Nutritional Ergogenic Aids in Tennis a Brief.1

Nutritional ErgogenicAids in Tennis: ABrief ReviewAlvaro Lopez-Samanes, MSc,1 Juan F. Ortega Fonseca, PhD,1 Valentin E. Fernandez Elıas, PhD,1

Sebastien Borreani, PhD,2 Jose L. Mate-Munoz, PhD,3 and Mark S. Kovacs, PhD4

1Exercise Physiology Lab, University of Castilla La Mancha, Madrid, Spain; 2Laboratory of Physical Activity and Health,University of Valencia, Valencia, Spain; 3Department of Physical Activity and Sports Sciences, Alfonso X el SabioUniversity, Madrid, Spain; and 4International Tennis Performance Association, Life Sport Science Institute, LifeUniversity, Marietta, Georgia

A B S T R A C T

IN RECENT YEARS, THE INTEREST

OF ERGOGENIC AIDS HAS

GROWN IN THE COMPETITIVE

SPORTS ARENA. AS A RESULT,

SUPPLEMENTATION COMPANIES

HAVE FOUND A NEW MARKET AND

HAVE CREATED AN ARRAY OF

PRODUCTS TARGETING COMPET-

ITIVE ATHLETES. HOWEVER, ONLY

A FEW LEGAL SUPPLEMENTS

HAVE BEEN RECOGNIZED BY

SCIENTIFIC LITERATURE AS BEING

ABLE TO ENHANCE PERFOR-

MANCE. THESE COMPOUNDS ARE

CAFFEINE, CREATINE, AND BICAR-

BONATE. MORE RECENTLY,

OTHER SUBSTANCES SUCH AS

b-ALANINE AND NITRIC OXIDE

PRECURSORS HAVE SHOWN ER-

GOGENIC EFFECTS, BUT MORE

RESEARCH IS NEEDED. THE

OBJECTIVE OF THIS REVIEW IS TO

PROVIDE TENNIS COACHES AND

SPORTS SCIENCE RESEARCHERS

THE LATEST INFORMATION.

INTRODUCTION

The use of nutritional ergogenicaids has become more popularfor professional and recreational

athletes to enhance their performanceand to accelerate their recovery process(14). In sports sciences, a nutritional

ergogenic aid can be defined as substan-ces or procedures used for the purpose ofenhancing performance. Although theterm nutritional ergogenic aids is themost common name in scientific litera-ture referring to anything that enhancesperformance, these products are alsocommonly known as nutritional supple-ments, dietary supplements, or sportssupplements (89,90). Nutritional ergo-genic aidsmarketed in the formof dietarysupplements accounted for approxi-mately $660 million in US sales in 2013(Internacional E. Vitamins and DietarySupplements in the US. 2014. http://www.euromonitor.com/vitamins-and-dietary-supplements-in-the-us/report).In addition, 80% of German athletes(17), 89% of American university ath-letes (43), 98.6% of Canadian univer-sity athletes (80), and 88.57% of Irishathletes confirmed taking at least 1supplement (105).

Tennis is an intermittent sport withmatch duration from 1 hour to morethan 5 hours characterized by shortbouts of high intensity intermittentexercise (4–10 seconds), a short breakbetween points (10–20 seconds), andmoderate rest between games and sets(90–120 seconds) (38,75). Because ofintermittent activity during tennis play,tennis players could enhance their per-formance on court with use of severalergogenic aids; caffeine (CAFF) maydelay fatigue in long matches, creatine

(Cr) may enhance the resynthesis of

phosphocreatine, b-alanine (BA) and

sodium bicarbonate (SB)may buffer lac-tic acid, and nitric oxide precursors may

promote cardiovascular responses.

Another aspect is thermoregulation intennis players. A few tournaments dur-ing the year are played in extremeweather conditions (.408C) (i.e.,Australian Open). Recent publishedstudies in tennis (46,102) simulatingthese conditions in the extreme condi-tions mentioned above (the trials wererealized at 36.8 and 39.38C) found thatphysical performance deterioratedafter 2 hours. Tournaments in heat con-ditions could lead to heat-related ill-nesses such as heat exhaustion andheat stroke. Also, it was reported thattennis players need at least 24 hoursafter matches to recover. See thereview by Kovacs (77) for more infor-mation. Some recovery strategies couldspeed recovery such as cold treat-ments, compressive clothing, and fluidreplacement. Regarding hydrationtechniques, ranges of sweat lossescould vary between 1 and 2.5 L/h,and tennis players should avoid 2%dehydration during tennis matches.Some researchers have reported

KEY WORDS :

ergogenic aid; tennis;physical performance

Copyright � National Strength and Conditioning Association Strength and Conditioning Journal | www.nsca-scj.com 1

hydration strategies such as to drink.200–400 mL of a fluid replacementbeverage per changeover (76).

The aim of this review is to clarifywhich ergogenic aids can improve per-formance in a sport as complex astennis, which requires a mixture ofshort-distance speed between 0 and20 m (47) agility (111) and power(107), combined with medium to highaerobic and anaerobic demands (38).This review looks specifically at 3 in-gredients with an abundance of scien-tific support (i.e., CAFF, Cr, and SB)and 2 others that show promise in thescientific literature (i.e., nitric oxidemodulators (NO) and BA).

CAFFEINE

CAFF (1,3,7 trimethylxanthine) ismetabolized by the liver and, throughenzymatic actions, and results in 3metabolites: paraxanthine, theophyl-line, and theobromine (51,53,57).

The most common administrationmethod for CAFF is oral consumption.It is interesting to note that 74% ofSpanish athletes in national and inter-national events consume CAFF at dif-ferent doses (31) and 27% of Americanand Canadian youths (11–19 years)also take CAFF before competitions(127). This supplement has global ef-fects on the central nervous system(affecting cognitive performance andmood states), including hormonal (cate-cholamine excretions), metabolic (glyco-gen sparing), muscular (enhancingendurance and strength and power val-ues), cardiovascular (increasing heartrate), pulmonary (higher values of venti-lation), and renal functions (more bloodflow) during rest and exercise (117). Since2004, when the World Anti-DopingAgency eliminated CAFF from the listof banned substances, its consumptionby athletes has increased (31,35).

The recommended CAFF dose toobtain significant improvement in per-formance is 3–6 mg/kg bw (bodyweight) (14,26,30). Therefore, the useof lower doses (i.e., less than 2 mg/kgbw) has shown inconsistent results froma performance perspective (10,68).

CAFF is rapidly absorbed by thebody and appears in the blood within5–15 minutes (52), reaching a peakbetween 45 and 60 minutes after inges-tion, without showing statistical differ-ences when it is administered ascapsules or in beverages (80). However,CAFF chewing gum has demonstratedfaster absorption when compared withCAFF capsules (71). The half-life ofCAFF is between 2.5 and 10 hours (84).

In endurance sports, CAFF intake hasdemonstrated a strong performanceenhancing effect with low to mediumdoses (i.e., 3–6 mg/kg bw) (51–53,83,92); however, similar results arenot obtained with doses higher than 9mg/kg bw (50,100). The same resultshave been observed in activities thatrequire short efforts such as multiplesprints (i.e., tennis rallies) (48,115). Untilrecently, there has been much debateabout the usefulness of CAFF in sportsthat are highly dependent on strengthlevels. Recent research has demon-strated that small to moderate CAFFdoses (3–6 mg/kg bw) increase strengthand power output (32,49,96,131). How-ever, maximum strength is onlyenhanced with high doses (9 mg/kgbw), and the secondary effects associ-ated with CAFF ingestion should beconsidered (98). CAFF ingestion couldalso repair the detrimental effects onneuromuscular performance associatedwith the circadian rhythms when train-ing early in the morning (96), the effectsbeing more evident in the lower-bodymusculature (97).

