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ARTICLE IN PRESS ModelSAMS-814; No. of Pages 6Journal of Science and Medicine in Sport xxx (2013) xxx xxx

Contents lists available at SciVerse ScienceDirect

Journal of Science and Medicine in Sport

j o ur nal homepage: www.elsev ier .com/ locate / j sams

riginal research

ncremental test design, peak aerobic running speed and enduranceerformance in runners

abiana A. Machadoa,b,, Ana Claudia P. Kravchychynb, Cecilia S. Pesericob,anilo F. da Silvab, Paulo V. Mezzarobab

Department of Physical Education, State University of Maring, BrazilAssociate Post-graduate Program in Physical Education UEM/UEL, State University of Maring, Brazil

r t i c l e i n f o

rticle history:eceived 27 September 2012eceived in revised form5 December 2012ccepted 22 December 2012vailable online xxx

eywords:eak treadmill velocityime trialerformance predictiontage duration

a b s t r a c t

Objectives: Peak running speed obtained during an incremental treadmill test (Vpeak) is a good predictor ofendurance run performance. However, the best-designed protocol for Vpeak determination and the bestVpeak definition remain unknown. Therefore, this study examined the influence of stage duration andVpeak definition on the relationship between Vpeak and endurance run performance.Design: Relationship.Methods: Twenty-seven male, recreational, endurance-trained runners (10-km running pace:1017 km h1) performed, in counterbalanced order, three continuous incremental treadmill tests ofdifferent stage durations (1-, 2-, or 3-min) to determine Vpeak, and two 5-km and two 10-km time trialson a 400-m track to obtain their 5-km and 10-km run performances. Vpeak was defined as either (a) thehighest speed that could be maintained for a complete minute (Vpeak-60 s), (b) the speed of the last com-plete stage (Vpeak-C), or (c) the speed of the last complete stage added to the multiplication of the speedincrement by the completed fraction of the incomplete stage (Vpeak-P).Results: The Vpeak determined during the 3-min stage duration protocol was the most highly correlated

with both the 5-km (r = 0.95) and 10-km (r = 0.92) running performances and these relationships wereminimally influenced by the Vpeak definition. However, independent of the stage duration, the Vpeak-Pprovided the highest correlation with both running performances.Conclusions: Incremental treadmill tests comprising 3-min stage duration is preferred to 1-min and 2-min stage duration protocols in order to determine Vpeak to accurately predict 5-km and 10-km runningperformances. Further, Vpeak-P should be used as standard for the determination of Vpeak.

2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.. Introduction

Peak running speed obtained during an incremental tread-ill test (Vpeak) is a good predictor of endurance performance in

unners13 and can be determined without the use of expensiveetabolic equipment or invasive techniques2 during incremental

readmill tests comprising short1,2 or long4,5 stage protocols. Forxample, Noakes et al.1 and Stratton et al.3 determined Vpeak dur-ng a maximal treadmill test using 1-min stages, whereas Machadot al.4 and Slattery et al.5 used a protocol comprising 3- and 4-Please cite this article in press as: Machado FA, et al. Incremental test designJ Sci Med Sport (2013), http://dx.doi.org/10.1016/j.jsams.2012.12.009

in stages, respectively. However, the effect of stage duration onhe relationship between Vpeak and endurance run performance, as

Corresponding author.E-mail addresses: famachado@uem.br, famachado uem@hotmail.com

F.A. Machado).

440-2440/$ see front matter 2013 Sports Medicine Australia. Published by Elsevier Lttp://dx.doi.org/10.1016/j.jsams.2012.12.009well as the best protocol for the determination of Vpeak, remainsunknown.

Peak power output obtained during an incremental exercisetest is highly correlated with long-distance cycling performance.68

Two studies examined the effect of stage duration during cycleexercise tests on the relationship between peak power output andcycling performance.9,10 Bentley and McNaughton9 showed thatthe peak power output derived from an incremental test com-prising 3-min stage durations had a higher correlation with theaverage power output sustained during a 90-min cycling time trial(r = 0.94; p < 0.01) than the peak power output derived from a 1-min stage duration test (r = 0.54; p > 0.05). McNaughton et al.10

reported similar correlation coefficients (r) between the averagepower output during a 30-min cycle time trial and the peak power, peak aerobic running speed and endurance performance in runners.

