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Journal of Strength and Conditioning Research, 2006, 20(2), 246-251' j^' 2006 National Strength & Conditioning Association

THE RELIABILITY OF TEN-METER SPRINT TIMEUSING DIFFERENT STARTING TECHNIQUESG R A N T M. DUTHIE,^-* DAVID B. P Y N E , ' A N G U S A. Ross , ' S T E U A R T G. LrviNGSTONE,^ A N D S U E LH O O P E R ''Department ofPhysiolog y, Australian Institute of Sport, Bruce, Australia; -Elite Player Development, AustraliRugby Union, North Sydney, Australia; 'School of Hum an Movement Studies, University of Queensland,St Lucia, Austraiia.

ABSTRACT. Duthie, G.M., D.B. Pyne, A A, Ross, S.G. Living-stone, and S.L. Hooper. The reliability of ten-m eter sprint timeusing different starting techniques. J. Strength Cond. Res.20(2l24G:-251. 2rjr;6".Acceleration is an important factor forsuccess in team-spo rt ath lete s. The purpose of this investigationwas tocompare the reliability of 10-m sprint timt's when usingdifferent starting techniques. Junior male rugby players (n =15) were tested for speed over 10 m on 2 different testing ses-sions. Three trials of 3 different sta rting techn iques (sta nding,foot, and thumb starts) were assessed. Despite large dilTerencesin the time taken toperform 10-m sprints from diRerent starts,there was minimal difference in the typical erro r! -^0.02 seconds,or

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SPRINT RELIABILITY 247

formance can be established as a small Cohen effect size(ES) calculated as 0.2 times the between-subject standarddeviation within a specific population (3). Elite rugbyunion players demonstrate a 0.67r variation (CV) insprint time (5). This calculation results in a smallestworthwhile change in performance over 10 m of 0.002seconds based on a 1.75-second sprint (16) (0.2 X 6% X1.75 seconds). Subsequently, the usefulness of 10-msprint testing using timing lights is questionable, giventhe magnitude of noise 10.04 seconds) compared with theworthwhile change (0.002 seconds) (17).

There is currently a need to establish the reliabilityof short ( 10-m) sprint tests and examine methods of re-ducing the random error associated with such tests byusing different starting techniques. The purpose of thisinvestigation is to examine the reliability and variabilityof different starting techniques on sprinting speed overthe acceleration phase of a maximal sprint {10 m).METHODSExperimental Approach to the ProblemTo assess the variability in 10-m time from differentstarting techniques, elite junior rugby union players weretested over 10 m from a variety of starting positions on 3separate occasions, consisting of 1 familiarization and 2testing sessions. The within-subject, between-day typicalerror for each of the starting techniques was established.The magnitude of differences between the starting tech-niques was calculated.SubjectsFifteen elite junior male rugby players were involved inthe investigation. Players were selected from the Austra-lian Capital Territory Rugby Union and had been train-ing consistently in a structured elite junior program fora minimum of 2 months. All testing was performed he-tween 1600 and 1700 hours on the same day each week.Players were 17 0.7 years of age, had a body mass of89.2 16.8 kg, and were 179.9 5.2 cm in stature. Allplayers were familiar with the requirements of sprinttesting and had completed specific sprint and accelerationtraining and testing prior to the study. The training pro-gram of the players was standardized over the testingperiod and they were not in regular competition. Players'parents provided written consent for their sons to partakein the training program and scientific investigation as-sociated with the program. Players and parents were ad-vised that participants were free to withdraw from thestudy at any time.Speed AssessmentPlayers attended 3 testing sessions, all performed indoorson an artificial grass surface. The first session was des-ignated as a familiarization session, followed by 2 desig-nated testing sessions on different days. Familiarizationsessions have been suggested to be unnecessary for speedassessment (16); however, because players had been ex-posed to 1 sprint-start method (standing start) more thanthe other method, we included this session in an attemptto limit bias. Each session was separated hy 7 days, withstandardized training performed on the days prior to eachsession. Within each session, players performed 9 maxi-mal-effort 20-m sprints. The players regularly performedmaximal sprint efforts during their training and were

well accustomed to the high-intensity nature of eachsprint. Three sets of 3 sprints were performed, with a fulrecovery between sprints. Each set of 3 sprints was per-formed with a different start ing technique (Figure 1). The3 different starting techniques were (Eigure la) a standing start with timing commenced when tbe first gate wasactivated (standing start), (Figure lb) a standing starwith timing activated when the front foot left a fixed timing mat (foot start), and (Figure Ic) a conventional 3-poinstart using a thumb switch to commence the timing(thumb start). The order of the 3 sets of sprints was coun-terhalanced between subjects to eliminate an order effectPrior to the testing sessions, all players were remindedof tbe particular requirements for each of the 3 startingtechniques.

