The effect of caffeine ingestion on skill maintenance and fatigue in epee fencers by Esgrima Brasil

Journal of Sports Sciences, 2013 Vol. 31, No. 10, 1091–1099, http://dx.doi.org/10.1080/02640414.2013.764466

The effect of caffeine ingestion on skill maintenance and fatigue in epee fencers

LINDSAY BOTTOMS1, ANDREW GREENHALGH2, & KIM GREGORY3,4 1

University of East London, Health and Bioscience, Water Lane, Stratford, E15 4LZ United Kingdom, 2University of Hertfordshire, School of Life Sciences, Hatﬁeld, United Kingdom, 3University of Bath, Sport and Exercise Science, Bath, United Kingdom, and 4West Midlands Deanery, Sport and Exercise Medicine, Birmingham, United Kingdom (Accepted 1 January 2013)

Abstract The ergogenic effect of caffeine on sports performance focuses predominantly on endurance sports (Doherty & Smith, 2004) with little research on intermittent high intensity sports. This study aimed to explore the effect of caffeine ingestion on skill maintenance following fencing simulated exercise. Eleven competitive fencers participated (four female; seven male; age 33 ± 6.5 years). Following a maximal test to exhaustion, fencers completed two trials assessing accuracy and reaction times (Stroop test) before and after a fatiguing protocol designed to simulate the demands of a fencing competition. Skill testing involved 30 lunges to hit a target. 500 ml placebo or 3 mg · kg−1 caffeine supplemented drink was administered after the initial reaction and skill tests in a single-blind crossover design. The fatiguing protocol involved simulating six ﬁghts with 6-minute rests between each. Fencers rated their perceived exertion (arm, legs, overall) using the Borg scale. There was no overall effect of caffeine on total skill score (P = 0.40), however there was a tendency for fewer misses with caffeine (P = 0.10). Caffeine had no effect on the Stroop Test. Caffeine produced signiﬁcantly lower perceived fatigue for overall (P < 0.01). These results provide some support for caffeine producing maintenance of skill and reducing perceived fatigue during fencing. Keywords: caffeine, fencing, skill, fatigue

Introduction Caffeine was removed from the world anti-doping association (WADA) banned list in 2004 (WADA, 2012) but remains on the monitoring list to detect patterns of misuse in sport. Consequently interest in the ergogenic effects of caffeine on sporting performance has increased. The effects of sports drinks on exercise capacity, performance and recovery have been well documented (Tarnopolsky & Cupido, 2000; Cureton & Warren, 2007). Caffeine has generally not been added to sports drinks because of a purported diuretic effect (Cureton & Warren, 2007), which could potentially have detrimental thermoregulatory effects in sports (ACSM [American College of Sports Medicine], 2009; Cureton & Warren, 2007; Pipe & Ayotte, 2002). However, contrary to popular beliefs, a review of literature by Armstrong, Casa, Maresh, & Ganio (2007) has shown that caffeine consumption does not result in water-electrolyte imbalances or hyperthermia. Fencing is an open-skilled combat sport (Roi & Bianchedi, 2008). Fencing involves frequent short

high intensity bursts of exercise, lunging towards an opponent during an attack; followed by periods of lower intensity exercise, bouncing preparatory movements (Paul, Miller, Bottoms, & Beasley, 2011). A competition can last between 9 and 11 hours but this consists of an effective fight time between 17 and 48 minutes. The distance covered by fencers has been reported to be between 250–1000 metres (Roi & Bianchedi, 2008). A competition consists of a first round where each fencer has between 5–6 fights up to five hits with a maximum duration of 3 minutes per fight. The fight ends when a fencer reaches five hits, or when 3 minutes of fencing time has been reached. If the scores are even after 3 minutes a minute of extra time is given. Following the first round a series of direct elimination fights is undertaken which consists of 15 hits and each fight can last up to 9 minutes with 2 × 1 minute breaks. If they have not achieved 15 hits and the score is even after 9 minutes of fencing time, an extra minute is given to decide the winner. The eventual winner of a