output derived from tests consisting of either 3- or 5-min workloadincrements (0.96 vs. 0.96; p < 0.001), suggesting that an increase instage duration from 3- to 5-min during incremental cycle exercisedoes not affect the association between peak power output and

td. All rights reserved.

dx.doi.org/10.1016/j.jsams.2012.12.009dx.doi.org/10.1016/j.jsams.2012.12.009http://www.sciencedirect.com/science/journal/14402440http://www.elsevier.com/locate/jsamsmailto:famachado@uem.brmailto:famachado_uem@hotmail.comdx.doi.org/10.1016/j.jsams.2012.12.009

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ARTICLESAMS-814; No. of Pages 6F.A. Machado et al. / Journal of Scienc

hort-distance cycling performance. However, comparisons of theelationship between Vpeak determined during different runningrotocols and endurance run performance to determine the bestunning protocol have not yet been conducted.

The definition of Vpeak in running tests remains equivocal. Vpeakas already been defined as the highest speed that can be main-ained for a complete minute1,3,5 or as the speed of the last completetage during a maximal test.4 Additionally, Kuipers et al.11 definedpeak proportionally as the speed of the last complete stage addedo the multiplication of the speed increment by the completed frac-ion of the incomplete stage. This last definition seems less arbitrarynd not influenced by subjective judgments because the Vpeak of anthlete who sustains a speed during 58, 59, or 60 s should be sim-lar. Given that there exists three differing definitions of Vpeak, theefinition of Vpeak may affect its relationship with endurance runerformance.Therefore, the main purpose of this study was to examine the

nfluence of stage duration and Vpeak definition on the relation-hip between Vpeak and endurance run performance over 5-kmnd 10-km time trials. A second aim of this study was to generate

predictive equation for the indirect determination of the 5-kmnd 10-km time trials from the best-defined Vpeak. Based on cyclergometer studies, we hypothesized that the Vpeak determined dur-ng the 3-min stage protocol would correlate more strongly withndurance run performance than that determined during the 1- or-min stage protocols. Additionally, we expected that the best def-nition of Vpeak would be the proportional definition11 because it isot influenced by subjective judgments.

. Methods

Twenty-seven male, recreational, endurance-trained runners ofegional and local level with a minimum of 2 years of trainingxperience and a training volume of at least 20 km wk1 vol-nteered to take part in this study. The 10-km running timesf the participants were between 35 and 60 min, with a paceetween 10 and 17 km h1 (4475% of the world record). Char-cteristics of the participants (mean SD) were age 40.5 12.1ears, height 173.1 6.9 cm, body mass 67.8 8.6 kg and body massndex (BMI) 22.6 2.1 kg m2. The training characteristics wererequency 5.1 1.3 days wk1 and distance 63.1 27.5 km wk1,anging from 20 to 100 km wk1. Prior to testing, all participantsrovided written informed consent and the local ethics committeepproved the experimental protocol.In a counterbalanced order, participants who were habituated

o running tests performed three continuous incremental exer-ise tests of different stage durations on a motorized treadmillSuper ATL; Inbrasport, Porto Alegre, Brazil), with the gradientet at 1%. The tests were performed over 2 weeks, with eachest separated from the other by at least 48 h. The different stageuration protocols were as follows: (a) short stage duration of

min (P1 min), (b) intermediate stage duration of 2 min (P2 min),nd (c) long stage duration of 3 min (P3 min). After a warm-uphat consisted of walking at 6 km h1 for 3 min, each protocoltarted with an initial treadmill speed of 8 km h1, followed byn increase of 1 km h1 between each successive stage until par-icipants reached their volitional exhaustion (i.e., participant wasnable to continue running). Consistently across each trial, par-icipants were strongly encouraged, verbally, to invest maximumffort. The tests were performed at the same time of the day, underormal laboratory conditions (temperature = 2022 C and rela-Please cite this article in press as: Machado FA, et al. Incremental test designJ Sci Med Sport (2013), http://dx.doi.org/10.1016/j.jsams.2012.12.009

ive humidity = 5060%). Participants were instructed to report foresting well-rested, well-nourished, and well-hydrated, wearingightweight comfortable clothing. Participants were also instructedo avoid eating 2 h before the maximal exercise tests, to abstain PRESSedicine in Sport xxx (2013) xxx xxx

from caffeine and alcohol, and to refrain from strenuous exercisefor 24 h before testing.