Research on the effects of CAFF on ten-nis performance has been less extensivethan in endurance sports. There is littleevidence showing CAFF’s effect on ten-nis performance (Table). As mentionedbefore, tennis is an intermittent sportbecause performance is the product ofthe interaction of different qualities(speed, power, endurance, etc.) (38,75).CAFF has demonstrated performanceenhancement in prolonged exercise,such as multiple sprints, strength, andmuscle power, all of which are qualitiesrequired for success in tennis. To ourknowledge, all research that has assessedtennis performance related to CAFF

ingestion used small to moderate CAFFdoses (between 3 and 6 mg/kg bw). Inone study, Klein et al. (74) found thatCAFF administration of 6 mg/kg bwhad positive impacts on enhancing ten-nis performance during a tennis skill testwhen compared with placebo (PLAC).However, the effect of CYP1A2 (a liverenzyme that contributes to CAFFmetabolism) increasing has no apparentinfluence on tennis performance (74). Inanother study, 4.5 and 4 mg/kg bw ofCAFF was administered to men andwomen tennis players respectively. Thestudy evaluated different parameters dur-ing a 4-h tennis match (i.e, sprint perfor-mance, hitting accuracy and games won)(41). Only women reported improve-ments in the number of games won withrespect to PLAC conditions, with nochanges observed in men between thedifferent protocols. The researchersclaim that the differences found couldbe due to the normally lower CAFFconsumption among females versusmales (70 versus 110 mg/d) althoughrelative CAFF dose across gendersmight be similar. However, anotherstudy performed with the same groupand with the same CAFF doses formen and women (4.48 mg/kg bw) didnot report any benefits in any of thephysical parameters that weremeasured (124).

Hornery et al. (65) compared the con-sumption of CAFF (3 mg/kg bw), a 6%carbohydrate (CHO) solution, coolinguse, and PLAC during 4 simulated ten-nis matches; only the CAFF protocolwas able to reduce the effects of fatigueduring tennis matches and increaseserve velocity in the final set of thematches. Strecker et al. performed 2studies to determine the influence ofCAFF ingestion on tennis skills perfor-mance. In the first study (122), the sub-jects received a CAFF dose of 3 mg/kgbw combined with a CHO solution orPLAC before 90-minute trials of simu-lated tennis against a ball machine. Forevery 30 minutes of the match, the sub-jects performed a tennis skill test con-sisting of 15 groundstrokes (forehand/backhand) in all 4 directions: cross-court and down-the-line to a specific

Ergogenic Aids, Tennis, and Performance

VOLUME 37 | NUMBER 3 | JUNE 20152

target on the court. Although forehandperformance was enhanced in CAFFprotocols, backhand performance didnot reach statistical differences betweenCAFF versus PLAC. The second study(123) used the same CAFF doses as inthe previous study (3 mg/kg bw) but ina liquid form, and the subjects of thestudy played 90 minutes of simulatedmatches. The CAFF protocol showedan increase in tennis performance at lat-ter stages of the matches. The CAFFdose administered did not have a nega-tive effect on hydration status before orduring matches when compared withPLAC conditions.

Reyner and Horne (110) studiedwhether CAFF ingested in smallamounts (80 mg) could counteract thedetrimental effects associated with a 33%reduction in sleep (5 hours) comparedwith normal sleep (8 hours) in a servingaccuracy test. The researchers con-cluded that CAFF ingestion is no sub-stitute for lost sleep. However, theweakness of the study, in our opinion,was that the dose of CAFF administered

did not reach the ergogenic threshold of3–6 mg/kg bw. Future studies shouldconsider enhancing the CAFF dosesadministered to know whether CAFFingestion could really counteract the ef-fects associated with sleep loss. In a clas-sic study, Vergauwen et al. (128)compared the consumption of CHO(0.7 mg/kg bw), CHO + CAFF(5 mg/kg bw), and PLAC and examinedthe effects on 2 different performanceprotocols; the Leuven Tennis Perfor-mance Test (LTPT) and shuttle run(for protocols details see (129)). On eachoccasion, they performed each testbefore and after 2 hours of strenuoustraining sessions. These protocolsshowed that CHO + CAFF ingestiondid not produce any benefits comparedwith CHO conditions.

Finally, a recent study by Gallo-Salazaret al. (44) showed that 3 mg/kg bwCAFF in liquid form increased handgripforce in both hands, running pace at highintensity, and the number of sprints com-pared with the PLAC protocol, whereasother aspects such as ball velocity during

the service test remained unchangedduring simulated tennis matches.

Side effects associated with CAFF aremixed. Historically, it has been reportedthat ingestion of CAFF affected fluidbalance causing an increase in the uri-nation rate and, consequently, increaseddehydration. However, a recent studyby Killer et al. (73) has shown thatingestion of moderate doses of CAFFdid not affect the rate of fluid reductionand, hence, the rate of dehydration. IfCAFF ingestion is high (.9 mg/kg bw)(100), these negative hydration effectsdo occur. Therefore, CAFF is a usefuland safe substance that has been shownto benefit performance in low and mod-erate doses (3–6 mg/kg bw). Only theuse of high doses (.9mg/kg bw) seemsto cause undesirable effects such asincreased urine flow, gastrointestinalproblems, heart palpitations, etc. CAFFingestion before matches/training ses-sions may be a useful ergogenic aid toincrease tennis performance, althoughfuture studies should determine theoptimum dose.

TableCaffeine effects on tennis performance

Studies Subjects Dose Effects on performance

Ferrauti (41) 8 M 4.5 mg/kg 4Performance in males

8 F 4 mg/kg [Number of game winners during simulated matches in females

Vergauwen (128) 13 M 5 mg/kg 4Performance

Struder (124) 8 M 4.48 mg/kg 4Performance

Strecker (122) [Forehand performance

10 M 3 mg/kg 4Backhand performance

Hornery (65) 12 M 3 mg/kg [Serve velocity

Strecker (123) 10 M 3 mg/kg [Performance in tennis skill in the later stages of match

Klein C (74) 9 M 6 mg/kg [Performance in tennis-specific test

9 F

Reyner and Horne (110) 6 M 80 mg 4Serving accuracy tennis test

6 F

Gallo-Salazar (44) 10 M 3 mg/kg [Handgrip force, [ points with the serve

4 F 4Ball velocity

F 5 female; M 5 male; 4 5 no effects; [ 5 increase.

Strength and Conditioning Journal | www.nsca-scj.com 3

CREATINE

Cr or a-methylguanidinoacetic acid isa nitrogenous compound that naturallyexists in the skeletal muscle in equilib-rium with phosphocreatine (70). Thefirst studies of Cr supplementationbegan in the 1900s; and in the last cen-tury, the studies on this ergogenic aidhave increased substantially. Cr is pro-duced endogenously, mainly in the liver,at a rate of 1–2 g/d and an additional1–2 g/d of Cr is obtained from dietaryintake (27,95). This substance has beenproven to be an important stimulant aidfor neuromuscular (130) and cardiovas-cular diseases (91), and in the nearfuture, it appears that this substancemay have even more therapeutic effects(i.e., cancer, type 2 diabetes, etc.) (54).Cr is currently considered to be an effec-tive ergogenic supplement by differentnutritional and sports medicine organi-zations (18,126).

The most common use of Cr adminis-tration starts with a loading phase, con-sisting of 4 repeated doses of 5 gseparated by 5–7 hours during 3–5 daysand a maintenance dose of 3–5 g/d,which show a 17–20% increase in intra-muscular Cr levels (95). Other protocolshave proven to have the same successor even better results, such as doses of0.25 g Cr/kg fat-free mass/d (19), 3 g ofCr per day during 30 days (69), or 20doses of 1 g of Cr during the day (114).Furthermore, Cr bioavailability is betterwhen it is consumed in conjunctionwith carbohydrates (CHO). Ideally,the CHO loading should be ingested30minutes after Cr ingestion to producepeak Cr and insulin concentrations (95).Oral administration of low-mediumdoses of Cr in humans (1–5g) reachesits maximum plasma Cr concentrationsin less than 2 hours, whereas dosesabove 10 gr reach maximal plasma con-centrations of Cr over 3 hours (114).Therefore, the clearance rate of Cr fromthe blood is highly variable and depen-dent on intramuscular Cr levels, hor-mone levels, muscle mass, and kidneyfunction (103).

