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Effects of Ramadan fasting on match-related changes in skill performance in elite Muslim badminton players
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ORIGINAL ARTICLE
Effects of Ramadan fasting on match-related changes in skill performance in elite Muslim badminton players Effets du jeûne du Ramadan sur les changements techniques de performance lors de matchs exécutés par des joueurs de badminton élites A.R. Aziz a,b,∗, D.S.L. Lim a, S. Sahrom a,c, A.M. Che Muhamed d, M. Ihsan a,e, O. Girard f, M.Y.H. Chia b a
Sport Science and Sport Medicine, Singapore Sport Institute, Sport Singapore, Singapore Physical Education and Sports Science Academic Group, National Institute of Education, Nanyang Technological University, Singapore c Centre for Exercise and Sports Science research, School of Medical and Health science, Edith Cowan University, Perth, Australia d Advanced Medical and Dental institute, Universiti Sains Malaysia, Penang, Malaysia e Research and Scientific Support, Aspetar-Qatar orthopaedic and Sports Medicine Hospital, Doha, Qatar f Murdoch Applied Sports Science Laboratory, Murdoch University, Perth, Australia b
Received 31 July 2018; accepted 11 July 2019
KEYWORDS Religious fasting; Stroke effectiveness; Skill performance; Fatigue
∗
Summary We examined the extent to which Ramadan fasting affects badminton skill performance under simulated (i.e., competitive) match play conditions. Ten male Muslim national-level badminton players performed a 40-minute (2 sets × 20 minutes per set in each match) badminton single-matches in a non-fasted (CON) and in Ramadan-fasted (RAM) state on separate occasions. Skills assessment involved performing eight low-serves and eight overhead smashes at baseline, at the end of set 1 and set 2 (mid- and end-match, respectively). Players’ pre-match diet was standardised between conditions and consumed either at ∼12:00 or at ∼05:00 for CON and RAM, respectively. There were no differences in the accuracy, consistency and speed of the low-serve between CON and RAM at the three match play time-points (all P > 0.05). Likewise, accuracy and consistency of the overhead smash were not affected by RAM (P > 0.05), but overhead smash velocity was slower in RAM than CON at the mid- (−7.3 ± 7.1%; P = 0.016) and end-match (−5.3 ± 4.4%; P = 0.007). Blood glucose, blood lactate, heart rate and ratings of perceived exertion were similar throughout the match play protocol (all P > 0.05).
Corresponding author at: Sports science and medicine, Singapore Sport Institute, Sport Singapore, 3, Stadium Drive, 397630, Singapore. E-mail address: abdul rashid [email protected] (A.R. Aziz).
https://doi.org/10.1016/j.scispo.2019.07.014 0765-1597/© 2019 Elsevier Masson SAS. All rights reserved.
Please cite this article in press as: Aziz AR, et al. Effects of Ramadan fasting on match-related changes in skill performance in elite Muslim badminton players. Sci sports (2019), https://doi.org/10.1016/j.scispo.2019.07.014
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A.R. Aziz et al. No differences were observed between conditions in players’ overnight sleep, daytime nap duration and level of daytime sleepiness (all P > 0.05), whereas pre-match perceived tiredness and fatigue ratings were higher in RAM (both P < 0.01). In conclusion, although Ramadan fasting resulted in increased sensations of fatigue and tiredness during match play, skill performances were however largely maintained, with the only observed decrement being a decrease in overhead smash velocity. © 2019 Elsevier Masson SAS. All rights reserved.
MOTS CLÉS Jeûne religieux ; Efficacité de l’AVC ; Performance d’habileté ; Fatigue
Résumé Cette étude examinait dans quelle mesure le jeûne du Ramadan affecte l’exécution technique d’habiletés spécifiques au badminton dans des conditions de jeu simulées proches de la compétition. Dix joueurs de badminton masculins et Musulmans de niveau national ont réalisé, lors de jours séparés, un match en simple de 40 minutes (2 sets × 20 minutes par set pour chaque match) soit dans un état de non jeûne (CON) ou lors du jeûne du Ramadan (RAM). L’évaluation des compétences impliquait l’exécution de huit services courts et de huit smashs, ceci avant et à la fin du premier et du second set (milieu et fin du match, respectivement). Des repas standards étaient pris à ∼12h00 pour la condition CON et à ∼5h00 du matin pour la condition RAM. Il n’y avait aucune différence en terme de précision, consistence et vitesse du volant lors du service avec des valeurs similaires entre les deux conditions et pour chacun des trois points de mesure lors du match (p > 0,05). De même, la condition RAM n’était pas associée à une modification de la précision ou de la cohérence du service (p > 0,05), alors que la vitesse du smash était plus lente pour la condition RAM comparativement à CON, ceci aussi bien au milieu (−7,3 ± 7,1 %, p = 0,016) qu’à la fin (−5,3 ± 4,4 %, p = 0,007) du match. Le taux de glucose dans le sang, la lactatémie sanguine, la fréquence cardiaque et la perception de l’effort étaient similaires tout au long du match (p > 0,05). Aucune différence existait entre les conditions concernant le sommeil la nuit, la durée de la sieste en journée et l’état de somnolence (p > 0,05). En revanche, que les sensations de fatigue avant et pendant le match étaient plus élevées pour la condition RAM (p < 0,01). En conclusion, bien que le jeûne du Ramadan entraine un majoration des sensations de fatigue avant et pendant le match, la qualité d’exécution technique n’était pas altérée puisque la seule modification observée était une diminution de la vitesse du smash. © 2019 Elsevier Masson SAS. Tous droits r´ eserv´ es.
1. Introduction Badminton is regarded as the fastest racquet game in the world. It is characterised by repeated directional change involving sharp accelerations, decelerations, jumps, leaps, lunges, as well as requires considerable upper body power and endurance [1]. While skill execution and tactical awareness are crucial aspects for success in this sport, it has been suggested that sub-optimal levels of physical fitness will likely precipitate fatigue, and result in reduced stroke accuracy, velocity and weak positional play [1,2]. The Ramadan fast is an annual religious obligation that requires Muslims of pubertal age to abstain from the ingesting food and fluid daily for over 29 or 30 days [3]. Fasting is undertaken from dawn to dusk, and as such, the daily fasting duration is dependant on both the geographical location as well as the climatic season in which the month of Ramadan falls [3]. Muslims typically consume their main meals at two sittings daily; before the commencement of the day’s fast (just prior to the breaking of dawn i.e., termed as the sahur meal, and following the adherence of the day’s fast, i.e., iftar meal) [3]. Such prolonged nutritional restrictions would likely result in dehydration [4] and reduced blood glucose
levels [5], which in turn could potentially hinder physical, as well as cognitive performances [6]. Further, the drastic and sustained shift in eating habits to primarily the nocturnal period may result in poor sleep (in both pattern and duration) [6]. This, in turn, can severely alter the fasted individual’s circadian rhythm leading to increased mood disturbances and lethargy, as well as decreased vigilance and concentration [7]. These effects are likely to negatively affect physical performance and may, perhaps, be more pronounced when athletes undertake physical activities between sunrise and sunset [3,7]. While there is considerable research detailing the effects of Ramadan fasting on exercise performance [7], only a few studies have focussed on skill execution, with considerable discrepant findings [8—10]. For instance, fasting during Ramadan has been shown to decrease ball-dribbling time by 9.4% in professional footballers [8] and the number of throws by 20% during a specific judo test amongst elite judokas [8]. On the other hand, Ramadan fasting has been shown to not influence ball-dribbling and passing skills in young, welltrained football players [10]. It should be noted that in these studies, skills assessment was undertaken in the absence of physical fatigue, which to some extent limits the ecological
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Effects of Ramadan fasting on match-related changes in badminton players validity and practical importance of these findings. Indeed, moderate to high levels of physical fatigue has been shown to impair passing skills amongst well-trained football players [11,12]. Within badminton, maintaining a high level of technique or skills execution after intense rallies and/or in the latter stages of a match (i.e., when athletes are considerably fatigued) is vital to securing a positive outcome. During Ramadan, exercising and fasting athletes would possibly encounter considerable levels of physical fatigue and loss of vigilance due to the lack of food, fluid and sleep, which may amplify the loss in skill performance when combined with the normal prevailing levels of fatigue typically encountered in match play [3,7]. Given the considerable number of Muslim badminton players engaged in the badminton world circuit, it is imperative that there is a greater understanding of how badminton skills performance is influenced by Ramadan fasting when fatigued. As such, the purpose of this study was to examine the effects of Ramadan fasting on the time course of changes in badminton-specific skills (i.e., low-serve and overhead smash) in response to simulated match play badminton in elite male Muslim players. It was hypothesised that Ramadan-fasted state would lead to further decline in performance of the two motor skills compared to playing in the non-fasted state as fatigue develops.
2. Methods 2.1. Participants Ten highly trained male Muslim badminton players participated in this study (mean ± SD; age 22.8 ± 3.4 y, stature 1.71 ± 0.3 m, body mass 67.1 ± 5.5 kg; maximal aerobic power or VO2max [estimated from performance in the 20 m Multistage Shuttle Run or Beep test] [2] 56.6 ± 3.8 mL·kg−1 ·min−1 ; maximal heart rate or HRmax 189.4 ± 10.3 b·min−1 ). All players were event-specialist in either singles or doubles from the Singapore national squad and have had participated in various international tournaments for a period of 6.4 ± 3.2 y. At the time when this study was conducted, two of the players were in the top 20; another two in the top 50 and the rest were in the top 200 of the Badminton World Federation (BWF) ranking. The players were accustomed to Ramadan fasting, and have been performing this annual religious obligation for at least eight years prior to this study. Players resided in a boarding school throughout the study, equipped with full training and accommodation facilities, as well as food catering services. During this period, the players were training eight to ten sessions per week for a total of 20—25 hours. This included six to eight 2—3 hour sessions of skills, technical, tactical and simulation match play, and two to three 1.5-hour sessions of physical conditioning of either resistance and/or aerobictype of training. Training activities in the 24 hours prior to the experimental trials were reduced and standardised to moderate for fatigue during the experimental sessions. Players provided written informed consent and the study was approved by the Institutional Human Research Ethics Committee (IRB 12-04/02). The study’s procedures were conducted according to ethical standards of the Helsinki Declaration. Daily fasting were from ∼05:35 to ∼19:20,
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resulting in a typical fasting duration of approximately 14 hours.
