks of the judoka begingenerally with the action of coming to grip and displaying push–pull forces on therival to bring his opponent into an unstable equilibrium condition. Thus, the abilityto maintain equilibrium represents a significant component of success during a judomatch. It is critical, therefore, for judokas, coaches and researchers to determine therole of RIF on the postural control of judo athletes.

Materials and methods

Subjects

Eleven judokas (22.5+ 2.8 yrs, 173.8+ 6.9 cm and 70.3+ 4.4 kg) volunteered totake part in this study. After receiving a thorough explanation of the possible risksand discomforts associated with the experimental procedures, they gave a writteninformed consent. The protocol was fully approved by the Clinical Research EthicsCommittee of the National Centre of Medicine and Science of Sports of Tunis andmeets the ethical standards of the Declaration of Helsinki. All the judokasparticipated in official judo competitions during that year, were trained four to fivetimes a week and were first kyu (brown belt) or first dan (black belt). According to

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their weight categories, all judokas who participated in this study compete in theunder 73 kg.

Experimental design

During the week before the experiment, all participants were fully familiarized withthe procedure and tests involved, to minimize learning effects during the experiment.Then, each subject was evaluated during two test sessions, which took place oneweek before and during the second week of RIF. Test sessions were conducted in acounterbalanced order. During each session, the judokas were asked to completethree trials on three tests with 15-s rest interval between trials. The mean of the threetrials for each test was used in the statistical analysis.

To avoid the effect of time-of-day on postural control (Gribble et al. 2007), alltests were performed in the morning between 08:00 h and 09:00 h.

Postural assessments

The measurement of postural stability was done using the NeuroCom1 Balancemaster. Three protocols were selected from a broad spectrum and each parameterwas measured as a three-trial average score.

Weight-bearing squat (WBS)

During the WBS assessment, the judoka is instructed to maintain equal weight onthe two legs while standing erect and then squatting in three positions of kneeflexion. The percentage of body weight borne by each leg (left and right body weight)is measured with the judoka standing at 08 (erect position), 308, 608 and 908 of kneeflexion.

Bipodal stance

The subjects were placed according to precise markers. They were asked to stand asstill as possible for 30 s the handing along the body. The subjects were requested tomaintain balance with the eyes opened (EO) and then with the eyes closed (EC) in afirm and an unstable surface. During the EO condition, subjects were instructed tofocus their vision on a fixed-level target. In the EC condition, they were asked tokeep their gaze straight ahead. The test lasted 30 s. The bipodal stance quantifiespostural sway velocity while the judokas stands calmly on two foot on the forceplate.

Unipodal stance

The subjects were placed according to precise markers. They were asked to stand asstill as possible for 30 s the handing along the body. The subjects were requested tomaintain balance with the EO and then with the EC on the firm surface. During theEO condition, subjects were instructed to focus their vision on a fixed-level target. Inthe EC condition, they were asked to keep their gaze straight ahead. The test lasted30 s. The unipodal stance quantifies postural sway velocity of the COG with thejudoka standing on either the right or left foot on the force plate.

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Statistical analyses

All statistical tests were processed using STATISTICA Software (StatSoft, France).Mean, standard deviation and standard error (SE) were calculated for the selectedvariables. The Shapiro-Wilk W-test of normality revealed that the data werenormally distributed. Once the assumption of normality was confirmed, parametrictests were performed. The paired Student t-test was used to determine differencesbetween before and during RIF. A probability level of 0.05 was selected as thecriterion for statistical significance.

Results

Bipodal and unipodal stance

Data of the sway velocity obtained at the two times of testing (i.e., before and duringRIF) during bipedal stance in a firm and an unstable surface and during unipedalstance on the right and the left foot with the EO and the EC are shown in Figures 1–4, respectively.

Figure 1. The effect of RIF on sway velocity during bipedal stance in a firm surface with theEO and the EC (mean+SE; n¼ 11). *: significant difference between before and during RIF atthe level of p5 0.05.

Figure 2. The effect of RIF on sway velocity during bipedal stance in an unstable surfacewith the EO and the EC (mean+SE; n¼ 11). *: significant difference between before andduring RIF at the level of p5 0.05.

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Statistical analysis showed that the sway velocities during bipedal stance in a firmand an unstable surface with the EO and the EC are significantly lower during RIFin comparison with that before RIF (p5 0.05). Likewise, sway velocities duringunipedal stance on the right and left foot with the EO and the EC are significantlyaffected by RIF (p5 0.05).