In general, the studies with Cr supple-mentation have been based on sportshighly dependent on strength and

hypertrophy levels (9,118). However,the increase in muscle mass and strengthvalues associated with Cr ingestion havedrawn the attention of intermittent sports(e.g., soccer, handball) because of the factthat different physical capacities such asrepeated sprints, agility performance,jumping ability, and maximum lower-body strength are necessary for successin intermittent sports. However, otherstudies did not find improvement in per-formance in repeated sprints and othervariables associated with performance inintermittent sports (28). Regarding tennisperformance, Cr ingestion has been lessreported; only 2 studies have used Cringestion to observe the effects on per-formance. Eijnde et al. (37) used a Crdose of 20 g/d during 5 days (dividedinto 4 doses per day) with 8 well-trainedtennis players and evaluated perfor-mance on the LTPTand the 70-m shuttlerun on 2 different occasions (Cr protocolversus PLAC protocol). No significantdifferences were reported between treat-ments in any of the variables, and theyconcluded that short-term high dose Cringestion does not benefit tennisperformance.

Pluim et al. (104) observed the effectsof both Cr supplementation over short(6 days) and medium terms (4 weeks)compared with PLAC conditionperiod in tennis players. A Cr interven-tion with a loading phase of 0.3 mg/kgbw during 6 days and a maintenancephase of 0.03 mg/kg bw during 28 dayswas used. No gains in body weightwere reported in the short-term inter-vention, but gains were reported in themedium term between Cr versusPLAC (+1.4 versus 20.2 kg). Some as-pects related to tennis performancewere evaluated (i.e., sprint velocity over5, 10, and 20 m, upper and lower-bodystrength values, and groundstrokes per-formance drills). No differences werefound for the short or medium termin any variable. As a result, it was con-cluded that Cr should not be recom-mended to tennis players.

The controversial secondary effects ofCr ingestion lack supportive scientificevidence. According to the literature, itseems that Cr ingestion may be related

to an increase of 1–2% in body weight(79) possibly associated with waterretention. Other secondary effectslinked to Cr consumption, such as gas-trointestinal, renal, and liver damage,have only been anecdotally reported.Future investigations should clarifythe issue (18). Currently, Cr is a safeergogenic aid regarding athlete’s health(116) possibly with the ability to posi-tively impact tennis recovery.

SODIUM BICARBONATE

SB (NaHCO3) is an extracellular bufferwith an important role in maintaininga stable electrolyte gradient betweenintracellular and extracellular environ-ments (20). SB has been extensivelystudied in recent years mainly for itsproperties as a buffering agent. In nor-mal human conditions, arterial bloodpH is 7.4 and human muscle pH isnormally 7.0. After exhaustive exercise,arterial pH tends to fall to 7.1 and mus-cle pH to 6.8 resulting in fatigue (94).

The acid-base balance has been stud-ied since the 1930s. In those years,some scientists postulated that theingestion of alkaloid agents mightreduce the decline of muscle pH (33).Studies on SB and athletic perfor-mance have been published since the1980s. The best time for NaHCO3

ingestion is 60–120 minutes beforethe event, and it must be diluted pref-erably in about 400 mL of water(101,108); peak blood alkalosis can beexpected ;120–150 minutes afteringestion (24).

The optimum dose of SB ingestion hasbeen a cause of debate. Costill et al. re-ported several studies demonstratingthe efficacy of SB in enhancing perfor-mance in several sports (i.e., swimmingand cycling) (29,45). In a well-designedexperiment (93) with different doses(0.1, 0.2, 0.3, 0.4, and 0.5 g/kg bw),McNaughton et al. were the first toestablish that 0.3 g/kg bw wasthe minimum dose with which changeswere noticeable in the variables mea-sured in the study: total work performedand peak power output. Men andwomen responded the same way tothe ingestion of SB, showing the same,



or nearly the same, improvements withthis ergogenic aid (24). A different pub-lished meta-analysis that described SBas a useful ergogenic aid to improveathletic performance reported a smallto moderate effect size (0.44 versus0.36, respectively) (87,101). Training sta-tus seems to impact the effect seen fromSB use (i.e., untrained people benefitmore from SB intake when comparedwith high-performance athletes, partic-ularly in repeated bouts protocols, timeexhaustion test, and short [,2 minutes],medium [2–10 minutes], and long pro-tocols [.10 minutes]) (103). However,although the effects are less pronouncedin highly trained athletes, there seems tobe evidence that in events characterizedby high-intensity protocols and thosethat recruit largemuscle groups, athletescan benefit from SB intake (109). Effectson neuromuscular performance are notclear; although some studies reportedpositive results (25,36), others havenot (133).

Regarding tennis, Wu et al. (134) devel-oped the only study with SB ingestion.Nine male college tennis players ina randomized crossover, PLAC-controlled, and double-blind studyinvestigated the intake of SB (0.3 g/kgbw) or PLAC (0.209 g/kg bw NaCl);the researchers investigated the effecton a skilled tennis performance test(Loughborough Tennis Skill Test)before and after a simulated game oftennis (a duration of approximately50 minutes). This study suggested thatSB supplementation could prevent thedecline in skilled tennis performanceafter a simulated match. Others suggestthat SB could be useful for tennis per-formance (13) through improvement inRSA performance, a quality that hasbeen demonstrated to be importantin intermittent sports (e.g., tennis,soccer) (39,106).

SB is associated with a wide spectrumof secondary effects: gastrointestinalupset, diarrhea, and cramps (23). Sev-eral strategies have been suggestedto minimize the secondary effects, suchas familiarization trials and intravenousadministration (109). The consump-tion of food alongside SB reduces

gastrointestinal side effects relative tothe same dose taken on an emptystomach, and serum increases of bicar-bonate seem to be highest when in-gested with food (24).

Because of the lack of research regardingthe intake of SB on tennis performance,more studies need to be developedregarding this topic. Likewise, becauseof the minor effect reported in highlytrained athletes, interventions wouldneed to examine the effectiveness, orotherwise, of SB in highly trained tennisplayers. Additionally, studies that com-bine extracellular buffers (such as SB)and intracellular buffers (BA) need tobe conducted to determine whether thissubstance should be considered an ergo-genic aid to tennis performance.

b-ALANINE

BA is found in muscles in combinationwith L-histidine forming the dipeptidecarnosine. This is found in high con-centration in the mammalian skeletalmuscle. It is synthesized by the enzymecarnosine synthase from the aminoacids L-histidine and BA (34).Although it was discovered more than100 years ago, the use of this substanceto enhance athletic performance is stilla new topic (56). It shows a good mus-cle buffering capacity (MBC) of H+ ata higher rate during intense exerciseand is perhaps the most importantintracellular buffer (1). The majorityof the body’s carnosine, over 99%, ispresent in muscles, whereas other pla-ces in the body have small quantities(e.g., brain) (34), with more pro-nounced quantities in fast twitch fibersat the end compared with those in slowtwitch fibers. Furthermore, studieshave demonstrated that men haveapproximately 20–25% more carnosinecontent than do women (86). How-ever, BA is a nonessential amino acidsynthesized by the liver (88), which canbe ingested through a diet containinganimal sources (meat) or through die-tary supplements (6). The study of BAhas attracted interest because of itsdirect relation to the synthesis of carno-sine. The body is unable to absorb car-nosine directly from the bloodstream

(88), and concentrations of BA in themuscle are relatively small compairedwith histadine and carnosine synthetase(61). Endogenous synthesis of BA islimited to a small amount produced inthe liver (88). The synthesis of carnosinein skeletal muscle may be limited by theavailability of BA in the diet (113).

The most commonly used dosing regi-men to enhance performance providesa total dose of 4–6.4 g/d over severalweeks. This total dose is typicallyachieved by ingesting multiple dosesper day (i.e., 4–6 doses) (72,121) in indi-vidual dosing amounts of 4–10 g thathave shown to cause a 40–80% increasein intramuscular carnosine (57,72). Thewashout period may take .9 weeks toreturn to baseline levels (7,119) witha decline rate of 2–4% per week on aver-age, which is a longer (7) and slower pro-cess if compared with other substancessuch as CAFF. A recent meta-analysisshowed that the median effect of BA sup-plementation is 2.85%, being especiallyeffective in events of between 60–240 sec-onds and.240 seconds but not reachingstatistical differences in events whose du-rations are ,60 seconds (58).