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competition will undertake about seven of these direct elimination fights. A key factor in performance success is the fencer’s reaction time in response to their opponent’s actions (Paul et al., 2011). Although there is a general paucity of research in fencing, studies have identified that an adequate psychological condition is required to prevent central and peripheral fatigue (Daya, Donne, & O’Brien, 2002; Roi & Bianchedi, 2008). Fatigue is one explanation for overt performance reductions during competitive sport (Noakes, 2000). Therefore, reducing the negative effect of fatigue, could potentially improve fencers’ responses and thus performance. There is a growing body of evidence suggesting that caffeine has an ergogenic effect through both peripheral and central mechanisms (ACSM, 2009; Cureton & Warren, 2007; Del Coso, Estevez, & Mora-Rodriguez, 2008; Doherty & Smith, 2004; Fredholm, Battig, Homen, Nehlig & Zvartaue, 1999; Glastier et al., 2008; Kalmar, 2005; Lopes, Aubier, Jardim, Aranda, & Macklem, 1983; Pipe & Ayotte, 2002; Plaskett & Cafarelli, 2001; Spriet, 1995; Tarnopolsky & Cupido, 2000). Caffeine has been demonstrated to have a direct action on skeletal muscle (Tarnopolsky & Cupido, 2000) during low stimulation frequency replicating endurance exercise, this could potentially lead to lower heart rate at a given workload. This action on the skeletal muscle demonstrates a peripheral action of caffeine, whereas it has also been shown to act through central mechanisms such as on the basal ganglia (Spriet, 1995) which improves motivation and cognitive function and reduces perception of fatigue. These central and peripheral mechanisms of action of caffeine may potentially benefit fencing performance by improving repeated high intensity exercise (Del Coso et al., 2012) and improving reaction time and finally reducing fatigue consequently preventing the associated deterioration in performance. However, caffeine can be ergolytic in high doses, producing tremor, mental agitation and tachycardia, all of which could negatively impact performance (Cureton & Warren, 2007). Evidence from previous research investigating tennis and cycling identified physiological and cognitive fatigue characteristics which were demonstrated to negatively influence skill-performance (Davey, Thorpe, & Williams, 2002; Hornery, Farrow, Mujika, & Young, 2007; Murray, Cook, Werner, Schlege, & Hawkins, 2001; Royal et al., 2006; Vergauwen, Spaepen, Lefevre, & Hespel 1998). Fencing performance which encompasses both physiological and cognitive demands may therefore be significantly influenced by the effects of fatigue. Thus ergogenic aids such as caffeine may have a beneficial effect on fencing performance.

This study aims to investigate the effect of caffeine on skill maintenance, cognitive function, perceived fatigue and physiological response following an exercise protocol developed to reflect the intensity of a fencing competition. It was hypothesised that caffeine ingestion would attenuate changes in skill within fencers and improve cognitive function. Methods Participants Eleven healthy adult epee fencers (four female; seven male; 33 ± 6.5 years; body mass 76.3 ± 14.3 kg; height 1.77 ± 0.09 m) who were all regularly competing in UK national level competitions and had been fencing for over two years (mean ± s 11.5 ± 6.0 years) volunteered to participate in the study. All participants were given written information concerning the nature and purpose of the study, completed a pre-participation medical screening questionnaire and gave written consent prior to participation. A post hoc statistical power analysis was conducted using the Hopkins method, and it was found that the sample size was sufficient to provide more than 80% statistical power. University Ethics Committee approval for the study’s experimental procedures was obtained and followed the principles outlined in the Declaration of Helsinki. Procedure The current investigation incorporated a single blind randomised cross over design; with all participants performing a maximal oxygen uptake test (VO2max) performed on a treadmill prior to data collection. This allowed for identification of the participants VO2max and their maximum heart rate in order to determine relative intensity during the experimental trials. The participants then completed two experimental trials separated by a week, where they either consumed 500 ml of sugar free fruit juice with 3 mg · kg · bw−1 of caffeine or 500 ml of the same fruit juice (Placebo). Preliminary trial The VO2max test was performed at least seven days prior to the experimental trials. The exercise test was carried out on a treadmill (H/P/Cosmos, Germany) using an initial running speed of 10 km · h−1 with a 1% gradient. Speed increments of 1 km · h−1 were made every two minutes for the first six minutes and thereafter the gradient increased by 2% every minute until volitional fatigue (Bottoms, Hunter, & Galloway, 2006; Bottoms, Taylor, Sinclair, Polman, & Fewtrel, 2012). Heart rate (Polar RS800, Finland)

