Effect of Astaxanthin on Cycling Time Trial Performance

Transcription

1 882 Nutrition Effect of Astxnthin on Cycling Time Tril Performnce Authors C. P. Ernest 1, M. Lupo 1, K. M. White 2, T. S. Church 3 Affilitions 1 Pennington Biomedicl Reserch Center, Exercise Biology Lortory, Bton Rouge, United Sttes 2 Gtorde, Sports Science Institute, Brrington, United Sttes 3 Pennington Biomedicl Reserch Center, Preventive Medicine, Bton Rouge, United Sttes Key words cycling nutrition ergogenic id performnce supplement ccepted fter revision My 16, 211 Biliogrphy DOI /s Pulished online: Octoer 7, 211 Int J Sports Med 211; 32: Georg Thieme Verlg KG Stuttgrt New York ISSN Correspondence Dr. Conrd. P. Ernest, PhD Pennington Biomedicl Reserch Center Exercise Biology Lortory Perkins Rod 788 Bton Rouge United Sttes 64 Tel.: +1/225/ Fx: +1/225/ Conrd.Ernest@prc.edu Astrct We exmined the effect of Astxnthin (AST) on sustrte metolism nd cycling time tril (TT) performnce y rndomly ssigning 21 competitive cyclists to 28d of encpsulted AST (4 mg/d) or plceo (PLA) supplementtion. Testing included VO 2mx test nd on seprte dy 2 h constnt intensity pre-exhustion ride, fter 1 h fst, t 5 % elow VO 2mx stimulted onset of 4 mmol/l lctic cid followed 5 min lter y 2 km TT. Anlysis included ANOVA nd posthoc testing. Dt re Men (SD) nd (95 % CI) when expressed s chnge (pre vs. post). Fourteen prticipnts successfully completed the Introduction Astxnthin (AST) is crotenoid elonging to lrger clss of phytochemicls known s terpenes tht cn e found in microlge, yest, slmon, trout, krill, shrimp, cryfish, crustcens, nd the fethers of some irds [5,7,9, 1, 16 ]. Currently, the FDA permits the use of AST s food coloring, s well s n dditive for niml nd fish foods. Perhps AST s most notle use is s feed dditive for frm rised slmon, giving the slmon its reddish tissue color. While AST is nturl nutritionl component found in food it cn lso e purchsed over-the-counter s dietry supplement. Astxnthin hs recently received ttention due to its ility to scvenge free rdicls, decrese inflmmtion, improve indices of lipid metolism nd ttenute lipid ccretion, nd increse exercise time to exhustion in mice [1, 2, 7, 12, 15 ]. To dte, only one study hs exmined the efficcy of AST supplementtion on endurnce exercise performnce in humns, wherey 4 weeks of AST supplementtion ws shown to reduced lctic cid uild up following 1 2 m of running [ 14 ]. tril. Overll, we oserved significnt improvements in 2 km TT performnce in the AST group (n = 7; 121 s; 95 %CI, 185, 53), ut not the PLA (n = 7; 19 s; 95 %CI, 84, 45). The AST group ws significntly different vs. PLA (P <.5). The AST group significntly incresed power output (2 W; 95 %CI, 1, 38), while the PLA group did not (1.6 W; 95 %CI, 17, 2). The mechnism of ction for these improvements remins uncler, s we oserved no tretment effects for crohydrte nd ft oxidtion, or lood indices indictive of fuel moiliztion. While AST significntly improved TT performnce the mechnism of ction explining this effect remins oscure. However, if enhnced lipid metolism is proposed enefit of AST supplementtion, it seems more intuitive to exmine exercise outs of longer durtion. Accordingly we re unwre of ny pulished studies exmining the effect of AST supplementtion for prolonged periods of exercise endurnce performnce in humns. The primry im of our current study ws to exmine whether 28 dys of AST supplementtion would improve exercise following 2 h pre-exhustion ride designed to minimize crohydrte contriution during exercise performnce. Our secondry im ws to determine whether 28 dys of AST supplementtion modultes indices of crohydrte nd lipid metolism. Mteril nd Methods Prticipnts We recruited mteur endurnce-trined mles from 18 to 39 yers of ge who hd VO 2 mx 5 ml/kg/min, were ctively prticipting in competitive cycling ctivities such s competitive rod cycling or trithlons, nd were ccumu-