Before testing, participants were familiarized with the 620Borg scale,12 which was used to measure the rating of perceivedexertion (RPE) during the last 15 s of each stage and at exhaus-tion. The highest RPE value was adopted as the peak RPE (RPEpeak).Heart rate (HR) was recorded every five seconds throughout thetests (Polar RS800sd, Kempele, Finland) and HRmax was definedas the highest HR value recorded during the test.13 Neither respi-ratory gases nor blood lactate was monitored during the testsgiven that such interventions could affect the performance of theparticipants.14 Earlobe capillary blood samples (25 L) were col-lected into a capillary tube at the end of the tests (time zero ofrecovery) and at the third, fifth, and seventh minutes of passiverecovery, sitting in a comfortable chair. From these samples, bloodlactate concentration was subsequently determined by electroen-zymatic methods using an automated analyzer (YSI 2300 STAT,Ohio, USA). Peak blood lactate concentration (LApeak) was definedfor each participant as the highest post-exercise blood lactate con-centration value.

The Vpeak was defined as either (a) the highest speed that couldbe maintained for a complete minute (Vpeak-60 s), (b) the speedof the last complete stage (Vpeak-C), i.e., the highest speed thatcould be maintained for more than 90% of the stage duration,or (c) the speed of the last complete stage added to the mul-tiplication of the speed increment by the completed fraction ofthe incomplete stage11 (Vpeak-P), calculated according to the equa-tion Vpeak-P = Vcomplete + (Inc t/T), in which Vcomplete is the runningspeed of the last complete stage, Inc the speed increment (i.e.,1 km h1), t the number of seconds sustained during the incom-plete stage, and T the number of seconds required to complete astage (i.e., 60 s for P1 min, 120 s for P2 min, and 180 s for P3 min).

The maximal effort was deemed to be achieved if the incremen-tal test met two of the following criteria: (1) LApeak 8 mmol L1,(2) HRmax 100% of endurance-trained age-predicted HRmax(APMHR) using the age-based 206 0.7 age equation13 and (3)RPEpeak 19 in the 620 Borg scale.15

Thereafter, participants undertook two 5-km and two 10-kmtime trials on a 400-m outdoor running track, which took placewithin a 15-day period after the laboratory testing. Participantscontinued their regular training between the laboratory testing andtime trial performances. They were tested twice on each of the 5-kmand 10-km runs to ensure an accurate performance measure.2 Thetrials were at least 48 h apart, began at 18:00 h, and were precededby a self-determined warm-up of 10 min duration. A hydrationstation was set up on the track with natural water. All of the par-ticipants were encouraged to give their best performance. The best5-km and 10-km times for each runner were recorded and the mean5-km running speed (S5 km) and 10-km running speed (S10 km) fromthe best trials were calculated in km h1.16

Data are presented as mean SD and were analyzed using theStatistical Package for the Social Sciences 17.0 software (SPSSInc., USA). The ShapiroWilk test was used to check the nor-mality of the data distribution. The relationship between Vpeakand endurance run performance was examined using Pearsonproductmoment correlation coefficient (r), adjusted coefficient ofdetermination (R2), and standard error of estimate (SEE) for the68% confidence interval. Simple linear regression analyses wereused to generate a predictive equation for S5 km and S10 km fromVpeak. The variables were compared using a repeated measuresANOVA followed by the Bonferroni post hoc test. The spheric-ity assumption was checked by Mauchlys test of sphericity, peak aerobic running speed and endurance performance in runners.

and, where violations occurred, degrees of freedom were cor-rected using GreenhouseGeisser (epsilon 0.75) or HuyndFeldt(epsilon > 0.75) estimates of sphericity. Statistical significance wasset at p < 0.05.

dx.doi.org/10.1016/j.jsams.2012.12.009

ARTICLE IN PRESSG ModelJSAMS-814; No. of Pages 6F.A. Machado et al. / Journal of Science and Medicine in Sport xxx (2013) xxx xxx 3

Table 1Physiological variables obtained during incremental treadmill tests comprising stage durations of 1 min (P1 min), 2 min (P2 min), and 3 min (P3 min).