Effect of caffeine on epee fencing performance and gas analysis measurements (Cosmed K4, UK) were monitored throughout the test period. Following the test the participants undertook a familiarisation of the experimental procedures.

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obtained immediately after completion of the fatiguing protocol and again at the end of the study. The experimental protocol is represented in Figure 1. Reaction test

Experimental trials Each participant completed two trials each involving a reaction time test and a fencing specific skills test both pre and post a fatiguing protocol (Figure 1). All testing was carried out on a shock absorbing sports surface with fencers using their own protective equipment and epees. The two trial sessions were conducted one week apart. Participants were asked to abstain from caffeine, alcohol and heavy training for 48 hours prior to each trial and also to replicate the same diet in these time periods. Immediately prior to each trial session body mass (Salter, 9141WH3R, UK), blood pressure (Omron, M4) and resting heart rates were recorded. Baseline blood glucose (Accu-Chek, Aviva, UK) and lactate (Lactate Pro, Bodycare, UK) levels were obtained before participants completed a 15 minute individual warm up routine as they generally would within a fencing competition. Following the warm up a reaction time test and skill test lasting approximately five minutes, were completed before ingesting the intervention drink. A 30-minute rest period was then undertaken by the participant followed by a fatiguing protocol. The fatiguing protocol consisted of a series of six simulated fights representing the first round of a fencing competition with duration of 60 minutes. One litre of fruit juice (125 ml fruit juice: 875 ml water) was ingested by the participants during the fatiguing protocol to simulate fluid ingestion during a competition. The reaction and skill tests were performed after completion of the fatiguing protocol. Ratings of perceived exertion were recorded after every fight for the sword arm (RPEarm), legs (RPElegs) and total exertion (RPEoverall) using the Borg scale. Blood lactate and glucose measures were

Figure 1. A schematic diagram representing the main study protocol.

The participants performed an online version of the Stroop test (http://www.onlinestrooptest.com) which displayed 20 word-colour combinations (a mixture of congruent and incongruent). The total response time for congruent and incongruent correct answers was recorded. Skill test The skill test used within the study focused on the central chest as a target. A 5 cm × 5 cm target graduated in 1 cm divisions was placed centrally on the fencing dummy’s chest. The fencer lunged to hit the target replicating a fencing competitive attack. The position of their front foot was marked from each participants ideal lunge distance (i.e. they performed a correct lunge technique and did not over or under extend during the lunge) and they returned to this position after each lunge. A cumulative score for each successful hit was recorded (3 if central, 2 if the point hit the inner ring, 1 if the outer ring, 0 if target missed) from 30 successive hits. During the skill tests, participants wore shorts and t-shirt whilst also wearing their own glove, mask and fencing footwear. Fatiguing protocol The fatiguing protocol simulated six poule fights from a previously developed lab based fencing specific protocol (Bottoms, Rome, Gregory, & Price, 2009) with a work to rest ratio during a fight of 1:0.8 which is comparable to previous published data (Roi & Bianchedi, 2008). The fatiguing protocol was designed to replicate competition fencing to the completion of the first

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L. Bottoms et al. Table I. Example of a poule ﬁght within the study fatiguing protocol. On (s) 9 9 9 9 9 9 9

Off (s)