2.2. Experimental design and procedures Each athlete performed two separated sessions of badminton match play undertaken in either a Ramadan-fasted (RAM) or non-fasted (CON) state. The CON trials were conducted within the week prior to the start of Ramadan, while the RAM trials were conducted two weeks after the commencement of Ramadan. The RAM trials were conducted two weeks into Ramadan to allow the athletes to better adjust to the change in lifestyle [13]. All trials commenced at approximately 18:00, where players reported 30 minutes before the commencement of the exercise trial. Upon arrival players completed several questionnaires documenting their sleep times, mood state and readiness to compete (details below). Afterwards, players provided a urine sample for the assessment of urine specific gravity (USG; PR series, Atago, Tokyo, Japan), and were subsequently weighed (wearing only shorts) to determine pre-match body mass (Spider 2-150-P, Mettler Toledo, Albstadt, Germany). After the weigh-in, players’ capillary blood samples were taken to determine resting blood glucose (Advantage, Roche Diagnostics Corp., IN, USA) and blood lactate concentrations (Accutrend, Boehringer Manneheim, Germany). Players then proceeded with a standardised warm-up consisting of 3 minutes of dynamic stretching and 5 minutes of stroke rallying. Baseline assessments of the low-serve and overhead smash were then undertaken (see below for details), before embarking on a 40-minute singles match play (2 sets × 20 minutes per set) (see Fig. 1). Capillary blood samples to determine blood glucose and lactate were taken again at the end of set 1 (mid-point of match) and set 2 (end of match), prior to the assessment the selected skills. Heart rate (HR) was recorded throughout the match via short-distance telemetry (RS400, Polar Electro Oy, Finland). Players’ ratings of perceived exertion (RPE), using Borg’s categorical scale of 1—10, was obtained at pre-match (after players have warmed-up), at the end of set 1 and at the end of set 2. Fluid (only water) was allowed ad libitium during CON matches but not for RAM matches. Body mass was retaken following the completion of the match, after players had towelled dried.
2.3. Pre-exercise questionnaires and sleep All players were residing in the dormitory setting as part of a boarding school, which was governed by a headmaster. The school had strict regulations and lights-out was typically at ∼23:30 every evening and morning breakfast was at 08:00. Moreover, the players have been undertaking a compulsory daily afternoon nap, as part of the squad’s training-recovery programme for the last two years. During Ramadan, special arrangements were made for the Muslim athletes to consume their sahur meal between 05:00—05:30 and they were then allowed to go to bed after that. Players’ sleep and wake times for the previous 24 h, as well as the duration of their daytime nap were recorded. They then rated their daytime sleepiness via the nine-point Karolinska Sleepiness Scale (KSS) [14]. Players also completed the
Please cite this article in press as: Aziz AR, et al. Effects of Ramadan fasting on match-related changes in skill performance in elite Muslim badminton players. Sci sports (2019), https://doi.org/10.1016/j.scispo.2019.07.014
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Figure 1
Schematic representation of the study protocol.
validated Brunel Mood State (BRUMS) [15] and their current levels of ‘‘readiness to train’’, ‘‘tiredness’’, ‘‘alertness’’ and ‘‘concentration’’ on a 100-mm visual analogue scale [9].
2.4. Pre-exercise dietary intake Dietary intake for last meal consumed by players prior to their match trials (i.e., lunch for CON and sahur meal for RAM) were standardized and provided for. To ensure for the ecological validity of the study’s findings under Ramadanfasted and non-fasted conditions, players consumed their sahur meal (prior to RAM match) between 05:00—05:30 and their lunch (prior to CON match) between 12:00—12:30. Meal composition was individualized for each participant: carbohydrate of 2.0 g.kg body mass−1 and 800 ml of fluid. The total caloric content of the meal was 855 ± 206 kcal.
2.5. Simulated competitive badminton singles match play Players were paired according to level of play (as advised by the squad’s coach) and competed against the same opponent in both the CON and RAM match. Match was played under the official rules of the BWF and scoring was based on rallypoints of the better of two sets. However, instead of playing to complete the 21 points in a single set, each set was played for a fixed 20-minute duration (no matter the prevailing scores) with rest period of 2 minutes between each set. The choice of 20-min per set and thus total of 40 minutes per match was based on the duration of the singles men match in the 2008 Olympics [16] and 2010 Spanish Championship [17], which lasted for 39.6 ± 6.5 and 42.7 ± 11.3 minutes respectively. For skill assessment, the player performed a total of eight low-serves and eight overhead smashes, at pre-match (or baseline), at post-set 1 (mid-match) and at post-set 2 (end-match) (see Fig. 1). Players wore the same attire (including shoes) and used their own personal rackets for all their matches. The same brand of shuttlecocks (ASA 4, Yonex, Japan) was used throughout and the shuttlecocks were replaced when necessary. All matches were played in an enclosed gymnasium where the ambient temperature was between 23—26 ◦ C and relative humidity 58—64%
(Kestrel4000 Kellerman, Boothwyn, PA, USA) throughout the study.
2.6. Assessment of the badminton low-serve and overhead smash The low-serve and the overhead smash are considered crucial in a badminton player’s repertoire of technique, and require considerable motor skill, accuracy and technical ability [17,18]. Data for all eight successful shots were averaged to represent the players’ skills performance at each time-point. The low-serve involves dispatching the shuttlecock as low as possible above the net to land onto the opposing service box area. A short perpendicular distance between the net and shuttlecock is critical, as otherwise presents an opportunity for the opposing player to attack while returning the serve. For the present study, a low-serve was considered valid when the shuttlecock cleared the net and landed within the demarcated service area, while an invalid serve was when the shuttlecock was impeded by the net. For accuracy, there were two criterion measures: i) the height distance of the shuttlecocks when it is perpendicularly above the net during the serve (i.e., a lower mean distance denotes a higher accuracy) and ii) the distance of the landed shuttlecocks to the marked target within the service area (i.e., a lower mean distance denotes higher accuracy), regardless of the direction of the landed shuttle to the marked target. For speed, shuttlecock velocity perpendicular to the net during the serve trajectory was determined. Consistency of the serve was determined by the number of error shots, that is when the shuttlecock landed outside the court playing boundary or did not clear the net (i.e., a lower number of errors denotes better consistency). For the overhead smash, the pair-matched competing players each took turns to be a feeder and smasher. The feeder delivered a high serve to the right side of the court where the smasher immediately shuffled backwards to execute a cross-court smash, directed towards a demarcated target area. The validity of the feeding serve was decided by the primary investigator who was positioned at the strategic location for observation. The serve was considered valid when the shuttlecock, if not intercepted would land within the back line of the court. If a player executed a smash,
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Effects of Ramadan fasting on match-related changes in badminton players which was from an invalid feed (i.e., the fed shuttlecock was either too close to the net or too far from the baseline of the court), data from this smash was omitted and another trial was conducted. A smash was deemed successful when the shuttlecock landed on the opposing court within the playing area. If the smash was unable to clear the net or landed beyond the playing area, it was considered as an unsuccessful or error smash. Smash accuracy was determined as the mean distance between the landed shuttlecocks to the target mark regardless of the direction of the landed shuttles to the marked target. Shuttlecock speed was determined as the mean velocity of the shuttlecocks when it was perpendicularly to the net during the smash trajectory, while consistency was determined by the number of invalid or error shots.
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CON and RAM × time: baseline, mid- and end-match). The assumption of sphericity was checked by Mauchly’s test of sphericity and where violations occurred, the GreenhouseGeisser Epsilon was applied. If a significant main effect was found, post-hoc t-test was used to detect where the differences occurred with a Bonferroni correction for multiple comparisons, P = 0.05/3 = 0.017. In addition, effect size (d) was utilised to determine the practical meaningfulness of the differences [20]. The magnitude of the effects size was classified as trivial (< 0.2), small (> 0.2—0.6), moderate (> 0.6—1.2), large (> 1.2—2.0) and very large (> 2.0—4.0) [21].
3. Results 2.7. Kinematics measures of the low-serve and overhead smash Square grids measuring 0.5 m and 0.5 m for the serve and 1.0 m by 1.0 m for the smash, were marked as target landing areas (Fig. 2). These positions on the court have been suggested to represent the optimal target areas for service and smash [19], and tested players were instructed to land the shuttlecock as close as possible to the centre of these marked areas, i.e., X1 and X2 for the low-serve and smash, respectively. Three-dimensional kinematics data of the shuttlecock were analysed using a 11-camera motion analysis system (Pro-Reflex series, Qualysis, Sweden), sampling at 240 Hz.. Cameras were calibrated using a calibration wand kit before every service/smash set. The rounded base of the shuttlecocks were pasted with retro-reflective tape to allow for the cameras to detect its position within the data capture area. Key positions on the court were also marked with spherical retro-reflective markers, i.e., the location of the low-serve target point (X1), location of the smash target point (X2) and along the top lining of the net (X3). Data of the position of the shuttlecocks were identified manually to ensure it met the criterion for each parameter (e.g., directly above the net or on the court playing area). The position data and its 1st derivative were subsequently smoothened using a 4th order Butterworth filter, and determined using the Qualysis Track Manager (Qualysis, Sweden) analysis software. Similarly, the velocity data of the shuttlecock was determined using three positional data above the net. With the known sampling interval of 4.0 ms, the speed calculation was performed by the same data acquisition software.
2.8. Statistical analyses SPSS (Chicago, IL, USA) software was used for all statistical analyses. All data were reported as mean ± SD. The level of statistical significance for primary effects was set at P < 0.05. All data was checked for normality of distribution, and if not normally distributed, the non-parametric statically analysis was used. Differences in normally distributed measures between CON and RAM matches were determined using the paired Student’s t-test. Data with continuous time component was determined using an analysis of variance (ANOVA) test with two-way repeated measures (condition:
3.1. Performance of the low-serve and overhead smash (Table 1) For the low-serve, no significant condition, time and interaction effects were evident for height distance of shuttlecock over the net, in the distance of the landed shuttles from the target point, velocity of the low-serve, and the number of errors made in the low-serve throughout the match (F ratios for all variables were P > 0.05). For the overhead smash, main effects for condition, time and interaction were not significant for distance of the shuttlecocks from the target point and for the number of errors made during the smash throughout the matches (both F ratios, P > 0.05). While there were no significant main effects of either time or interaction (both F ratios, P > 0.05), smash velocity was significantly affected by condition (F1,9 = 6.68, P = 0.03). Post-hoc analysis indicated that the velocity of smash was significantly higher for CON than RAM at the mid- (7.3 ± 7.1%; P = 0.02, d = 0.70, moderate) and end-match (5.3 ± 4.4%; P = 0.007, d = 0.53, small), but not at baseline (P = 0.86, d = 0.09, trivial).
