Effect of CR Supplementation on Athletic Performance

Effect of CR Supplementation on Athletic exerciseIntroductionTo succeed in a given sport at every(prenominal) level of competition, athletes must possess fractionicular physiologic, psychologic, and biomechanic traits critical to succeeder in that sport, but they must excessively receive optimal animal(prenominal), psychological, and biomechanical raising to maximise this genetic electromotive force (Williams, Kreider Branch, 1999). only many athletes believe that the cabal of genetic traits and optimal develop alone argon non sufficient to achieve maximum death penalty, thus the intake of ergogenic aids has extend common to change sports effect beyond the effect of training (Sundgot-Borgen, Berglund Torstveit, 2003). The use of goods and services of ergogenic aids lead allow athletes to gain that competitive favor everywhere opponents indeed leading to effectiveness success. According to Williams, Kreider Branch, (1999) ergogenic aids be substances or t reatments that ar theoretically externaliseed to enhance bodily power, mental strength or mechanical contact in that locationfore potentially better athletic cognitive process.Given the miscellaneous demands of team sports much(prenominal) as Soccer, Rugby and Hockey, which require small sporadic bouts of uplifted vehemence purpose which be interspersed by low level exert, it seems workable the use of ergogenic aids in such(prenominal) sports whitethorn enhance and benefit per descriptorance to gain that competitive march every view opponents. unitary ergogenic aid which has become popular among amateur, professional and volunteer(a) athletes over recent years is Creatine Monohydrate (Cr). Creatine is a of course occurring amino acid derivative which is name in boney muscular tissue, but is as well a prevalent fastetical constituent with a daily requirement of just about 2 to 3 grams depending on frame size (Ostojic, 2001). The absolute majority of creatine in muscles is stored in the form of phosphocreatine (PCr) which serves as an important contributor to zipper metabolism during lofty meretriciousness exercise (Williams, Kreider Branch, 1999). PCr provides the superior postcode phosphate for adenine diphosphate (ADP) to recuperate adenine triphosphate (ATP) niggardness rapidly via the Cr kinase (CK) reaction (Clarkson, 1996).Hultman, Bergstrom and McLennan-Anderson, (1967) demonstrate that depletion of PCr stores within the muscles feces lead to a decline in athletic execution during tall garishness exercise, so theoretically increasing PCr stores done Cr supplement would enhance the ability to bear on postgraduate warmth exercise over a prolonged purpose of time, leading to increases in sporting mathematical operation. Ahmun (2005) and Hultman, Soderlund, Timmons, Cederblad, Greenhaff, (1996) show that the come out Cr concentration in human muscle evict be increased finished and through Cr ac cessory over a 7 sidereal day period from 20% pre Cr to 50% post Cr.Since PCr is a substrate for the ATP-PCr energy system which is essential for gritty intensity exercise of 30 seconds or slight it seems logical that the supplement of Cr would be beneficial to exercise tasks of this date. in that respectfore the majority of previous question has foc employ on bouts of anaerobic cognitive operation of To date the effect of Cr subjoining on athletic carrying out has been widely look fored. This includes include absolute cause of Cr accessory over a prolonged period of over 4 weeks which is otherwise known as the aliment configuration (Knehans, Bemben, Bemben and Loftiss, 1998 Larson, Hunter, Trowbridge, Turk, Harbin and Torman, 1998). Also demonstrated shed been positive personal pass on of Cr supplement on exercise mathematical process victimisation a shorter intake period known as the fill phase (Stout, Echerson, Noonan, Moore, and Cullen, 1999 Volek, Boe tes, Bush, Putukian, Sebastianelli and Kraemer, 1997a). This includes improvements in military operation variables such as strength, speed and delaying the assault of bear (Okudan and Gokbel, 2004 Volek, Kraemer, Bush, Boetes, Incledon, Clark and Lynch 1997b Kocak Karli , 2003)Team sports consist of repetitioned bouts of intermittent richly intensity exercise indeed consistently relying on the ATP-PCr energy system which if depleted nonify devote a major cistron on surgical operation and the outcome of a endorse (Ostojic, 2004). one and only(a) such sport which consists of repeated bouts of high intensity exercise is association foot evening gown. Soccer unravelers are required to seduce high power outputs and maintain or repeat them with only a few seconds of recovery, (Reilly and Williams, 2003). such(prenominal) high intensity obiter dictums could be the decision making instrument of a game, for example dashing back to make a game saving tackle or hyphenin g one-time(prenominal) a defender to the hunk to make a shot. angiotensin converting enzyme high intensity exercise instance which occurs in a association football game tint are bouts of dahing, which are estimated to consist of 8.1% of a 90 slight ascertain and occur approximately every 90 seconds long-lasting amongst dickens to quadruple seconds in duration (Bangsbo, Norregard Thorso, 1991). Given the fact that in that location is considerable curb for Cr as an ergogenic aid it would be reasonable to suggest that a association football raceers hyphen surgical physical process would benefit from Cr subjoining. However there is minimal research which has looked into the set up of Cr on bolt performance and variables of association football harmonise play such as agility running, lateral pass stepping and running backwards( Cox, Mujika, Tumilty and murder 2002 Ostojic, 2004 Mujika, Padilla, Ibanez, Izquierdo and Gorostiaga, 2000). The aforementioned studies bedevil crackd the personal effectuate of Cr on elite association football players, fe manful association football players and youth association football players (Ostojic, 2004 Mujika et al., 2000 Smart et al 1998 Cox et al., 2002). However there is no present research that looks into the effects of nifty ( Another opinion to consider upon riddleing the effects of Cr on style performance on amateur association football players is the communications protocol to be use. Although there fuddle been many protocols which have been designed to measure and simulate association football performance, plenty of these have failed to adequately simulate the diametric travail patterns ( dahing, base on balls, running backwards, lateral stepping) which are pertain in a game of soccer (Drust, Reilly and parentage, 2000 Abt, Reaburn, Holmes and Gear, 2003 Thatcher and Batterham, 2004). It seems rational that when assessing components of soccer performance that the protocol that is utilized replicates the dis connatural natural action patterns and demands of soccer add together. If this is not taken into shape it becomes unmanageable to determine whether Cr supplementation will have any benefit on soccer performance. so the utilize protocol carrys to short replicate movement patterns in soccer so that a valid assumption faeces be made to determine the erogeneity of bang-up Cr supplementation on elan performance in amateur soccer players.Thus the purpose of this culture is to conduct an probe that will determine the effect of corking Cr supplementation on sprint performance in Caucasian staminate amateur soccer players, using a soccer cloak protocol in an accurate, valid and reliable manner with cardinal political campaigns consisting over a 7 day