Variables P1 min P2 min P3 min

RPEpeak (620 Borg scale) 19.7 0.7 19.8 0.4 19.9 0.4LApeak (mmol L1) 9.2 1.9b 8.9 1.9 7.6 2.0%APMHR (%) 102.0 3.1a 103.9 4.1 103.2 4.0Vpeak-60 s (km h1) 18.0 1.8a,b 16.9 1.7b 16.2 1.6Vpeak-C (km h1) 18.2 1.6a,b 16.6 1.6b 16.0 1.7Vpeak-P (km h1) 18.3 1.6a,b 16.9 1.6b 16.2 1.6

Values are mean SD, n = 22. RPEpeak, maximum rating of perceived exertion; LApeak, peak blood lactate concentration; %APMHR, percentage of age-predicted maximumheart rate; Vpeak-60 s, highest speed maintained for a complete minute; Vpeak-C, highest speed maintained for more than 90% of the stage duration; Vpeak-P, speed of the lastcomplete stage added to the multiplication of the speed increment by the completed fraction of the incomplete stage.

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. Results

Five of the 27 participants did not meet at least two criteria ofaximal effort in at least one test. Additionally, one participant didot perform the 10-km time trials. The tests from these participantsere not included in the results.The summary of the physiological variables obtained during

he incremental tests (mean SD) is given in Table 1. Analysis ofariance revealed a significant effect of the stage duration on thepeak-60 s (p < 0.001), Vpeak-C (p < 0.001), Vpeak-P (p < 0.001), LApeakp = 0.005), and percentage of APMHR (%APMHR; p = 0.018). ThePEpeak did not significantly differ among the three protocolsp = 0.38). The Vpeak-60 s, Vpeak-C, and Vpeak-P differed significantlyetween the three protocols and were inversely related to theength of the stage duration.

The values of Vpeak-60 s, Vpeak-C, and Vpeak-P were highly cor-elated with each other during P1 min, P2 min, or P3 min (r 0.96;

< 0.001). The values of Vpeak-C during P1 min, P2 min and P3 min wereighly correlated with each other (0.91 r 0.93; p < 0.001). Simi-arly, the values of Vpeak-P during P1 min, P2 min and P3 min were highlyorrelated with each other (0.92 r 0.95; p < 0.001). Nevertheless,he correlations between Vpeak-60 s during P1 min and P3 min (r = 0.83;

< 0.001), or during P2 min and P3 min (r = 0.87; p < 0.001) were notoo high.

The average times for the best 5-km and 10-km time trialsere 20.5 2.7 and 43.3 6.1 min, respectively. Their respectiveean speeds were 14.9 1.8 (S5 km) and 14.1 1.8 km h1 (S10 km).able 2 presents the relationship between S5 km and Vpeak duringhe three protocols of different stage duration. The Vpeak during3 min presented the highest correlation (0.94 r 0.95; p < 0.001)nd lowest SEE with S5 km, independent of how Vpeak was definedPlease cite this article in press as: Machado FA, et al. Incremental test designJ Sci Med Sport (2013), http://dx.doi.org/10.1016/j.jsams.2012.12.009

i.e., Vpeak-60 s, Vpeak-C, or Vpeak-P), followed by the Vpeak during2 min (0.88 r 0.93; p < 0.001) and by the Vpeak during P1 min0.83 r 0.89; p < 0.001). Specifically, the Vpeak-P during P3 min pre-ented the highest significant correlation and lowest SEE with S5 km

able 2elationship between 5-km running speed (S5 km) and peak running speed obtained duri

min (P2 min), and 3 min (P3 min).

Protocol Variable X (km h1) Correlation (95% CI)

P1 min Vpeak-60 s 0.83a (0.620.93) P1 min Vpeak-C 0.88a (0.730.95) P1 min Vpeak-P 0.89a (0.750.95) P2 min Vpeak-60 s 0.88a (0.730.95) P2 min Vpeak-C 0.93a (0.830.97) P2 min Vpeak-P 0.93a (0.840.97) P3 min Vpeak-60 s 0.94a (0.860.97) P3 min Vpeak-C 0.95a (0.880.98) P3 min Vpeak-P 0.95a (0.890.98)

alues are mean SD, n = 22. CI, confidence interval; Vpeak-60 s, highest speed maintained tage duration; Vpeak-P, speed of the last complete stage added to the multiplication of thea p < 0.001.(r = 0.95; SEE = 0.57 km h1) and could alone explain 91% of the S5 kmvariation. Further, Vpeak-P and Vpeak-C presented similar high corre-lations and low SEE with S5 km performance. In contrast, Vpeak-60 spresented the lowest correlation and highest SEE with S5 km dur-ing P1 min (r = 0.83; p < 0.001), P2 min (r = 0.88; p < 0.001), and P3 min(r = 0.94; p < 0.001).

