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J~umal of Strength and Cond:!loc.ine- Rese~rch. 2006. 20(3l. .•92-499 '. 2006 ;>.lational Strength I>: Cccltlomng :\SSOClatlOn [ha' Illal
DYNAMIC vs. STATIC ..STRETCHING WARM UP: THE EFFECT ON POWER AND AGILITY PERFORMANCE
thei [ :1E'
ti"ia Cln,
60 ~ DA..NNY J.
l\'1Cl\'1ILLL;\N/
JOSEF
H. l\'100RE,2
BRL>\N
S.
HATLER.,3
AND DEAN
C.
i<'mf
TAYLOR3
Sub.
IUS. Army MEDDAC, Heidelberg, Germany; "US. Army-Baylor University Doctoral Physical Therapy Program, US. Army Medical Department Center and School, Fort Sam Houston, Texas 78234; 'Keller Army Community Hospital, West Point, New York 10996.
ABSTRACT, McMillian, D.J., J.H. Moore, B.S. Hatler, and D.C. Taylor. Dynamic vs. static-stretching warm up: The effect On power and agility performance. J Strength Condo Res. 20(31:492499. 2006.-The purpose of this study was to compare the effect of a dynamic warm up (DWUj with a static-stretching warm up (SWlJ) on selected measures of power and agility. Thirty cadets at the United States Military Academy completed the study (14 women and 16 men, ages 18-24 years). On 3 consecutive days, subjects performed 1 of the 2 warm up routines (DWU or S\VU) or performed no warm up (l';"vv1.'). The 3 warm up protocols lasted 10 minutes each and were counterbalanced to avoid carryover effects. After 1-2 minutes of recovery, subjects performed 3 tests of power or agility. The order of the performance tests (T-shuttle run. underhand medicine ball throw for distance, and 5-step jump! also was counterbalanced. Repeated measures analysis of variance revealed better performance scores after the D'A-l..:for all 3 performance tests 'P < O.Oli, relative to the SWU and N'vVU. There were no significant differences between the 8\Vl: and N-wD for the medicine ball throw and the T-shuttle run. but the SWU was associated with better scores on the 5-step jump (p < 0.0u. Because the results of this study indicate a relative performance enhancement with the DWU, the utility of warm up routines that use static stretching as a stand-alone activity should be reassessed.
KEy WORDS. flexibility, isthenics
performance
testing,
conditioning,
JI
re-exercise warm up routines are common practice, despite limited scientific evidence supporting one protocol over another. For this reason, warm up protocols tend to reflect the experience of individual coaches, trainers, and athletes. Traditionally, static-stretching exercises have been a prominent feature of wann up routines (6, 34, 371. Support for a more dynamic warm up tDWU1 has grown in recent years, because several investigations have shown the potential for acute, static stretching to degrade performance on vertical jumps, short sprints, tasks requiring maximal voluntary contractions, muscle strength-endurance performance, balance challenges, and reaction time ;2. 3,6, 10. 11,20, 21, 2:~, :27, 37l. Additionally, several ~tudies now indicate that pre-exercise static stretching does not offer the presumed benefit of injury risk reduclion (5.14,17,26,30'Sniith-..L32.l-irialGau .•. d-that tl1l' g(iner:ll 1")u.rpose. of a-pre~~ ,'xercise Will'm up j,; to increas,' rnusclf.! and tendon "uppleness, to stimulate hlood flow to tbe pc'riphel'.v. to increase body tempernture. and t.o l'nhancf.! free. ('oordinatl'J mOVl'l11ent. Pl'Ofl~ssionals in thl' streng-th and conditioning cOlllmunity h,l\'l' incl'l'asingly touted \'arinus D\\'L-,; a,; lilt' bl';;[ IVa\' l<J 1JI','p"n' athll'l,'s for tIlt' pfn'''lcLJi
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demands of their sport (12). Although many variations on the nwu theme exist, most feature progressive, continuous movement. Calisthenics such as squatting and lunging movements often are paired with running drills that include forward, lateral, and change-of-direction movement. Investigators have shown DWU to improve knee joint position sense, to increase oxygen uptake, to lower lactate concentration and raise blood pH, to improve efficiency of thermoregulation, and to improve performance for bicycle sprints and vertical jumps n, 6, 7, 15, 20, 37). Recently the United States Ann.y Physical Fitness School (APFS) developed a DWlJ for individuals and military units. The stated objectives are to increase body temperature and heart rate, pliability of joints and muscles, and responsiveness of nerves and muscles in preparation for physical readiness training activities. This DV>LJwas used before each exercise session as part of an intervention to decrease injuries and to improve physical performance among soldiers in a basic training battalion. Static stretching, a prominent feature of the warm up for generations of soldiers, was not included. Although multiple interventions confounded the effect of the DWU, injury rates over the 9-week training period were significantly decreased compared with both a control battalion and historic trends. Perfonnance on physical fitness testing generally was improved (l9l. Given the ubiquity of static stretching in warm up activities, the purpose of this study was to compare the ef~ fect of a DWU (based on the APFS model) V\lith that of a static-stretching warm up (SWU) or no warm up (NWU) on selected measures of power and agility. Dependent variables to assess power and agility were chosen, because these attributes are common requirements for a vatiety of sports. The DWU protocol in this study closely mimicked the power and agility requirements of many sports, so we hypothesized that it would result in a performance enhancement relative to the SWU or NWU.