Splits were taken at 10 and 20 m using timing light(Swift Performance Equipment, Goonellabah, Australia)The purpose of testing the sprints over 20 m was to elim-inate a finishing dip at 10 m by players attempting torecord a faster time. Sprint protocols for team-sport athletes regularly involve a 10-m split (7), and we attemptedto replicate the standard testing protocols. A thorough 15minute, standardized warm-up preceded all testing sessions. The warm-up involved light jogging, short accelerations, and dynamic stretching.Statistical AnalysesMeasures of centrality and spread are shown as mean between-subject SD. Uncertainty in the estimate of differences between starts is expressed as the mean effect+90% confidence limits. Differences between the startingmethods were assessed with independent sample ^-testwith unequal variance. The reliability of 10-m times foeach method between the 2 testing sessions was also established as the SD of the difference scores between trialdivided by root two (11). Intraclass correlation coefficientfor the 2 testing trials were also calculated for each of thedifferent starts. The mean change between the first andsecond testing session was also established and effectassessed with dependant sample ^-tests (StatisticaSTATSOFT, Tulsa, OK). Magnitudes of differences andchanges are expressed qualitatively as an effect size usingthe following criteria: 0.0, trivial; 0.2, small; 0.6, moderate; 1.2, large; and >2.0, very large (15).

The smallest worthwhile change in 10-m performancwas established from previously reported variance (0.6%in sprint performance for elite rugby players (5) or 0.0second for 10 m. The magnitude of change in 10-m sprinperformance required before it could be established thaan individual player had likely changed performance wacalculated using methods previously described (12, 15)Briefly, the probability of observing a worthwhile changein performance was calculated from the smallest worthwhile change, the typical error, and a 75% (likely) probability (15).RESULTSThe mean SD 10-m times for each of the different starpositions are presented in Figure 2. The results show thathere were large differences between tbe foot start andthe standing start (0.22 0.00 seconds, ES: 1.8) and thefoot start and the thumb start (0.38 0.00 seconds, ES1.9), with the foot start being faster in both cases. Therwas also evidence of a large difference between the stand

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248 DuTHiE, P Y N E , R O S S ET AL.

a

2.5 -,

2.0 -

(L II 1.5

0,0 -IFool Stand Thumb

Starting techniqueF I G U R E 2. Mean standard deviation 10-m sprint times fothe different starting techniques. * significantly different tofoot start (p < 0.01). "i" significantly different to stand start(p < 0.01).

0 02 -Q JE 0 01 -P

0,00 -

-0.02 -

-003 -

ThumbF I G U R E 3. The mean (909; confidence limits) change in 10m time between trial 1 and trial 2.

ing start and thumb start, with the standing start bei0.16 0.06 seconds (ES : 1.6) faster.The changes in the 10-m times between testing sesions are shown in Figure 3. There was a small, 0.020.02 second, decrease (ES: 0.4) in 10-m time between sesions for the foot start. The mean time for the standiand thumb starts were relatively unchanged between trals with a trivial, 0.01 0.02 second, decrease (ES: 0for the standing start and a trivial, 0.00 0.02 secondecrease for the thumb start (ES; 0.0).

F I G U R E 1. The 3 different sprint-starting techniques as-sessed, (a) Standing start, (b) foot start, and (c) thumb start.Timing in the standing start (a) commences when the initiallight gate is broken. Timing in the foot (b) and thumb (c)starts commences when pressure on the timing switcb is re-leased. For all starts, the initial timing gate/switch is placed 0 m.

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SPRINT RELIABILITY 2490 045 -,

0.040 -

0 035 -

0015 -

0010 -

0.005 -

FIGURE 4. The typical error (90% confidence limits) of 10-mtimes using different starting techniques.

2 0 -I

1,6 -

0.8 -

0.4 -IFoot Stand Thumb

FIGURE 5. The percent typical error (90% confidence limits)of 10-m times using different starting techniques.

