Relationship Between Optimal Lactate Removal Power Output and Olympic Triathlon Performance

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Relationship Between Optimal Lactate Removal Power Output and Olympic Triathlon Performance
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  1160 Journal of Strength and Conditioning Research, 2007, 21(4), 1160–1165   2007 National Strength & Conditioning Association R ELATIONSHIP  B ETWEEN  O PTIMAL  L  ACTATE R EMOVAL  P OWER  O UTPUT AND  O LYMPIC  T RIATHLON P ERFORMANCE C  ARLO  B  ALDARI , 1 L UIGI  D I  L UIGI , 1 S ERGIO  G. D  A   S ILVA  , 2 M  ARIA   C. G  ALLOTTA  , 1 G IAN  P. E MERENZIANI , 1 C  ATERINA   P ESCE , 3  AND  L  AURA   G UIDETTI 1 1  Department of Health Sciences and  3  Department of Educational Sciences for Motor Activities and Sports,University of Rome ‘‘IUSM,’’ Rome, Italy;  2  Department of Physical Education, Federal University of Parana´ (UFPR), Curitiba, Brazil.  A  BSTRACT . Baldari, C., L. Di Luigi, S.G. Da Silva, M.C.Gallotta,G.P. Emerenziani, C. Pesce, and L. Guidetti. Relationship be-tween optimal lactate removal power output and Olympic tri-athlon performance.  J. Strength Cond. Res. 21(4):1160–1165. 2007. —To investigate the relationships between race perfor-mance and parameters at the optimal power output for lactateremoval, 10 male triathletes were examined. Exerciseintensitiesfor lactate removal were defined by calculating 50% of difference(  T) between running velocity (V  r ) at individual anaerobicthreshold (IAT) and at individual ventilatory threshold (IVT),then choosing 3 V  r : at IVT plus 50%  T (IVT  50%  T ), at IVT, andat IVT minus 50%   T (IVT  50%  T ). After a 6-minute treadmillrun at 75% of difference between IAT and V ˙ O 2 max, alltriathletesperformed a 30-minute active recovery run at IVT  50%  T , IVT,and IVT  50%  T . Capillary blood lactate was determined at 1, 3, 6,9, 12, 15, 20, 25, and 30 minutes of recovery. The IVT  50%  T  re-covery was the most efficient V  r  for lactate removal. Running velocities at IVT and IVT  50%  T  were highly (  p  0.01) related tocycle, run, and overall race time. V ˙ O 2  values at IAT, IVT  50%  T ,and IVT were less (  p    0.05) related to split and overall racetime. The variable most related to overall race time, as deter-mined by stepwise multiple linear regression analysis, was the V  r  at IVT  50%  T  ( r    0.87,  p    0.001). The  R 2 value of 0.76 indi-cated that V  r  at IVT  50%  T  could account for 76% of the variancein triathlon race time. This study shows that the race perfor-mances of triathletes are highly related to the V  r  at which themost efficient lactate removal (IVT  50%  T ) occurs. These findingssuggest that the assessment of V  r  at IVT and IAT (from which V  r  at IVT  50%  T  are calculated) may be a useful method for mon-itoring training-induced adaptations and performance improve-ments in athletes who participate in Olympic triathlons.K  EY   W ORDS . lactate metabolism, treadmill ergometer, running,male triathletes I NTRODUCTION T he triathlon is a multisport event consisting of sequential swimming, cycling, and running over ‘‘long’’ or ‘‘short’’ distances. The distancesof each competition segment may vary substan-tially, so that the total competition time ranges from 30minutes to several hours (25, 26). In particular, the stan-dard distance (also known as ‘‘short distance’’ and ‘‘Olym-pic triathlon’’) consists of 1,500 m of swimming, 40 km of cycling, and 10 km of running. A previous study (12) demonstrated an unexpectedrise in blood lactate (8.1 mmol·L  1 ) after the first segment(swimming) followed by declining levels after the other 2segments (5.1 and 4.4 mmol·L  1 cycling and running, re-spectively). This lactate trend during a prolonged effort,such as the Olympic triathlon, has been related with anearly appearance of ventilatory threshold and an impair-ment of performance after swimming