Table 3 presents the relationship between S10 km and Vpeak dur-ing the three protocols of different stage duration. The Vpeak duringP3 min presented the highest correlation (0.91 r 0.92; p < 0.001)and lowest SEE with S10 km independent of how Vpeak was defined(i.e., Vpeak-60 s, Vpeak-C, or Vpeak-P), followed by the Vpeak duringP2 min (0.86 r 0.90; p < 0.001) and by the Vpeak during P1 min(0.76 r 0.83; p < 0.001). Specifically, the Vpeak-P during P3 min pre-sented the highest significant correlation and lowest SEE withS10 km (r = 0.92; SEE = 0.74 km h1) and could alone explain 84% ofthe S10 km variation. Additionally, Vpeak-P and Vpeak-C presented sim-ilar high correlations and low SEE with S10 km performance. Incontrast, Vpeak-60 s presented the lowest correlation and highestSEE with S10 km during P1 min (r = 0.76; p < 0.001) and P2 min (r = 0.86;p < 0.001).

The predictive equations for the indirect determination of 5-kmand 10-km time trials from the best-defined Vpeak were:

5-km time trial (min) = 46.4 1.6 Vpeak-Pduring P3 min(km h

1); R2 = 0.92; SEE = 0.8 min10-km time trial (min) = 98.0 3.4 Vpeak-Pduring P3 min(km h

1); R2 = 0.83; SEE = 2.5 min

4. Discussion, peak aerobic running speed and endurance performance in runners.

The major finding of the present study was that Vpeak deter-mined during the protocol comprising 3-min stage durations wasthe most highly correlated with both the 5-km (r = 0.95) and

ng incremental treadmill tests (Vpeak) comprising stage durations of 1 min (P1 min),

Regression equation Adjusted R2 SEE (km h1)

S5 km = 0.68 + 0.87 X 0.67 1.07S5 km = 4.02 + 1.04 X 0.76 0.90S5 km = 3.48 + 1.00 X 0.78 0.87S5 km = 1.71 + 0.98 X 0.77 0.89S5 km = 2.68 + 1.06 X 0.85 0.71S5 km = 3.01 + 1.06 X 0.86 0.70S5 km = 2.35 + 1.06 X 0.87 0.65S5 km = 1.87 + 1.04 X 0.89 0.60S5 km = 2.89 + 1.10 X 0.91 0.57

for a complete minute; Vpeak-C, highest speed maintained for more than 90% of the speed increment by the completed fraction of the incomplete stage.

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ARTICLE IN PRESSG ModelJSAMS-814; No. of Pages 64 F.A. Machado et al. / Journal of Science and Medicine in Sport xxx (2013) xxx xxx

Table 3Relationship between 10-km running speed (S10 km) and peak running speed obtained during incremental treadmill tests (Vpeak) comprising stage durations of 1 min (P1 min),2 min (P2 min), and 3 min (P3 min).

Protocol Variable X (km h1) Correlation (95% CI) Regression equation Adjusted R2 SEE (km h1)

P1 min Vpeak-60 s 0.76a (0.490.90) S10 km = 0.12 + 0.78 X 0.55 1.22P1 min Vpeak-C 0.83a (0.620.93) S10 km = 3.46 + 0.96 X 0.67 1.05P1 min Vpeak-P 0.83a (0.630.93) S10 km = 2.76 + 0.92 X 0.68 1.04P2 min Vpeak-60 s 0.86a (0.690.94) S10 km = 1.60 + 0.93 X 0.73 0.95P2 min Vpeak-C 0.89a (0.740.95) S10 km = 2.30 + 0.98 X 0.78 0.86P2 min Vpeak-P 0.90a (0.760.96) S10 km = 2.68 + 0.99 X 0.80 0.82P3 min Vpeak-60 s 0.92a (0.800.97) S10 km = 2.18 + 1.00 X 0.83 0.76P3 min Vpeak-C 0.91a (0.800.96) S10 km = 1.53 + 0.97 X 0.83 0.76P3 min Vpeak-P 0.92a (0.810.97) S10 km = 2.48 + 1.02 X 0.84 0.74

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0-km (r = 0.92) running performances. Furthermore, the relation-hips between Vpeak determined during P3 min and endurance runerformance were minimally influenced by the Vpeak definition.owever, independent of the stage duration, the Vpeak-P providedhe highest significant correlation and lowest SEE with 5-km and0-km running performances. This finding suggests that Vpeak-Phould be used as standard for the determination of Vpeak.