2 Nutrition 883 All (N=14) Astxnthin (n=7) Plceo (n=7) VO 2mx (L/min) 3.88 (.4) 3.98 (.3) 3.79 (.4) VO 2mx (ml/kg/min) (3.5) (4.1) (2.4) Mximl PO (W) 33 (26) 335 (17) 325 (34) HR mx (/min) 185 (9) 183 (11) 187 (7) PO 2 mmol/l BL 141 (57) 144 (62) 138 (57) percent of 2 mmol/l BL 5.9 (12.9) 49.8 (14.7) (12.) PO 4 mmol/l BLA 228 (47) 227 (43) 229 (55) percent of 4 mmol/l BL (9.7) (8.9) (1.) Dt re men nd SD Tle 1 Bseline fitness chrcteristics of study prticipnts. Withdrwn N=1, Illness N=1, Computer Filure N=1, Unle to Complete Protocol N=1, Invlid pretest Fig. 1 Emil Response (N=79) Eligile for Bseline (N=26) Successfully Completed Bseline (N=21) Rndomized to Tretment (N=21) Tretment (N=11) Completed (N=7) Plceo (N=1) Completed (N=7) CONSORT digrm of study enrollment. Exclusion N=53, Filed to meet inclusion criteri Exclusion N=3, Insufficient VO 2mx N=2 Filure to complete 2 hr ride Withdrwn N=2, Unle to Complete Protocol N=1, Invlid pretest lting weekly cycling volume of 16 km per week. Initilly, we considered using mixed cohort of men nd women, however, decided ginst it for 2 primry resons. First, it hs een purported tht crohydrte nd ft metolism differ etween genders with respect to prolonged exercise [ 18 ]. Thus, mixed cohort would dd vrince to our study tht we would not e le to ccount for using reltively smll smple size. Second, we, nd others in our community (Bton Rouge, LA, USA), hve found it difficult to recruit women for more strenuous exercise protocols such s the one undertken for this study. Hence, we focused our current recruitment efforts on men, whose crdiorespirtory fitness mesures re presented in Tle 1. The ethicl review committee t Pennington Biomedicl Reserch Center pproved our study nd informed consent ws otined from ll prticipnts efore entering the tril. All study procedures conformed to the Declrtion of Helsinki nd ethicl stndrds of IJSM [ 8 ]. We hve provided CONSORT schemtic outlining the overll study timeline in Fig. 1. Recruitment nd seline testing We initited our recruitment efforts y contcting locl cycling clus vi emil, who therein posted our study detils on vrious online forums nd discussion ords. Upon expressing interest in the study, we contcted potentil cndidtes vi phone nd emil. Following successful screening procedure we invited study cndidtes to come to the Pennington Biomedicl Reserch Center Exercise Biology Lortory Testing Core where they were further screened to prticipte in our study protocol. The entire length of the study for ech prticipnt rnged from 35 to 4 dys. Briefly, prticipnts ttended seline run-in period, inclusive of exercise testing to determine mximl crdiorespirtory cpcity (detils elow), 2 km TT rehersls, nd fsted 2 h pre-exhustion ride tht ws followed immeditely y 2 km TT (detils elow) on their own ike using Computriner ergometer (Settle, WA). Before ech Computriner test the ergometer ws turned on nd llowed to wrm-up for 3 min. Immeditely efore ech TT we lso performed n individulized clirtion procedure tht ccounts for rolling resistnce. We hve presented schemtic of ll testing procedures in Fig. 2. Mximl crdiorespirtory exercise We instructed ech suject to prepre for his VO 2mx test s if prepring for rce nd to stin from exercise for 24 h efore the test. This preprtion included not chnging their trining prmeters or dietry ptterns for the week preceding ech test. We sked prticipnts to record wht they te in food log 3 dys efore testing nd to duplicte the sme food intke on the penultimte dy efore testing during the follow-up visit. Prticipnts were lso instructed to et light snck ~3 h efore their tests nd to stin from ingesting ny medictions tht would influence hert rte on the dy of ech test. The one exception ws cffeine, which we sked prticipnts not to consume for t lest 5 h efore testing. We performed ll VO 2mx exercise tests on Lode Excliur Sport Ergometer (Groningen, The Netherlnds) nd nlyzed the riders for vrious crdiorespirtory prmeters using Prvomedics TrueMx Metolic System (Slt Lke City, UT). Ech cycling test egn with wrm-up t 5 W (1 min) nd then progressed to 75 W (2 min). After the wrm-up, the test egn y incresing the power output (PO) to 1 W. Once PO ws set t 1 W, ech stge inclusive of the 1-W stge lsted 3 min nd progressed 35 W every 3 min until the rider reched exhustion or could no longer mintin pedl cdence of 5 rpm. We llowed ech rider to choose their preferred cdence within rnge of 7 9 rpm. We collected gs exchnge dt continuously using n utomted computerized reth-y-reth Prvomedics TrueMx Metolic System. The TrueMx system uses pneumotchometer, prmgnetic O 2 nlyzer, nd n infrred CO 2 nlyzer to nlyze respirtory O 2 nd CO 2, respectively. Before ech test, we followed stndrd clirtion procedure for ech metolic crt including flow clirtion using 3-L clirtion syringe nd clirtion ginst stndrdized gses (16 % O 2, 4 % CO 2, nd lnced nitrogen) otined from the mnufcturer of the metolic system. We verged ll gs exchnge dt in 6 s intervls nd only the lst minute of ech stge ws used in our nlyses. Blood smples (25 ul) for the mesurement of lood lctte (Lctte Pro, Quesnel, BC, Cnd) were tken from the riders fingertips t rest nd during the lst 3 s of ech stge strting t 75 W. From these lc-

3 884 Nutrition Overview of testing nd supplementtion timeline. Dys 6 33 Fig. 2 Overview of study timeline (pnel ) nd testing procedures (pnel ). Bseline Testing Supplement (28 d) Post Testing Screening Dy 1 Dy 2 Dy 3 Dy 4 Dy 5 Dy 32 Dy 33 Dy 34 Determine Eligiility Ht Wt Prctice Time Tril Prctice Time Tril Rest 2 hr ride 2 km TT Rest 2 hr ride 2 km TT VO 2mx (2 km) (2 km) VO 2mx Sequence of dt collection during testing Pre-Ride procedures 2 hr stedy stte ride pre-exhustion ride Stndrdized respirtory nd lood collections every 2 minutes Rest (5 min) Time Tril 3 min 1 min 16 2 min 36 4 min 56 6 min 76 8 min 96 1 min min min 125 min+ Insert Ctheter Mesure: Glucose Lctic cid Chem-15 CBC Glycerol NEFA Extr Serum Plsm Wrm 1 W Mesure ( 2m): Glucose Lctic cid Glycerol NEFA NEFA: Non-esterified ftty cid TT: Time Tril PO: Power Output in wtts Respirtory dt (4 min of collection) (VO2 & VCO2) Mesure: Glucose Lctic cid Glycerol NEFA tte mesurements we determined the corresponding PO ssocited with the ccumultion of 2 mmol/l nd 4 mmol/l of lctic cid ccumultion y drwing 3 rd order line of est fit through ll dt points. For the 2 h ride we sked riders to work t PO corresponding to 5 % lower thn the PO ssocited with the ccumultion of 4 mmol/l of lctic cid. Two-hour nd 2 km TT performnce testing We hve presented schemtic outlining the procedures for the 2 h pre-exhustion nd TT ride performed t seline nd follow-up in Fig. 2. For the 2 h pre-exhustion fsting ride, we sked prticipnts to report to the Pennington Exercise Testing Core on the morning of their test where we plced n indwelling ctheter into n ntecuitl vein 3 min efore their ride. We lso determined prticipnt hydrtion sttus designted s hving urine specific grvity (USG) less thn During the TT we instructed prticipnts to ride the 2 km distnce s fst s possile on his own icycle. To ensure miniml vriility etween tests we sked the prticipnts ride the sme ike with the sme configurtion for positioning during the rehersl, seline nd follow-up testing conditions. Approximtely 2 min fter the insertion of the ctheter, we collected n initil series of lood smples to ssess resting lood vlues in order to monitor the pre- nd post-tretment sfety corresponding to supplementtion with AST. These mesures included stndrd serum 15-pnel lood test to mesure cretinine, potssium, uric cid, lumin, clcium, mgnesium, cretine phosphokinse (CPK), lnine minotrnsferse (ALT), lkline phosphtse (ALK), iron, cholesterol (LDL & HDL), nd triglycerides. We lso performed complete lood count (CBC) with differentils to determine hemogloin, hemtocrit, men cell volume, pltelet count, white lood count, grnulocytes, neutrophils, eosinophils, nd sophils. 