The typical error of each of the starting techniquesbetween tests is provided in Figure 4 and th e relativetypical error in Figure 5. Intraclass correlations coeffi-cients w ere 0.86, 0.92, and 0.92 for the foot sta rt, stand ingstart, and thumb start, respectively. The poor reliabilityin relation to the smallest worthwhile change suggeststha t th e curren t methods of assessment are poor in iden-tifying changes of substantial practical importance. In allcases, the magnitude of the typical error was substan-tially g reater than the sm allest worthwhile change. Toobserve a likely change in 10-m sprint time for an indi-vidual, a player would be required to change performanceby 0.02 second for all ofthe starts assessed in this inves-tigation.DISCUSSIONWe have demonstrated that the reliability of th e 10-msprint time when using dual-beam light gates is approx-imately 0.02 seconds (-1%). There were substantial dif-ferences in 10-m time when using different st arti ng m eth-ods; however, there was no substantial difference in re -

liability. It is apparent from the results of this study thatdifferent sprint starts cannot be used interchangeably,and a consistent starting technique is required when com-paring different teams and assessing change in an indi-vidual. The typical error observed for 10-m sprint time isgreater than the smallest worthwhile change in 10-mtime. Strict guidelines for testing should be followed andthe likelihood of observing a small, but substantial,change calculated by accounting for the typical error andsmallest worthwhile cbange.Our values for the percentage typical error were lowerthan the 1.9-2.6% previously reported for male physical-education students (16), possibly due to the current sub-jects' familiarization with the different starts in the test-ing protocol. Moreover, the previous investigation used astanding start 0.5 m behind the initial timing gate (16)and single-beam photocells (Moir, personal communica-tion, 2004) that can he triggered by an arm or leg ratherthan the torso (7). Preferably, th e configuration of light-gate systems for elite-athle te testing should be dual beamand require the simultaneous breaking of 2 beams to reg-ister a valid time. Quantification of reliability (typical er-ror) is useful for practitioners working with trained ath-letes from a variety of team sports, an d also for research-ers interested in characterizing th e na tur e of accelerationqualities in athletes and the effectiveness of training in-terventions aimed at improving acceleration.Despite having the lowest typical error, there was asubstantial decrease in 10-m time between tests conduct-ed 7 days apart when using the foot start. This decreasewas not evident in the other starting methods and mayhave been a result of the players having less prior expo-sure to this starting method. With more familiarizationthis method may have produced more consistent sprinttimes. In contrast, players had performed the standingstart (0.02 second typical error) regularly in previous test-ing, possibly negating the requirement for further famil-iarization (16). The thumb start ha d th e poorest reliabil-ity (0.03 second typical error) of the different starts as-sessed. It must be recognized that th e reliability of 10-mtime observed in this study was for sprints conducted in-doors and following a standardized warm-up. Sprint test-ing should be performed following a standardized warmup and on an even and consistent surface in standardizedenvironmental conditions. Such standardization is not always possible and needs to be accounted for in any analysis. For example, results can be adjusted for wind speedusing formulas adapted from track and field (14) whentesting is performed outdoors.It appears that the major source of variation whenusing photocells to assess sprint performance is the momentum gathered prior to activating the initial timinggate. In the 3 different starts under examination in thisstudy, the center of mass was moving prior to the timingcommencing, which results in the subject having somemomentum, that is, a flying start. The 3-point starts(thumb and foot start) were an attempt to decrease th evariation in the amount of momentum developed beforetiming was commenced. However, given tbe similar magnitude of reliability between th e different sta rts , it is stilunclear whether implementing a 3-point sprint s tar t fotesting purposes is advisable, especially in populationwhere familiarization would be required. Further, forugby and other football players, the 3-point s tar t tech

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250 DUTHIK, P\-NE, Ross KT AL.

nique may disadvantage players of large stature or bodymass.When assessing an individual's measured perfor-mance change, the observed change in performance (sig-nal) needs to account for the typical error (noise) associ-ated with the test (11). The typical error is the SD of thechange scores from test to test in an individual athlete'srepeated measurements (11). A better typical error for atest implies less random noise and therefore a greaterability or likelihood of detecting a change in the perfor-mance, or signal. Eurther, knowledge of the magnitude ofthe smallest worthwhile change inperformance is usefulin identifying the practical significance of feedback pro-vided to the player and coach. Expressed as a SD,aneffect size of 0.2 has been suggested to represent thethreshold for a small, hut substantial, change in perfor-mance (11). Eor 10-m sprint performance, an effect sizeof 0.2 based on the between-subject variation of 0.04 sec-ond gives a smallest worthwhile change of 0.008 (0.2 X0.04) or

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RFI.IABILITY 251

parison of physical an d performance characteris tics of NCAA sprint performance an d vertical jump height in elite soccedivision I football players: 1987 an d 2000. J. Strength Cond. players. Br. J. Sports Med. 38:285-288. 2004.Res. 18:286-291. 2004.

21. WisLOEF, U., C. CASTAGNA, J . HKLGERUD, R . JONES , AND J . A d d r e s s c o r r e s p o n d e n c e t o G r a n t D u t h i e , g r a n t. d u t h i e H oFF. S trong correlation of maximal squat streng th with a u s p o r t . g o v . a u .

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