Previous studies have shown that Vpeak is a good predictor ofndurance run performance13 that can be determined withoutxpensive metabolic equipment or invasive techniques during anncremental treadmill test. However, it is critical that maximumffort has been exerted in any test to determine Vpeak. Despite someriticism, a plateau in oxygen uptake with a continued increasen exercise intensity is usually considered the main criterion forhe attainment of maximal effort.15 In the present study, oxygenptake was not monitored during any of the Vpeak tests becauseuch intervention may affect the Vpeak (unpublished data) and con-equently could have influenced the present finding. Additionally,t is common that subjects fail to demonstrate a plateau in oxygenptake during a maximal incremental test.15 For these reasons, theresent study used secondary criteria to define the maximal effortncluding high levels of blood lactate after maximum test, HRmaxnd RPEpeak.15,17,18 In addition, each participant was encouragederbally to produce maximal effort and only the participants thatet at least two of the above three maximal effort criteria during

he three incremental tests were included in the data analysis.In relation to the HRmax criterion, we used a conservative cri-

erion (i.e., HRmax 100% of APMHR) to avoid the inclusion ofarticipants who did not exercise maximally. Midgley et al.19

howed that the liberal HRmax criterion HRmax 85% of APMHRould be satisfied at as little as 68% of maximal oxygen uptake.oole et al.20 reported that of 5 out of 8 subjects who exceed theirage-predicted HRmax 10 bpm criterion, oxygen uptake at thatriterion averaged only 76% of maximal oxygen uptake. Hence,idgley et al.19 proposed a novel set of criteria to identify whether

subject has elicited maximal oxygen uptake including HRmax ver-fication. If the difference between HRmax during the incrementalnd verification phases is 4 bpm, then this is accepted as sufficientvidence of maximal effort.19 Unfortunately, in the present study,articipants did not perform a verification phase.19,20 While this is

limitation of this study, the use of a conservative HRmax criterionossibly restricted the impact on the reported findings.Similar to the findings of Bentley and McNaughton9 who exam-

ned nine well-trained triathletes during cycle ergometer tests, thepeak derived from an incremental run test in our study comprising-min stage durations was the most highly correlated with the 5-Please cite this article in press as: Machado FA, et al. Incremental test designJ Sci Med Sport (2013), http://dx.doi.org/10.1016/j.jsams.2012.12.009

m and 10-km running performances. Bentley and McNaughton9

howed that the peak power output derived from an incrementalest comprising 3-min stage durations had a higher correlation withhe average power output sustained during a 90-min cycling timefor a complete minute; Vpeak-C, highest speed maintained for more than 90% of the speed increment by the completed fraction of the incomplete stage.

trial (r = 0.94; p < 0.01) than the peak power output derived froma 1-min stage duration test (r = 0.54; p > 0.05). It must be empha-sized that, different from our study, these researchers derived thepeak power output from two different protocols, not only in termsof stage duration, but also in terms of initial power output andincremental rates. The 1-min stage duration test started at 150 Wwith increments of 30 W. The 3-min stage duration test startedat a power output representing 50% of the peak power outputobtained from the 1-min stage duration test followed by increasesin power output by 5% every 3 min until exhaustion. In contrast tothe present study, these authors reported strikingly different cor-relations between the 90-min cycling performance and the peakpower output obtained from the 1-min and 3-min stage dura-tion protocols. The 1-min protocol was designed to induce fatiguewithin 810 min and the 3-min protocol lasted 24 min (i.e., 8workloads). Given that participants performed a 90-min cycle timetrial to obtain their average sustained power output, it is not sur-prising that this correlated better with the peak power outputattained during the long than the short test. Besides that, the dif-ference between both correlations could have been affected by thesmall sample and also by the reproducibility of the tests. We alsoreported that the 5-km was more correlated with Vpeak than the10-km running performance. Unfortunately, we did not measureparticipants running pace during the 5-km and 10-km running per-formances. Such a measure every 400 m, for example, would allowus check whether any participant altered his pace excessively influ-encing the correlation between Vpeak and running performances.

