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Effects of Ramadan intermittent fasting on postural control in judo athletes a

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Nefaa Souissi , Hamdi Chtourou , Amira Zouita , Catherine b

Dziri & Nizar Souissi

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Research Laboratory “Sports performance Optimization”, National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia b

Service de Médecine Physique-Réadaptation Fonctionnelle, Institut Kassab d'Orthopédie, La Manouba, Tunisie c

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, Biological Rhythm Research, DOI:10.1080/09291016.2012.667980 To link to this article: http://dx.doi.org/10.1080/09291016.2012.667980

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Biological Rhythm Research 2012, 1–8, iFirst article

Effects of Ramadan intermittent fasting on postural control in judo athletes Nefaa Souissia, Hamdi Chtouroua, Amira Zouitab, Catherine Dzirib and Nizar Souissia,c*

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a Research Laboratory ‘‘Sports performance Optimization’’, National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia; bService de Me´decine Physique-Re´adaptation Fonctionnelle, Institut Kassab d’Orthope´die, La Manouba, Tunisie; cInstitut Supe´rieur de Sport et 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 male judokas (22.5 + 2.8 yrs, 173.8 + 6.9 cm and 70.3 + 4.4 kg; mean + standard deviation) were asked to perform three protocols of postural control one week before and during the second week of RIF. The sway velocity was measured during the unipodal (on the right and left foot) and the bipodal (on a firm and an unstable surface) stance with the eyes opened and then with the eyes closed. In addition, the percentage of body weight borne during the weight-bearing squat test 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 sway velocity during bipodal and unipodal stance and the percentages of the body weight were significantly lower during RIF in comparison with that before RIF (p 5 0.05). In conclusion, RIF may negatively affect the postural control of judo athletes, which might affect their performances during competitions scheduled in this month. In fact, equilibrium was worthy during RIF in comparison with that before RIF. Keywords: equilibrium; Ramadan fasting; Judo

Introduction Ramadan intermittent fasting (RIF) is a fundamental Islamic rule that requires Muslims to abstain from eating, drinking, smoking or having sexual relationship during the daytime between sunrise and sunset. These changes in eating habits and lifestyle may affect daytime activities and the performance in the mental, physical and social domains (Waterhouse 2010). As the month of Ramadan shifts from year to year and the training and competition 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 during Ramadan (Chaouachi et al. 2009; Hamouda et al. 2011)]. Thus, it is important to determine whether this religious fast has any untoward effects on performance. *Corresponding author. Email: [email protected] ISSN 0929-1016 print/ISSN 1744-4179 online Ó 2012 Taylor & Francis http://dx.doi.org/10.1080/09291016.2012.667980 http://www.tandfonline.com

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By polysomnographically comparing the nocturnal sleep of Muslims between RIF and pre-RIF baselines, BaHammam (2005) and Roky et al. (2003) showed an increase 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 in the slow-wave sleep. Thus, the normal sleep-wake cycle is known to be disturbed by the RIF due to rising earlier and/or retiring later, which can cause partial sleep deprivation (Waterhouse 2010). Sleep loss results in a fall in the level of performance of tasks requiring sensorimotor 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 the position of the body’s centre of gravity (COG) vertically over the base of support and relies on rapid, continuous feedback from visual, vestibular and somatosensory structures and then executing smooth and coordinated neuromuscular actions (Hrysomallis 2011). In this context, Maki and Mcllory (1996) found that postural sway increased as the attention load of the cognitive tasks given to the subjects increased. Some studies have investigated the effects of sleep deprivation on postural control using centre of pressure, centre of pressure area and centre of pressure velocity as stabilometric indexes (Uimonen et al. 1994; Gribble and Hertel 2004) and showed that postural control efficiency decreases after one night of sleep deprivation while 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 sleep deprivation reduced the ability to maintain balance (i.e., during the stork stand test of the dominant leg) when tests were performed at 18:00 h. In light of these observations, along with the fact that no previous investigation studied the relation between RIF and postural control, the aim of the present study was to determine the effect of RIF on postural control in young judo athletes. In judo, to move the opponent into a posture from which it is possible to throw down him, judoka must shift the centre of mass of the opponent, so that the vertical projection is outside the supporting surface. The attacks of the judoka begin generally with the action of coming to grip and displaying push–pull forces on the rival to bring his opponent into an unstable equilibrium condition. Thus, the ability to maintain equilibrium represents a significant component of success during a judo match. It is critical, therefore, for judokas, coaches and researchers to determine the role 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 to take part in this study. After receiving a thorough explanation of the possible risks and discomforts associated with the experimental procedures, they gave a written informed consent. The protocol was fully approved by the Clinical Research Ethics Committee of the National Centre of Medicine and Science of Sports of Tunis and meets the ethical standards of the Declaration of Helsinki. All the judokas participated in official judo competitions during that year, were trained four to five times 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 the under 73 kg.