and cycling (8). Thecorrelation between the ventilatory threshold and the en-durance performance is well known; in fact, for triathlonperformance the V ˙ O 2  at ventilatory threshold was report-ed to be a better predictor than V ˙ O 2 max (30) for both run-ning time and total time (8, 31).During a triathlon event, blood lactate was observedto decrease progressively after the first segment. The lac-tate decrement was observed to occur regardless of theorder of segments (12). It is important to remember thatlactate removal is accomplished mainly throughoxidationwithin mitochondria of active well-oxygenated red mus-cles, as suggested by the lactate shuttle hypothesis of Brooks (6). Whether lactate can be oxidized by working muscles depends on the intensity of the exercise, becausedifferent intensities can lead to different muscle behaviorfrom uptake to output of lactate (10, 13). Thus, becauselactate can be regarded as an energy substrate for work-ing muscles during competition, particularly competitionof a long duration, a high exercise intensity during whichthe most efficient lactate removal occurs could be consid-ered a positive factor for successful performance. This isbecause whenever exercise intensity is not efficient forlactate removal, the resulting lactate accumulation is as-sociated with an attenuate adenosine triphosphate pro-duction that inhibits the glycolytic rate-limiting enzymesand decreases the lipolysis rate (14); lactateaccumulationis also associated with a rise in muscle and blood H  con-centration, which has been related directly (19) or indi-rectly (27) to local fatigue. Moreover, the lactate anioncan cause fatigue in skeletal muscle independent of as-sociated reductions in pH (15).We recently studied the optimal lactate removal pow-er output in soccer players (2), quantifying the exerciseintensity not in percent of V ˙ O 2 max but in relation to val-idated metabolic reference points (23), such as the indi-vidual anaerobic threshold (IAT) and the individual ven-tilatory threshold (IVT). In this study, we wanted to de-termine whether the power output at which the most ef-ficient lactate removal occurs is related to short-distancetriathlon performance. M ETHODS Experimental Approach to the Problem This study was designed to determine the relationshipbetween power output for optimal lactate removal andperformance during an Olympic triathlon. For this pur-pose, we verified, in laboratory conditions, the effect of some exercise intensities below the IAT calculated in re-  L ACTATE  R EMOVAL AND  T RIATHLON  P ERFORMANCE  1161 lation to the IAT and the IVT. As previously reported forstudying lactate removal (2), 3 recovery intensities wereconsidered: running velocity (V  r ) at (a) IVT, (b) middleintensity between IVT and IAT, i.e., at 50% of IAT minusIVT (  T) above IVT (IVT  50%  T ), and (c) 50%  T below theIVT (IVT  50%  T ). We then investigated the relationshipbe-tween race time recorded during a triathlon competitionand such laboratory variables as V ˙ O 2  and V  r  measured atIVT  50%  T  IVT and IVT  50%  T  power outputs. Subjects Ten triathlon male athletes participated in the study. Af-ter approval was received from the institute’s EthicsCommittee, subjects gave their written informed consent.Their mean (   SD ) physical characteristics were as fol-lows: height, 1.81    0.03 m; body mass, 73    3 kg; age,24    3 years; V ˙ O 2 max, 70.7    4.6 mL·kg   1 ·min  1 ; V ˙ O 2IAT ,53.6    3.9 mL·kg   1 ·min  1 ; V ˙ O 2IVT , 43.2    4.7mL·kg   1 ·min  1 . All subjects had been training regularlyfor approximately 12–15 hours a week for at least theprevious 3 years. All subjects were in good health and were not taking any medications, amino acids, or other drugs, including anabolic doping agents that would affect the results of this study. None of the subjects was a smoker. All sub- jects were counseled by a nutritionist and had a diet reg-imen