Highly trained anaerobic athletes havegreater buffering capacity and intramus-cular carnosine than untrained people orendurance athletes (99), but BA supple-mentation improves the carnosine de-posits in all of the cases mentionedbefore. Regarding neuromuscular perfor-mance, the ingestion of BA does notseem to improve maximum strength(60,72). These finding are not surprisingconsidering that the improvement inbuffering capacity and maximum neuro-muscular performance is not limited byacidosis (6). In the tennis field, no studieshave been conducted yet, but in complexintermittent sports such as tennis inwhich the bouts of exercise require thatplayers have a good buffering capacity,BA could be an interesting ergogenic aid.In fact, other alkalinizing agents such asSB have shown good results against thedecline in performance during simulatedtennismatches (134). Although themainbuffering of H+ is generated by bicarbon-ate, the pH of carnosine (6.83) is closerto the physiological system than the pH


of bicarbonate (6.37), which means thatit may be used primarily in high-intensity exercise (66). Therefore BAsupplementation could contribute tothe ability of muscle carnosine to bufferbetween 7 and 25% of the acid produced(6,56,86). The contribution of carnosinefor these purposes may differ dependingon the fiber type involvement withgreater contributions coming from typeII fibers (86).

Secondary effects reported with BAingestion are symptoms of paresthesia(an unpleasant sensation characterizedby the irritation of the skin and pricklysensation) and are reduced or elimi-nated when the quantity is less than800 mg per day. To avoid these symp-toms, BA should be administered in sev-eral doses during the day (58) becauseof the fact that symptoms of paresthesiaare associated with peak blood values ofBA serum (120). However, these symp-toms of paresthesia were not observedwhen BA was ingested in conjunctionwith carbohydrates. (61) This suggeststhat administering BAwith food reducesthe maximum concentration in serumby up to 50% because of delayed gastricemptying (56).

In tennis, no studies have been con-ducted regarding the use of BA, but incomplex intermittent sports such as ten-nis, in which the bouts of exercise requirethat players have a good buffer capacity,BA could be an interesting ergogenic aidthat should be studied. Furthermore, co-ingestion with other buffering agentssuch as SB could be another area toexplore in future publications.

NITRIC OXIDE

Nitric oxide (NO) is a labile lipid-soluble gas synthesized at several loca-tions in the body with antioxidant andvasodilator properties that also regulatethe use of glucose and oxygen (3). Theproduction of nitric oxide occurs in 2different ways: NO synthase (NOS)dependent and NOS independent (12).Importantly, it is the first gaseous chem-ical that has been shown to be producedby living cells to send intracellular sig-nals. The different properties (i.e., vaso-dilator mechanism) have caught the

attention of the exercise physiology fieldbecause of the potential beneficial effectsof this substance as an ergogenic aid.

NOS-dependent pathway L-arginine(L-Arg) is a semiessential amino acidand also a precursor to nitric oxide(NO), which can be synthesized bythe kidneys where L-Arg is formed fromL-citrulline. The dietary intake of L-Argis close to 4–5 g/d (125). Scientific find-ings have reported that L-Arg supple-mentation varied between 1.5 and 20g/d in different studies, with durationsof between 1 and 180 days (22,42). Thehalf-life L-Arg after oral ingestion of 6 gis between 50 and 120 minutes (15), andits excretion varies according to the foodconsumption and renal function ofindividuals.

The ingestion of nitrate and nitrite canalso be reduced to nitric oxide (NO).Nitric oxide deposits can be obtainedexogenously through diet, knowingthat some kinds of vegetables containlarge amounts of nitrates (i.e., beets,spinach, or lettuce). The most com-mon supplementation reported isbetween 300 and 600 mg of nitrateper day for 1–15 days, eliciting favor-able physiological effects (65,71). Afterbolus nitrate ingestion, plasma nitrateingestion (nitrate) peaks after 1–2hours and plasma nitrite peaks after2–3 hours (71). Finally, baseline valuesreturn to normal 24 hours afteringestion.

Over the last several years, consump-tion of L-Arg has increased considerablyamong athletes because it increases theblood’s acute vasodilatation and hasbeen associated with a neuromus-cular and cardiovascular performanceenhancement (4). A study on NCAAathletes showed that 8% of males and5% of females regularly used L-Arg as anergogenic aid (85). However, the scien-tific evidence is not so clear. The acuteeffects of L-Arg administration showedthat the majority of the studies havebeen developed using aerobic protocols,with different results. Although somestudies showed an improvement insome parameters with L-Arg ingestion,such as reduced oxygen consumption

(VO2), cost of moderate-intensity cycleexercise, and time to exhaustion (8,135),other studies did not find the same re-sults (81). The scientific literatureregarding chronic ingestion of L-Arg ismore extensive compared with the lit-erature regarding acute ingestion of thisergogenic aid. However, the results areinconclusive as well. Although somestudies showed L-Arg use to have pos-itive effects on cardiovascular and neu-romuscular performance (21,22), otherstudies did not find any differences(2,132). Bescos et al.(11) have devel-oped the only study pertaining to tennis,which included 9 highly trained maletennis players. They followed 3 differentdiets during 3 days (with 5.5, 9, and 20g/d of L-Arg) with washout periods of 4days between trials. Participants per-formed a submaximal treadmill test until85–90% VO2max in which oxygenuptake, heart rate, and blood lactatewere measured. No differences werenoted between the various protocolswith various doses of L-Arg.

The most common method of NOS-independent pathway intake reportedis through beetroot juice. A recentmeta-analysis by Hoon et al. (63)showed that untrained or recreationalathletes showed better improvementswith nitrate intake, reported modestimprovement with protocols untilexhaustion, and showed small im-provements in time trial protocols that,though not statistically significant,might be useful for elite athletes. How-ever, the controversy over the useful-ness of nitrate ingestion in elite athletescontinues because although some stud-ies reported benefits in highly trainedrowing athletes (64), other studies didnot find improvement in time trial per-formances (62) or at 1,500 m (16).Regarding tennis, the only study to havebeen developed is by Aksit et al. (3). Theobjective of this study was to establisha relationship between tennis perfor-mance test results and NOx levels (thesum of nitrate + nitrite). Twenty well-trained tennis players performed three4-minute bouts and 2 minutes of con-tinuous groundstrokes with balls shotfrom a tennis ball machine at speeds



of 50, 55, 62, and 70 km/h. After thisexercise, the participants had 20minutesof passive rest. After each period andduring the recovery phase, NOx levels,glucose, lactate levels, and lactate elim-ination speedweremeasured. The studysuggested that no significant correlationwas found between NOx levels and ten-nis performance. However, it was sug-gested that the addition of loads in thethird period of tennis training may bebeneficial and that the relationshipbetween performance on court andNOx levels and glucose should be stud-ied in real game situations (i.e., officialtennis matches).

Secondary effects associated with L-Argand NO are not well reported in theliterature. Basically, the most commonside effect reported with L-Arg is diar-rhea. An excellent review that has beenpublished recently by Alvares et al. (5)showed that low oral doses of L-Arg(#20 g) could obtain the same resultsas those of higher doses (21–30 g) with-out secondary effects such as nausea,diarrhea, etc., which are associated withdoses above 20 g. Regarding nitrateingestion, it has been reported that sup-plementation through vegetable sources(mainly beetroot juice) is unlikely to beharmful or have side effects for theorganism, even at higher doses. How-ever, nitrite in higher doses may causehypotension, especially if combined withother vasodilatory drugs (82).

Because of the limited evidence avail-able from studies using L-Arg or NOx

in the scientific literature on tennis per-formance, we should be cautious andwait for further studies to clarifywhether this ergogenic aid could beuseful in sports as complex as tennis.

PRACTICAL APPLICATIONS

Despite the limited evidence we haveabout ergogenic aids on the tennis court(except for CAFF), a series of recom-mendations are presented to coaches,strength and conditioning coaches,and tennis-related medical personnel.