McNaughton et al.10 reported similar correlation coefficientsbetween the average power output during a 30-min cycle time trialand the peak power output derived from tests consisting of either3- or 5-min workload increments, suggesting that an increase instage duration from 3- to 5-min during incremental cycle exercisedoes not affect the association between peak power output andshort-distance cycling performance. A protocol comprising 5-minstage duration was not analyzed in the present study. However, weverified that an increase in stage duration from either 1 to 2 or 2 to3 min increased the correlation between the Vpeak and endurancerun performances, increasing its values in recreational runners.

The present data suggest that the protocols comprising 3-min stage durations should be used to determine Vpeak, ratherthan 1-min stage duration protocol in recreational runners. Incontrast, previous studies found high correlations between Vpeakdetermined during 1-min stage duration treadmill protocols andlong distance running performance in highly-trained competitiverunners.1,3 For example, Noakes et al.1 reported a very high andsignificant correlation (r = 0.94) between the Vpeak during a 1-, peak aerobic running speed and endurance performance in runners.

min stage duration protocol (21.3 2.0; range: 1724 km h1) andthe 10-km race time (35.0 3.9 min) in 43 specialist marathon andultra-marathon runners. In our study, the performance level ofthe participants was lower than that during the study of Noakes

dx.doi.org/10.1016/j.jsams.2012.12.009

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Use the proposed equations to accurately predict 5-km and10-km running performance from peak aerobic running speedduring incremental treadmill tests in male recreational runnersARTICLESAMS-814; No. of Pages 6F.A. Machado et al. / Journal of Scienc

t al.1 (i.e., Vpeak-60 s during P1 min = 18.0 1.8; range: 1421 km h1;0-km time trial = 43.3 6.1 min). Thus, the findings from presenttudy should be used with caution to the population of endurance-rained runners with higher level of performance than recreationalunners.

Scott and Houmard2 also recruited competitive male runnersn = 14) who had trained a minimum of 48 km wk1 and had per-ormed a 5-km time trial in 15.9 0.8 min. Participants performed

self-paced 5-km run time under controlled laboratory conditionsnd a maximal treadmill test to determine Vpeak. The initial speedf the maximal treadmill test was 2.7 m s1 (9.7 km h1) and wasncreased by 0.14 m s1 (0.5 km h1) every 30 s until volitionalatigue. The Vpeak, defined as the final speed attained for more than

s during any fraction of the test, presented a high correlation with-km time trial performance (r = 0.83; p < 0.001). In our study, theecruited recreational runners had a training volume higher than0 km wk1 and a relatively low level of performance (i.e., 5-kmime trial: 20.5 2.7 min). However, during P1 min, the protocol thatas the most similar to that used by Scott and Houmard2, Vpeakhowed a correlation with 5-km run performance similar to thatound by Scott and Houmard2 irrespective of the Vpeak definitioni.e., 0.83 r 0.89; p < 0.001).

Another interesting study was conducted by Stratton et al.3 thatssessed 39 previously untrained volunteers (17 males, 22 females)efore and after 6 weeks of endurance training. Participants com-leted a 5-km run performance, conducted at a recreational park,nd a discontinuous incremental treadmill test until volitionalxhaustion to determine Vpeak. The initial speed of the maximalreadmill test was set at 9 km h1 and this speed was increasedy 1 km h1 between each of the 1-min successive stages. Eachtage was separated by a 1-min period of rest. The average 5-kmun performance increased significantly after training (11.9 1.6s. and 12.6 1.7 km h1). The Vpeak, defined as the final speedhat could be sustained for 1 min, also increased significantly afterraining (18.4 2.1 vs. 18.9 1.9 km h1) but the correlation (r)etween Vpeak and 5-km time trial decreased slightly from 0.89pre-training) to 0.83 (post-training). In our study, the recreational,ndurance-trained participants had a higher level of 5-km run per-ormance (S5 km = 14.9 1.8 km h1), but the correlation betweenpeak during P1 min and S5 km was also similar to that reported bytratton et al.3 Thus, based on the present study and studies fromcott and Houmard2 and Stratton et al.3 it seems that the correla-ion between Vpeak and endurance run performance is minimallynfluenced by training states (untrained vs. trained) or level of per-ormance.