period. Concluding whether or not acute Cr supplementation can be used as an ergogenic aid to improve a footballers sprint performance, therefore recommending to athletes and coaches alike. litera ry productions ReviewCreatine Monohydrate BackgroundCreatine monohydrate is one of the closely popular sporting supplements in the terra firma today and is used by high school athletes, the elderly, professional and recreational athletes in the hope of upward(a) physical performance (Bemben and Lamont, 2005). It is the most unremarkably avai science laboratoryle Cr supplement and the form primarily used in most research studies. Cr monohydrate comes in a progeny of forms including powder, tablets, gel, liquid, chewing gum and edulcorate (Williams, Kreider and Branch, 1999, p.43). Greenhaff (1997) indicated powdered Cr, ingested with solution to have a quicker assimilation rate at raising muscle Cr concentration than using Cr supplementation of a tablet form. Conversely Vuckovich and Michaelis (1999) reported no probative difference in absorption rate surrounded by the deuce unalike forms.Dosage methodsThe supplementation dosages of Cr can be broken down into ii disparat e phases, otherwise known as the loading phase and maintenance phase. The loading phase that is commonly used in research consists of ingesting daily, 20-30g of Cr in four equal doses of 5-7g dissolved in well-nigh 250ml of fluid interspersed throughout the course of the day (preferably morning, noon, afternoon and evening) for a period of 5 to 7 long time (Greenhaff, 1997 Kreider, 1997). Hultman et al (1996) utilise a less intense loading method of 3g/day for 28 years and proposed it to be just as rough-and-ready as the aforementioned loading protocol.However this method pop outs a longer dependency on subjects to abide by with the supplementation program, therefore placing more variables into the reliability of results. Following the loading phase, maintenance dosages are considerably lower. virtually research investigating the effects of Cr using the maintenance phase, have use dosages of 3 to 15g over a 4 to 10 week period (Bemben et al., 2001 Kreider et al., 1998 gemst one et al., 1999 new wavedenberghe et al., 1997). It is recommended to consume Cr with warm physical structure of water, as it facilitates the dissolving of the solution and also aid absorption (Harris et al., 1992). It should also be noted that the ingestion of caffeine during Cr supplementation eradicates its potential ergogenic effect (Vandenberghe et al., 1996 Van Leemputte, Vanstapel Hespel, 1997). Vandenberghe et al (1996) demonstrated that a control meeting that ingested Cr combined with caffeine to have a change magnitude ergogenic potential compared to a group that ingested Cr without caffeine during repeated bouts of high intensity exercise.Side effects There is no conclusive scientific evidence to suggest that Cr ingestion has any proscribe side effects utilising the proposed dosage methods ( Larson et al., 1998 Schroder, Terrados Tramullas, 2005). There is further evidence to support this as Kreider et al (1999) embed no negative side effects in athletes who had been ingesting Cr for up to 3 years. Poortmans and Francaux (1999) demonstrated similar decisions for athletes for taking Cr for up to 5 years. Only undocumented anecdotal reports have reported any adverse negative side effects through Cr supplementation, this includes gastroin examineinal distress, muscle cramping and dehydration (Associated pack 1997, 1998).Taking dehydration into consideration such anecdotal research can be scrutinised. Oopik, Timpmann and Medijainen, (1995) demonstrated that Cr supplementation increased body slew, enchantment also reporting increases in total body water. Such findings signify that Cr supplementation may prevent dehydration rather than be a cause, referable to the fact it can promote water retention.Cr supplementation has been demonstrated to increase body mass by up to 2kg over an acute period of time (Balsom et al., 1995 Becque et al., 1997). This could be recognised as a negative side effect for athletes that fence in weight control sport s, as Cr ingestion may impede their ability to make regulated weight in a forthcoming event. This gives a consensus that athletes in such activities need to be made aware that although Cr can promote gains in strength and power, it can increase body mass.Physiology of SoccerSoccer players are frequently required to originate high power outputs and maintain of repeat them with only a few seconds of recovery (Reilly and Thomas, 2003). This includes intermittent bouts of kicking, tackling, turning, sprinting, ever-changing pace and maintaining balance and control of the ball whilst at a lower place pressure from an opponent (Wisloff, Helgerud Hoff, 1998). To gain a scientific perspective of the different physiological demands of soccer performance, pair and time motion analysis have been utilised (Bangsbo, 1994). This analysis has allowed researchers to determine the overall workload of players during a 90 second base match by sharp total outmatch cover, and the pattern of acti vities performed during a game (e.g. sprinting, cruising, walking etc).Movement patterns of SoccerIt is estimated that the total distance cover during a 90 minute soccer match varies from 8.7km to 11.5km ( Bangsbo Lindquist, 1992 Ekblom, 1986 Ohashi et al., (1988) Reilly and Thomas, 1976 1988 Rampini et al., 2007 Wade, 1962). The large variance in distances covered are collect(p) in take leave to the differing styles of play, levels of competition and skill level of the teams that were utilised (Luxbacher, 1997).Reilly (1994) documented the different activity patterns of elite outfield players from the English die division and other major national leagues in europium and Japan using different methods of match analysis. Results run aground that a 90 minute match consists of 24% walking, 36% jogging, 20% cruising sub maximumly (striding), 11% sprinting, 7% piteous backwards and 2% moving in possession of the ball.The categories of sprinting and cruising are delineate as high intensity exercise. In terms of distances covered the ratio of low intensity exercise to high intensity exercise during a soccer match is 7 to 1 denoting that the outlay of energy for soccer is predominately aerobic ( Reilly and Thomas, 1976). However the importance for high intensity bouts during soccer match play should not be underestimated. The timing of such a bout could be the defining factor of a game whether in possession of the ball or without the ball. Although work-rate profiles are comparatively consistent for players from game to game it is the high intensity exercise which is the most constant feature (Bangsbo, 1994).The number of sprints reported in a soccer game varies greatly from 17 to 62 (Bangsbo et al., 1991 Mohr, Krustrup Bangsbo, 2003). This variance is mostly headstrong by the positional single-valued function of the player. Findings by Reilly (1996) demonstrated that midfielders and strikers completed more sprinting bouts than centre backs or good backs therefore relying more on the anaerobic energy system.However if there is not a prolonged recovery period or an individual is not properly conditioned they will not subsequently recovery from high intensity bouts of exercise and fatigue will occur (Reilly, 1996). This is evident as Reilly (1996, p.72) documented that the majority of goals conceded during a soccer match occurred in the final ten proceedings of play. A popular theory for this occurrence has been implant to be mental fatigue or lapses in concentration