2 km TT Time to complete Ave PO PO e. 5 km After we collected the first set of lood smples we sked ech rider to perform 1 min wrm up t low intensity (5 W) efore inititing the 2 h ride. During the 2 h pre-lod ride we collected lood smples every 2 min to determine severl indices indictive of crohydrte nd lipid metolism including glucose, lctic cid, glycerol, nd non-esterified ftty cids (NEFA). At these sme time intervls we lso mesured crdiorespirtory prmeters (VO 2 nd VCO 2, L/min) to determine the reltive contriutions of crohydrte nd ft oxidtion during testing using stndrd stoichiometric equtions [6 ]. Riders consumed 25 ml of wter every 15 min throughout the test. For the lood mesurements we collected ech lood smple during the lst 3 s of the 2 min period. For VO 2 nd VCO 2 we egn dt collection 4 min efore ech 2 min demrction in order to otin stedy stte vlues. However, we only used the lst minute of this collection period for our nlysis. All lood smples were spun on centrifuge nd stored t 8 C until we could nlyze them in tch (i. e., pre/post test smple together) using Beckmn Coulter DXC6 (Bre, CA) nlyzer. We nlyzed glucose nd lctic cid using n oxygen electrode nd enzymtic endpoint method of nlysis, respectively. For glucose, ll smples were spun on centrifuge t 3 5 rpm for 15 min t room temperture. For lctic cid, ech smple ws spun t the sme speed t 4 C. For glycerol nd NEFA we nlyzed ech smple using enzymtic colorimetric detection nlysis, respectively. For glycerol, centrifugtion took plce t 3 5 rpm for 15 min t room temperture, while for NEFA the centrifuge speed ws 3 rpm for 15 min t 4 C. Rndomiztion nd tretment After completing the entire seline testing procedures, we rndomized ech prticipnt, in doule-lind, plceo controlled, prllel group designed mnner to receive either 4 mg/d of encpsulted AST or mtched plceo for 4 weeks. We chose

4 Nutrition weeks s studies in mice hve shown tht AST improves lipid metolism nd exercise performnce within 4 5 week period [2, 11 ]. All supplements were provided y Fuji Helth Science, Inc. (Burlington, NJ). Ech tretment ws delivered in lck soft gel cpsule nd ech AST soft gel contined 8 mg of 5 % nturl stxnthin extrct from Hemtococcus pluvilis lge, yielding 4 mg of ctive stxnthin per soft gel, nd 12 mg of medium chin triglyceride s filler. The plceo soft gel ws comprised of 2 mg medium chin triglyceride plus smll mount of crmel food coloring to mke the cpsules identicl in ppernce to the ctive soft gels. We sked ll prticipnts to consume their respective tretments with mel nd provided ech person with enough supplement for 5 extr dys in cse they required n extended period to complete the study protocol. This ltter spect of our study lso etter enled us to perform pill count t the end of the study to determine the degree of complince to the study protocol. Lstly, people independent of the study dispersed ll tretments using unique, individulized 4-digit numer sequence. We chose rndomized numer sequence in cse we oserved ny side effects during the course of the study. This procedure llows for the reking of single tretment code without scrificing the integrity of the entire tretment cohort. Sttisticl nlysis Our primry outcome nlysis ws imed t determining whether AST supplementtion improved vrious indices of cycling performnce following 2 h pre-exhustion out of exercise intended to minimize crohydrte contriution. The primry outcomes for our investigtion were the rider s ility to complete 2 km TT immeditely following 2 h pre-exhustion ride. Accordingly, we exmined TT performnce in terms of the time it took to complete the 2 TT km ride nd the verge PO generted y the rider. As secondry nlysis we exmined severl lortory indices of physicl performnce such s VO 2mx, mximl PO, nd the PO oserved t lctte threshold (2 mmol/l) nd onset of lood lctte ccumultion (4 mmol/l) during the VO 2mx test. As tertiry nlysis we ssessed severl metolic prmeters trditionlly used s mens of providing mechnism of ction should performnce chnges e oserved. These indices included the nlysis of lood vriles indictive of improved crohydrte nd ft