sufficient for their individual needs (44–50kcal·kg   1 ·d  1 : 55–60% carbohydrates, 15–20% proteins,and   25% lipids). This diet regimen started 2 weeks be-fore the experimental phases and was maintainedthroughout the study. The subjects were counseled week-ly and their food records reviewed to maintain the correctdiet and fluid consumption throughout the study. Theseguidelines recommended that all subjects maintain theirfood intake and remain well hydrated, especially beforeeach test. They also maintained their habitual sleep pat-terns. Detecting Optimal Lactate Removal Power Output Subjects performed a treadmill presession test to evalu-ate the V ˙ O 2 max, IAT, and IVT. Subsequently, subjectsperformed in random order 3 experimental recovery trialson treadmill on 3 separate occasions. A minimum of 48hours separated each exercise test; the tests took placeover 3 consecutive weeks and ended 2 weeks before thenational triathlon competition. They began at about thesame time of day for a given subject (between 8:30 and10:30  AM ), and the environmental conditions were alwaysidentical (temperature 21–22   C; humidity 50–60%). Thesubjects were requested to have breakfast (about thesame kcal·kg   1 and nutrient composition) 2 hours beforethe experimental test. No intensive training was allowedon the day before each test.  Presession Test.  To determine the V ˙ O 2 max, IVT, andIAT, each subject performed a continuous, graded tread-mill test. The treadmill maximal test consisted of a3-min-ute walking warm-up at 6 km·h  1 with 0% slope, followedby a velocity increment of 2 km·h  1 every 3 minutes upto the power output subsequent to IAT (1). Then a 3%increment in slope every minute was given. When the V ˙ O 2 max was obtained, an active recovery of 1 minutewalking at 6 km·h  1 with 0% slope followed. V ˙ O 2 max wasidentified at the occurrence of a plateau of V ˙ O 2 , despite afurther increase in power output or an increase in V ˙ O 2  1mL·kg   1 ·min  1 in comparison with that produced by theprevious power output (11). Secondary criteria were alsoapplied to verify the maximal effort, such as an attain-ment of age-predicted maximum heart rate and/or a re-spiratory exchange ratio   1.15 (11). V ˙ O 2 , V ˙ E , and heartrate were acquired breath by breath and then averagedevery 30 seconds during the test by a telemetric gas anal-ysis system (K4 COSMED, Rome, Italy) that has beenshown to be valid and reliable (24).To determine the oxygen consumption at ventilatory(IVT) and lactate (IAT) thresholds, the average of the lastminute of each corresponding level was used. Determi-nation of blood lactate was carried out using capillaryblood from a fingertip. Blood lactate concentration wasimmediately analyzed during the treadmill test using an Accusport lactate analyzer (Boehringer Mannheim,Mannheim, Germany) that has been shown to be validand reliable (4). Blood lactate evaluations wereperformedat the third minute of a given power output for each workload until the power output subsequent to that corre-sponded to the IAT.The IVT was determined as the level of V ˙ O 2  at whichthe minimum value of the ventilatory equivalent of oxy-gen (V ˙ E  /V ˙ O 2 ) calculated from an individual V ˙ O 2  vs. V ˙ E  /V ˙ O 2 plot was observed (2, 16). To determine the IAT, we useda simplified method previously validated (1). The IATwasdetermined plotting an individual curve of V ˙ O 2  vs. lactate.In this curve, each lactate value was assigned to the pow-er output immediately prior to that of its measurement,and consequently the individual V ˙ O 2  vs. lactate curve wasplotted (1). The IAT was defined as the power output cor-responding to the second lactate increase of at least 0.5mmol·L  1 from the previous value, where the second in-crease was greater than (or equal to) the first one (1).  Experimental Recovery Trials.  