from defenders (Reilly, 1996, p.72). However this can theory can be scrutinised as research piece that the onset of fatigue in intermittent exercise such as soccer is caused by low muscle glycogen stores (Balsom et al., 1999).Acute Cr supplementation and sprint performance in team sportsAthletes in team sports such as soccer, rugby, hockey and American football are required to repeatedly reproduce intermittent bouts of high intensity exercise with minimal recovery. be ing able to consistently reproduce such bouts at supreme ability (e.g. sprinting, stomaching, running backwards) could be the deciding factor in competition to gain that extra edge of an opponent. During high intensity exercise of an intermittent nature the main contributor of energy is PCr (Williams, Kreider Branch, 1999, p29). Depletion of PCr stores during high intensity exercise has been found to be a factor which has lead to a decline in athletic performance (Hultman, Bergstrom and McLennan-Anderson, 1967). Through the supplementation of Cr, it hypothesised that PCr stores are replenished at a faster rate therefore improving an athletes ability to recover and perform intermittent high intensity bouts of exercise, leading to improved athletic performance (Greenhaff et al, 1993).There have been various studies that have tried this hypothesis by investigating the ergogenic effect of acute Cr supplementation on sprint performance of athletes in team sports (Ahmun et al., 2005 C ornish, Chilibeck Burke, 2006 Izquierdo et al., 2001 Kocak Karli, 2003 Romer et al., 2001 Vandebuerie et al., 1998). However the aforementioned studies have credit lineing findings with a quantity of studies finding a world-shattering improvement in sprint performance through Cr supplementation (Izquierdo et al., 2001 Romer et al., 2001 Vandebuerie et al., 1998). On the contrary other studies have found no prodigious improvements in sprint performance through acute Cr ingestion (Ahmun et al., 2005 Cornish, Chilibeck Burke, 2006 Kocak Karli, 2003).Ahmun et al., (2005) investigated the ergogenic effect of Cr on sprint performance in mannish rugby players. For this matter a Wingate running protocol was utilised prior and post Cr supplementation. Findings of this need were that there was no substantial improvement in maximal cycle sprints through Cr ingestion. However in contrast Izquierdo et al., (2001) found that acute Cr supplementation improved sprint times in male hand ball players. For this study subjects were either assign Cr or placebo over a 5 day period. The protocol that was utilised consisted of repeated sprint runs that were consistent with sprint distances achieved during handball match play. One issue that could have had a determining factor of the non significant results found by Ahmun et al (2005) is the protocol that was utilised.A Wingate test was utilised to test the sprint performance in rugby players, still the relevancy of a Wingate test to measure rugby performance is not sports specialized there scrutinising the boldness of the results. In contrast Izquierdo et al (2001) utilised a protocol which successfully replicated distances found in handball match play therefore maintaining rigour. Ahmun et al (2005) also failed to incorporate a dietetical analysis into the data- found design of the protocol, therefore whether or not Cr stores within the subjects utilised were full cannot be determined, which gives rationale for res ults showing no significant improvement. In contrast Izquierdo et al (2001) apply a dietary examination of subjects that were utilised this was initiated to determine whether any subjects had ingested Cr or any ergogenic aids prior to baseline interrogatory. This assisted with maintaining validity during research. This can be supported by Romer et al (2001) and Vandebuerie et al (1998) who utilised a protocol containing a dietary analysis and concluded a significant improvement in sprint times within subjects.Cr supplementation and Soccer performanceGiven the intermittent physical demands of soccer, which requires players to produce high power outputs and maintain or repeat them with only a few seconds of recovery, (Reilly and Williams, 2003) it seems feasible that soccer players would benefit from the supplementation of Cr as an ergogenic aid to improve their overall performance. However research that has investigated the effect on acute Cr supplementation on different variables of soccer performance and predominately sprint performance utilising a soccer poser protocol is limited (Ostojic, 2004 Mujika et al 2000 Cox et al 2002).The same studies have primarily focused on the effects of Cr supplementation on highly teach athletes that are competing at a high standard of competition. However no previous research has looked into the effects of acute Cr supplementation on amateur soccer players. Being as though Cr monohydrate is an immensely popular ergogenic aid not only among professional athletes but also amateur and recreational athletes, the benefit to amateur athletes needs to recognised. earlier research that has looked into the effects of acute Cr supplementation on soccer players using a soccer excuse protocol is discussed below.Ostojic (2004) examined the effects of acute Cr supplementation (3 x 10g doses for 7 days) on 20 childly male soccer players (16.6 1.9 years). For the examination procedure a double blind method was used and where subjec ts were either administered either Cr or placebo. Subjects completed two resolve trials prior and post to Cr or placebo. The examination procedure consisted of a number of soccer peculiar(prenominal) skill tests which included a dribble test, sprint-power test, endurance test and a upended jump test. Results found that there was a significant improvement in a number of the soccer specific tests this includes superior improvements in sprint times, vertical jump scores and the dribble test.However no significant improvements were made on endurance performance after the two trials. Although a significant improvement was found in vertical jump performance, it is of denote to future researchers to whether the vertical jump test that was utilised during the design is a soccer specific test. During the test subjects were instructed to keep their trunk as straight as come-at-able whilst keeping their hands on their hips to neutralise contribution from the arms which doesnt successfull y replicate jumping movements in soccer therefore questioning the validity of the vertical jump test as to whether or not it is a measure of soccer specific performance.The age of the subjects in this research can also be scrutinised. Eichner, King, Myhal, Prentice and Ziegenfuss (1999) confirmed that there was depleted research to determine the acute and chronic side effects of Cr consumption in athletes under the age of 18 therefore places the subjects which were used in the mentioned study under possible risk. Eichner et al (1999) also highlighted that Cr supplementation in young athletes could have a possible degradation of ethics, by where a win at all costs mentality is fostered and an carriage by where ergogenic aids are requirement to win, which is the wrong message to be installing in young athletes.Likewise Mujika, Padilla, Ibanez, Izquerido and Gorostiaga (2000) concluded acute Cr supplementation (20g a day x 6 days) importantly improved sprint performance and found n o significant improvement in endurance performance using a soccer simulation protocol. Mujika et al (2000) also documented no increase in vertical jump performance using a similar protocol to Ostojic (2004) which has minimal