CAFF, in small doses (3 mg/kg bw)may improve tennis performance (i.e.,more points won with the serve),although further studies should be

performed with different doses to deter-mine whether there is an optimum dose.

Although SB and BA, because of theirbuffer capacities, could have a place ina sport such as tennis in which theability to recover between efforts iscritical, additional studies should beperformed to determine their useful-ness in the world of tennis. As forL-Arg and NOx, studies in real gamesituations could be developed to con-sider them for use as ergogenic aids.

Finally, because of the weight gain intennis players associated with Cr inges-tion and the lack of scientific evidence(because little has been published aboutCr on tennis performance), moreresearch is needed during competitivematches and during training blocks todetermine whether it may be appropri-ate at certain times of competition/training.

Conflicts of Interest and Source of Funding:The authors report no conflicts of interestand no source of funding.

Alvaro Lopez

Samanes isa member of theExercise Physiol-ogy Lab at Cas-tilla la ManchaUniversity.

Juan Fernando

Ortega

Fonseca isa member of theExercise Physiol-ogy Lab at Cas-tilla la ManchaUniversity.

Valentin Emilio

Fernandez

Elias is a memberof the ExercisePhysiology Labat Castilla LaManchaUniversity.

Sebatien

Borreani isa member of theresearch group inSports andHealth in theDepartament ofPhysical Educa-

tion and Sports at the University ofValencia.

Jose Luis Mate-

Munoz is a mem-ber of the De-partament ofPhysical Activityand Sports Sci-ence at Alfonso XUniversity.

Mark Kovacs isCEO of theInternational Ten-nis PerformanceAssociation andmember of SportsScience Institute atLife University.

REFERENCES1. Abe H. Role of histidine-related

compounds as intracellular proton

buffering constituents in vertebrate

muscle. Biochemistry (Mosc) 65: 757–

765, 2000.

2. Abel T, Knechtle B, Perret C, Eser P, von

Arx P, and Knecht H. Influence of chronic

supplementation of arginine aspartate in

endurance athletes on performance and

substrate metabolism—A randomized,

double-blind, placebo-controlled study.

Int J Sports Med 26: 344–349, 2005.

3. Aksit T, Turgay F, Kutlay E, Ozkol M, and

Vural F. The relationships between

simulated tennis performance and

biomarkers for nitric oxide synthesis.

J Sports Sci Med 12: 267–274, 2013.

4. Alvares TS, Conte CA, Paschoalin VM,

Silva JT, Meirelles Cde M, Bhambhani YN,

and Gomes PS. Acute l-arginine

supplementation increases muscle blood

volume but not strength performance.

Appl Physiol Nutr Metab 37: 115–126,

2012.


5. Alvares TS, Meirelles CM, Bhambhani YN,

Paschoalin VM, and Gomes PS. L-Arginine

as a potential ergogenic aid in healthy

subjects. Sports Med 41: 233–248, 2011.

6. Artioli GG, Gualano B, Smith A, Stout J,

and Lancha AH Jr. Role of beta-alanine

supplementation on muscle carnosine and

exercise performance. Med Sci Sports

Exerc 42: 1162–1173, 2010.

7. Baguet A, Reyngoudt H, Pottier A,

Everaert I, Callens S, Achten E, and

Derave W. Carnosine loading and

washout in human skeletal muscles.

J Appl Physiol (1985) 106: 837–842,

2009.

8. Bailey SJ, Winyard PG, Vanhatalo A,

Blackwell JR, DiMenna FJ, Wilkerson DP,

and Jones AM. Acute L-arginine

supplementation reduces the O2 cost of

moderate-intensity exercise and enhances

high-intensity exercise tolerance. J Appl

Physiol (1985) 109: 1394–1403, 2010.

9. Becque MD, Lochmann JD, and

Melrose DR. Effects of oral creatine

supplementation on muscular strength

and body composition. Med Sci Sports

Exerc 32: 654–658, 2000.

10. Bellar DM, Kamimori G, Judge L,

Barkley JE, Ryan EJ, Muller M, and

Glickman EL. Effects of low-dose caffeine

supplementation on early morning

performance in the standing shot put

throw. Eur J Sport Sci 12: 57–61, 2012.

11. Bescos R, Gonzalez-Haro C, Pujol P,

Drobnic F, Alonso E, Santolaria ML,

Ruiz O, Esteve M, and Galilea P. Effects of

dietary L-arginine intake on

cardiorespiratory and metabolic

adaptation in athletes. Int J Sport Nutr

Exerc Metab 19: 355–365, 2009.

12. Bescos R, Sureda A, Tur JA, and Pons A.

The effect of nitric-oxide-related

supplements on human performance.

Sports Med 42: 99–117, 2012.

13. Bishop D. Improve lactate tolerance in

tennis players. 10th International Tennis

Simposium. Milan, Italy, November

15–16, 2008.

14. Bishop D. Dietary supplements and team-

sport performance. Sports Med 40: 995–

1017, 2010.

15. Bode-Boger SM, Boger RH, Galland A,

Tsikas D, and Frolich JC. L-arginine-

induced vasodilation in healthy humans:

Pharmacokinetic-pharmacodynamic

relationship. Br J Clin Pharmacol 46:

489–497, 1998.

16. Boorsma RK, Whitfield J, and Spriet LL.

Beetroot juice supplementation does not

improve performance of elite 1500-m

runners.Med Sci Sports Exerc 46: 2326–

2334, 2014.

17. Braun H, Koehler K, Geyer H, Kleiner J,

Mester J, and Schanzer W. Dietary

supplement use among elite young

German athletes. Int J Sport Nutr Exerc

Metab 19: 97–109, 2009.

18. Buford TW, Kreider RB, Stout JR,

Greenwood M, Campbell B, Spano M,

Ziegenfuss T, Lopez H, Landis J, and

Antonio J. International society of sports

nutrition position stand: Creatine

supplementation and exercise. J Int Soc

Sports Nutr 4: 6, 2007.

19. Burke DG, Chilibeck PD, Parise G,

Candow DG, Mahoney D, and

Tarnopolsky M. Effect of creatine and

weight training on muscle creatine and

performance in vegetarians. Med Sci

Sports Exerc 35: 1946–1955, 2003.

20. Burke LM and Pyne DB. Bicarbonate

loading to enhance training and

competitive performance. Int J Sports

Physiol Perform 2: 93–97, 2007.

21. Camic CL, Housh TJ, Zuniga JM,

Hendrix RC, Mielke M, Johnson GO, and

Schmidt RJ. Effects of arginine-based

supplements on the physical working

capacity at the fatigue threshold. J Strength

Cond Res 24: 1306–1312, 2010.

22. Campbell B, Roberts M, Kerksick C,

Wilborn C, Marcello B, Taylor L, Nassar E,

Leutholtz B, Bowden R, Rasmussen C,

Greenwood M, and Kreider R.

Pharmacokinetics, safety, and effects on

exercise performance of L-arginine alpha-

ketoglutarate in trained adult men.

Nutrition 22: 872–881, 2006.

23. Carr AJ, Hopkins WG, and Gore CJ.

Effects of acute alkalosis and acidosis on

performance: A meta-analysis. Sports

Med 41: 801–814, 2011.

24. Carr AJ, Slater GJ, Gore CJ, Dawson B,

and Burke LM. Effect of sodium

bicarbonate on [HCO3-], pH, and

gastrointestinal symptoms. Int J Sport

Nutr Exerc Metab 21: 189–194, 2011.

25. Carr BM, Webster MJ, Boyd JC,

Hudson GM, and Scheett TP. Sodium

bicarbonate supplementation improves

hypertrophy-type resistance exercise

performance. Eur J Appl Physiol 113:

743–752, 2013.

26. Conway KJ, Orr R, and Stannard SR.

Effect of a divided caffeine dose on

endurance cycling performance,

postexercise urinary caffeine

concentration, and plasma paraxanthine.

J Appl Physiol (1985) 94: 1557–1562,

2003.