To determine the poweroutput for optimal lactate removal, 3 recovery exerciseintensities below the IAT (2) were investigated: (a) IVT,(b) IVT  50%  T , and (c) IVT  50%  T . Trial sequences were ran-domized to eliminate bias. Each recovery trial consistedof a warm-up of 3 minutes of walking at 6 km·h  1 then a6-minute run at 75% of the difference between the IATand the individual V ˙ O 2 max. This constant load exercisecorresponded to 90% V ˙ O 2 max previously utilized to studylactate removal (2, 22). Immediately at the end of thisintense exercise, the desired recovery power output wasset and maintained for 30 minutes. The IVT power outputwas the V  r  at which the IVT (V  r IVT ) was found. TheIVT  50%  T  power output was defined as the V  r  halfway be-tween the V  r  at IVT and V  r  at IAT. The IVT  50%  T  poweroutput was defined as the V  r  at IVT minus the half-dif-ference between the V  r  at IAT and V  r  at IVT.During each recovery trial, blood lactate measure-ments were performed at rest and at 1, 3, 6, 9, 12, 15, 20,25, and 30 minutes of exercise recovery without running interruptions. Triathlon Race Performance Within 2 weeks after the last laboratory test, all subjectscompeted in the national triathlon championship. Theweather conditions during the race were 20.6  C, 52% hu-midity, and a wind speed of 2.9 m·s  1 . The short-distancerace was held at sea level on a flat out and back courseand consisted of a 1,500-m pool swim, a 40-km cycle, and10-km run. Drafting was allowed. The time to completethe race was recorded by the race organizers to the near-est second. Statistical Analyses For each subject and each recovery condition, a blood lac-tate recovery curve as a percentage of accumulated lac-  1162 B  ALDARI , D I  L UIGI , D  A   S ILVA ET AL . T  ABLE  1.  Swim, cycle, run, and overall triathlon performance times for 10 male triathletes.1,500-m swim 40-km cycle 10-km run Overall timeMean    SD  (min:s) 23:13    1:47 62:58    2:23 37:50    2:28 124:01   6:12Range (min:s) 20:18–26:35 59:29–66:14 34:50–41:8 116:17–132:57Correlation with overall time 0.74* 0.90** 0.94***  r    0.63,  p    0.05; **  r    0.75,  p    0.01. T  ABLE  2.  Running velocity (V  r ) and oxygen consumption (V ˙ O 2 ) at selected submaximal power outputs.IAT* IVT  50%  T  IVT IVT  50%  T  V  r  (m·s  1 ) 4.4    0.4 3.8    0.4 3.2    0.4 2.6    0.5 V ˙ O 2  (mL·kg   1 ·min  1 ) 53.6    4.0 47.8    4.4 43.2    4.7 38.1    5.0* Values are mean    SD . IAT    individual anaerobic threshold; IVT    individual ventilatory threshold. F IGURE  1.  Blood lactate curves comparison among 3 recoveryconditions (IVT  50%  T , IVT, IVT  50%  T ) in triathlon athletes. IVT   individual ventilatory threshold. * indicates a significant dif-ference between recovery blood lactate curves at a given timepoint. tate (mmol·L  1 ) vs. time (minutes) was plotted. Resultsare reported as mean    SD.  Analysis of variance for re-peated measures was used to detect significant effects of the recovery power output (IVT  50%  T , IVT, IVT  50%  T ).Posthoc analysis of significant differences was performedusing the Student-Newman-Keuls test. A significancelev-el of   p    0.05 was selected.Pearson’s Product moment correlations describe therelationship between the individual physiological vari-ables measured and race performance in each phase of the triathlon, as well as overall race performance time forall triathletes. A stepwise multiple linear regressionanal-ysis was used to determine the physiological variablesmost related to overall race time. Correlation coefficientsof    r     0.63 and   r     0.75 corresponded to  0.05 and    0.01 with a statistical power of 0.76 and 0.95, re-spectively. R ESULTS Triathlon Race Performance Table 1 shows the mean overall race time along with thesplits for each segment of the race. The corresponding correlation coefficients for each segment of the race vs.the overall race time are also displayed. The race time forboth cycle and run sections was highly