signification in a soccer simulation study. Mujika et al (2000) tested 19 elite male soccer players who at the time of investigating were highly trained, nevertheless only 17 fully completed the testing collect to illness or injury.The protocol for this investigation consisted of a circuit of different exercises which consisted of a repeated sprint test (5 and 15m), vertical jump test and an intermittent endurance test. Findings in this study concluded that blotto sprint times improved significantly (pThis de-training effect is evident for the vertical jump test as no significant improvement between the two trials was found. However if there was a significant de training effect it would have had negative consequences on other testing variables such as spri nt performance, this however is not the case as sprint performance significantly improved. Mujika et al (2000) should have took into consideration a possible detraining effect when devising the observational design as this could have negatively affect the validity of the results.Cox, Mujika, Tumilty and Burke (2002) devised a study which tested Cr supplementation (20g a day) or placebo (20g glucose a day) on 14 elite female soccer players from the Australian institute of sport (AIS) using a soccer simulated protocol. The experimental design consisted of two trials before and after Cr or placebo over a 6 day period. The protocol consisted of cubic decimeter five 20m sprints, ten agility runs and a precision ball kicking drill which are separate by recovery walks, jogs and runs. The main findings in this study were that the average 20m sprint time in the Cr group decreased from 3.75 0.19 to 3.69 0.18s however this decrease in sprint time failed to r to each one the statistical si gnificance level (pCox et al (2002) also incorporated a interchangeable training regime and a controlled diet for the intervention week and also scheduled testing so that it would occur at the homogeneous time of day before and after supplementation. In contrast Mujika et al (2000) failed to utilise effective like procedures during their experimental design. As previously mentioned Mujika et al (2000) testing procedures took place 3 days after the subjects indurate had finished therefore training was not standardised due to the fact that subjects had no organised training sessions during the intervention week. Mujika et al (2000) also lacked a familiarisation trial, subjects were only inform with the testing procedures prior to arriving for the 1st trial which could substantially affect the results. However although Cox et al (2000) standardised procedures by included a controlled diet for the subjects, it is interesting to note that one of the subjects was a vegetarian, whos C r gist is virtually zero (Greenhaff, 1997). Research has found that vegetarians respond quicker and more effectively to Cr supplementation than those who follow a normal sedentary diet and have natural muscle creatine case (Burke, Chilibeck, Parise, Candow, Mahoney Tamopolsky., 2003 Watt, Garnham Snow, 2004) therefore scrutinising the validity of the results. It may be of future reference to eradicate vegetarians in a experimental design which utilises Cr supplementation due to the diet implications that vegetarians have.Soccer Simulation performance testsTo date there has been a number of soccer simulation performance tests which have been utilised to assess and measure different physiological aspects of the game (Bangsbo and Lindquist, 1992 Cox, 2002 Drust, Reilly and Cable, 2000 Nicholas, Nuttall and Williams, 2000). These protocols have been implemented so that they take into consideration different aspects of soccer performance and try to replicate the exercise patterns tha t are observed during match play, however due to the spontaneity of the soccer it is difficult to assess every physical or metabolic demand (Drust, Reilly and Cable, 2000). Researchers have used different protocols when investigating the metabolic and physical demands of soccer, these can documented into laboratory based protocols (Drust, Reilly and Cable, 2000 Thatcher and Batterham, 2004) and field based protocols (Bangsbo and Lindquist, 1992 Cox, 2002 Nicholas et al 2000).Laboratory based soccer performance protocolsDrust, Reilly and Cable (2000) devised a laboratory based protocol on a motorised treadmill what represented the work rates that are observed during soccer match play. For the experimental design 7 male university soccer players (24 2 years) were used and the testing consisted of three separate testing blocks which were separated by 6 days. The protocol consisted of the different exercise intensities that are utilised during soccer match play this consisted of walk ing, jogging, cruising and sprinting. The speeds at which these exercises were performed on the treadmill were consistent with speeds observed by Van Gool, Van Gervan and Boutmans (1988) during a match analysis. Each testing block consisted of two 22.5 minute cycles which consisted of 23 bouts which were followed by a recovery period of 71 seconds.During each bout the duration of each activity was as follows walking 35 seconds (s), jogging 50.3s, cruising 51.4s and sprinting 10.5s. However in relevance to this research project it should be noted that the duration covered during the sprint bouts of the protocol of Drust, Reilly and Cable (2000) which is 10.5s does not successfully coincide with match analysis from several(prenominal) soccer studies that have documented the duration of sprint bouts during soccer match play. Research has found that the average sprint time during soccer match play lasts between on average two to four seconds in duration (Bangsbo, Norregard Thorso,1991 Mayhew and Wenger, 1985) therefore lowest in some instances Drust, Reilly and Cables (2000) laboratory based soccer specific protocol can be deemed as in valid as it fails to accurately replicate different soccer performance variables that take place in match play.Another lab based test that was utilised to measure specific variables in soccer performance was devised by Thatcher and Batterham (2004). For this protocol six male professional soccer players were used and the testing consisted of 29 minute exercise bouts on a non motorised treadmill that focused on replicating different speeds, durations, distances and heart rates that occur during soccer match play. Findings from this study suggest that the protocol that was utilised generate a similar physiological load to soccer match play and can be determined as a valid measure of soccer performance.Although lab based soccer specific protocols have been found to replicate some instances of soccer performance it is of consideratio n of this research project that the limitations and positives of such protocols be noted. The aforementioned lab based failed to perform a re-test procedure to conclude whether their protocols maintained reliability therefore the amount of error in each protocol cannot be determined. Another limitation of lab based testing is that due to tests being performed on treadmills, this limits the subjects to straight-line running only, therefore does not take into consideration lateral movements and agility patterns, which have found to be major characteristics of soccer performance (Bangsbo and Lindquist, 1992). These unorthodox movement patterns need to be taken into consideration when assessing soccer performance as they increase energy expenditure significantly (Nicholas et al., 2000). One positive aspect of lab based protocols are that procedures such as air temperature, equipment utilised