usge including: plsm lctte, glucose, non-esterified ftty cids, nd glycerol. We pproched our nlysis of these vriles in 2 wys. First, we nlyzed the overll effectiveness of AST on these vriles y using n integrted re-under-the-curve (AUC) ssessment for ll time intervls ssocited with our dt collection eginning with the resting mesurement s time. Our second strtegy ws to exmine potentil differences in these vriles t ech 2 min time point during the 2 h ride. These specific time points included resting lood vlues otined fter 1 h fst, the end of wrm-up, nd every 2 min therein during the 2 h ride. During these sme time intervls we lso exmined the respirtory derived mesurements for the stoichiometric ssessment of crohydrte nd ft oxidtion. For our primry nlysis we exmined ech vrile s chnge from seline. Determintions for within group significnce were sed on the men chnge nd ccompnying 95 % confidence intervl (95 % CI) for ech respective performnce prmeter. We used generl liner model to exmine etween group differences. Effect sizes were clculted for time to complete nd verge power output during the 2 km TT using Cohen s d (ES) [ 4 ]. For the AUC nlysis we nlyzed our dt using 2 2 [tretment (plceo/tretment) time (pre/ post)] ANOVA. For the time prmeter nlysis we used repeted mesures ANOVA. Lstly, we lso exmined the men chnge in outcomes etween the pre-test nd post-test condition using one-wy ANOVA. We exmined lood chemistry vlues (i. e., Chem-15/CBC) nd food frequency evlutions using the sme sttisticl techniques s descried for the primry outcome dt. The reson for the lood chemistry nlysis ws to determine whether AST supplementtion might dversely ffect heptorenl function, in order to ensure tht supplementtion with AST ws sfe. Lstly, we exmined y pill count the numer of ssigned tretment cpsules vs. the numer of supplement dys during the study period. We excluded ny outliers in the studies who fell outside 3 SD for time chnges from pre to post tretment. All individul time point dt in our pper re presented s men ± SD. Sttisticl significnce ws set t P.5. Results We rndomized 21 prticipnts into our study (AST = 11, PLA = 1). However, only 7 prticipnts from ech tretment group completed the entire testing protocol. The resons for this completion rte re presented in Fig. 1, ut generlly fll under the ctegories of illness, equipment filure or inility to complete the 2 h pre-exhustion ride or the susequent TT. We did however remove 2 outlier performnces from our nlysis. In one instnce, we removed rider from the AST group for demonstrting 7 min time improvement from the pre to post test condition. In the other instnce we removed one rider from the PLA group for n norml performnce loss of 5 min. Though we could hve kept these 2 riders in our nlysis, their reltive chnges in performnce given their respective tretment groups, only served to seprte our hypothesis further from the null. In essence, leving these 2 riders in the nlysis incresed the tretment effect for the AST group, while simultneously mking the PLA group pper slower. For those who completed the study, we oserved no sttisticl difference t seline etween tretment groups for ny of our mesurements ssocited with the study including ge (28 ± 6 yers), ody mss (74.6 ± 8.8 kg), nd height (175.6 ± 8.5 cm). For our post-test nlysis, we oserved significnt within group improvement for the time it took to complete the 2 km TT for the AST supplemented riders (2 387 ± 26 s vs ± 19 s; rnge, 2, 251 s) nd the verge power output mesured during the TT ride (162 ± 37 W vs. 186 ± 34 W; rnge, 5 4 W, P <.5). For our nlysis of time to complete the 2 km TT, we oserved tht the AST group s time improvement ws significntly different from the PLA group (P <.2). Though some improvement in time ws oserved for the PLA group, neither TT time (2251 ± 26 s vs ± 283 s; rnge, 11, 62) or PO (186 ± 57 W vs. 187 ± 75 W) ws sttisticlly significnt following the 28 d supplementtion period. The ES for the difference etween tretment groups in their time to complete the time tril ws 1.25, whilst the ES for the etween group difference in PO ws.95. According to Cohen, these ES would e considered lrge [ 4 ].We hve presented the men nd 95 % CI chnge for time nd PO long with ccompnying individul responses for ech tretment group in Fig. 3. For our nlysis of fuel utiliztion we were unle to detect significnt tretment difference for ny lood mrker indictive