3.2. Physiological and perceptual measures (Table 2) Players consumed an averaged volume of 125.1 ± 66.4 mL (range: 46.4—251.2 mL) of fluid during CON match. Sweat loss at the end of match play was lower in RAM compared to CON (P = 0.04) trials. Exercise HR throughout the match were not significantly different between conditions (all F ratios, P > 0.05). Blood glucose concentrations demonstrated significant main effects for condition (F1,9 = 10.52, P = 0.01), time (F2,18 = 6.38, P = 0.008) and interaction (F2,18 = 4.99, P = 0.019). Post-hoc analysis however, indicated that blood glucose was significantly higher in CON compared with RAM at baseline (P = 0.009) but not at mid- (P = 0.25) and endmatch (P = 0.66). For blood lactate concentrations, there were no significant main effects of condition and interaction (both F ratios, P > 0.05), although a significant time effect was evident (F2,18 = 143.68, P < 0.001). For the RPE, there were no significant main effects of condition (F1,9 = 0.10, P = 0.75) and interaction (F2,18 = 0.47, P = 0.63), but a significant time effect (F2,18 = 80.37, P < 0.001) was observed.
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Figure 2 Schematic illustration of the badminton half-court (court not drawn to scale) including the target area for low-serve and overhead smash. 䊉 = spherical reflective markers placed in the centre of target area (X1 for overhead smash and X2 for low-serve) and along the top linings of the net (X3).
3.3. Readiness questionnaires, sleep variables and profile of mood state (Table 3 and Fig. 3) Perceived tiredness was significantly greater in RAM compared with CON (P = 0.011; d = 1.04, large). Similarly, in the BRUMS, greater levels of subjective fatigue were reported in RAM compared with CON (P < 0.001; d = 1.86, very large). Overnight sleep duration (P = 0.49), daytime nap duration (P = 0.10) and KSS scores (P = 0.24) were similar between CON and RAM trials.
4. Discussion We examined, for the first time, the influence of Ramadan fasting on the consistency, accuracy and shuttle-velocity in executing the low-serve and overhead smash in response to a simulated, 40-minute competitive badminton game in elite Muslim players. Our results demonstrate increased sensation of perceived tiredness and fatigue, in line with decreased
smash velocity after 20 minutes of match play following Ramadan fasting. However, no accompanying decrements in smash accuracy or consistency were observed, along with no decrements in skill performance for the low-serve. Our findings indicate that key badminton skills such as the overhead smash and low-serve are largely preserved following Ramadan fasting. However, some aspects within skills that require considerable physical effort could potentially be impaired (i.e., smash velocity). Smash velocities were similar between conditions at baseline but were significantly reduced in RAM compared with CON following set 1 and 2, with no changes in shot accuracy and consistency (Table 1). This finding agrees with previous non-Ramadan fasting related studies examining the effects of fatigue on tennis forehand stroke, in which stroke velocity was particularly impaired within skills that required considerably physical effort [22,23]. A likely reasoning is that under fatigue, players might consciously or sub-consciously, reduce the speed of the smash (i.e., a lowering of physical exertion) in order to increase the accuracy
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Table 1 Performance variables in the low-serve and overhead smash during match play in the non-fasted (CON) and Ramadanfasted (RAM) conditions (n = 10). CON Low-serve Height distance of shuttle above the net (cm) Baseline End of set 1 End of set 2 Distance of shuttlecock from target (cm) Baseline End of set 1 End of set 2 Velocity of shuttle above the net (km·h−1 ) Baseline End of set 1 End of set 2 Number of errors Baseline End of set 1 End of set 2 Overhead smash Distance of shuttle from target (cm) Baseline End of set 1 End of set 2 Velocity of shuttle above the net (km·h−1 ) Baseline End of set 1 End of set 2 Number of errors Baseline End of set 1 End of set 2 a
RAM
Effect size, descriptor
11.4 ± 2.6 10.9 ± 2.1 12.0 ± 4.3
10.7 ± 2.5 11.2 ± 3.5 12.6 ± 8.4
0.27, small 1.07, large 0.09, trivial
25.4 ± 7.6 20.4 ± 2.9 21.9 ± 6.1
26.4 ± 7.9 23.6 ± 9.0 28.2 ± 13.4
0.12, trivial 0.55, small 0.65, moderate
18.1 ± 1.0 17.2 ± 1.0 17.7 ± 1.4
17.6 ± 1.2 17.6 ± 0.8 17.6 ± 1.2
0.45, small 0.44, small 0.09, trivial
0.9 ± 0.9 0.5 ± 0.7 0.6 ± 0.8
0.8 ± 0.8 0.7 ± 0.8 0.5 ± 0.7
0.12, trivial 0.27, small 0.13, trivial
157.9 ± 60.7 164.2 ± 61.1 147.7 ± 66.7
195.4 ± 70.5 156.3 ± 41.2 159.4 ± 43.9
0.57, small 0.15, trivial 0.21, small
95.6 ± 11.6 91.8 ± 8.6a 94.7 ± 9.9a
94.7 ± 9.5 85.1 ± 10.5 89.8 ± 8.7
2.3 ± 1.3 1.7 ± 1.5 1.7 ± 1.3
1.5 ± 1.7 1.7 ± 0.9 1.3 ± 1.8
0.09, trivial 0.70, moderate 0.53, small 0.53, small 0.0, trivial 0.26, small
Post-hoc significantly different between CON and RAM condition, P < 0.017.
of the shot [24] which is in line with the strategy of motor movement pattern when performing the skill in a fatigued relative to a non-fatigued state [25,26]. Although success in badminton is suggested to relate to positional play and shot accuracy, rather than absolute power [1], it would be incautious to disregard a 5—8% (with no effect on accuracy) decrease in smash velocity observed in the present study. Moreover, during major tournaments or team events, players might be required to play up to two matches a day during the qualifying stages. As such, athletes undertaking training or competing whilst fasting should incorporate some acute recovery strategies (e.g., facial fanning/cooling) [27] to mitigate subtle decrements in performance during match play. The mechanism(s) underpinning the observed decline in the smash velocity is currently not well understood. Previous studies showing a decline in kicking velocity of the ball after a fatiguing exercise protocol suggested that the negative effect was caused by muscular incapacity due to decrements in muscle strength or posture stability [28,29]. No such measures were taken in the present study to verify this possibility. Reduced blood glucose availability, dehydration and sleep disturbances have been previously reported
in response to Ramadan fasting [3—10], and may have accounted for the decline in smash performance [30—32]. However, these factors are unlikely to have had any influence on the decrease in smash velocity observed in the current study, as Ramadan fasting has had no influence on any of these parameters (Tables 2 and 3). We did observe, however, increased pre-match ratings of perceived tiredness and fatigue in the readiness questionnaires (Table 3) and BRUMS (Fig. 3), respectively. These observations could at least in part account for the decrease in smash velocity performance. Indeed, it is possible that higher levels of pre-exercise fatigue and tiredness in RAM trial might have amplified the development of physical fatigue during match play, resulting in lower smash velocities as was observed in other sports of tennis and squad [33,34]. However, this does not explain how smash velocities were similar at baseline, when there was an apparent difference in fatigue and tiredness between RAM and CON. The authors postulate that skill performances may be more influenced by sensations of fatigue and tiredness in an exercised, compared with a non-exercised state (i.e., baseline). In contrast to the overhead smash, all aspects (i.e., consistency, accuracy and velocity of shuttlecock) of the
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A.R. Aziz et al. Other physiological and perceptual variables assessed in the non-fasted (CON) and Ramadan-fasted (RAM) conditions CON
Body mass (kg) Pre-match Post-match Urine specific gravity (au) Sweat lost (% of pre-match body mass) Blood glucose concentration (mmol·l−1 ) Pre-match End of set 1 End of set 2 Blood lactate concentration (mmol·l−1 ) Pre-match End of set 1 End of set 2 Mean heart rate (b·min−1 ) Pre-match During set 1 During set 2 Ratings of perceived exertion (au) Pre-match End of set 1 End of set 2
67.08 66.28 1.014 1.4
RAM ± ± ± ±
5.50 5.12 0.004a 0.4a
66.18 65.49 1.021 1.1
Effect size, descriptor ± ± ± ±
5.74 5.17 0.005 0.2
0.16, trivial 0.15, trivial 1.56, large 1.0, large
5.1 ± 0.5b 5.1 ± 0.4 4.9 ± 0.3
4.5 ± 0.3 5.0 ± 0.3 5.0 ± 0.3
1.5, large 0.29, small 0.33, small
1.1 ± 0.3 3.4 ± 0.3 4.7 ± 1.0
0.9 ± 0.1 3.3 ± 0.6 4.3 ± 0.7
1.0, large 0.05, trivial 0.47, small
111 ± 8 141 ± 14 146 ± 14
109 ± 9 142 ± 13 148 ± 17
0.24, trivial 0.07, trivial 0.13, trivial
7.7 ± 1.0 12.1 ± 1.7 13.3 ± 1.8
7.6 ± 1.0 11.9 ± 2.0 14.0 ± 1.6
0.10, trivial 0.11, trivial 0.41, small
No fluid was consumed during match play in the RAM trial. au: arbitrary unit. a P < 0.05 between CON and RAM condition; Post-hoc significant difference between CON and RAM condition. b Post-hoc significant difference between CON and RAM condition, P < 0.017.