and humidity can be easily standardised to stay put constant throughout performance testing. th eater TestsNicholas et al (2000) devised the Loughborough Intermittent Shuttle test (LIST) to simulate the activity patterns during a game of soccer. The LIST consisted of two separate stages which were known as part A and part B. Part A lasted 70 minutes and consisted of five 15 minute exercise peEffect of CR Supplementation on Athletic PerformanceEffect of CR Supplementation on Athletic PerformanceIntroductionTo succeed in a given sport at any level of competition, athletes must possess specific physiologic, psychologic, and biomechanic traits critical to success in that sport, but they must also receive optimal physical, mental, and biomechanical training to maximise this genetic potential (Williams, Kreider Branch, 1999). However many athletes believe that the combination of genetic traits and optimal training alone are not sufficient to achieve maximum performance, therefore the use of ergogenic aids has become common to improve sports performance beyond the effect of training (Sundgot-Borgen, Berglund Torstveit, 2003). The use of ergogenic aids will allow athletes to gain that competitive advantage over opponents therefore leading to potential success. According to Williams, Kreider Branch, (1999) ergogenic aids are substances or treatments that are theoretically designed to enhance physical power, mental strength or mechanical edge therefore potentially improving athletic performance.Given the various demands of team sports such as Soccer, Rugby and Hockey, which require short intermittent bouts of high intensity exercise which are interspersed by low level exercise, it seems feasible the use of ergogenic aids in such sports may enhance and benefit performance to gain that competitive edge over opponents. One ergogenic aid which has become popular among amateur, professional and recreational athletes over recent years is Creatine Monohydrate (Cr). Creatine is a naturally occurring amino acid derivative which is found in skeletal muscle, but is also a normal dietary constituent with a daily requirement of approximately 2 to 3 grams depending on body size (Ostojic, 2001). The majority of creatine in muscles is stored in the form of phosphocreatine (PCr) which serves as an important contributor to energy metabolism during high intensity exercise (Williams, Kreider Branch, 1999). PCr provides the high energy phosphate for adenine diphosphate (ADP) to restore adenine triphosphate (ATP) concentration rapidly via the Cr kinase (CK) reaction (Clarkson, 1996).Hultman, Bergstrom and McLennan-Anderson, (1967) demonstrated that depletion of PCr stores within the muscles can lead to a decline in athletic performance during high intensity exercise, so theoretically increasing PCr stores through Cr supplementation would enhance the ability to maintain high intensity exercise over a prolonged period of time, leading to increases in sporting performance. Ahmun (2005) and Hultman, Soderlund, Timmons, Cederblad, Greenhaff, (1996) demonstrated t hat the average Cr concentration in human muscle can be increased through Cr supplementation over a 7 day period from 20% pre Cr to 50% post Cr.Since PCr is a substrate for the ATP-PCr energy system which is essential for high intensity exercise of 30 seconds or less it seems logical that the supplementation of Cr would be beneficial to exercise tasks of this duration. Therefore the majority of previous research has focused on bouts of anaerobic performance of To date the effect of Cr supplementation on athletic performance has been widely researched. This includes include positive effects of Cr supplementation over a prolonged period of over 4 weeks which is otherwise known as the maintenance phase (Knehans, Bemben, Bemben and Loftiss, 1998 Larson, Hunter, Trowbridge, Turk, Harbin and Torman, 1998). Also demonstrated have been positive effects of Cr supplementation on exercise performance using a shorter ingestion period known as the loading phase (Stout, Echerson, Noonan, Moore, a nd Cullen, 1999 Volek, Boetes, Bush, Putukian, Sebastianelli and Kraemer, 1997a). This includes improvements in performance variables such as strength, speed and delaying the onset of fatigue (Okudan and Gokbel, 2004 Volek, Kraemer, Bush, Boetes, Incledon, Clark and Lynch 1997b Kocak Karli , 2003)Team sports consist of repeated bouts of intermittent high intensity exercise therefore consistently relying on the ATP-PCr energy system which if depleted can have a major factor on performance and the outcome of a game (Ostojic, 2004). One such sport which consists of repeated bouts of high intensity exercise is soccer. Soccer players are required to produce high power outputs and maintain or repeat them with only a few seconds of recovery, (Reilly and Williams, 2003). Such high intensity instances could be the deciding factor of a game, for example sprinting back to make a game saving tackle or sprinting past a defender to the ball to make a shot.One high intensity exercise instance whi ch occurs in a soccer match are bouts of sprinting, which are estimated to consist of 8.1% of a 90 minute match and occur approximately every 90 seconds lasting between two to four seconds in duration (Bangsbo, Norregard Thorso, 1991). Given the fact that there is considerable support for Cr as an ergogenic aid it would be reasonable to suggest that a soccer players sprint performance would benefit from Cr supplementation. However there is minimal research which has looked into the effects of Cr on sprint performance and variables of soccer match play such as agility running, lateral stepping and running backwards( Cox, Mujika, Tumilty and Burke 2002 Ostojic, 2004 Mujika, Padilla, Ibanez, Izquierdo and Gorostiaga, 2000). The aforementioned studies have determined the effects of Cr on elite soccer players, female soccer players and youth soccer players (Ostojic, 2004 Mujika et al., 2000 Smart et al 1998 Cox et al., 2002). However there is no present research that looks into the effe cts of acute ( Another aspect to consider upon testing the effects of Cr on sprint performance on amateur soccer players is the protocol to be used. Although there have been many protocols which have been designed to measure and simulate soccer performance, plenty of these have failed to adequately simulate the different movement patterns (sprinting, walking, running backwards, lateral stepping) which are involved in a game of soccer (Drust, Reilly and Cable, 2000 Abt, Reaburn, Holmes and Gear, 2003 Thatcher and Batterham, 2004). It seems rational that when assessing components of soccer performance that the protocol that is utilised replicates the different activity patterns and demands of soccer match. If this is not taken into consideration it becomes difficult to determine whether Cr supplementation will have any benefit on soccer performance. Therefore the utilised protocol needs to concisely replicate movement patterns in soccer so that a valid assumption can be made to determ ine the erogeneity of acute Cr supplementation on sprint performance in amateur soccer players.Thus the purpose of this study is to conduct an investigation that will determine the effect of acute Cr supplementation on sprint performance in Caucasian male amateur soccer players, using a soccer simulation protocol in an accurate, valid and reliable manner with two trials consisting over a 7 day period. Concluding whether or not acute Cr supplementation can be used as an ergogenic aid to improve a footballers sprint performance, therefore recommending to