5 886 Nutrition Time (sec) seconds (95% CI, 185.2, 56.5) Astxnthin 19 seconds (95% CI, 83.5, 45.2) Plceo Cro hydrte Oxidtion (g/min) Min 2 Min 4 Min 6 Min 8 Min 1 Min Power Output (W) W (95% CI, 1., 38.1) 1.6 W (95% CI, 17, 2.3) Astxnthin Plceo Fig. 3 Dt represent the men nd 95% CI within group chnges in time performnce (pnel ) nd power output (pnel ) for cyclists receiving 28 d of AST (left side) or PLA (right side) supplementtion. *P<.5 for etween group differences. of enhnced crohydrte or ft oxidtion ( Fig. 4, ), neither were we le to detect chnge in ny lood prmeter suggestive of shift in fuel metolism ( Fig. 5 d ) for ny given 2 min time intervl. While we did oserve significnt increse in plsm concentrtions of NEFA with incresing exercise time, these increses were similr within ech group ut not different etween groups or the pre/post tretment condition. When we further nlyzed our lood work dt s n AUC for the entire 2 h pre-exhustion ride we were lso unle to detect significnt difference for tretment group. Lstly, we did not oserve ny differences in either the lood chemistries suggesting the tretment group significntly ltered heptorenl function during the tretment period (dt not shown). Discussion The primry im of our study ws to exmine the effect of AST supplementtion on 2 km TT performnce following 2 h preexhustion ride undertken fter 1 h fst. The gol in using this type of protocol ws to minimize the contriutions of crohydrte for energy provision; hence, creting n incresed relince on ft oxidtion. This decision ws sed on oservtions from niml studies showing n incresed relince on ft utiliztion while simultneously incresing time to exhustion during exercise [1, 2,11, 12 ]. We oserved n pproximte 2 min men improvement (5 %) in the time necessry to complete the 2 km Ft Oxidtion (g/min) Min 2 Min 4 Min 6 Min 8 Min 1 Min 12 Fig. 4 Dt represent men nd stndrd devitions for crohydrte (pnel ) nd ft oxidtion (pnel ) oserved during the 2 h pre-exhustion ride. TT tht ws ccompnied y 2 W increse (15 %) in the verge power output generted y riders during the TT condition. Chnges in time nd power output for the PLA group were.8 % nd.5 %, respectively. An exmintion of Fig. 3 lso shows tht ech of the riders in the AST group improved 2 km performnce time nd power output, while the PLA group showed miniml improvements nd were firly evenly split etween fster nd slower performnces. Despite these improvements in cycling performnce the mechnism of ction to explin our findings remin enigmtic. Most of the reserch conducted on AST to dte hs used murine models to exmine exercise performnce nd energy distriution ptterns. For exmple, Aoi et l. [ 2 ] exmined mice divided into 4 groups of mice tht were either () sedentry, () sedentry, yet, treted with AST, or ssigned to run on tredmill (c) without or (d) with AST supplementtion [ 2 ]. In their study, the uthors reported tht ech exercise group ws le to run longer on the tredmill efore exhustion; however, those mice treted with AST lso incresed ft utiliztion during exercise compred to mice on norml diet. At cellulr level these findings were supported y the oservtion tht AST fed mice incresed the locliztion of ftty cid trnslocse (FAT/CD36) nd crnitine plmitoyltrnsferse I (CPT I) in skeletl muscle. In essence, AST improved vrious mechnisms ssocited with trnsporting long chin ftty cids into the mitochondri. In our current study, however, we see no evidence for the preferentil use of ft. A question tht my e rised pertins to dosing equivlents etween murine nd humn studies. In one such study, Ikeuchi