Table 3 Players’ subjective responses to the pre-exercise questionnaires and sleep variables in the non-fasted (CON) and Ramadan-fasted (RAM) conditions (n = 10). CON Pre-exercise questionnaires Perceived level of readiness to compete (mm)a Perceived level of tiredness (mm)a Perceived level of alertness (mm)b Perceived level of concentration (mm)b Sleep variables Sleep duration (h) Daytime nap duration (min) Karolinska Sleepiness Scale (au)
33 21 77 82
RAM ± ± ± ±
25 15c 20 15
7.5 ± 1.0 142.5 ± 23.5 4.2 ± 1.8
35 43 79 80
Effect size, descriptor ± ± ± ±
23 27 16 15
7.1 ± 2.3 119.5 ± 30.2 4.8 ± 2.9
0.08, 1.05, 0.11, 0.13,
trivial large trivial trivial
0.24, small 0.86, moderate 0.26, small
au: arbitrary unit. a Low scores indicate more able to compete and lower level of tiredness. b Low scores indicate higher level of alertness and concentration. c P < 0.01 between CON and RAM condition.
low-serve performance were well maintained in RAM compared to CON (Table 1). It is possible that Ramadan fasting may influence the ‘physical’ component to a greater extent, compared with the ‘technical’ aspect of the performed skill. This reasoning is somewhat supported by a recent study, where decrements in total running distance and frequency of accelerations during a football match were evident only in the high but not within the low intensity zones following Ramadan fasting [35]. Collectively, the present findings seem to indicate that the effect of Ramadan fasting on skill
performance may depend on the physical demand involved; the greater the effort required, the more likely that the execution of the skill might be impaired by Ramadan fasting, albeit further research is required to confirm this assertion. In the present study, the authors have carefully controlled a number of variables to isolate the physiological changes inherent in Ramadan that might influence skill execution during badminton match play. For instance, calorie and fluid intake were matched and properly controlled for between the RAM and CON trials. Likewise, players’ sleep
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Figure 3 Players’ Brunel Mood Scale (BRUMS) state at pre-exercise in Ramadan-fasted. (RAM) and non-fasted (CON) conditions (n = 10). Key: T = tension; D = depression; A = anger; V = vigour; F = fatigue; C = confusion.
variables were equivalent between conditions (Table 3) as the players were residing in a boarding residence with strict regulations with regards to sleep times and afternoon naps. Further, there were no differences in physiological parameters such as blood glucose, blood lactate and HR between CON and RAM, indicating a similar physical demand during match play. As such, it is suggested that any alterations in skill performance is largely cognitive (i.e., sensation of fatigue and tiredness). We do, however, acknowledge that the poorer smash performances (i.e., lower shuttlecock speeds) could have been influenced by placebo effects (or nocebo as the case in the present study) [36,37] of observing the Ramadan fast. Nevertheless, when competing in the month of Ramadan, it is recommended that specific strategies such as intermittent mouth rinsing during the match play [3,4], be undertaken to try to reduce the influence of Ramadan fasting on physical and cognitive performances.
5. Conclusion Our findings indicate that although Ramadan fasting resulted in increased sensations of fatigue and tiredness during match play, skill performances were however largely maintained, with the only observed decrement being a decrease in overhead smash velocity, possibly due to interference in players’ cognitive functions. Further interventional targeted at preserving cognitive performance should be undertaken to examine the influence of Ramadan fasting on skill performance during match play.
Disclosure of interest The authors declare that they have no competing interest.
Acknowledgements The authors would like to thank the national badminton players for their effort and commitment to the study procedures and the Singapore Badminton Association for their generous assistance.
References [1] Phomsoupha M, Laffaye G. The science of badminton: game characteristics, anthropometry, physiology, visual fitness and biomechanics. Sports Med 2015;45:473—95. [2] Ooi CH, Tan A, Ahmad A, Kwong KW, Sompong R, Ghazali KA, et al. Physiological characteristics of elite and sub-elite badminton players. J Sports Sci 2009;27:1591—9. [3] Lim VTW, Damit NF, Aziz AR. Recommendations for optimal competitive exercise performance and effective traininginduced adaptations when Ramadan fasting. In: Chtourou H, editor. Effects of Ramadan fasting on health and athletic performance, OMICS Group eBook. California, USA: OMICS Group Incorporation; 2015. p. 204—21. [4] Che Muhamed AM, Mohamad NG, Ismail N, Aziz AR, Singh R. Mouth rinsing improves cycling endurance performance during Ramadan fasting in a hot humid environment. Appl Physiol Nutr Metab 2014;39:458—64. [5] Faye J, Fall A, Badji L, Cisse F, Stephan H, Tine P. Effects of Ramadan fast on weight, performance and glycemia during training for resistance. Dakar Med 2005;50:146—51 [In French with English Abstract]. [6] Tian HHR, Aziz AR, Png W, Wahid MF, Yeo HHD, Png CAL. Effect of intermittent fasting during Ramadan month on cognitive function in Muslim athletes. As J Sports Med 2011;2:145—53. [7] Shephard RJ. The impact of Ramadan observance upon athletic performance. Nutrients 2012;4:491—505. [8] Aloui A, Chtourou H, Masmoudi L, Chaouachi A, Chamari K, Souissi N. Effects of Ramadan fasting on male judokas’
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+Model SCISPO-3389; No. of Pages 10
ARTICLE IN PRESS
xxx.e10
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19] [20] [21] [22]
performances in specific and non-specific judo tasks. Biol Rhythm Res 2013;44:645—54. Kirkendall DT, Leiper JB, Bartagi Z, Dvorak J, Zerguini Y. The influence of Ramadan on physical performance measures in young Muslim footballers. J Sports Sci 2012;26(Suppl. 3):S15—27. Zerguini Y, Kirkendall D, Junge A, Dvorak J. Impact of Ramadan on physical performance in professional soccer players. Br J Sports Med 2007;41:398—400. Lyons M, Al-Nakeeb Y, Nevill A. Performance of soccer passing skills under moderate and high intensity localized muscle fatigue. J Streng Cond Res 2006;20:197—202. Rampinini E, Impellizzeri FM, Castagna C, Azzallin A, Bravo DF, Wisloff U. Effect of match-related fatigue on shortpassing ability in young soccer players. Med Sci Sports Exerc 2008;40:934—42. Roy J, Ooi CH, Singh R, Aziz AR, Chai WJ. Self-generated coping strategies among Muslim athletes during Ramadan fasting. J Sports Sci Med 2011;10:137—44. Kaida K, Takahashi M, Akerstedt T, Nakata A, Otsuka Y, Haratani T, et al. Validation of the Karolinska Sleepiness Scale against performance and EEG variables. Clin Neurophysiol 2006;117:1574—81. Terry PC, Lane AM, Lane HJ, Keohane L. Development and validation of a mood measure for adolescents. J Sports Sci 1999;17:861—72. Abián-Vicén J, Castanedo A, Abián P, González-Millán C, Salinero JJ, Del Coso J. Influence of successive badminton matches on muscle strength, power, and body-fluid balance in elite players. Int J Sports Physiol Perform 2014;9:689—94. Abián-Vicén J, Castanedo A, Abián P, Sampedro J. Temporal and notational comparison of badminton matches between men’s singles and women’s singles. Int J Sports Perform Analy 2013;13:310—20. Gowitzke BA, Waddell DB. Technique of badminton stroke production. In: Terauds J, editor. Science in rackets sports. Del Mar, CA: Academic Publishers; 1979. p. 17—41. Davis P. Badminton: the complete practice guide. London: David and Charles; 1982. Cohen J. A power primer. Psychol Bull 1992;112:155—9. Batterham AM, Hopkins WG. Making meaningful inferences about magnitudes. Int J Sports Physiol Perform 2006;1:50—7. Ferrauti A, Pluim BM, Weber K. The effect of recovery duration on running speed and stroke quality during intermittent training drills in elite tennis players. J Sports Sci 2001;19: 235—42.
A.R. Aziz et al. [23] Vergauwen L, Spaepen AJ, Lefevre J, Hespel P. Evaluation of stroke performance in tennis. Med Sci Sports Exerc 1998;30:1281—8. [24] Mudie KL, Gupta A, Green S, Clothier PJ. Adaptation of lower limb movement patterns when maintaining performance in the presence of muscle fatigue. Hum Movem Sci 2016;48:28—36. [25] Fitts PM. The information capacity of the human motor system in controlling the amplitude of movement. J Experim Psychol 1954;47:381—91. [26] Brechbuhl C, Girard O, Millet GP, Schmitt L. Technical alterations during an incremental field test in elite male tennis players. Med Sci Sports Exerc 2017;49:1917—26. [27] Armada-da-Silva PA, Woods J, Jones DA. The effect of passive heating and face cooling on perceived exertion during exercise in the heat. Eur J Appl Physiol 2004;91:563—71. [28] Forestier N, Nougier V. The effects of muscular fatigue on the coordination of a multijoint movement in human. Neurosci Letters 1998;252:187—90. [29] Kellis E, Katis A, Vrabas IS. Effects of an intermittent exercise fatigue protocol on biomechanics of soccer kick performance. Scand J Med Sci Sports 2006;16:334—44. [30] Clarke ND, Duncan MJ. Effect of carbohydrate and caffeine ingestion on badminton performance. Int J Sports Physiol Perform 2016;11:108—15. [31] Girard O, Millet GP. Neuromuscular fatigue in racquet sports. Neurol Clin 2008;26:181—94. [32] Reyner LA, Horne JA. Sleep restriction and serving accuracy in performance tennis players, and effects of caffeine. Physiol Behav 2013;120:93—6. [33] Girard O, Micallef J-P, Noual J, Millet GP. Alteration of neuromuscular function in squash. J Sci Med Sport 2010;13:172—7. [34] Girard O, Lattier G, Maffiuletti NA, Micallef JP, Millet GP. Neuromuscular fatigue during a prolonged intermittent exercise: application to tennis. J Electromyogr Kinesiol 2008;18:1038—46. [35] Aziz AR, Che Muhamed AM, Ooi CH, Singh R, Chia MYH. Effects of Ramadan fasting on the physical activity profile of trained Muslim soccer players during a 90-minute match. Sci Med Footb 2018;2:29—38. [36] Carlino E, Piedimonte A, Frisaldi E. The effects of placebos and nocebos on physical performance. Handb Experim Pharmacol 2014;225:149—57. [37] Farooq A, Herrera CP, Zerguini Y, Almudahka F, Chamari K. Knowledge, beliefs and attitudes of Muslim footballers towards Ramadan fasting during the London 2012 Olympics: a crosssectional study. BMJ Open 2016;6:e012848.