athletes and coaches alike.Literature ReviewCreatine Monohydrate BackgroundCreatine monohydrate is one of the most popular sporting supplements in the world today and is used by high school athletes, the elderly, professional and recreational athletes in the hope of improving physical performance (Bemben and Lamont, 2005). It is the most commonly available Cr supplement and the form primarily used in most research studies. Cr monohydr ate comes in a number of forms including powder, tablets, gel, liquid, chewing gum and candy (Williams, Kreider and Branch, 1999, p.43). Greenhaff (1997) indicated powdered Cr, ingested with solution to have a quicker absorption rate at raising muscle Cr concentration than using Cr supplementation of a tablet form. Conversely Vuckovich and Michaelis (1999) reported no significant difference in absorption rate between the two different forms.Dosage methodsThe supplementation dosages of Cr can be broken down into two different phases, otherwise known as the loading phase and maintenance phase. The loading phase that is commonly used in research consists of ingesting daily, 20-30g of Cr in four equal doses of 5-7g dissolved in around 250ml of fluid interspersed throughout the course of the day (preferably morning, noon, afternoon and evening) for a period of 5 to 7 days (Greenhaff, 1997 Kreider, 1997). Hultman et al (1996) utilised a less intense loading method of 3g/day for 28 days an d proposed it to be just as effective as the aforementioned loading protocol.However this method places a longer dependency on subjects to comply with the supplementation program, therefore placing more variables into the reliability of results. Following the loading phase, maintenance dosages are considerably lower. Most research investigating the effects of Cr using the maintenance phase, have utilised dosages of 3 to 15g over a 4 to 10 week period (Bemben et al., 2001 Kreider et al., 1998 Stone et al., 1999 Vandenberghe et al., 1997). It is recommended to consume Cr with warm water, as it facilitates the dissolving of the solution and also aid absorption (Harris et al., 1992). It should also be noted that the ingestion of caffeine during Cr supplementation eradicates its potential ergogenic effect (Vandenberghe et al., 1996 Van Leemputte, Vanstapel Hespel, 1997). Vandenberghe et al (1996) demonstrated that a control group that ingested Cr combined with caffeine to have a lessene d ergogenic potential compared to a group that ingested Cr without caffeine during repeated bouts of high intensity exercise.Side effects There is no conclusive scientific evidence to suggest that Cr ingestion has any negative side effects utilising the proposed dosage methods ( Larson et al., 1998 Schroder, Terrados Tramullas, 2005). There is further evidence to support this as Kreider et al (1999) found no negative side effects in athletes who had been ingesting Cr for up to 3 years. Poortmans and Francaux (1999) demonstrated similar findings for athletes for taking Cr for up to 5 years. Only undocumented anecdotal reports have reported any adverse negative side effects through Cr supplementation, this includes gastrointestinal distress, muscle cramping and dehydration (Associated press 1997, 1998).Taking dehydration into consideration such anecdotal research can be scrutinised. Oopik, Timpmann and Medijainen, (1995) demonstrated that Cr supplementation increased body mass, while also reporting increases in total body water. Such findings signify that Cr supplementation may prevent dehydration rather than be a cause, due to the fact it can promote water retention.Cr supplementation has been demonstrated to increase body mass by up to 2kg over an acute period of time (Balsom et al., 1995 Becque et al., 1997). This could be recognised as a negative side effect for athletes that compete in weight control sports, as Cr ingestion may impede their ability to make regulated weight in a forthcoming event. This gives a consensus that athletes in such activities need to be made aware that although Cr can promote gains in strength and power, it can increase body mass.Physiology of SoccerSoccer players are frequently required to produce high power outputs and maintain of repeat them with only a few seconds of recovery (Reilly and Thomas, 2003). This includes intermittent bouts of kicking, tackling, turning, sprinting, changing pace and maintaining balance and control o f the ball whilst under pressure from an opponent (Wisloff, Helgerud Hoff, 1998). To gain a scientific perspective of the different physiological demands of soccer performance, match and time motion analysis have been utilised (Bangsbo, 1994). This analysis has allowed researchers to determine the overall workload of players during a 90 minute match by calculating total distance covered, and the pattern of activities performed during a game (e.g. sprinting, cruising, walking etc).Movement patterns of SoccerIt is estimated that the total distance covered during a 90 minute soccer match varies from 8.7km to 11.5km ( Bangsbo Lindquist, 1992 Ekblom, 1986 Ohashi et al., (1988) Reilly and Thomas, 1976 1988 Rampini et al., 2007 Wade, 1962). The large variance in distances covered are due in part to the differing styles of play, levels of competition and skill level of the teams that were utilised (Luxbacher, 1997).Reilly (1994) documented the different activity patterns of elite outfield players from the English top division and other major national leagues in Europe and Japan using different methods of match analysis. Results found that a 90 minute match consists of 24% walking, 36% jogging, 20% cruising sub maximally (striding), 11% sprinting, 7% moving backwards and 2% moving in possession of the ball.The categories of sprinting and cruising are defined as high intensity exercise. In terms of distances covered the ratio of low intensity exercise to high intensity exercise during a soccer match is 7 to 1 denoting that the outlay of energy for soccer is predominately aerobic ( Reilly and Thomas, 1976). However the importance for high intensity bouts during soccer match play should not be underestimated. The timing of such a bout could be the defining factor of a game whether in possession of the ball or without the ball. Although work-rate profiles are relatively consistent for players from game to game it is the high intensity exercise which is the most constant feature (Bangsbo, 1994).The number of sprints reported in a soccer game varies greatly from 17 to 62 (Bangsbo et al., 1991 Mohr, Krustrup Bangsbo, 2003). This variance is largely determined by the positional role of the player. Findings by Reilly (1996) demonstrated that midfielders and strikers completed more sprinting bouts than centre backs or full backs therefore relying more on the anaerobic energy system.However if there is not a prolonged recovery period or an individual is not properly conditioned they will not subsequently recovery from high intensity bouts of exercise and fatigue will occur (Reilly, 1996). This is evident as Reilly (1996, p.72) documented that the majority of goals conceded during a soccer match occurred in the final ten minutes of play. A popular theory for this occurrence has been found to be mental fatigue or lapses in concentration from defenders (Reilly, 1996, p.72). However this can theory can be scrutinised as research found that the onset of fatig ue in intermittent exercise such as soccer is caused by low muscle glycogen stores (Balsom et al., 1999).Acute Cr supplementation and sprint performance in team sportsAthletes in team sports such as soccer, rugby, hockey