Weight-bearing squat (WBS)

Data of the body weight born during 08, 308, 608 and 908 before and during RIF areshown in Figures 5(A)–(D), respectively. Statistical analysis showed that the bodyweight born are significantly higher during RIF in comparison with that before RIF(p5 0.05) for both the right and left foot.

Discussion

The aim of the present study was to evaluate the influences of RIF on posturalcontrol using static balance tests in judo athletes. The results show that RIF seems toinfluence measures of postural control of judokas.

Figure 4. The effect of RIF on sway velocity during unipedal stance on the left foot with theEO and the EC (mean+SE; n¼ 11). *: significant difference between before and during RIF atthe level of p5 0.05.

Figure 3. The effect of RIF on sway velocity during unipedal stance on the right foot withthe EO and the EC (mean+SE; n¼ 11). *, **: significant difference between before and duringRIF at the levels of p5 0.05 and p5 0.01, respectively.

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To our knowledge, the effects of RIF on postural control during both static anddynamic tests have not been investigated. It is, therefore, difficult to compare thepresent results referring to the literature. In addition, the mechanism responsible forsuch an effect is difficult to understand at present. However, it seems possible topropose some hypotheses. As Muslims rose earlier and/or retire later during RIF, thenormal sleep–wake cycle is disturbed (Souissi et al. 2007). This can cause a partialsleep deprivation (Roky et al. 2003; BaHammam 2005; Waterhouse 2010). Otherstudies focused on the efficiency of postural control during sustained waking for upto 36 h. It has been suggested that sleep deprivation could negatively affect physicalperformances (Souissi et al. 2003, 2008) and the postural control (Gomez et al. 2008).To date, the results of the scientific literature concerning the effect of sleepdeprivation on balance abilities recorded in the morning (between 08:00 and 09:00h), as in the present study, are controversial. In fact, although some studieshighlighted a deleterious effect (Avni et al. 2006; Patel et al. 2008), others found noeffect (Uimonen et al. 1994; Gribble and Hertel 2004; Patel et al. 2008; Bougard andDavenne 2012; Bougard et al. 2011) or observed a decrease in postural efficiency onlyunder particularly demanding conditions (Bougard and Davenne 2012; Bougardet al. 2011).

Various assumptions have been made to explain sleep deprivation effects onpostural control. In this context, previous studies suggested that the increase inpostural sway following sleep deprivation is due to a decrease in the vestibularsystem efficiency (Avni et al. 2006; Morad et al. 2007) and/or due to the integrationof the various sensory inputs (Teasdale and Simoneau 2001). In fact, maintaining astable base of support during a balance control task requires the integration of

Figure 5. The effect of RIF on body weight borne at 08 (A), 308 (B), 608 (C) and 908 (D) onthe right and the left foot (mean+SE; n¼ 11). *: significant difference between before andduring RIF at the level of p5 0.05.

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sensory input to create the appropriate motor responses needed to make limb andtrunk corrections (Gribble et al. 2007).

It has been shown that psychomotor performances, such as critical flicker fusion(Ali and Amir 1989), subjective alertness (Lagarde et al. 1996) and memory (Hakkouet al. 1994) were affected during Ramadan fasting. These RIF-related changes might,in part, explain the findings of the present study. In fact, the tasks of minimizingone’s base of support require a heightened level of attention (Gribble et al. 2007).Recent study by Dolu et al. (2007) showed that attention levels decreased duringRIF. In this context, previous studies showed that alertness is impaired by caloricrestriction or by sleep length limitation (Dinges et al. 1997). Since there is a diurnalvariation in alertness as measured by subjective rating scale (Monk 1994), immediatememory (Folkard and Monk 1980), logical reasoning test (Folkard et al. 1983) andmanual dexterity test (Monk 1994), the decrease in alertness in the morning duringRIF could be related to two factors: (i) the delay in rising time (i.e., sleepiness,especially in the morning) and (ii) the abstinence of breakfast with its usual coffeedrink content (Roky et al. 2000, 2003).

In conclusion, the present study suggested that RIF may negatively affect thepostural control of judo athletes. In fact, static equilibrium was worthy during RIFin comparison with that before RIF. This effect might, in part, result in a markedlypoor performance of judoka during competitions scheduled in RIF. This is animportant point for coaches who plan training programs, and it may benefit athletesbecause it implies that all training sessions must be programmed throughout the daytaking into consideration the effect of RIF on judoka’s postural control.

Acknowledgment

The authors thank all subjects for their voluntary participation in this study.

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