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ORIGINAL ARTICLE
Effects of Ramadan fasting on match-related changes in skill performance in elite Muslim badminton players Effets du jeûne du Ramadan sur les changements techniques de performance lors de matchs exécutés par des joueurs de badminton élites A.R. Aziz a,b,∗, D.S.L. Lim a, S. Sahrom a,c, A.M. Che Muhamed d, M. Ihsan a,e, O. Girard f, M.Y.H. Chia b a
Sport Science and Sport Medicine, Singapore Sport Institute, Sport Singapore, Singapore Physical Education and Sports Science Academic Group, National Institute of Education, Nanyang Technological University, Singapore c Centre for Exercise and Sports Science research, School of Medical and Health science, Edith Cowan University, Perth, Australia d Advanced Medical and Dental institute, Universiti Sains Malaysia, Penang, Malaysia e Research and Scientific Support, Aspetar-Qatar orthopaedic and Sports Medicine Hospital, Doha, Qatar f Murdoch Applied Sports Science Laboratory, Murdoch University, Perth, Australia b
Received 31 July 2018; accepted 11 July 2019
KEYWORDS Religious fasting; Stroke effectiveness; Skill performance; Fatigue
∗
Summary We examined the extent to which Ramadan fasting affects badminton skill performance under simulated (i.e., competitive) match play conditions. Ten male Muslim national-level badminton players performed a 40-minute (2 sets × 20 minutes per set in each match) badminton single-matches in a non-fasted (CON) and in Ramadan-fasted (RAM) state on separate occasions. Skills assessment involved performing eight low-serves and eight overhead smashes at baseline, at the end of set 1 and set 2 (mid- and end-match, respectively). Players’ pre-match diet was standardised between conditions and consumed either at ∼12:00 or at ∼05:00 for CON and RAM, respectively. There were no differences in the accuracy, consistency and speed of the low-serve between CON and RAM at the three match play time-points (all P > 0.05). Likewise, accuracy and consistency of the overhead smash were not affected by RAM (P > 0.05), but overhead smash velocity was slower in RAM than CON at the mid- (−7.3 ± 7.1%; P = 0.016) and end-match (−5.3 ± 4.4%; P = 0.007). Blood glucose, blood lactate, heart rate and ratings of perceived exertion were similar throughout the match play protocol (all P > 0.05).
Corresponding author at: Sports science and medicine, Singapore Sport Institute, Sport Singapore, 3, Stadium Drive, 397630, Singapore. E-mail address: abdul rashid [email protected] (A.R. Aziz).
https://doi.org/10.1016/j.scispo.2019.07.014 0765-1597/© 2019 Elsevier Masson SAS. All rights reserved.
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A.R. Aziz et al. No differences were observed between conditions in players’ overnight sleep, daytime nap duration and level of daytime sleepiness (all P > 0.05), whereas pre-match perceived tiredness and fatigue ratings were higher in RAM (both P < 0.01). In conclusion, although Ramadan fasting resulted in increased sensations of fatigue and tiredness during match play, skill performances were however largely maintained, with the only observed decrement being a decrease in overhead smash velocity. © 2019 Elsevier Masson SAS. All rights reserved.
MOTS CLÉS Jeûne religieux ; Efficacité de l’AVC ; Performance d’habileté ; Fatigue
Résumé Cette étude examinait dans quelle mesure le jeûne du Ramadan affecte l’exécution technique d’habiletés spécifiques au badminton dans des conditions de jeu simulées proches de la compétition. Dix joueurs de badminton masculins et Musulmans de niveau national ont réalisé, lors de jours séparés, un match en simple de 40 minutes (2 sets × 20 minutes par set pour chaque match) soit dans un état de non jeûne (CON) ou lors du jeûne du Ramadan (RAM). L’évaluation des compétences impliquait l’exécution de huit services courts et de huit smashs, ceci avant et à la fin du premier et du second set (milieu et fin du match, respectivement). Des repas standards étaient pris à ∼12h00 pour la condition CON et à ∼5h00 du matin pour la condition RAM. Il n’y avait aucune différence en terme de précision, consistence et vitesse du volant lors du service avec des valeurs similaires entre les deux conditions et pour chacun des trois points de mesure lors du match (p > 0,05). De même, la condition RAM n’était pas associée à une modification de la précision ou de la cohérence du service (p > 0,05), alors que la vitesse du smash était plus lente pour la condition RAM comparativement à CON, ceci aussi bien au milieu (−7,3 ± 7,1 %, p = 0,016) qu’à la fin (−5,3 ± 4,4 %, p = 0,007) du match. Le taux de glucose dans le sang, la lactatémie sanguine, la fréquence cardiaque et la perception de l’effort étaient similaires tout au long du match (p > 0,05). Aucune différence existait entre les conditions concernant le sommeil la nuit, la durée de la sieste en journée et l’état de somnolence (p > 0,05). En revanche, que les sensations de fatigue avant et pendant le match étaient plus élevées pour la condition RAM (p < 0,01). En conclusion, bien que le jeûne du Ramadan entraine un majoration des sensations de fatigue avant et pendant le match, la qualité d’exécution technique n’était pas altérée puisque la seule modification observée était une diminution de la vitesse du smash. © 2019 Elsevier Masson SAS. Tous droits r´ eserv´ es.
1. Introduction Badminton is regarded as the fastest racquet game in the world. It is characterised by repeated directional change involving sharp accelerations, decelerations, jumps, leaps, lunges, as well as requires considerable upper body power and endurance [1]. While skill execution and tactical awareness are crucial aspects for success in this sport, it has been suggested that sub-optimal levels of physical fitness will likely precipitate fatigue, and result in reduced stroke accuracy, velocity and weak positional play [1,2]. The Ramadan fast is an annual religious obligation that requires Muslims of pubertal age to abstain from the ingesting food and fluid daily for over 29 or 30 days [3]. Fasting is undertaken from dawn to dusk, and as such, the daily fasting duration is dependant on both the geographical location as well as the climatic season in which the month of Ramadan falls [3]. Muslims typically consume their main meals at two sittings daily; before the commencement of the day’s fast (just prior to the breaking of dawn i.e., termed as the sahur meal, and following the adherence of the day’s fast, i.e., iftar meal) [3]. Such prolonged nutritional restrictions would likely result in dehydration [4] and reduced blood glucose
levels [5], which in turn could potentially hinder physical, as well as cognitive performances [6]. Further, the drastic and sustained shift in eating habits to primarily the nocturnal period may result in poor sleep (in both pattern and duration) [6]. This, in turn, can severely alter the fasted individual’s circadian rhythm leading to increased mood disturbances and lethargy, as well as decreased vigilance and concentration [7]. These effects are likely to negatively affect physical performance and may, perhaps, be more pronounced when athletes undertake physical activities between sunrise and sunset [3,7]. While there is considerable research detailing the effects of Ramadan fasting on exercise performance [7], only a few studies have focussed on skill execution, with considerable discrepant findings [8—10]. For instance, fasting during Ramadan has been shown to decrease ball-dribbling time by 9.4% in professional footballers [8] and the number of throws by 20% during a specific judo test amongst elite judokas [8]. On the other hand, Ramadan fasting has been shown to not influence ball-dribbling and passing skills in young, welltrained football players [10]. It should be noted that in these studies, skills assessment was undertaken in the absence of physical fatigue, which to some extent limits the ecological
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Effects of Ramadan fasting on match-related changes in badminton players validity and practical importance of these findings. Indeed, moderate to high levels of physical fatigue has been shown to impair passing skills amongst well-trained football players [11,12]. Within badminton, maintaining a high level of technique or skills execution after intense rallies and/or in the latter stages of a match (i.e., when athletes are considerably fatigued) is vital to securing a positive outcome. During Ramadan, exercising and fasting athletes would possibly encounter considerable levels of physical fatigue and loss of vigilance due to the lack of food, fluid and sleep, which may amplify the loss in skill performance when combined with the normal prevailing levels of fatigue typically encountered in match play [3,7]. Given the considerable number of Muslim badminton players engaged in the badminton world circuit, it is imperative that there is a greater understanding of how badminton skills performance is influenced by Ramadan fasting when fatigued. As such, the purpose of this study was to examine the effects of Ramadan fasting on the time course of changes in badminton-specific skills (i.e., low-serve and overhead smash) in response to simulated match play badminton in elite male Muslim players. It was hypothesised that Ramadan-fasted state would lead to further decline in performance of the two motor skills compared to playing in the non-fasted state as fatigue develops.
2. Methods 2.1. Participants Ten highly trained male Muslim badminton players participated in this study (mean ± SD; age 22.8 ± 3.4 y, stature 1.71 ± 0.3 m, body mass 67.1 ± 5.5 kg; maximal aerobic power or VO2max [estimated from performance in the 20 m Multistage Shuttle Run or Beep test] [2] 56.6 ± 3.8 mL·kg−1 ·min−1 ; maximal heart rate or HRmax 189.4 ± 10.3 b·min−1 ). All players were event-specialist in either singles or doubles from the Singapore national squad and have had participated in various international tournaments for a period of 6.4 ± 3.2 y. At the time when this study was conducted, two of the players were in the top 20; another two in the top 50 and the rest were in the top 200 of the Badminton World Federation (BWF) ranking. The players were accustomed to Ramadan fasting, and have been performing this annual religious obligation for at least eight years prior to this study. Players resided in a boarding school throughout the study, equipped with full training and accommodation facilities, as well as food catering services. During this period, the players were training eight to ten sessions per week for a total of 20—25 hours. This included six to eight 2—3 hour sessions of skills, technical, tactical and simulation match play, and two to three 1.5-hour sessions of physical conditioning of either resistance and/or aerobictype of training. Training activities in the 24 hours prior to the experimental trials were reduced and standardised to moderate for fatigue during the experimental sessions. Players provided written informed consent and the study was approved by the Institutional Human Research Ethics Committee (IRB 12-04/02). The study’s procedures were conducted according to ethical standards of the Helsinki Declaration. Daily fasting were from ∼05:35 to ∼19:20,
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resulting in a typical fasting duration of approximately 14 hours.