In fact, previous studies have not reported the error of theirstimates and have not examined the Vpeak during protocols com-rising 3-min stage duration. The correlation coefficient is sensitiveo the heterogeneity (spread) of values between participants21 ands more affected by extreme values than the mean. Additionally,t is affected by intraindividual differences (i.e., the variability of

variable during repeated measures). According to Hopkins andewson,22 the variability of performance of distance runners isffected by age groups and level of performance. Thus, it is notecommended to conclude something through correlation coeffi-ients arising from studies with different samples. Hence, furthertudies are needed to examine whether the findings of the presenttudy are valid to competitive runners of higher performanceevel.

An important finding of present study was that the defini-ion of Vpeak as the highest speed that could be maintained for

complete minute (i.e., Vpeak-60 s) should be avoided especiallyuring protocols comprising 1-min or 2-min stage durations. ThePlease cite this article in press as: Machado FA, et al. Incremental test designJ Sci Med Sport (2013), http://dx.doi.org/10.1016/j.jsams.2012.12.009

peak-60 s presented the lowest correlation with S5 km and S10 km foroth P1 min and P2 min. In contrast, it is strongly recommended toefine Vpeak as the speed of the last complete stage added to the PRESSedicine in Sport xxx (2013) xxx xxx 5

multiplication of the speed increment by the completed fractionof the incomplete stage (i.e., Vpeak-P). The present data show thatVpeak-P presented the highest correlation with both S5 km and S10 kmindependent of the stage duration of the three protocols.

In the present study, the P3 min test started with an initialspeed of 8 km h1 and speed increments of 1 km h1 every 3 min.Although the test duration during P1 min was shorter than that dur-ing P3 min, it is unlikely that the P3 min protocol would last longerthan 60 min. One possible solution to shorten the overall length ofa test would be to adopt an intermediate protocol comprising 2-minstage durations. Indeed, Vpeak-P during P2 min was highly related to5-km and 10-km running performances. Additionally, increasingthe magnitude of the increments reduces the total duration of thetest as the subject is brought to exhaustion earlier.23 Consequently,further studies are needed to examine the effects of both incremen-tal rates and initial test speed on the relationship between Vpeak andendurance run performance.

The proposed predictive equations for the indirect determina-tion of 5-km and 10-km time trials from the Vpeak-P during P3 minpresented a small error. Thus, these generated equations can beused to predict accurately 5-km and 10-km running performances ifapplied to individuals with characteristics similar to those involvedin the present study (e.g., 10-km running pace between 10 and17 km h1). However, it is important to emphasize some limita-tions of this study. Besides the maximal effort criteria previouslydiscussed, we must emphasize that the running performances wereperformed on a 400-m outdoor running track, subject to environ-mental conditions and terrain. Alterations in these variables couldaffect the generated predictive equations and associations betweenVpeak and endurance run performance.

5. Conclusion

In summary, Vpeak determined during the protocol compris-ing 3-min stage durations was the most highly correlated withboth the 5-km and 10-km running performances. Furthermore,the relationship between Vpeak determined during P3 min andendurance run performance were minimally influenced by theVpeak definition. However, independent of the stage duration,the Vpeak-P provided the highest correlation with 5-km and 10-km running performances and should be used as standard forthe determination of Vpeak. Additionally, we provided predictiveequations that can be used to accurately predict 5-km and 10-km endurance running performance in recreational runners fromtreadmill tests. Further research is also warranted to examine theuse of Vpeak to prescribe training intensity and evaluate trainingeffects.

6. Practical implications

Use incremental treadmill tests comprising 3-min, rather than 1-min or 2-min stage durations, to determine peak aerobic runningspeed in male recreational runners with a 10-km running pacebetween 10 and 17 km h1.

Define peak aerobic running speed during incremental treadmilltests proportionally as the speed of the last complete stage addedto the multiplication of the speed increment by the completedfraction of the incomplete stage avoiding subjective judgments., peak aerobic running speed and endurance performance in runners.

with a 10-km running pace between 10 and 17 km h1, whichcan be non-invasively measured by coaches and practitionerswithout expensive costs.

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cknowledgements

This work was supported by the Ministrio da Cincia e Tecnolo-ia MCT and Conselho Nacional de Desenvolvimento Cientfico eecnolgico CNPq, Brazil.

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Incremental test design, peak aerobic running speed and endurance performance in runners1 Introduction2 Methods3 Results4 Discussion5 Conclusion6 Practical implicationsAcknowledgementsReferences