related to totalrace time ( r    0.94 and  r  0.90,  p  0.01, respectively). Also, the swimming time was significantly correlated tothe overall competition time ( r    0.74,  p    0.05). Optimal Lactate Removal Power Output Time courses of blood lactate concentration during recov-ery at IVT  50%  T , IVT, and IVT  50%  T  exercise intensitieswere significantly different (  p  0.001) (Figure 1). In par-ticular, the lactate removal showed a similar curve atIVT  50%  T  and IVT until the 20 th minute. At IVT  50%  T , thelactate removal curve presented significantly lower val-ues vs. the other 2 exercise intensities from the ninth to30 th minute. Relationship Between Race Performance andLaboratory Parameters Selected submaximal physiological variables are reportedin Table 2. These variables include V  r  and V ˙ O 2  values atIAT, IVT  50%  T , IVT, and IVT  50%  T . The interrelationshipsamong these variables and race performance variablesare displayed in Table 3 as correlation coefficients. V ˙ O 2 values at IAT were significantly (  p    0.05) related to cy-cle, run, and overall race time. V ˙ O 2  values at IVT  50%  T and IVT were significantly (  p  0.05) correlated to overallrace time. The V  r  at IAT was only significantly (  p  0.05)related to running race time. The V  r  at IVT  50%  T  was cor-related to cycle, run, and overall race time (  p  0.05,  p  0.01, and  p    0.05, respectively). The V  r  at IVT andIVT  50%  T  were highly (  p  0.01) related to cycle, run, andoverall race time. None of the selected submaximal phys-iological variables was correlated with the swim racetime. The submaximal variable most related to overallrace time, as determined by stepwise multiple linear re-gression analysis, was the running velocity at IVT  50%  T ( r  0.87,  p  0.001). The  R  2 value of 0.76 indicated thatthis laboratory measure could account for 76% of the var-iance in triathlon race time (Figure 2). D ISCUSSION The physical characteristics (age, weight, height) of tri-athletes in the present study were similar to those pre-viously reported for male triathletes (8, 25, 28). V ˙ O 2 maxvalues during treadmill running were similar to those re-cently reported for elite triathletes (17, 25, 28). It is al-ready known that the wide range in V ˙ O 2 max (from 52 to  L ACTATE  R EMOVAL AND  T RIATHLON  P ERFORMANCE  1163 T  ABLE  3.  Correlations of split and overall race times with running velocity (V  r ) and oxygen consumption (V ˙ O 2 ) at selected sub-maximal power outputs.*1,500-m swim 40-km cycle 10-km run Overall time V  r  (m·s  1 ) IAT   0.26   0.48   0.63†   0.59IVT  50%  T   0.39   0.69†   0.77‡   0.72†IVT   0.47   0.81‡   0.91‡   0.85‡IVT  50%  T   0.49   0.82‡   0.93‡   0.87‡ V ˙ O 2  (mL·kg   1 ·min  1 ) IAT   0.47   0.67†   0.63†   0.69†IVT  50%  T   0.55   0.61   0.61   0.68†IVT   0.48   0.58   0.60   0.64†IVT  50%  T   0.41   0.56   0.57   0.60* IAT  individual anaerobic threshold; IVT  individual ventilatory threshold. Significant correlations: †   r   0.63,  p  0.05; ‡   r    0.75,  p    0.01. F IGURE  2.  Relationship between overall race time in short-distance triathlon (minutes) and running velocity at IVT  50%  T . 72 mL·kg   1. min  1 ) reported by different investigators (26,31) indicates that factors other than V ˙ O 2 max contributemore significantly to triathlon performance. In fact, theventilatory threshold with the economy of motion (26)and, more recently, the peak treadmill running velocityassociated with blood lactate concentration during steady-state cycling at 4 W·kg   1 body mass (28) have beenproposed as predictive parameters of triathlon perfor-mance.In the current study, IVT, also known as the first ven-tilatory threshold (9) and point of optimum ventilatoryefficiency (16), and IAT, also known as the maximal lac-tate steady state (MLSS), cannot be directly comparedwith other studies because of different methods of thresh-old determination. As