No. of Lunges

No. of Retreats

No. of arm extensions

8 8 8 8 8 8 8

1 1 1 1 1 1 1

0 0 1 0 0 0 1

2 2 2 2 3 2 2

round of poules. The participants started by facing the static fencing dummy opponent in the on-guard position. A series of bouncing movements (9 seconds on 8 seconds off) with a standardised number of retreats, arm extensions and lunges whilst bouncing were then performed to replicate competition fighting attacks. An example of a fight is illustrated in Table I. A six-minute rest was timed between each fight to reproduce the maximum rest period within official competition. Heart rate data was recorded throughout each simulated fight to determine minimum, maximum and mean heart rates. Ratings of perceived exertion were recorded immediately after each simulated fight. Physiological data Body mass was recorded pre- and post-trial for each condition to calculate sweat loss. Blood glucose and lactate measurements were taken via capillary sampling (20 μl) at the finger at the start of the trial, immediately prior to starting the fatiguing protocol, on completion of the fatiguing protocol and at the end of the study for both trials. Data analysis The Shapiro-Wilk statistic confirmed that the normal distribution assumption was met for all variables. Therefore data were analysed using a repeated measures two-way (Treatment X Time) analysis of variance (ANOVA; SPSS v20). Appropriate post hoc analyses were conducted using a Bonferroni correction to control for type I error. Partial effect sizes were calculated using an η2. Data are presented as mean ± standard deviation in tables and figures. Significance was set at P < 0.05.

Results Participant characteristics and physiological data from the preliminary testing are presented in Table II. The participants were unaware whether they were ingesting caffeine or placebo. No significant differences were observed in the baseline values of any outcome measures between trials. Blood glucose and lactate Blood glucose concentrations remained constant throughout the protocol as there was no effect of time (P = 0.21, η2 = 0.14; Figure 2). There was also no effect of caffeine on blood glucose as there was no significant difference between trials (P = 0.96, η2 = 0.00) with mean concentrations of 5.2 (± 1.3) and 5.2 (± 0.8) mmol · l−1 for placebo and caffeine, respectively. There was a significant main effect for time for blood lactate (P < 0.01, η2 = 0.54; Figure 2). Blood lactate increased from rest (1.3 ± 1.2 and 1.4 ± 1.0 mmol · l−1 for placebo and caffeine, respectively) to the end of the fatiguing exercise (3.3 ± 1.9 and 3.2 ± 1.6 mmol · l−1 for placebo and caffeine, respectively). However, caffeine had no effect on blood lactate as there were no differences between trials observed (P = 0.99, η2 = 0.14). Skill test There was no effect of time on the total skill test scores as can be seen from Figure 3 (P = 0.69, η2 = 0.04), therefore fatigue had no effect on skill performance. There was also no effect of caffeine on the skill test (P = 0.40, η2 = 0.13). However,

Table II. Characteristics of the participants (n = 11).

Mean (± s)

Age (years)

Height (m)

Weight (kg)

Fencing Experience (years)

33.0 (± 6.5)

1.77 (± 0.09)

76.3 (± 14.3)

11.5 (± 6.0)

(ml−1

VO2max · min−1 · kg−1) 48.3 (± 6.8)

Maximum Heart Rate (beats · min−1)

Maximum blood lactate (mmol · l−1)

200 (± 6)

11.6 (± 0.9)

Effect of caffeine on epee fencing performance Placebo-glucose

Caffeine-glucose

Placebo-lactate

Caffeine-lactate

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7.0

Blood level (mmol · l−1)

6.0 5.0 4.0 3.0 2.0 1.0 0.0 Resting

Pre protocol

Post protocol

Final

Time Figure 2. Mean (± s) blood glucose and lactate concentrations during exercise for both placebo (PL) and caffeine (CAF).

Figure 3. Mean (± s) total skill test score pre and post fatiguing exercise for both PL and CAF.

comparing the number of misses between trials there was a tendency for caffeine to reduce the number of misses (P = 0.10, η2 = 0.31). During the placebo trial the number of ‘0’scores (indicating the fencer missed the target) after the fatiguing protocol was 7 ± 4 compared to 3 ± 3 during the caffeine trial. There were no differences in the number of 3s, 2s and 1s scored between trials (P > 0.05; Figure 4). There was also no difference in pre skill test scores on both trials indicating the skills test was reliable (P = 0.78).