2.2. Experimental design and procedures Each athlete performed two separated sessions of badminton match play undertaken in either a Ramadan-fasted (RAM) or non-fasted (CON) state. The CON trials were conducted within the week prior to the start of Ramadan, while the RAM trials were conducted two weeks after the commencement of Ramadan. The RAM trials were conducted two weeks into Ramadan to allow the athletes to better adjust to the change in lifestyle [13]. All trials commenced at approximately 18:00, where players reported 30 minutes before the commencement of the exercise trial. Upon arrival players completed several questionnaires documenting their sleep times, mood state and readiness to compete (details below). Afterwards, players provided a urine sample for the assessment of urine specific gravity (USG; PR series, Atago, Tokyo, Japan), and were subsequently weighed (wearing only shorts) to determine pre-match body mass (Spider 2-150-P, Mettler Toledo, Albstadt, Germany). After the weigh-in, players’ capillary blood samples were taken to determine resting blood glucose (Advantage, Roche Diagnostics Corp., IN, USA) and blood lactate concentrations (Accutrend, Boehringer Manneheim, Germany). Players then proceeded with a standardised warm-up consisting of 3 minutes of dynamic stretching and 5 minutes of stroke rallying. Baseline assessments of the low-serve and overhead smash were then undertaken (see below for details), before embarking on a 40-minute singles match play (2 sets × 20 minutes per set) (see Fig. 1). Capillary blood samples to determine blood glucose and lactate were taken again at the end of set 1 (mid-point of match) and set 2 (end of match), prior to the assessment the selected skills. Heart rate (HR) was recorded throughout the match via short-distance telemetry (RS400, Polar Electro Oy, Finland). Players’ ratings of perceived exertion (RPE), using Borg’s categorical scale of 1—10, was obtained at pre-match (after players have warmed-up), at the end of set 1 and at the end of set 2. Fluid (only water) was allowed ad libitium during CON matches but not for RAM matches. Body mass was retaken following the completion of the match, after players had towelled dried.
2.3. Pre-exercise questionnaires and sleep All players were residing in the dormitory setting as part of a boarding school, which was governed by a headmaster. The school had strict regulations and lights-out was typically at ∼23:30 every evening and morning breakfast was at 08:00. Moreover, the players have been undertaking a compulsory daily afternoon nap, as part of the squad’s training-recovery programme for the last two years. During Ramadan, special arrangements were made for the Muslim athletes to consume their sahur meal between 05:00—05:30 and they were then allowed to go to bed after that. Players’ sleep and wake times for the previous 24 h, as well as the duration of their daytime nap were recorded. They then rated their daytime sleepiness via the nine-point Karolinska Sleepiness Scale (KSS) [14]. Players also completed the
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Figure 1
Schematic representation of the study protocol.
validated Brunel Mood State (BRUMS) [15] and their current levels of ‘‘readiness to train’’, ‘‘tiredness’’, ‘‘alertness’’ and ‘‘concentration’’ on a 100-mm visual analogue scale [9].
2.4. Pre-exercise dietary intake Dietary intake for last meal consumed by players prior to their match trials (i.e., lunch for CON and sahur meal for RAM) were standardized and provided for. To ensure for the ecological validity of the study’s findings under Ramadanfasted and non-fasted conditions, players consumed their sahur meal (prior to RAM match) between 05:00—05:30 and their lunch (prior to CON match) between 12:00—12:30. Meal composition was individualized for each participant: carbohydrate of 2.0 g.kg body mass−1 and 800 ml of fluid. The total caloric content of the meal was 855 ± 206 kcal.
2.5. Simulated competitive badminton singles match play Players were paired according to level of play (as advised by the squad’s coach) and competed against the same opponent in both the CON and RAM match. Match was played under the official rules of the BWF and scoring was based on rallypoints of the better of two sets. However, instead of playing to complete the 21 points in a single set, each set was played for a fixed 20-minute duration (no matter the prevailing scores) with rest period of 2 minutes between each set. The choice of 20-min per set and thus total of 40 minutes per match was based on the duration of the singles men match in the 2008 Olympics [16] and 2010 Spanish Championship [17], which lasted for 39.6 ± 6.5 and 42.7 ± 11.3 minutes respectively. For skill assessment, the player performed a total of eight low-serves and eight overhead smashes, at pre-match (or baseline), at post-set 1 (mid-match) and at post-set 2 (end-match) (see Fig. 1). Players wore the same attire (including shoes) and used their own personal rackets for all their matches. The same brand of shuttlecocks (ASA 4, Yonex, Japan) was used throughout and the shuttlecocks were replaced when necessary. All matches were played in an enclosed gymnasium where the ambient temperature was between 23—26 ◦ C and relative humidity 58—64%
(Kestrel4000 Kellerman, Boothwyn, PA, USA) throughout the study.
2.6. Assessment of the badminton low-serve and overhead smash The low-serve and the overhead smash are considered crucial in a badminton player’s repertoire of technique, and require considerable motor skill, accuracy and technical ability [17,18]. Data for all eight successful shots were averaged to represent the players’ skills performance at each time-point. The low-serve involves dispatching the shuttlecock as low as possible above the net to land onto the opposing service box area. A short perpendicular distance between the net and shuttlecock is critical, as otherwise presents an opportunity for the opposing player to attack while returning the serve. For the present study, a low-serve was considered valid when the shuttlecock cleared the net and landed within the demarcated service area, while an invalid serve was when the shuttlecock was impeded by the net. For accuracy, there were two criterion measures: i) the height distance of the shuttlecocks when it is perpendicularly above the net during the serve (i.e., a lower mean distance denotes a higher accuracy) and ii) the distance of the landed shuttlecocks to the marked target within the service area (i.e., a lower mean distance denotes higher accuracy), regardless of the direction of the landed shuttle to the marked target. For speed, shuttlecock velocity perpendicular to the net during the serve trajectory was determined. Consistency of the serve was determined by the number of error shots, that is when the shuttlecock landed outside the court playing boundary or did not clear the net (i.e., a lower number of errors denotes better consistency). For the overhead smash, the pair-matched competing players each took turns to be a feeder and smasher. The feeder delivered a high serve to the right side of the court where the smasher immediately shuffled backwards to execute a cross-court smash, directed towards a demarcated target area. The validity of the feeding serve was decided by the primary investigator who was positioned at the strategic location for observation. The serve was considered valid when the shuttlecock, if not intercepted would land within the back line of the court. If a player executed a smash,
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Effects of Ramadan fasting on match-related changes in badminton players which was from an invalid feed (i.e., the fed shuttlecock was either too close to the net or too far from the baseline of the court), data from this smash was omitted and another trial was conducted. A smash was deemed successful when the shuttlecock landed on the opposing court within the playing area. If the smash was unable to clear the net or landed beyond the playing area, it was considered as an unsuccessful or error smash. Smash accuracy was determined as the mean distance between the landed shuttlecocks to the target mark regardless of the direction of the landed shuttles to the marked target. Shuttlecock speed was determined as the mean velocity of the shuttlecocks when it was perpendicularly to the net during the smash trajectory, while consistency was determined by the number of invalid or error shots.
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CON and RAM × time: baseline, mid- and end-match). The assumption of sphericity was checked by Mauchly’s test of sphericity and where violations occurred, the GreenhouseGeisser Epsilon was applied. If a significant main effect was found, post-hoc t-test was used to detect where the differences occurred with a Bonferroni correction for multiple comparisons, P = 0.05/3 = 0.017. In addition, effect size (d) was utilised to determine the practical meaningfulness of the differences [20]. The magnitude of the effects size was classified as trivial (< 0.2), small (> 0.2—0.6), moderate (> 0.6—1.2), large (> 1.2—2.0) and very large (> 2.0—4.0) [21].
3. Results 2.7. Kinematics measures of the low-serve and overhead smash Square grids measuring 0.5 m and 0.5 m for the serve and 1.0 m by 1.0 m for the smash, were marked as target landing areas (Fig. 2). These positions on the court have been suggested to represent the optimal target areas for service and smash [19], and tested players were instructed to land the shuttlecock as close as possible to the centre of these marked areas, i.e., X1 and X2 for the low-serve and smash, respectively. Three-dimensional kinematics data of the shuttlecock were analysed using a 11-camera motion analysis system (Pro-Reflex series, Qualysis, Sweden), sampling at 240 Hz.. Cameras were calibrated using a calibration wand kit before every service/smash set. The rounded base of the shuttlecocks were pasted with retro-reflective tape to allow for the cameras to detect its position within the data capture area. Key positions on the court were also marked with spherical retro-reflective markers, i.e., the location of the low-serve target point (X1), location of the smash target point (X2) and along the top lining of the net (X3). Data of the position of the shuttlecocks were identified manually to ensure it met the criterion for each parameter (e.g., directly above the net or on the court playing area). The position data and its 1st derivative were subsequently smoothened using a 4th order Butterworth filter, and determined using the Qualysis Track Manager (Qualysis, Sweden) analysis software. Similarly, the velocity data of the shuttlecock was determined using three positional data above the net. With the known sampling interval of 4.0 ms, the speed calculation was performed by the same data acquisition software.
2.8. Statistical analyses SPSS (Chicago, IL, USA) software was used for all statistical analyses. All data were reported as mean ± SD. The level of statistical significance for primary effects was set at P < 0.05. All data was checked for normality of distribution, and if not normally distributed, the non-parametric statically analysis was used. Differences in normally distributed measures between CON and RAM matches were determined using the paired Student’s t-test. Data with continuous time component was determined using an analysis of variance (ANOVA) test with two-way repeated measures (condition:
3.1. Performance of the low-serve and overhead smash (Table 1) For the low-serve, no significant condition, time and interaction effects were evident for height distance of shuttlecock over the net, in the distance of the landed shuttles from the target point, velocity of the low-serve, and the number of errors made in the low-serve throughout the match (F ratios for all variables were P > 0.05). For the overhead smash, main effects for condition, time and interaction were not significant for distance of the shuttlecocks from the target point and for the number of errors made during the smash throughout the matches (both F ratios, P > 0.05). While there were no significant main effects of either time or interaction (both F ratios, P > 0.05), smash velocity was significantly affected by condition (F1,9 = 6.68, P = 0.03). Post-hoc analysis indicated that the velocity of smash was significantly higher for CON than RAM at the mid- (7.3 ± 7.1%; P = 0.02, d = 0.70, moderate) and end-match (5.3 ± 4.4%; P = 0.007, d = 0.53, small), but not at baseline (P = 0.86, d = 0.09, trivial).