previously proposed, we used a3-minute incremental test for both IVT (1, 16) and IAT(1). These 2 thresholds indicate 2 different exercise inten-sities. The IVT indicates the upper limit of an almost ex-clusive aerobic exercise (16, 18, 23) with a low blood lac-tate concentration (about 2 mmol·L  1 ). The IAT indicatesthe highest power output at MLSS (1, 23, 33, 34), i.e.,when the production and the removal of lactate are inequilibrium (at about 4 mmol·L  1 ). A previous study inelite triathletes (V ˙ O 2 max 71.8    7.6 mL·kg   1 ·min  1 ) esti-mated the MLSS by assessing the respiratory compen-sation threshold during an every 1-minute increment-load protocol (17). However, it was recently observed thatrespiratory compensation threshold (1-minute incremen-tal protocol) overestimates the MLSS by 10% V ˙ O 2 max (9).Conversely, the protocol we used can underestimate theMLSS by 5–7% (1). Therefore, the treadmill running ve-locities we observed for IVT and IAT are lower than thosereported by Hue (17). However, we found V  r  at IAT some-what higher than that reported (3.7–3.9 m·s  1 ) by otherauthors (21) who estimated the lactate threshold using 4different methods in nonelite triathletes (V ˙ O 2 peak 56.6  1.3 mL·kg   1 ·min  1 ).Whereas different studies have reported the physio-logical characteristics (3, 25, 28) and physiological factorsor predictors of success in the Olympic triathlon (8, 17,28), we have focused on the relationship between raceperformance and the individual efficient power output forlactate removal. The present data show that performancein running and cycle segments was highly (  p    0.01) re-lated to overall race time, as previously reported (8, 28). A certain relationship (  p    0.05) was also observed be-tween swim time and overall race time. Different resultsin the literature could be due to the difference betweenperforming the swimming segment in a pool or in the sea.The studied recovery power outputs (IVT  50%  T , IVT,and IVT  50%  T ) produced different lactate removal curves.The significant lower values of the lactate removal curveat IVT  50%  T  indicated that this was the most efficient in-dividual power output for lactate removal.The V  r  at different submaximal power outputs (IAT,IVT  50%  T , IVT, and IVT  50%  T ) was related differently tosplit and overall race time. In particular, the V  r  atIVT  50%  T  was highly related to cycle, run, and overallrace time ( r    0.82,  r    0.93, and  r    0.87, respec-tively;  p    0.01). Also, the V  r  at IVT was highly relatedto cycle, run, and overall race time ( r  0.81,  r  0.91,and  r    0.85, respectively;  p    0.01). In short-distancetriathlon, Schabort and colleagues (28) reported that per-cent V ˙ O 2 max sustained at 15 km·h  1 was significantlycor-related with a 10-km running time ( r    0.83,  p    0.01)and with the total time ( r    0.81,  p    0.01).The V ˙ O 2  values at IAT, IVT  50%  T , and IVT were lessrelated (  p    0.05) to split and overall race times. In par-ticular, the V ˙ O 2  at IAT was related to cycle, run, and over-all race time ( r    0.67,  r    0.63,  r    0.69, respectively),and the V ˙ O 2  at IVT was related to overall race time ( r  0.64). The relationship between the V ˙ O 2  at lactate thresh-old and the 40-km cycle performance has been previouslyreported (7). Also, for overall successful performance, ahigh V ˙ O 2  at ventilatory (8) and anaerobic (30) thresholdswas reported.The main finding of the present study was that V  r  at  1164 B  ALDARI , D I  L UIGI , D  A   S ILVA ET AL . the power output of optimal lactate removal was the var-iable most related to overall race performance. In fact,thecorrelation coefficient of    0.87 and the  R  2 of 0.76 deter-mined by multiple stepwise linear regression indicatedthat V  r  at IVT  50%  T  alone could account for 76% of thevariance in triathlon race time. Apparently such a rela-tionship between