27. Cooper R, Naclerio F, Allgrove J, and

Jimenez A. Creatine supplementation with

specific view to exercise/sports

performance: An update. J Int Soc Sports

Nutr 9: 33, 2012.

28. Cornish SM, Chilibeck PD, and

Burke DG. The effect of creatine

monohydrate supplementation on sprint

skating in ice-hockey players. J Sports

Med Phys Fitness 46: 90–98, 2006.

29. Costill DL, Verstappen F, Kuipers H,

Janssen E, and Fink W. Acid-base

balance during repeated bouts of

exercise: Influence of HCO3. Int J Sports

Med 5: 228–231, 1984.

30. Cox GR, Desbrow B, Montgomery PG,

Anderson ME, Bruce CR, Macrides TA,

Martin DT, Moquin A, Roberts A,

Hawley JA, and Burke LM. Effect of

different protocols of caffeine intake on

metabolism and endurance performance.

J Appl Physiol (1985) 93: 990–999,

2002.

31. Del Coso J, Munoz G, and Munoz-

Guerra J. Prevalence of caffeine use in

elite athletes following its removal from

the World Anti-Doping Agency list of

banned substances. Appl Physiol Nutr

Metab 36: 555–561, 2011.

32. Del Coso J, Salinero JJ, Gonzalez-

Millan C, Abian-Vicen J, and Perez-

Gonzalez B. Dose response effects of

a caffeine-containing energy drink on

muscle performance: A repeated

measures design. J Int Soc Sports Nutr 9:

21, 2012.

33. Dennig H, Talbott JH, Edwards HT, and

Dill DB. Effect of acidosis and alkalosis

upon capacity for work. J Clin Invest 9:

601–613, 1931.

34. Derave W, Everaert I, Beeckman S, and

Baguet A. Muscle carnosine metabolism

and beta-alanine supplementation in

relation to exercise and training. Sports

Med 40: 247–263, 2010.

35. Desbrow B and Leveritt M. Well-trained

endurance athletes’ knowledge, insight,

and experience of caffeine use. Int J Sport

Nutr Exerc Metab 17: 328–339, 2007.

36. Duncan MJ, Weldon A, and Price MJ. The

effect of sodium bicarbonate ingestion on

back squat and bench press exercise to

failure. J Strength Cond Res 28: 1358–

1366, 2014.

37. Eijnde BO, Vergauwen L, and Hespel P.

Creatine loading does not impact on

stroke performance in tennis. Int J Sports

Med 22: 76–80, 2001.

38. Fernandez J, Mendez-Villanueva A, and

Pluim BM. Intensity of tennis match play.



Br J Sports Med 40: 387–391, 2006;

discussion 391.

39. Fernandez-Fernandez J, Zimek R,

Wiewelhove T, and Ferrauti A. High-

intensity interval training vs. repeated-

sprint training in tennis. J Strength Cond

Res 26: 53–62, 2012.

40. Fernandez-Fernandez JS-R, Sanz-Rivas D,

and Mendez-Villanueva A. A review of the

activity profile and physiological demands

of tennis match play. Strength Cond J 31:

15–26, 2009.

41. Ferrauti A, Weber K, and Struder HK.

Metabolic and ergogenic effects of

carbohydrate and caffeine beverages in

tennis. J Sports Med Phys Fitness 37:

258–266, 1997.

42. Fricke O, Baecker N, Heer M, Tutlewski B,

and Schoenau E. The effect of L-arginine

administration on muscle force and power

in postmenopausal women. Clin Physiol

Funct Imaging 28: 307–311, 2008.

43. Froiland K, Koszewski W, Hingst J, and

Kopecky L. Nutritional supplement use

among college athletes and their sources

of information. Int J Sport Nutr Exerc

Metab 14: 104–120, 2004.

44. Gallo-Salazar C, Areces F, Abian-Vicen J,

Lara B, Salinero JJ, Gonzalez-Millan C,

Portillo J, Munoz V, Juarez D, and Del

Coso J. Caffeinated energy drinks

enhance physical performance in elite

junior tennis players. Int J Sports Physiol

Perform 10: 305–310, 2015.

45. Gao JP, Costill DL, Horswill CA, and

Park SH. Sodium bicarbonate ingestion

improves performance in interval

swimming. Eur J Appl Physiol Occup

Physiol 58: 171–174, 1988.

46. Girard O, Christian RJ, Racinais S, and

Periard JD. Heat stress does not

exacerbate tennis-induced alterations in

physical performance. Br J Sports Med

48(Suppl 1): i39–i44, 2014.

47. Girard O and Millet GP. Physical

determinants of tennis performance in

competitive teenage players. J Strength

Cond Res 23: 1867–1872, 2009.

48. Glaister M, Howatson G, Abraham CS,

Lockey RA, Goodwin JE, Foley P, and

McInnes G. Caffeine supplementation and

multiple sprint running performance. Med

Sci Sports Exerc 40: 1835–1840, 2008.

49. Goldstein E, Jacobs PL, Whitehurst M,

Penhollow T, and Antonio J. Caffeine

enhances upper body strength in

resistance-trained women. J Int Soc


50. Goldstein ER, Ziegenfuss T, Kalman D,

Kreider R, Campbell B, Wilborn C,

Taylor L, Willoughby D, Stout J,

Graves BS, Wildman R, Ivy JL, Spano M,

Smith AE, and Antonio J. International

society of sports nutrition position stand:

Caffeine and performance. J Int Soc


51. Graham TE. Caffeine and exercise:

Metabolism, endurance and performance.

Sports Med 31: 785–807, 2001.

52. Graham TE, Hibbert E, and Sathasivam P.

Metabolic and exercise endurance effects

of coffee and caffeine ingestion. J Appl

Physiol (1985) 85: 883–889, 1998.

53. Graham TE and Spriet LL. Metabolic,

catecholamine, and exercise performance

responses to various doses of caffeine.

J Appl Physiol (1985) 78: 867–874,

1995.

54. Gualano B, Roschel H, Lancha-Jr AH,

Brightbill CE, and Rawson ES. In sickness

and in health: The widespread application

of creatine supplementation. Amino Acids

43: 519–529, 2012.

55. Harland BF. Caffeine and nutrition.

Nutrition 16: 522–526, 2000.

56. Harris RC, Tallon MJ, Dunnett M,

Boobis L, Coakley J, Kim HJ,

Fallowfield JL, Hill CA, Sale C, and

Wise JA. The absorption of orally supplied

beta-alanine and its effect on muscle

carnosine synthesis in human vastus

lateralis. Amino Acids 30: 279–289,

2006.

57. Hill CA, Harris RC, Kim HJ, Harris BD,

Sale C, Boobis LH, Kim CK, and Wise JA.

Influence of beta-alanine supplementation

on skeletal muscle carnosine

concentrations and high intensity cycling

capacity. Amino Acids 32: 225–233,

2007.

58. Hobson RM, Saunders B, Ball G,

Harris RC, and Sale C. Effects of beta-

alanine supplementation on exercise

performance: A meta-analysis. Amino

Acids 43: 25–37, 2012.

59. Hoffman J, Ratamess N, Kang J,

Mangine G, Faigenbaum A, and Stout J.

Effect of creatine and beta-alanine

supplementation on performance and

endocrine responses in strength/power

athletes. Int J Sport Nutr Exerc Metabol

16: 430–446, 2006.

60. Hoffman J, Ratamess NA, Ross R, Kang J,

Magrelli J, Neese K, Faigenbaum AD, and

Wise JA. Beta-alanine and the hormonal

response to exercise. Int J Sports Med

29: 952–958, 2008.

61. Hoffman JR, Emerson NS, and Stout JR.

Beta-Alanine supplementation. Curr

Sports Med Rep 11: 189–195, 2012.

62. Hoon MW, Hopkins WG, Jones AM,

Martin DT, Halson SL, West NP,

Johnson NA, and Burke LM. Nitrate

supplementation and high-intensity

performance in competitive cyclists. Appl

Physiol Nutr 39: 1043–1049, 2014.

63. Hoon MW, Johnson NA, Chapman PG,

and Burke LM. The effect of nitrate

supplementation on exercise performance

in healthy individuals: A systematic review

and meta-analysis. Int J Sport Nutr Exerc

Metabol 23: 522–532, 2013.