and American football are required to repeatedly reproduce intermittent bouts of high intensity exercise with minimal recovery. Being able to consistently reproduce such bouts at maximal ability (e.g. sprinting, jumping, running backwards) could be the deciding factor in competition to gain that extra edge of an opponent. During high intensity exercise of an intermittent nature the main contributor of energy is PCr (Williams, Kreider Branch, 1999, p29). Depletion of PCr stores during high intensity exercise has been found to be a factor which has lead to a decline in athletic performance (Hultman, Bergstrom and McLennan-Anderson, 1967). Through the supplementation of Cr, it hypothesised that PCr stores are replenished at a faster rate therefore improving an athlete s ability to recover and perform intermittent high intensity bouts of exercise, leading to improved athletic performance (Greenhaff et al, 1993).There have been various studies that have tested this hypothesis by investigating the ergogenic effect of acute Cr supplementation on sprint performance of athletes in team sports (Ahmun et al., 2005 Cornish, Chilibeck Burke, 2006 Izquierdo et al., 2001 Kocak Karli, 2003 Romer et al., 2001 Vandebuerie et al., 1998). However the aforementioned studies have contrasting findings with a quantity of studies finding a significant improvement in sprint performance through Cr supplementation (Izquierdo et al., 2001 Romer et al., 2001 Vandebuerie et al., 1998). On the contrary other studies have found no significant improvements in sprint performance through acute Cr ingestion (Ahmun et al., 2005 Cornish, Chilibeck Burke, 2006 Kocak Karli, 2003).Ahmun et al., (2005) investigated the ergogenic effect of Cr on sprint performance in male rugby play ers. For this study a Wingate test protocol was utilised prior and post Cr supplementation. Findings of this study were that there was no significant improvement in maximal cycle sprints through Cr ingestion. However in contrast Izquierdo et al., (2001) found that acute Cr supplementation improved sprint times in male hand ball players. For this study subjects were either assigned Cr or placebo over a 5 day period. The protocol that was utilised consisted of repeated sprint runs that were consistent with sprint distances achieved during handball match play. One issue that could have had a determining factor of the non significant results found by Ahmun et al (2005) is the protocol that was utilised.A Wingate test was utilised to test the sprint performance in rugby players, however the relevance of a Wingate test to measure rugby performance is not sports specific there scrutinising the validity of the results. In contrast Izquierdo et al (2001) utilised a protocol which successfull y replicated distances found in handball match play therefore maintaining validity. Ahmun et al (2005) also failed to incorporate a dietary analysis into the experimental design of the protocol, therefore whether or not Cr stores within the subjects utilised were full cannot be determined, which gives rationale for results showing no significant improvement. In contrast Izquierdo et al (2001) implemented a dietary examination of subjects that were utilised this was initiated to determine whether any subjects had ingested Cr or any ergogenic aids prior to baseline testing. This assisted with maintaining validity during research. This can be supported by Romer et al (2001) and Vandebuerie et al (1998) who utilised a protocol containing a dietary analysis and concluded a significant improvement in sprint times within subjects.Cr supplementation and Soccer performanceGiven the intermittent physical demands of soccer, which requires players to produce high power outputs and maintain or r epeat them with only a few seconds of recovery, (Reilly and Williams, 2003) it seems feasible that soccer players would benefit from the supplementation of Cr as an ergogenic aid to improve their overall performance. However research that has investigated the effect on acute Cr supplementation on different variables of soccer performance and predominately sprint performance utilising a soccer simulation protocol is limited (Ostojic, 2004 Mujika et al 2000 Cox et al 2002).The Aforementioned studies have primarily focused on the effects of Cr supplementation on highly trained athletes that are competing at a high standard of competition. However no previous research has looked into the effects of acute Cr supplementation on amateur soccer players. Being as though Cr monohydrate is an immensely popular ergogenic aid not only among professional athletes but also amateur and recreational athletes, the benefit to amateur athletes needs to recognised. Previous research that has looked into the effects of acute Cr supplementation on soccer players using a soccer simulation protocol is discussed below.Ostojic (2004) examined the effects of acute Cr supplementation (3 x 10g doses for 7 days) on 20 young male soccer players (16.6 1.9 years). For the testing procedure a double blind method was used and where subjects were either administered either Cr or placebo. Subjects completed two separate trials prior and post to Cr or placebo. The testing procedure consisted of a number of soccer specific skill tests which included a dribble test, sprint-power test, endurance test and a vertical jump test. Results found that there was a significant improvement in a number of the soccer specific tests this includes superior improvements in sprint times, vertical jump scores and the dribble test.However no significant improvements were made on endurance performance after the two trials. Although a significant improvement was found in vertical jump performance, it is of concern to fu ture researchers to whether the vertical jump test that was utilised during the design is a soccer specific test. During the test subjects were instructed to keep their trunk as straight as possible whilst keeping their hands on their hips to avoid contribution from the arms which doesnt successfully replicate jumping movements in soccer therefore questioning the validity of the vertical jump test as to whether or not it is a measure of soccer specific performance.The age of the subjects in this research can also be scrutinised. Eichner, King, Myhal, Prentice and Ziegenfuss (1999) confirmed that there was insufficient research to determine the acute and chronic side effects of Cr consumption in athletes under the age of 18 therefore places the subjects which were used in the mentioned study under possible risk. Eichner et al (1999) also highlighted that Cr supplementation in young athletes could have a possible degradation of ethics, by where a win at all costs mentality is fostered and an attitude by where ergogenic aids are necessary to win, which is the wrong message to be installing in young athletes.Likewise Mujika, Padilla, Ibanez, Izquerido and Gorostiaga (2000) concluded acute Cr supplementation (20g a day x 6 days) significantly improved sprint performance and found no significant improvement in endurance performance using a soccer simulation protocol. Mujika et al (2000) also documented no increase in vertical jump performance using a similar protocol to Ostojic (2004) which has minimal significance in a soccer simulation study. Mujika et al (2000) tested 19 elite male soccer players who at the time of investigation were highly trained, however only 17 fully completed the testing due to illness or injury.The protocol for this investigation consisted of a circuit of different exercises which consisted of a repeated sprint test (5 and 