individual overall performance and therunning velocity at the optimal lactate removal poweroutput has not yet been reported.Previous studies have shown that blood lactate, al-though elevated after the swimming segment, decreasesprogressively during triathlon races (12), indicating theuse of lactate as an energy substrate by exercising mus-cle. Lactate oxidation from active muscles has been de-scribed as the major pathway of lactate metabolism (6).Slow-twitch fibers of skeletal muscle are metabolicallyox-idative fibers that tend to consume lactate (6, 32), where-as fast-twitch fibers are glycolic anaerobic fibers that pro-duce lactate (10). Which type of fiber is predominantlyactive during an exercise depends not only on the exerciseintensity but also on the training status of the subject(13). A triathlete may have a high percentage of slow-twitch fibers as a consequence of metabolic adaptationsinduced by endurance training (5, 13). P RACTICAL  A  PPLICATIONS The present findings suggest that better overall race timeis associated with a higher running velocity at which thesubject has his most efficient lactate removal (IVT  50%  T ).Having a high V  r  at IVT  50%  T  indicates that the triathletehas a high V  r  at IVT and little difference between IATand IVT (  T). The shift towards a higher V  r  of IAT witha greater shift towards a high V  r  at IVT led to higher V  r at IVT  50%  T , the optimal V  r  for lactate removal, whichwas associated with better overall race performance.These findings are of particular interest to coachesand triathletes and are especially relevant to designing proper training sessions. Previous studies have recom-mended high-intensity interval training as a viable meth-od for improving endurance performance, suggesting alsothat regular assessments of training status and subse-quent adjustments to the training program are requiredto maximize performance improvements (20, 29). Intervaltraining alternates brief high-intensity exercise boutswith rest or relief periods. We suggest performing the re-lief periods at the exercise intensity corresponding to theindividual optimal lactate removal, such as Vr atIVT  50%  T , in order to allow the next exercise bouts to con-tinue with minimal fatigue and thus to increase the timeto exhaustion. In addition, because a high V  r  at IVT  50%  T is related to better overall triathlon race performance, wesuggest that regular measurement of V  r  at IVT and IAT(from which Vr at IVT  50%  T  can be calculated) may be auseful method for monitoring training-induced adapta-tions and performance improvements in athleteswho par-ticipate in Olympic triathlons.During a triathlon, high levels of blood lactate wereobserved after the swimming and cycling segments (8.1and 5.1 mmol·l  1 , respectively) (12). This may result in asignificant power reduction on the subsequent cycling and running segments. In draft-legal triathlon, partici-pants could adopt an individualized strategy becausedrafting results in a considerable lowering of power out-put (3). Moreover, race organizers may include 1 or sev-eral hill sections within each loop of the course, such thatthe race would involve a ‘‘stochastic’’ burst of very highpower output interspersed with more submaximal exer-cise (25). The submaximal exercise would be performedat IVT  50%  T  intensity, and the lactate removal would beoptimized. In this sense, it is advantageous for athletesto have a high V  r  at IVT  50%  T , the power output at whichworking muscles can efficiently oxidize lactate. In conclu-sion, individual overall race performance in short-dis-tance triathlons is highly related to the athlete’s V  r  atwhich the most efficient lactate removal (IVT  50%  T ) oc-curs. R EFERENCES 1. B  ALDARI , C.,  AND  L. G UIDETTI . A simple method for individual anaerobicthreshold as predictor of max lactate steady state.  Med. 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