3.2. Physiological and perceptual measures (Table 2) Players consumed an averaged volume of 125.1 ± 66.4 mL (range: 46.4—251.2 mL) of fluid during CON match. Sweat loss at the end of match play was lower in RAM compared to CON (P = 0.04) trials. Exercise HR throughout the match were not significantly different between conditions (all F ratios, P > 0.05). Blood glucose concentrations demonstrated significant main effects for condition (F1,9 = 10.52, P = 0.01), time (F2,18 = 6.38, P = 0.008) and interaction (F2,18 = 4.99, P = 0.019). Post-hoc analysis however, indicated that blood glucose was significantly higher in CON compared with RAM at baseline (P = 0.009) but not at mid- (P = 0.25) and endmatch (P = 0.66). For blood lactate concentrations, there were no significant main effects of condition and interaction (both F ratios, P > 0.05), although a significant time effect was evident (F2,18 = 143.68, P < 0.001). For the RPE, there were no significant main effects of condition (F1,9 = 0.10, P = 0.75) and interaction (F2,18 = 0.47, P = 0.63), but a significant time effect (F2,18 = 80.37, P < 0.001) was observed.
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A.R. Aziz et al.
Figure 2 Schematic illustration of the badminton half-court (court not drawn to scale) including the target area for low-serve and overhead smash. 䊉 = spherical reflective markers placed in the centre of target area (X1 for overhead smash and X2 for low-serve) and along the top linings of the net (X3).
3.3. Readiness questionnaires, sleep variables and profile of mood state (Table 3 and Fig. 3) Perceived tiredness was significantly greater in RAM compared with CON (P = 0.011; d = 1.04, large). Similarly, in the BRUMS, greater levels of subjective fatigue were reported in RAM compared with CON (P < 0.001; d = 1.86, very large). Overnight sleep duration (P = 0.49), daytime nap duration (P = 0.10) and KSS scores (P = 0.24) were similar between CON and RAM trials.
4. Discussion We examined, for the first time, the influence of Ramadan fasting on the consistency, accuracy and shuttle-velocity in executing the low-serve and overhead smash in response to a simulated, 40-minute competitive badminton game in elite Muslim players. Our results demonstrate increased sensation of perceived tiredness and fatigue, in line with decreased
smash velocity after 20 minutes of match play following Ramadan fasting. However, no accompanying decrements in smash accuracy or consistency were observed, along with no decrements in skill performance for the low-serve. Our findings indicate that key badminton skills such as the overhead smash and low-serve are largely preserved following Ramadan fasting. However, some aspects within skills that require considerable physical effort could potentially be impaired (i.e., smash velocity). Smash velocities were similar between conditions at baseline but were significantly reduced in RAM compared with CON following set 1 and 2, with no changes in shot accuracy and consistency (Table 1). This finding agrees with previous non-Ramadan fasting related studies examining the effects of fatigue on tennis forehand stroke, in which stroke velocity was particularly impaired within skills that required considerably physical effort [22,23]. A likely reasoning is that under fatigue, players might consciously or sub-consciously, reduce the speed of the smash (i.e., a lowering of physical exertion) in order to increase the accuracy
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Effects of Ramadan fasting on match-related changes in badminton players
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Table 1 Performance variables in the low-serve and overhead smash during match play in the non-fasted (CON) and Ramadanfasted (RAM) conditions (n = 10). CON Low-serve Height distance of shuttle above the net (cm) Baseline End of set 1 End of set 2 Distance of shuttlecock from target (cm) Baseline End of set 1 End of set 2 Velocity of shuttle above the net (km·h−1 ) Baseline End of set 1 End of set 2 Number of errors Baseline End of set 1 End of set 2 Overhead smash Distance of shuttle from target (cm) Baseline End of set 1 End of set 2 Velocity of shuttle above the net (km·h−1 ) Baseline End of set 1 End of set 2 Number of errors Baseline End of set 1 End of set 2 a
RAM
Effect size, descriptor
11.4 ± 2.6 10.9 ± 2.1 12.0 ± 4.3
10.7 ± 2.5 11.2 ± 3.5 12.6 ± 8.4
0.27, small 1.07, large 0.09, trivial
25.4 ± 7.6 20.4 ± 2.9 21.9 ± 6.1
26.4 ± 7.9 23.6 ± 9.0 28.2 ± 13.4
0.12, trivial 0.55, small 0.65, moderate
18.1 ± 1.0 17.2 ± 1.0 17.7 ± 1.4
17.6 ± 1.2 17.6 ± 0.8 17.6 ± 1.2
0.45, small 0.44, small 0.09, trivial
0.9 ± 0.9 0.5 ± 0.7 0.6 ± 0.8
0.8 ± 0.8 0.7 ± 0.8 0.5 ± 0.7
0.12, trivial 0.27, small 0.13, trivial
157.9 ± 60.7 164.2 ± 61.1 147.7 ± 66.7
195.4 ± 70.5 156.3 ± 41.2 159.4 ± 43.9
0.57, small 0.15, trivial 0.21, small
95.6 ± 11.6 91.8 ± 8.6a 94.7 ± 9.9a
94.7 ± 9.5 85.1 ± 10.5 89.8 ± 8.7
2.3 ± 1.3 1.7 ± 1.5 1.7 ± 1.3
1.5 ± 1.7 1.7 ± 0.9 1.3 ± 1.8
0.09, trivial 0.70, moderate 0.53, small 0.53, small 0.0, trivial 0.26, small
Post-hoc significantly different between CON and RAM condition, P < 0.017.
of the shot [24] which is in line with the strategy of motor movement pattern when performing the skill in a fatigued relative to a non-fatigued state [25,26]. Although success in badminton is suggested to relate to positional play and shot accuracy, rather than absolute power [1], it would be incautious to disregard a 5—8% (with no effect on accuracy) decrease in smash velocity observed in the present study. Moreover, during major tournaments or team events, players might be required to play up to two matches a day during the qualifying stages. As such, athletes undertaking training or competing whilst fasting should incorporate some acute recovery strategies (e.g., facial fanning/cooling) [27] to mitigate subtle decrements in performance during match play. The mechanism(s) underpinning the observed decline in the smash velocity is currently not well understood. Previous studies showing a decline in kicking velocity of the ball after a fatiguing exercise protocol suggested that the negative effect was caused by muscular incapacity due to decrements in muscle strength or posture stability [28,29]. No such measures were taken in the present study to verify this possibility. Reduced blood glucose availability, dehydration and sleep disturbances have been previously reported
in response to Ramadan fasting [3—10], and may have accounted for the decline in smash performance [30—32]. However, these factors are unlikely to have had any influence on the decrease in smash velocity observed in the current study, as Ramadan fasting has had no influence on any of these parameters (Tables 2 and 3). We did observe, however, increased pre-match ratings of perceived tiredness and fatigue in the readiness questionnaires (Table 3) and BRUMS (Fig. 3), respectively. These observations could at least in part account for the decrease in smash velocity performance. Indeed, it is possible that higher levels of pre-exercise fatigue and tiredness in RAM trial might have amplified the development of physical fatigue during match play, resulting in lower smash velocities as was observed in other sports of tennis and squad [33,34]. However, this does not explain how smash velocities were similar at baseline, when there was an apparent difference in fatigue and tiredness between RAM and CON. The authors postulate that skill performances may be more influenced by sensations of fatigue and tiredness in an exercised, compared with a non-exercised state (i.e., baseline). In contrast to the overhead smash, all aspects (i.e., consistency, accuracy and velocity of shuttlecock) of the
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A.R. Aziz et al. Other physiological and perceptual variables assessed in the non-fasted (CON) and Ramadan-fasted (RAM) conditions CON
Body mass (kg) Pre-match Post-match Urine specific gravity (au) Sweat lost (% of pre-match body mass) Blood glucose concentration (mmol·l−1 ) Pre-match End of set 1 End of set 2 Blood lactate concentration (mmol·l−1 ) Pre-match End of set 1 End of set 2 Mean heart rate (b·min−1 ) Pre-match During set 1 During set 2 Ratings of perceived exertion (au) Pre-match End of set 1 End of set 2
67.08 66.28 1.014 1.4
RAM ± ± ± ±
5.50 5.12 0.004a 0.4a
66.18 65.49 1.021 1.1
Effect size, descriptor ± ± ± ±
5.74 5.17 0.005 0.2
0.16, trivial 0.15, trivial 1.56, large 1.0, large
5.1 ± 0.5b 5.1 ± 0.4 4.9 ± 0.3
4.5 ± 0.3 5.0 ± 0.3 5.0 ± 0.3
1.5, large 0.29, small 0.33, small
1.1 ± 0.3 3.4 ± 0.3 4.7 ± 1.0
0.9 ± 0.1 3.3 ± 0.6 4.3 ± 0.7
1.0, large 0.05, trivial 0.47, small
111 ± 8 141 ± 14 146 ± 14
109 ± 9 142 ± 13 148 ± 17
0.24, trivial 0.07, trivial 0.13, trivial
7.7 ± 1.0 12.1 ± 1.7 13.3 ± 1.8
7.6 ± 1.0 11.9 ± 2.0 14.0 ± 1.6
0.10, trivial 0.11, trivial 0.41, small
No fluid was consumed during match play in the RAM trial. au: arbitrary unit. a P < 0.05 between CON and RAM condition; Post-hoc significant difference between CON and RAM condition. b Post-hoc significant difference between CON and RAM condition, P < 0.017.