6 Nutrition Lctic Acid (mmol/l) Glucose (mmol/l) c * Rest Min 1 Min 2 Min 4 Min 6 Min 8 Min 1 Min 12 Rest Min 1 Min 2 Min 4 Min 6 Min 8 Min 1 Min 12 Rest Min 1 Min 2 Min 4 Min 6 Min 8 Min 1 Min 12 Fig. 5 Dt represent men nd stndrd devitions for plsm glucose (pnel ), lctic cid (pnel ), non-esterified ftty cid (pnel c ) nd glycerol concentrtions oserved during the 2 h pre-exhustion ride. *P <.5 for within group time point differences from rest through 4 min (ll groups). et l. [11 ] exmined the effects of AST supplementtion on exercise-induced ftigue in mice y dministering AST (1.2, 6, or 3 mg/kg ody weight) for 5 weeks vi stomch intution. Posttest nlysis showed n overll dose dependent increse in exercise time to exhustion in mice receiving 6 nd 3 mg/kg of AST vs. control. This would equte to pproximtely 42 mg nd 2.1 g of AST in humns, respectively, ssuming the AST ws given to 7 kg reference mle. Thus, the dosge given to the mice ws significntly higher thn wht we dministered in our study. The uthors of this study lso oserved significnt reduction in lctic cid nd higher concentrtion of non-esterified ftty cids nd plsm glucose concentrtions throughout exercise in the AST treted groups [ 11 ]. Though this lrger dosge pttern my ultimtely ffect energy sustrte utiliztion, it does not reconcile the improvements in performnce tht we oserved in our tril. Only two studies hve exmined the efficcy of AST for improving exercise performnce in humns, while only one of those studies exmined some type of endurnce performnce. In 2 2, Keisuke et l. exmined the effectiveness of AST on the uild up of lctic cid following 1 2 m of running efore nd fter 4 weeks of supplementtion nd found tht the 2 min post-running lctic cid concentrtion ws significntly lower in the AST supplemented runners vs. control [ 14 ]. In second study, Bloomer et l. supplemented resistnce trined men with AST (4 mg/d) for 3 weeks nd found no supplementtion relted effects on plsm levels of cretine Glycerol (mmol/l) Nonesterified fcty cids (mmol/l) d Rest Min 1 Min 2 Min 4 Min 6 Min 8 Min 1 Min 12 kinse, lctte dehydrogense, delyed onset muscle soreness or exercise performnce [ 3 ]. Strengths nd Limittions A strength of our current investigtion is tht we exmined the effectiveness of AST supplementtion under conditions imed t decresing the relince on crohydrte metolism y use of n overnight fst without the presence of CHO ingestion during the 2 h pre-exhustion ride. Though we were successful in demonstrting tht AST ppers to hve n ergogenic effect, we cknowledge tht the true effectiveness of AST supplementtion reltive to competitive exercise performnce is not yet known given tht our feeding schem does not dequtely represent dietry prctices ssocited with competition. Therefore, to test the true ergogenic effect of supplement would necessitte doing so under conditions tht est pproximte those conditions involved in competition. We further cknowledge tht our results re currently predicted on reltively smll smple size. One of the strengths of our findings is the oservtion tht ll of the prticipnts in the AST group improved their time in completing the 2 km TT vi n improvement in power output. Though n exmintion of the rnge of improvement vries from 2 to 251 s, the 95 % confidence intervls suggest tht the likely rnge for the true vlue of the AST tretment is s. Our clcultion of effect sizes for oth performnce indices *