(P = 0.48, η2 = 0.14) or incongruent conditions (P = 0.54, η2 = 0.17). Figure 5 illustrates the total response times for both congruent (e.g. the word blue written in blue ink) and incongruent (e.g. the word red written in black) questions of the Stroop test. Body mass Mean sweat losses were 0.57 ± 0.45 kg during PL and 0.58 ± 0.49 kg during the caffeine trial, with no signiﬁcant difference between trials (P = 0.89).

Reaction time test Caffeine had no effect on the reaction time test as there were no signiﬁcant differences demonstrated between caffeine and placebo for total response times throughout this study in relation to congruent conditions

Exercise intensity As can be seen from Table III, heart rate was signiﬁcantly lower during the caffeine trial compared to the placebo (P = 0.05, η2 = 0.34). This indicated

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Number of hits scoring 3,2,1 or 0

14 12 10 3 8

2 1

0 4 2 0 Pre Placebo Post Placebo Pre Caffiene Post Caffiene Study timepoint in relation to fatiguing protocol

Figure 4. Mean (± s) number of 3s, 2s, 1s and 0s scored pre and post fatiguing exercise for both PL and CAF. *denotes signiﬁcant difference from pre CAF.

18.00 incongruent time (secs)

16.00

congruent time (secs)

Total response time (s)

14.00 12.00 10.00 8.00 6.00 4.00 2.00 0.00

PLACEBO Pre

PLACEBO Post CAFFEINE Pre Time

CAFFEINE Post

Figure 5. Mean (±SD) congruent and incongruent response times to the Stroop test for both PL and CAF. Table III. Mean (± s) RPE (Borg Scale) and heart rate during all ﬁghts for PL and CAF trials for arm, legs and overall.

PL CAF

RPEarm

RPElegs

RPEoverall

Heart Rate (beats · min−1)

11 (± 2) 10 (± 2)

13 (± 3) 12 (± 3)

13 (± 2) 11 (± 2)*

143 (± 15) 133 (± 17)

*denotes signiﬁcant difference from PL.

that athletes were on average exercising at an intensity of 72 ± 6 and 67 ± 8% of their maximum heart rate for placebo and caffeine, respectively. In addition overall ratings of perceived exertion were lower during the caffeine trial compared to the placebo

trial (P = 0.03, η2 = 0.37; Table III). There was a main effect for time in all ratings of perceived exertion values with post hoc demonstrating an increase in ratings of perceived exertion as the ﬁght number increased (P < 0.01, η2 = 0.56). No effect of caffeine was observed for ratings of perceived exertion at the arm (P = 0.16, η2 = 0.21) or legs (P = 0.35, η2 = 0.09). Discussion The aim of this study was to examine the effects 3 mg · kg−1 of caffeine on skill and reaction time performance, and on perceived fatigue associated

Effect of caffeine on epee fencing performance with epee fencing. This dose of caffeine reduced perceived fatigue during fencing and also there was an observed tendency for maintenance of skill following simulated fencing, however there was no beneficial effect on reaction time. Epee fencing is a sport, which requires accurate body movements performed quickly in order to defeat the opponent. Measuring accuracy within the fencing skill paradigm is challenging given in epee the whole body is a valid target. The present study demonstrated that caffeine has a tendency to improve skill maintenance by reducing the number of non-scoring lunges. This finding is supported by previous research in other skill based sports, which has demonstrated caffeine increases passing accuracy in football (Foskett, Ali, & Gant, 2009) and rugby (Roberts et al., 2010; Stuart, Hopkins, Cook, & Cairns, 2005) and stroke accuracy in tennis (Hornery et al., 2007). Previous literature has shown that caffeine as low as 3 mg · kg−1 is sufficient to produce an ergogenic effect on performance (Graham & Spriet, 1995), however higher doses have been shown to produce significantly greater enhancements (Doherty & Smith, 2004). Therefore, it is possible that greater changes in accuracy would have been seen if a larger dose of caffeine (e.g. 6 mg · kg−1) was ingested. This is an area for further investigation. This study’s reaction time protocol used a computer Stroop test program as a measure of reaction times and thus cognitive function. The central mechanism of caffeine has been shown to improve cognitive function such as memory and reaction time (Jacobson & Edgley, 1987). The results obtained in the present study did not show an effect of caffeine on reaction times within the Stroop test, in contrast to other studies demonstrating reduced interference in response to caffeine ingestion (Kenemans, Wieleman, Zeegers, & Verbaten, 1999). Fatigue did not negatively affect the reaction time test results and this may be the reason why no difference was observed with caffeine ingestion. The movements within fencing are complex requiring coordination of upper and lower limbs in response to information given by their opponent to which the fencer then has to react. Studies have reported reaction times (some also commenting on accuracy) to protocols involving isolated touché, isolated lunge and sequential touché and lunge in response to light triggers (Harmenberg, Ceci, Barvestad, Hjerpe, & Nystrom, 1991; Roi & Bianchedi, 2008; Williams & Warmsley, 2000; Yiou & Do, 2000). These have been able to discriminate between the advanced and novice fencers. This reflects prior knowledge that elite fencers initiate a lunge by arm extension rather than foot movement and hit their target before the lead foot strikes