Table 3 Players’ subjective responses to the pre-exercise questionnaires and sleep variables in the non-fasted (CON) and Ramadan-fasted (RAM) conditions (n = 10). CON Pre-exercise questionnaires Perceived level of readiness to compete (mm)a Perceived level of tiredness (mm)a Perceived level of alertness (mm)b Perceived level of concentration (mm)b Sleep variables Sleep duration (h) Daytime nap duration (min) Karolinska Sleepiness Scale (au)
33 21 77 82
RAM ± ± ± ±
25 15c 20 15
7.5 ± 1.0 142.5 ± 23.5 4.2 ± 1.8
35 43 79 80
Effect size, descriptor ± ± ± ±
23 27 16 15
7.1 ± 2.3 119.5 ± 30.2 4.8 ± 2.9
0.08, 1.05, 0.11, 0.13,
trivial large trivial trivial
0.24, small 0.86, moderate 0.26, small
au: arbitrary unit. a Low scores indicate more able to compete and lower level of tiredness. b Low scores indicate higher level of alertness and concentration. c P < 0.01 between CON and RAM condition.
low-serve performance were well maintained in RAM compared to CON (Table 1). It is possible that Ramadan fasting may influence the ‘physical’ component to a greater extent, compared with the ‘technical’ aspect of the performed skill. This reasoning is somewhat supported by a recent study, where decrements in total running distance and frequency of accelerations during a football match were evident only in the high but not within the low intensity zones following Ramadan fasting [35]. Collectively, the present findings seem to indicate that the effect of Ramadan fasting on skill
performance may depend on the physical demand involved; the greater the effort required, the more likely that the execution of the skill might be impaired by Ramadan fasting, albeit further research is required to confirm this assertion. In the present study, the authors have carefully controlled a number of variables to isolate the physiological changes inherent in Ramadan that might influence skill execution during badminton match play. For instance, calorie and fluid intake were matched and properly controlled for between the RAM and CON trials. Likewise, players’ sleep
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Figure 3 Players’ Brunel Mood Scale (BRUMS) state at pre-exercise in Ramadan-fasted. (RAM) and non-fasted (CON) conditions (n = 10). Key: T = tension; D = depression; A = anger; V = vigour; F = fatigue; C = confusion.
variables were equivalent between conditions (Table 3) as the players were residing in a boarding residence with strict regulations with regards to sleep times and afternoon naps. Further, there were no differences in physiological parameters such as blood glucose, blood lactate and HR between CON and RAM, indicating a similar physical demand during match play. As such, it is suggested that any alterations in skill performance is largely cognitive (i.e., sensation of fatigue and tiredness). We do, however, acknowledge that the poorer smash performances (i.e., lower shuttlecock speeds) could have been influenced by placebo effects (or nocebo as the case in the present study) [36,37] of observing the Ramadan fast. Nevertheless, when competing in the month of Ramadan, it is recommended that specific strategies such as intermittent mouth rinsing during the match play [3,4], be undertaken to try to reduce the influence of Ramadan fasting on physical and cognitive performances.
5. Conclusion Our findings indicate that although Ramadan fasting resulted in increased sensations of fatigue and tiredness during match play, skill performances were however largely maintained, with the only observed decrement being a decrease in overhead smash velocity, possibly due to interference in players’ cognitive functions. Further interventional targeted at preserving cognitive performance should be undertaken to examine the influence of Ramadan fasting on skill performance during match play.
Disclosure of interest The authors declare that they have no competing interest.
Acknowledgements The authors would like to thank the national badminton players for their effort and commitment to the study procedures and the Singapore Badminton Association for their generous assistance.
References [1] Phomsoupha M, Laffaye G. The science of badminton: game characteristics, anthropometry, physiology, visual fitness and biomechanics. Sports Med 2015;45:473—95. [2] Ooi CH, Tan A, Ahmad A, Kwong KW, Sompong R, Ghazali KA, et al. Physiological characteristics of elite and sub-elite badminton players. J Sports Sci 2009;27:1591—9. [3] Lim VTW, Damit NF, Aziz AR. Recommendations for optimal competitive exercise performance and effective traininginduced adaptations when Ramadan fasting. In: Chtourou H, editor. Effects of Ramadan fasting on health and athletic performance, OMICS Group eBook. California, USA: OMICS Group Incorporation; 2015. p. 204—21. [4] Che Muhamed AM, Mohamad NG, Ismail N, Aziz AR, Singh R. Mouth rinsing improves cycling endurance performance during Ramadan fasting in a hot humid environment. Appl Physiol Nutr Metab 2014;39:458—64. [5] Faye J, Fall A, Badji L, Cisse F, Stephan H, Tine P. Effects of Ramadan fast on weight, performance and glycemia during training for resistance. Dakar Med 2005;50:146—51 [In French with English Abstract]. [6] Tian HHR, Aziz AR, Png W, Wahid MF, Yeo HHD, Png CAL. Effect of intermittent fasting during Ramadan month on cognitive function in Muslim athletes. As J Sports Med 2011;2:145—53. [7] Shephard RJ. The impact of Ramadan observance upon athletic performance. Nutrients 2012;4:491—505. [8] Aloui A, Chtourou H, Masmoudi L, Chaouachi A, Chamari K, Souissi N. Effects of Ramadan fasting on male judokas’
Please cite this article in press as: Aziz AR, et al. Effects of Ramadan fasting on match-related changes in skill performance in elite Muslim badminton players. Sci sports (2019), https://doi.org/10.1016/j.scispo.2019.07.014
+Model SCISPO-3389; No. of Pages 10
ARTICLE IN PRESS
xxx.e10
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19] [20] [21] [22]
performances in specific and non-specific judo tasks. Biol Rhythm Res 2013;44:645—54. Kirkendall DT, Leiper JB, Bartagi Z, Dvorak J, Zerguini Y. The influence of Ramadan on physical performance measures in young Muslim footballers. J Sports Sci 2012;26(Suppl. 3):S15—27. Zerguini Y, Kirkendall D, Junge A, Dvorak J. Impact of Ramadan on physical performance in professional soccer players. Br J Sports Med 2007;41:398—400. Lyons M, Al-Nakeeb Y, Nevill A. Performance of soccer passing skills under moderate and high intensity localized muscle fatigue. J Streng Cond Res 2006;20:197—202. Rampinini E, Impellizzeri FM, Castagna C, Azzallin A, Bravo DF, Wisloff U. Effect of match-related fatigue on shortpassing ability in young soccer players. Med Sci Sports Exerc 2008;40:934—42. Roy J, Ooi CH, Singh R, Aziz AR, Chai WJ. Self-generated coping strategies among Muslim athletes during Ramadan fasting. J Sports Sci Med 2011;10:137—44. Kaida K, Takahashi M, Akerstedt T, Nakata A, Otsuka Y, Haratani T, et al. Validation of the Karolinska Sleepiness Scale against performance and EEG variables. Clin Neurophysiol 2006;117:1574—81. Terry PC, Lane AM, Lane HJ, Keohane L. Development and validation of a mood measure for adolescents. J Sports Sci 1999;17:861—72. Abián-Vicén J, Castanedo A, Abián P, González-Millán C, Salinero JJ, Del Coso J. Influence of successive badminton matches on muscle strength, power, and body-fluid balance in elite players. Int J Sports Physiol Perform 2014;9:689—94. Abián-Vicén J, Castanedo A, Abián P, Sampedro J. Temporal and notational comparison of badminton matches between men’s singles and women’s singles. Int J Sports Perform Analy 2013;13:310—20. Gowitzke BA, Waddell DB. Technique of badminton stroke production. In: Terauds J, editor. Science in rackets sports. Del Mar, CA: Academic Publishers; 1979. p. 17—41. Davis P. Badminton: the complete practice guide. London: David and Charles; 1982. Cohen J. A power primer. Psychol Bull 1992;112:155—9. Batterham AM, Hopkins WG. Making meaningful inferences about magnitudes. Int J Sports Physiol Perform 2006;1:50—7. Ferrauti A, Pluim BM, Weber K. The effect of recovery duration on running speed and stroke quality during intermittent training drills in elite tennis players. J Sports Sci 2001;19: 235—42.
A.R. Aziz et al. [23] Vergauwen L, Spaepen AJ, Lefevre J, Hespel P. Evaluation of stroke performance in tennis. Med Sci Sports Exerc 1998;30:1281—8. [24] Mudie KL, Gupta A, Green S, Clothier PJ. Adaptation of lower limb movement patterns when maintaining performance in the presence of muscle fatigue. Hum Movem Sci 2016;48:28—36. [25] Fitts PM. The information capacity of the human motor system in controlling the amplitude of movement. J Experim Psychol 1954;47:381—91. [26] Brechbuhl C, Girard O, Millet GP, Schmitt L. Technical alterations during an incremental field test in elite male tennis players. Med Sci Sports Exerc 2017;49:1917—26. [27] Armada-da-Silva PA, Woods J, Jones DA. The effect of passive heating and face cooling on perceived exertion during exercise in the heat. Eur J Appl Physiol 2004;91:563—71. [28] Forestier N, Nougier V. The effects of muscular fatigue on the coordination of a multijoint movement in human. Neurosci Letters 1998;252:187—90. [29] Kellis E, Katis A, Vrabas IS. Effects of an intermittent exercise fatigue protocol on biomechanics of soccer kick performance. Scand J Med Sci Sports 2006;16:334—44. [30] Clarke ND, Duncan MJ. Effect of carbohydrate and caffeine ingestion on badminton performance. Int J Sports Physiol Perform 2016;11:108—15. [31] Girard O, Millet GP. Neuromuscular fatigue in racquet sports. Neurol Clin 2008;26:181—94. [32] Reyner LA, Horne JA. Sleep restriction and serving accuracy in performance tennis players, and effects of caffeine. Physiol Behav 2013;120:93—6. [33] Girard O, Micallef J-P, Noual J, Millet GP. Alteration of neuromuscular function in squash. J Sci Med Sport 2010;13:172—7. [34] Girard O, Lattier G, Maffiuletti NA, Micallef JP, Millet GP. Neuromuscular fatigue during a prolonged intermittent exercise: application to tennis. J Electromyogr Kinesiol 2008;18:1038—46. [35] Aziz AR, Che Muhamed AM, Ooi CH, Singh R, Chia MYH. Effects of Ramadan fasting on the physical activity profile of trained Muslim soccer players during a 90-minute match. Sci Med Footb 2018;2:29—38. [36] Carlino E, Piedimonte A, Frisaldi E. The effects of placebos and nocebos on physical performance. Handb Experim Pharmacol 2014;225:149—57. [37] Farooq A, Herrera CP, Zerguini Y, Almudahka F, Chamari K. Knowledge, beliefs and attitudes of Muslim footballers towards Ramadan fasting during the London 2012 Olympics: a crosssectional study. BMJ Open 2016;6:e012848.
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