7 888 Nutrition would e chrcterized s lrge y Cohen [ 4 ]. It should lso e noted tht our tril using AST ccompnied y fsting nd without crohydrte ingestion during the cyclists ride produced similr results to those of Smith et l., who recently reported similr findings to ours using crohydrte supplementtion during 2 km TT under similr feeding schem [ 17 ]. These findings re prticulrly intriguing s Jeukendrup nd Mrtin [13 ] estimte tht crohydrte nd cffeine will produce similr performnce enefits in 4 km TT [13 ]. For exmple, they project tht crohydrtes will improve 4 km TT performnce y :42 s, :36 s, nd :32 s for novice, welltrined, nd elite cyclists, respectively. In their model, it hs lso een suggested tht cffeine improves 4 km TT performnce y 1:24 (min:s), 1:3 (min:s), nd :55 s, respectively. Thus, if one is to plce vlue on the effectiveness of n ergogenic id during cycling performnce, the results of our study suggest tht supplementtion with AST my promote similr time gins s to those noted ove using other nutritionlly sed ergogenic ids. However, greter ody of conformtionl reserch findings needs to e ccumulted efore mking such conclusion. Despite our inility to identify mechnism of ction for the oserved chnges in exercise performnce our study does suggest tht AST supplementtion my e n effective supplement for improving exercise performnce. If ft metolism is of future reserch interest, those investigtors undertking tht tsk my wish to consider lower intensity exercise regime more closely identified with the purported rnge of mximl ft oxidtion. If performnce is n re of interest, we suggest tht these issues e exmined under conditions more closely relted to feeding strtegies of those thletes engged in the sport of interest. Acknowledgements Funding for this study ws otined from the Gtorde Sports Science Institute. Astxnthin nd plceo supplements were donted y Fuji Helth Science, Inc. References 1 Aoi W, Nito Y, Skum K, Kuchide M, Tokud H, Mok T, Toyokuni S, Ok S, Ysuhr M, Yoshikw T. Astxnthin limits exercise-induced skeletl nd crdic muscle dmge in mice. Antioxid Redox Signl 23 ; 5 : Aoi W, Nito Y, Tknmi Y, Ishii T, Kwi Y, Akgiri S, Kto Y, Osw T, Yoshikw T. Astxnthin improves muscle lipid metolism in exercise vi inhiitory effect of oxidtive CPT I modifiction. Biochem Biophys Res Commun 28 ; 366 : Bloomer RJ, Fry A, Schilling B, Chiu L, Hori N, Weiss L. Astxnthin supplementtion does not ttenute muscle injury following eccentric exercise in resistnce-trined men. Int J Sport Nutr Exerc Met 25 ; 15 : Cohen J. A power primer. Psychologicl Bulletin 1992 ; 112 : Fssett RG, Coomes JS. Astxnthin, oxidtive stress, inflmmtion nd crdiovsculr disese. Future Crdiol 29 ; 5 : Fryn KN. Clcultion of sustrte oxidtion rtes in vivo from gseous exchnge. J Appl Physiol 1983 ; 55 : Guerin M, Huntley ME, Olizol M. Hemtococcus stxnthin: pplictions for humn helth nd nutrition. Trends Biotechnol 23 ; 21 : Hrriss DJ, Atkinson G. Updte Ethicl Stndrds in Sport nd Exercise Science Reserch. Int J Sports Med 211 ; 32 : Higuer-Cipr I, Felix-Vlenzuel L, Goycoole FM. Astxnthin: review of its chemistry nd pplictions. Crit Rev Food Sci Nutr 26 ; 46 : Hussein G, Snkw U, Goto H, Mtsumoto K, Wtne H. Astxnthin, crotenoid with potentil in humn helth nd nutrition. J Nt Prod 26 ; 69 : Ikeuchi M, Koym T, Tkhshi J, Yzw K. Effects of stxnthin supplementtion on exercise-induced ftigue in mice. Biol Phrm Bull 26 ; 29 : Ikeuchi M, Koym T, Tkhshi J, Yzw K. Effects of stxnthin in oese mice fed high-ft diet. Biosci Biotechnol Biochem 27 ; 71 : Jeukendrup AE, Mrtin J. Improving cycling performnce: how should we spend our time nd money. Sports Med 21 ; 31 : Keisuke S, Hiroshi Y, Kzuhiro A, Ntsue K, Akito A, Kestoki K, Mshiro Y. Sports Performnce Benefits from Tking Nturl Astxnthin Chrcterized y Visul Acuity nd Muscle Ftigue Improvement in Humns. J Clin Therp Med 22 ; 18 : Mortensen A, Skisted LH, Truscott TG. The interction of dietry crotenoids with rdicl species. Arch Biochem Biophys 21 ; 385 : Pshkow FJ, Wtumull DG, Cmpell CL. Astxnthin: novel potentil tretment for oxidtive stress nd inflmmtion in crdiovsculr disese. Am J Crdiol 28 ; 11 : 58D 68D 17 Smith JW, Zchwiej JJ, Peronnet F, Psse DH, Mssicotte D, Lvoie C, Pscoe DD. Fuel selection nd cycling endurnce performnce with ingestion of [13C]glucose: evidence for crohydrte dose response. J Appl Physiol 21 ; 18 : Trnopolsky MA, Atkinson SA, Phillips SM, McDougll JD. Crohydrte loding nd metolism during exercise in men nd women. J Appl Physiol 1995 ; 78 :