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the ground (Harmenberg et al., 1991; Roi & Bianchedi, 2008). However, as all the fencers in the current investigation were experienced fencers, a generic reaction time test was deemed to be sufficient to determine effects of fatigue and thus subsequent effects of caffeine. Visual information also plays a role in fencing success as fencers respond to movements of opponents’ weapons and postures to anticipate feints and counterfeits during bouts, again supporting the concept of a generic visual reaction time test such as the Stroop test. Rapid reaction times to stimuli are critical for fencing performance. However, as no differences were observed either before and after exercise or between trials, it may be more beneficial to undertake a fencing specific reaction time test. In future the authors recommend a sports specific reaction time test should be implemented. This study demonstrated a significant effect of time on ratings of perceived exertion and caffeine significantly reduced overall body ratings. This provides support for the fatiguing protocol used in the study (Bottoms et al., 2009). Heart rate is dependent on intensity of a fencing bout and previous studies (Roi & Bianchedi, 2008) have indicated that heart rates during competition can reach 70% of maximum heart rate which was achieved in the present study. Caffeine acts as a stimulant and may heighten cardiovascular responses; well-known side effects include palpitations if subjects are sensitive reflecting variation in caffeine metabolism. Share, Sanders, and Kemp (2009) reported no effect on heart rate however; in this study caffeine significantly reduced heart rates during the fatiguing protocol. It may be that in reducing ratings of perceived exertion caffeine also influenced cardiovascular parameters either through reduced pain perception or induced metabolic changes. As previously mentioned, the peripheral actions of caffeine have been demonstrated to potentiate low frequency skeletal muscle force (Tarnopolsky & Cupido, 2000), the lower heart rate could be a result of this peripheral action. Lower stimulation of the muscle could be required for the same exercise output, consequently reducing heart rate. This is an area for further research, but could be important for fencing performance. The central mechanisms for caffeine as an ergogenic aid to sport arise, in that the observed reduced overall body ratings of perceived exertion may contribute to enhanced performance despite rising lactate levels. Blunting of pain combined with perceived reduced effort may enable prolonged duration of exercise resulting in increased lactate level (Davis & Green, 2009). Furthermore ergogenic effects in relation to substrate availability, in particular glycogen, are less limiting to performance at this exercise