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Experimental design During the week before the experiment, all participants were fully familiarized with the procedure and tests involved, to minimize learning effects during the experiment. Then, each subject was evaluated during two test sessions, which took place one week before and during the second week of RIF. Test sessions were conducted in a counterbalanced order. During each session, the judokas were asked to complete three trials on three tests with 15-s rest interval between trials. The mean of the three trials for each test was used in the statistical analysis. To avoid the effect of time-of-day on postural control (Gribble et al. 2007), all tests 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 Balance master. Three protocols were selected from a broad spectrum and each parameter was measured as a three-trial average score. Weight-bearing squat (WBS) During the WBS assessment, the judoka is instructed to maintain equal weight on the two legs while standing erect and then squatting in three positions of knee flexion. 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 knee flexion. Bipodal stance The subjects were placed according to precise markers. They were asked to stand as still as possible for 30 s the handing along the body. The subjects were requested to maintain balance with the eyes opened (EO) and then with the eyes closed (EC) in a firm and an unstable surface. During the EO condition, subjects were instructed to focus their vision on a fixed-level target. In the EC condition, they were asked to keep their gaze straight ahead. The test lasted 30 s. The bipodal stance quantifies postural sway velocity while the judokas stands calmly on two foot on the force plate. Unipodal stance The subjects were placed according to precise markers. They were asked to stand as still as possible for 30 s the handing along the body. The subjects were requested to maintain balance with the EO and then with the EC on the firm surface. During the EO condition, subjects were instructed to focus their vision on a fixed-level target. In the EC condition, they were asked to keep their gaze straight ahead. The test lasted 30 s. The unipodal stance quantifies postural sway velocity of the COG with the judoka 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 selected variables. The Shapiro-Wilk W-test of normality revealed that the data were normally distributed. Once the assumption of normality was confirmed, parametric tests were performed. The paired Student t-test was used to determine differences between before and during RIF. A probability level of 0.05 was selected as the criterion for statistical significance.

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Results Bipodal and unipodal stance Data of the sway velocity obtained at the two times of testing (i.e., before and during RIF) during bipedal stance in a firm and an unstable surface and during unipedal stance 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 the EO and the EC (mean+SE; n ¼ 11). *: significant difference between before and during RIF at the level of p 5 0.05.

Figure 2. The effect of RIF on sway velocity during bipedal stance in an unstable surface with the EO and the EC (mean+SE; n ¼ 11). *: significant difference between before and during RIF at the level of p 5 0.05.

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Figure 3. The effect of RIF on sway velocity during unipedal stance on the right foot with the EO and the EC (mean+SE; n ¼ 11). *, **: significant difference between before and during RIF at the levels of p 5 0.05 and p 5 0.01, respectively.

Figure 4. The effect of RIF on sway velocity during unipedal stance on the left foot with the EO and the EC (mean+SE; n ¼ 11). *: significant difference between before and during RIF at the level of p 5 0.05.

Statistical analysis showed that the sway velocities during bipedal stance in a firm and an unstable surface with the EO and the EC are significantly lower during RIF in comparison with that before RIF (p 5 0.05). Likewise, sway velocities during unipedal stance on the right and left foot with the EO and the EC are significantly affected by RIF (p 5 0.05). Weight-bearing squat (WBS) Data of the body weight born during 08, 308, 608 and 908 before and during RIF are shown in Figures 5(A)–(D), respectively. Statistical analysis showed that the body weight born are significantly higher during RIF in comparison with that before RIF (p 5 0.05) for both the right and left foot. Discussion The aim of the present study was to evaluate the influences of RIF on postural control using static balance tests in judo athletes. The results show that RIF seems to influence measures of postural control of judokas.

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Figure 5. The effect of RIF on body weight borne at 08 (A), 308 (B), 608 (C) and 908 (D) on the right and the left foot (mean+SE; n ¼ 11). *: significant difference between before and during RIF at the level of p 5 0.05.

To our knowledge, the effects of RIF on postural control during both static and dynamic tests have not been investigated. It is, therefore, difficult to compare the present results referring to the literature. In addition, the mechanism responsible for such an effect is difficult to understand at present. However, it seems possible to propose some hypotheses. As Muslims rose earlier and/or retire later during RIF, the normal sleep–wake cycle is disturbed (Souissi et al. 2007). This can cause a partial sleep deprivation (Roky et al. 2003; BaHammam 2005; Waterhouse 2010). Other studies focused on the efficiency of postural control during sustained waking for up to 36 h. It has been suggested that sleep deprivation could negatively affect physical performances (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 sleep deprivation on balance abilities recorded in the morning (between 08:00 and 09:00 h), as in the present study, are controversial. In fact, although some studies highlighted a deleterious effect (Avni et al. 2006; Patel et al. 2008), others found no effect (Uimonen et al. 1994; Gribble and Hertel 2004; Patel et al. 2008; Bougard and Davenne 2012; Bougard et al. 2011) or observed a decrease in postural efficiency only under particularly demanding conditions (Bougard and Davenne 2012; Bougard et al. 2011). Various assumptions have been made to explain sleep deprivation effects on postural control. In this context, previous studies suggested that the increase in postural sway following sleep deprivation is due to a decrease in the vestibular system efficiency (Avni et al. 2006; Morad et al. 2007) and/or due to the integration of the various sensory inputs (Teasdale and Simoneau 2001). In fact, maintaining a stable base of support during a balance control task requires the integration of

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sensory input to create the appropriate motor responses needed to make limb and trunk 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 (Hakkou et 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 minimizing one’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 during RIF. In this context, previous studies showed that alertness is impaired by caloric restriction or by sleep length limitation (Dinges et al. 1997). Since there is a diurnal variation in alertness as measured by subjective rating scale (Monk 1994), immediate memory (Folkard and Monk 1980), logical reasoning test (Folkard et al. 1983) and manual dexterity test (Monk 1994), the decrease in alertness in the morning during RIF 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 coffee drink content (Roky et al. 2000, 2003). In conclusion, the present study suggested that RIF may negatively affect the postural control of judo athletes. In fact, static equilibrium was worthy during RIF in comparison with that before RIF. This effect might, in part, result in a markedly poor performance of judoka during competitions scheduled in RIF. This is an important point for coaches who plan training programs, and it may benefit athletes because it implies that all training sessions must be programmed throughout the day taking 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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