64. Hoon MW, Jones AM, Johnson NA,

Blackwell JR, Broad EM, Lundy B,

Rice AJ, and Burke LM. The effect of

variable doses of inorganic nitrate-rich

beetroot juice on simulated 2,000-m

rowing performance in trained athletes. Int

J Sports Physiol Perform 9: 615–620,

2014.

65. Hornery DJ, Farrow D, Mujika I, and

Young WB. Caffeine, carbohydrate, and

cooling use during prolonged simulated

tennis. Int J Sports Physiol Perform 2:

423–438, 2007.

66. Hultman E and Sahlin K. Acid-base

balance during exercise. Exerc Sport Sci

Rev 8: 41–128, 1980.

67. Hultman E, Soderlund K, Timmons JA,

Cederblad G, and Greenhaff PL. Muscle

creatine loading in men. J Appl Physiol

(1985) 81: 232–237, 1996.

68. Jenkins NT, Trilk JL, Singhal A,

O’Connor PJ, and Cureton KJ. Ergogenic

effects of low doses of caffeine on cycling

performance. Int J Sport Nutr Exerc

Metabol 18: 328–342, 2008.

69. Jones AM. Dietary nitrate

supplementation and exercise

performance. Sports Med 44(Suppl 1):

S35–S45, 2014.

70. Juhn M. Popular sports supplements and

ergogenic aids. Sports Med 33: 921–

939, 2003.

71. Kamimori GH, Karyekar CS,

Otterstetter R, Cox DS, Balkin TJ,

Belenky GL, and Eddington ND. The rate

of absorption and relative bioavailability of

caffeine administered in chewing gum

versus capsules to normal healthy

volunteers. Int J Pharm 234: 159–167,

2002.

72. Kendrick IP, Harris RC, Kim HJ, Kim CK,

Dang VH, Lam TQ, Bui TT, Smith M, and

Wise JA. The effects of 10 weeks of

resistance training combined with beta-

alanine supplementation on whole body

strength, force production, muscular

endurance and body composition. Amino

Acids 34: 547–554, 2008.


73. Killer SC, BA, and Jeukendrup AE. No

evidence of dehydration with moderate

daily coffee intake: A counterbalanced

cross-over study in a free-living

population. PLoS One 9: e84154,

2014.

74. Klein C, Clawson A, Martin M,

Saunders MJ, Flohr JA, Bechtel MA,

Dunham W, Hancock M, and

Womack CJ. The effect of caffeine on

performance in collegiate tennis players.

J Caffeine Res 2: 111–116, 2013.

75. Kovacs MS. Tennis physiology: Training

the competitive athlete. Sports Med 37:

189–198, 2007.

76. Kovacs MS. A review of fluid and

hydration in competitive tennis. Int J

Sports Physiol Perform 3: 413–423,

2008.

77. Kovacs MS and Baker LB. Recovery

interventions and strategies for improved

tennis performance. Br J Sports Med 48

(Suppl 1): i18–21, 2014.

78. Kristiansen M, Levy-Milne R, Barr S, and

Flint A. Dietary supplement use by varsity

athletes at a Canadian university. Int J

Sport Nutr Exerc Metab 15: 195–210,

2005.

79. Kutz MR and Gunter MJ. Creatine

monohydrate supplementation on body

weight and percent body fat. J Strength

Cond Res 17: 817–821, 2003.

80. Liguori A, Hughes JR, and Grass JA.

Absorption and subjective effects of

caffeine from coffee, cola and capsules.

Pharmacol Biochem Behav 58: 721–

726, 1997.

81. Liu TH, Wu CL, Chiang CW, Lo YW,

Tseng HF, and Chang CK. No effects of

short-term arginine supplementation on

nitric oxide production, metabolism and

performance in intermittent exercise in

athletes. J Nutr Biochem 20: 462–468,

2009.

82. Lundberg JO, Larsen FJ, andWeitzberg E.

Supplementation with nitrate and nitrite

salts in exercise: A word of caution. J Appl

Physiol (1985) 111: 616–617, 2011.

83. MacIntosh BR and Wright BM. Caffeine

ingestion and performance of a 1,500-

metre swim. Can J Appl Physiol 20: 168–

177, 1995.

84. Magkos F and Kavouras SA. Caffeine use

in sports, pharmacokinetics in man, and

cellular mechanisms of action. Crit Rev

Food Sci Nutr 45: 535–562, 2005.

85. Malinauskas BM, Overton RF,

Carraway VG, and Cash BC.

Supplements of interest for sport-related

injury and sources of supplement

information among college athletes. Adv

Med Sci 52: 50–54, 2007.

86. Mannion AF, Jakeman PM, Dunnett M,

Harris RC, and Willan PL. Carnosine and

anserine concentrations in the quadriceps

femoris muscle of healthy humans. Eur J

Appl Physiol Occup Physiol 64: 47–50,

1992.

87. Matson LG and Tran ZV. Effects of

sodium bicarbonate ingestion on

anaerobic performance: A meta-analytic

review. Int J Sport Nutr 3: 2–28, 1993.

88. Matthews MM and Traut TW. Regulation

of N-carbamoyl-beta-alanine

amidohydrolase, the terminal enzyme in

pyrimidine catabolism, by ligand-induced

change in polymerization. J Biol Chem

262: 7232–7237, 1987.

89. Maughan RJ, Depiesse F, and Geyer H.

The use of dietary supplements by

athletes. J Sports Sci 25(Suppl 1):

S103–S113, 2007.

90. Maughan RJ, King DS, and Lea T. Dietary

supplements. J Sports Sci 22: 95–113,

2004.

91. McCarty MF. Supplemental creatine may

decrease serum homocysteine and

abolish the homocysteine “gender gap”

by suppressing endogenous creatine

synthesis. Med Hypotheses 56: 5–7,

2001.

92. McLellan TM and Bell DG. The impact of

prior coffee consumption on the

subsequent ergogenic effect of

anhydrous caffeine. Int J Sport Nutr Exerc

Metab 14: 698–708, 2004.

93. McNaughton LR. Sodium bicarbonate

ingestion and its effects on anaerobic

exercise of various durations. J Sports Sci

10: 425–435, 1992.

94. McNaughton LR, Siegler J, and Midgley A.

Ergogenic effects of sodium bicarbonate.

Curr Sports Med Rep 7: 230–236, 2008.

95. Mesa JL, Ruiz JR, Gonzalez-Gross MM,

Gutierrez Sainz A, and Castillo

Garzon MJ. Oral creatine

supplementation and skeletal muscle

metabolism in physical exercise. Sports

Med 32: 903–944, 2002.

96. Mora-Rodriguez R, Garcia Pallares J,

Lopez-Samanes A, Ortega JF, and

Fernandez-Elias VE. Caffeine ingestion

reverses the circadian rhythm effects on

neuromuscular performance in highly

resistance-trained men. PLoS One 7:

e33807, 2012.

97. Mora-Rodriguez R, Pallares JG, Lopez-

Gullon JM, Lopez-Samanes A, Fernandez-

Elias VE, and Ortega JF. Improvements on

neuromuscular performance with caffeine

ingestion depend on the time-of-day. J Sci

Med Sport 18: 338–342, 2015.

98. Pallares JG, Fernandez-Elias VE,

Ortega JF, Munoz G, Munoz-Guerra J, and

Mora-Rodriguez R. Neuromuscular

responses to incremental caffeine doses:

Performance and side effects. Med Sci

Sports Exerc 45: 2184–2192, 2013.

99. Parkhouse WS, McKenzie DC,

Hochachka PW, and Ovalle WK.

Buffering capacity of deproteinized

human vastus lateralis muscle. J Appl

Physiol (1985) 58: 14–17, 1985.

100. Pasman WJ, van Baak MA,

Jeukendrup AE, and de Haan A. The

effect of different dosages of caffeine on

endurance performance time. Int J Sports

Med 16: 225–230, 1995.

101. Peart DJ, Siegler JC, and Vince RV.

Practical recommendations for coaches

and athletes: A meta-analysis of sodium

bicarbonate use for athletic performance.