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intensity and duration (Bottoms et al., 2006; Davis & Green, 2009; Roberts et al., 2010). Conclusion The present study provides further limited support for caffeine demonstrating a positive effect on skill maintenance and reducing perceived levels of fatigue in sport characterised by intermittent high intensity exercise. A reduction in heart rate, potentially a result of a peripheral action of caffeine, appears to be supported from the results as a primary mechanism. Sport-speciﬁc research both in and out of competition is needed to increase applicability of results. The scope for using fencing as a sport in which to further this area of research is vast given the strong association between the physical, perceptual and psychological demands of the sport and both central and peripheral fatigue. Acknowledgements The authors would like to thank all the fencers who took part as well as Andy Smith and Anthony Tills for helping with some of the data collection. References ACSM American College of Sports Medicine/American Dietetic Association/Dieticians of Canada. (2009). Nutrition and athletic performance. Joint position statement. Medicine and Science in Sports and Exercise, 41(3), 709–731. Armstrong, L. A., Casa, D. J., Maresh, C. M., & Ganio, M. S. (2007). Caffeine, ﬂuid-electrolyte balance, temperature regulation, and exercise-heat tolerance. Exercise and Sports Science Reviews, 35(4), 135–140. Bottoms, L. M., Hunter, A. M., & Galloway, S. D. R. (2006). Effects of carbohydrate ingestion on skill maintenance in squash players. European Journal of Sport Science, 6(3), 187–195. Bottoms, L., Rome, P., Gregory, K., & Price, M. (2009). Development of a lab based fencing protocol for male epee fencers. Journal of Sports Sciences, 27(S2). s3–s135 Bottoms, L., Taylor, K., Sinclair, J., Polman, R., & Fewtrel, D. (2012). The effects of carbohydrate ingestion on the badminton serve following fatiguing exercise. Journal of Sports Sciences, 30(3), 285–293. Cureton, K. J., & Warren, G. L. (2007). Caffeinated sports drinks: Ergogenic effects and possible mechanisms. International Journal of Sport Nutrition and exercise Metabolism, 17, 35–55. Davey, P. R., Thorpe, R. D. & Williams, C. (2002). Fatigue decreases skilled tennis players. Journal of Sports Science, 20 (4), 318–8. Davis, J. K., & Green, J. M. (2009). Caffeine and anaerobic performance: Ergogenic value and mechanisms of action. Sports Medicine, 10, 813–832. Daya, A., Donne, B., & O’Brien, M. (2002). Newly designed fencing face mask: Effects on cardiorespiratory costs and submaximal performance. British Journal of Sports Medicine, 36, doi:10.1136/bjsm Del Coso, J., Estevez, E., & Mora-Rodriguez, R. (2008). Caffeine effects on short term performance during prolonged exercise in the heat. Medicine and Science in Sports and Exercise, 40(4), 744–751.