15m), vertical jump test and an intermittent endurance test. Findings in this study concluded that mean sprint times im proved significantly (pThis de-training effect is evident for the vertical jump test as no significant improvement between the two trials was found. However if there was a significant de training effect it would have had negative consequences on other testing variables such as sprint performance, this however is not the case as sprint performance significantly improved. Mujika et al (2000) should have took into consideration a possible detraining effect when devising the experimental design as this could have negatively affect the validity of the results.Cox, Mujika, Tumilty and Burke (2002) devised a study which tested Cr supplementation (20g a day) or placebo (20g glucose a day) on 14 elite female soccer players from the Australian institute of sport (AIS) using a soccer simulated protocol. The experimental design consisted of two trials before and after Cr or placebo over a 6 day period. The protocol consisted of fifty five 20m sprints, ten agility runs and a precision ball kicki ng drill which are separated by recovery walks, jogs and runs. The main findings in this study were that the average 20m sprint time in the Cr group decreased from 3.75 0.19 to 3.69 0.18s however this decrease in sprint time failed to reach the statistical significance level (pCox et al (2002) also incorporated a standardised training regime and a controlled diet for the intervention week and also scheduled testing so that it would occur at the same time of day before and after supplementation. In contrast Mujika et al (2000) failed to utilise effective standardised procedures during their experimental design. As previously mentioned Mujika et al (2000) testing procedures took place 3 days after the subjects season had finished therefore training was not standardised due to the fact that subjects had no organised training sessions during the intervention week. Mujika et al (2000) also lacked a familiarisation trial, subjects were only familiarised with the testing procedures prior to arriving for the 1st trial which could substantially affect the results. However although Cox et al (2000) standardised procedures by included a controlled diet for the subjects, it is interesting to note that one of the subjects was a vegetarian, whos Cr content is virtually zero (Greenhaff, 1997). Research has found that vegetarians respond quicker and more effectively to Cr supplementation than those who follow a normal sedentary diet and have natural muscle creatine content (Burke, Chilibeck, Parise, Candow, Mahoney Tamopolsky., 2003 Watt, Garnham Snow, 2004) therefore scrutinising the validity of the results. It may be of future reference to eradicate vegetarians in a experimental design which utilises Cr supplementation due to the diet implications that vegetarians have.Soccer Simulation performance testsTo date there has been a number of soccer simulation performance tests which have been utilised to assess and measure different physiological aspects of the game (Bangsb o and Lindquist, 1992 Cox, 2002 Drust, Reilly and Cable, 2000 Nicholas, Nuttall and Williams, 2000). These protocols have been implemented so that they take into consideration different aspects of soccer performance and try to replicate the exercise patterns that are observed during match play, however due to the spontaneity of the soccer it is difficult to assess every physical or metabolic demand (Drust, Reilly and Cable, 2000). Researchers have used different protocols when investigating the metabolic and physical demands of soccer, these can documented into laboratory based protocols (Drust, Reilly and Cable, 2000 Thatcher and Batterham, 2004) and field based protocols (Bangsbo and Lindquist, 1992 Cox, 2002 Nicholas et al 2000).Laboratory based soccer performance protocolsDrust, Reilly and Cable (2000) devised a laboratory based protocol on a motorised treadmill what represented the work rates that are observed during soccer match play. For the experimental design 7 male univers ity soccer players (24 2 years) were used and the testing consisted of three separate testing blocks which were separated by 6 days. The protocol consisted of the different exercise intensities that are utilised during soccer match play this consisted of walking, jogging, cruising and sprinting. The speeds at which these exercises were performed on the treadmill were consistent with speeds observed by Van Gool, Van Gervan and Boutmans (1988) during a match analysis. Each testing block consisted of two 22.5 minute cycles which consisted of 23 bouts which were followed by a recovery period of 71 seconds.During each bout the duration of each activity was as follows walking 35 seconds (s), jogging 50.3s, cruising 51.4s and sprinting 10.5s. However in relevance to this research project it should be noted that the duration covered during the sprint bouts of the protocol of Drust, Reilly and Cable (2000) which is 10.5s does not successfully coincide with match analysis from several soccer studies that have documented the duration of sprint bouts during soccer match play. Research has found that the average sprint time during soccer match play lasts between on average two to four seconds in duration (Bangsbo, Norregard Thorso,1991 Mayhew and Wenger, 1985) therefore concluding in some instances Drust, Reilly and Cables (2000) laboratory based soccer specific protocol can be deemed as in valid as it fails to accurately replicate different soccer performance variables that take place in match play.Another lab based test that was utilised to measure specific variables in soccer performance was devised by Thatcher and Batterham (2004). For this protocol six male professional soccer players were used and the testing consisted of 29 minute exercise bouts on a non motorised treadmill that focused on replicating different speeds, durations, distances and heart rates that occur during soccer match play. Findings from this study suggest that the protocol that was utilised indu ced a similar physiological load to soccer match play and can be determined as a valid measure of soccer performance.Although lab based soccer specific protocols have been found to replicate some instances of soccer performance it is of consideration of this research project that the limitations and positives of such protocols be noted. The aforementioned lab based failed to perform a re-test procedure to conclude whether their protocols maintained reliability therefore the amount of error in each protocol cannot be determined. Another limitation of lab based testing is that due to tests being performed on treadmills, this limits the subjects to straight-line running only, therefore does not take into consideration lateral movements and agility patterns, which have found to be major characteristics of soccer performance (Bangsbo and Lindquist, 1992). These unorthodox movement patterns need to be taken into consideration when assessing soccer performance as they increase energy expen diture significantly (Nicholas et al., 2000). One positive aspect of lab based protocols are that procedures such as air temperature, equipment utilised and humidity can be easily standardised to remain constant throughout performance testing.Field TestsNicholas et al (2000) devised the Loughborough Intermittent Shuttle test (LIST) to simulate the activity patterns during a game of soccer. The LIST consisted of two separate stages which were known as part A and part B. Part A lasted 70 minutes and consisted of five 15 minute exercise pe