J Strength Cond Res 26: 1975–1983,

2012.

102. Periard JD, Racinais S, Knez WL,

Herrera CP, Christian RJ, and Girard O.

Thermal, physiological and perceptual

strain mediate alterations in match-play

tennis under heat stress. Br J Sports Med

48(Suppl 1): i32–i38, 2014.

103. Persky AM and Brazeau GA. Clinical

pharmacology of the dietary supplement

creatine monohydrate. Pharmacol Rev

53: 161–176, 2001.

104. Pluim BM, Ferrauti A, Broekhof F,

Deutekom M, Gotzmann A, Kuipers H, and

Weber K. The effects of creatine

supplementation on selected factors of

tennis specific training. Br J Sports Med

40: 507–511, 2006; discussion 511–502.

105. Pumpa KL, Madigan SM, Wood

Martin RE, Flanagan R, and Roche N. The

development of nutritional-supplement

fact sheets for Irish athletes: A case study.

Int J Sport Nutr Exerc Metab 22: 220–

224, 2012.

106. Rampinini E, Coutts AJ, Castagna C,

Sassi R, and Impellizzeri FM. Variation in

top level soccer match performance. Int J

Sports Med 28: 1018–1024, 2007.

107. Reid M and Schneiker K. Strength and

conditioning in tennis: Current research

and practice. J Sci Med Sport 11: 248–

256, 2008.

108. Renfree A. The time course for changes in

plasma [h+] after sodium bicarbonate

ingestion. Int J Sports Physiol Perform 2:

323–326, 2007.

109. Requena B, Zabala M, Padial P, and

Feriche B. Sodium bicarbonate and



sodium citrate: Ergogenic aids?.

J Strength Cond Res 19: 213–224,

2005.

110. Reyner LA and Horne JA. Sleep

restriction and serving accuracy in

performance tennis players, and effects of

caffeine. Physiol Behavior 120: 93–96,

2013.

111. Roetert EG, Garrett GE, Brown SW, and

Camaione DN. Performance profiles of

nationally ranked junior tennis players.

J Strength Cond Res 6: 225–231, 1992.

112. Sale C, Harris RC, Florance J, Kumps A,

Sanvura R, and Poortmans JR. Urinary

creatine and methylamine excretion

following 4 x 5 g x day(-1) or 20 x 1 g x day

(-1) of creatine monohydrate for 5 days.

J Sports Sci 27: 759–766, 2009.

113. Sale C, Saunders B, and Harris RC.

Effect of beta-alanine supplementation on

muscle carnosine concentrations and

exercise performance. Amino Acids 39:

321–333, 2010.

114. Schedel JM, Tanaka H, Kiyonaga A,

Shindo M, and Schutz Y. Acute creatine

ingestion in human: Consequences on

serum creatine and creatinine

concentrations. Life Sci 65: 2463–2470,

1999.

115. Schneiker KT, Bishop D, Dawson B, and

Hackett LP. Effects of caffeine on

prolonged intermittent-sprint ability in

team-sport athletes. Med Sci Sports

Exerc 38: 578–585, 2006.

116. Schroder H, Terrados N, and Tramullas A.

Risk assessment of the potential side

effects of long-term creatine

supplementation in team sport athletes.

Eur J Nutr 44: 255–261, 2005.

117. Sokmen B, Armstrong LE, Kraemer WJ,

Casa DJ, Dias JC, Judelson DA, and

Maresh CM. Caffeine use in sports:

Considerations for the athlete. J Strength

Cond Res 22: 978–986, 2008.

118. Souza-Junior TP, Willardson JM,

Bloomer R, Leite RD, Fleck SJ,

Oliveira PR, and Simao R. Strength and

hypertrophy responses to constant and

decreasing rest intervals in trained men

using creatine supplementation. J Int Soc


119. Stellingwerff T, Anwander H, Egger A,

Buehler T, Kreis R, Decombaz J, and

Boesch C. Effect of two beta-alanine

dosing protocols on muscle carnosine

synthesis and washout. Amino Acids 42:

2461–2472, 2012.

120. Stellingwerff T, Decombaz J, Harris RC,

and Boesch C. Optimizing human in vivo

dosing and delivery of beta-alanine

supplements for muscle carnosine

synthesis. Amino Acids 43: 57–65, 2012.

121. Stout JR, Cramer JT, Zoeller RF, Torok D,

Costa P, Hoffman JR, Harris RC, and

O’Kroy J. Effects of beta-alanine

supplementation on the onset of

neuromuscular fatigue and ventilatory

threshold in women. Amino Acids 32:

381–386, 2007.

122. Strecker E, Foster EB, Taylor K, Bell L,

Pascoe, and David D. The effect of

caffeine ingestion on tennis skill

performance. Med Science Sports

Exercise 38: S175, 2006.

123. Strecker E, Foster EB, Taylor K, Bell L,

Pascoe D, and David D. The effect of

caffeine ingestion on tennis skill

performance and hydration status. Med

Sci Sports Exerc 2007: S43, 2007.

124. Struder H, Ferrauti A, Gotzmann A,

Webber K, and Hollman W. Effects of

carbohydrate and caffeine on plasma

amino acids, neuroendocrine reponses

and performance in tennis. Nutr Neurosci

1: 419–426, 1999.

125. Sureda A and Pons A. Arginine and

citrulline supplementation in sports and

exercise: Ergogenic nutrients?Med Sport

Science 59: 18–28, 2012.

126. Terjung RL, Clarkson P, Eichner ER,

Greenhaff PL, Hespel PJ, Israel RG,

Kraemer WJ, Meyer RA, Spriet LL,

Tarnopolsky MA, Wagenmakers AJ, and

Williams MH. American College of Sports

Medicine roundtable. The physiological

and health effects of oral creatine

supplementation. Med Sci Sports Exerc

32: 706–717, 2000.

127. Turley K, Rivas D, Townseed J, Morton A,

Kosarek J, and Cullum M. Effects of

caffeine on anaerobic exercise in boys.

Pediatr Exerc Sci: 210–219, 2012.

128. Vergauwen L, Brouns F, and Hespel P.

Carbohydrate supplementation

improves stroke performance in tennis.

Med Sci Sports Exerc 30: 1289–

1295, 1998.

129. Vergauwen L, Spaepen AJ, Lefevre J, and

Hespel P. Evaluation of stroke

performance in tennis. Med Sci

Sports Exerc 30: 1281–1288, 1998.

130. Vorgerd M, Grehl T, Jager M, Muller K,

Freitag G, Patzold T, Bruns N, Fabian K,

Tegenthoff M, Mortier W, Luttmann A,

Zange J, and Malin JP. Creatine therapy

in myophosphorylase deficiency

(McArdle disease): A placebo-controlled

crossover trial. Arch Neurol 57: 956–

963, 2000.

131. Warren GL, Park ND, Maresca RD,

McKibans KI, and Millard-Stafford ML.

Effect of caffeine ingestion on muscular

strength and endurance: A meta-analysis.

Med Sci Sports Exerc 42: 1375–1387,

2010.

132. Wax B, Kavazis AN, Webb HE, and

Brown SP. Acute L-arginine alpha

ketoglutarate supplementation fails to

improve muscular performance in

resistance trained and untrained men.

J Int Soc Sports Nutr 9: 17, 2012.

133. Webster MJ, Webster MN,

Crawford RE, and Gladden LB. Effect

of sodium bicarbonate ingestion on

exhaustive resistance exercise

performance. Med Sci Sports Exerc 25:

960–965, 1993.

134. Wu CL, Shih MC, Yang CC, Huang MH,

and Chang CK. Sodium bicarbonate

supplementation prevents skilled tennis

performance decline after a simulated

match. J Int Soc Sports Nutr 7: 33, 2010.

135. Yavuz HU, Turnagol H, and Demirel AH.

Pre-exercise arginine supplementation

increases time to exhaustion in elite male

wrestlers. Biol Sport 31: 187–191,

2014.


Documents

Nutritional Ergogenic Aids in Tennis a Brief.1