Del Coso, J., Muñoz-Fernández, V. E., Muñoz, G., FernándezElías, V. E., Ortega, J. F., Hamouti, N., … Muñoz-Guerra, J. (2012). Effects of a caffeine-containing energy drink on simulated soccer performance. PLoS One, 7(2), doi:10.1371/journal. pone.0031380 Doherty, M., & Smith, P. M. (2004). Effects of caffeine ingestion on exercise testing: A meta-analysis. International Journal of Sports Nutrition and Exercise Metabolism, 14, 626–646. Foskett, A., Ali, A., & Gant, N. (2009). Caffeine enhances cognitive function and skill performance during simulated soccer activity. International Journal of Sports Nutrition and Exercise Metabolism, 19, 410–423. Fredholm, B. B., Battig, K., Holmen, J., Nehlig, A., & Zvartau, E. E. (1999). Actions of caffeine in the brain with special reference to factors that contribute to its widespread use. Pharmacological Review, 51(1), 83–133. Glastier, M., Howatson, G., Abraham, C., Lockey, R. A. Goodwin, J. E., Foley, P., & McInnes, G. (2008). Caffeine supplementation and multiple sprint running performance. Medicine and Science in Sports and Exercise, 40(10), 1835–1840. Graham, T. E., & Spriet, L. L. (1995). Metabolic, catecholamine, and exercise performance responses to various doses of caffeine. Journal of Applied Physiology, 78, 867–874. Harmenberg, J., Ceci, R., Barvestad, P., Hjerpe, K., & Nystrom, J. (1991). Comparison of different tests of fencing performance. International Journal of Sports Medicine, 12, 573–576. Hornery, D. J., Farrow, D., Mujika, I., & Young, W. B. (2007). Caffeine, carbohydrate and cooling use during prolonged simulated tennis. International Journal of Sports Physiology and Performance, 2, 423–438. Jacobson, B. H., & Edgley, B. M. (1987). Effects of caffeine on simple reaction time and movement time. Aviation, Space and Environmental Medicine, 58(12), 1153–1156. Kalmar, J. M. (2005). The inﬂuence of caffeine on voluntary muscle activation. Medicine and Science in Sports and Exercise, 37(12), 2113–2119. Kenemans, J. L., Wieleman, J. S., Zeegers, M., & Verbaten, M. N. (1999). Caffeine and Stroop interference. Pharmacology Biochemistry and Behaviour, 63(4), 589–598. Lopes, J. M., Aubier, M., Jardim, J., Aranda, J. V. & Macklem, P. T. (1983). Effect of caffeine on skeletal muscle function before and after fatigue. Journal of Applied Physiology, 54(5), 1303–5. Murray, T. A., Cook, T. D., Werner, S. L., Schlegel, T. F., & Hawkins, R. J. (2001). The effects of extended play on professional baseball pitchers. American Journal of Sports Medicine, 29(2), 137–142. Noakes, T. D. (2000). Physiological models to understand exercise fatigue and the adaptations that predict or enhance athletic performance. Scandinavian Journal of Sports Medicine, 10, 123–145. Paul, S., Miller, W., Bottoms, L., Beasley, P. (2011). Epee fencing: A step-by-step guide to achieving Olympic gold with no guarantee you’ll get anywhere near it. Buxton, UK Wellard Publishing. Pipe, A., & Ayotte, C. (2002). Nutritional supplements and doping. Clinical Journal of Sports Medicine, 12(4), 245–249. Plaskett, C. J., & Cafarelli, E. (2001). Caffeine increases endurance and attenuates force sensation during submaximal isometric contractions. Journal of Applied Physiology, 91, 1535–1544. Roberts, S. P., Stokes, K. A., Trewartha, G., Doyle, J., Hogben, P., & Thompson, D. (2010). Effects of carbohydrate and caffeine ingestion on performance during a rugby union simulation protocol. Journal of Sports Sciences, 28(8), 833–842. Roi, G., & Bianchedi, D. (2008). The science of fencing: Implications for performance and injury prevention. Sports Medicine, 38(6), 465–481. Royal, K., Farrow, D., Mujika, I., Halson, S., Pyne, D., & Abernethy, B. (2006). The effects of fatigue on decision

Effect of caffeine on epee fencing performance making and shooting skill performance in water polo players. Journal of Sports Sciences, 24(8), 807–815. Share, B., Sanders, N., & Kemp, J. (2009). Caffeine and performance in clay target shooting. Journal of Sports Sciences, 27(6), 661–666. Spriet, L. L. (1995). Caffeine and performance. International Journal of Sport Nutrition, 5, S84–99. Stuart, G. R., Hopkins, W. G., Cook, C., & Cairns, S. P. (2005). Multiple effects of caffeine on simulated high-intensity teamsport performance. Medicine and Science in Sports and Exercise, 37(11), 1998–2005. Tarnopolsky, M. A., & Cupido, C. (2000). Caffeine potentiates low frequency skeletal muscle force in habitual and nonhabitual caffeine consumers. Journal of Applied Physiology, 89, 1719–1724.

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Vergauwen, L., Spaepen, A. J., Lefevre, J., & Hespel, P. (1998). Evaluation of stroke performance in tennis. Medicine and Science in Sports and Exercise, 30(8), 1281–1288. WADA. (2012). World anti-doping association banned list. Retrieved from http://www.wada-ama.org/en/World-Anti-Doping-Program/ Sports-and-Anti-Doping-Organizations/International-Standards/ Prohibited-List/QA-on-2011-Prohibited-List/ Williams, L. R. T., & Warmsley, A. (2000). Response timing and muscular coordination in fencing: A comparison of elite and novice fencers. Journal of Science and Medicine in Sport, 3(4), 460–475. Yiou, E., & Do, M. C. (2000). In fencing does intensive practice equally improve the speed performance of the touche when it is performed alone and in combination with the lunge? International Journal of Sports Medicine, 21, 122–126.

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