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"'ere aggYeg'ate ]o\,;er body Dower and stabililY, \Yiklandel' et '3:1. have sho\\'n th~ 5-step jump to be' a reliabie measure that correlates well \\'ith the vertical jump. long jump. and isokinetic leg strength (35i. The medicine ball thro\\' for distance was chosen as a measure of total-body power. Stockbrugger et a!. have shown this test to be a valid and reliable test for assessing explosive power for an analogous total-body mO\'ement pattern and general athletic ability (33l. The T-drill was chosen primarily as a measure of agility. For this test. the component tasks of (a) forward, T~' ~\' cadets at the Gnited States Military Academy backward, and lateral running: (b) stopping and changing ,i. ,:,I.--\.) volunteered for and completed the study. Subdirection; and I c) reaching with an upper extremity while jr::,- \\-ere recruited from USMA club sports. Cadets were lowering the center of gravity are all representative of e;i_' ole for the study if they were fit for full military duty commonly encountered tasks in sports. Pauole et al. have \1 ,: :;,~)lltrestrictions ....•.11 subjects completing the study shown this test to be a valid and reliable measure of agilII", members of rugby, lacrosse, or strength and condiity, leg power, and leg speed in college-age men and womt: ,'.:ng teams. Members of the rugby and lacrosse teams en (25). To emphasize lateral movement, the forward- and \1 ,;c' competing weekly. In addition, all cadets have roubackward-run portions of the T-drill were set at 5 m rathtil physical requirements. For these reasons, the suber than the 10-vd distance described bv Pauole, je·,;.- Il'ere screened by the primary investigator before the Data collection began the day aft~r the orientation st ,;:' to establish eligibility and before each training or and ran for 3 consecutive days. Subjects performed 1 tt· '"reI session to ensure continued eligibility. Exclusion warm up protocol (DWU, S\\'1--. or NWUJ before data colcr, ,:.;:~ were: (a) acute impairment of the spine or lower lection each dav. Subjects were instructed to avoid exere': ',",lities, vestibular dvsfunction, or balance disorder. cise or vigorous ph~'sical exertion the morning of testing, C ,:~LOry of surgery in either lower extremity, and (ci All tests were conducted at 6 A:-'lat the same test site hi -: .\ of a neurological disorder affecting the upper or each day. In.. '_ ,'xtremities. All subjects gave written, informed After completing 1 of the warm up conditions lor 10 CI, " :1~prior to participation in the study. The mean = minutes of rest for the i\TWU group), subjects proceeded 5t..':'::,rd deviation (SD) for age, height, and weight for to the performance testing stations. The time between tho men were 20.2 = 1.2 years, 182.4 ::+:: 6.6 cm, and finishing the warm up and beginning the performance 8i--.' :-: 9.0 kg, respectively. The mean::+:: SD for age, testing was approximately 2 minutes. The order of testing hr': _".L. and weight for the 14 women were 20.4 ::+::1.5 was counterbalanced to avoid carryover effects. A physiyl":.._--.167.1 ::: 7.9 cm. and 64.0 ::: 7.8 kg, respectively. cal therapist or physical therapy assistant who was un_-\1 ·t.hjects gave written informed consent prior to paraware of the subject's group assignment scored each pertiC,·",liol1. The study was approved by the Human Subformance test. None of the investigators participated in jp,.. - R,'search Review Board of Keller Army Community data collection. The primary investigator then compiled H, -"ll,t!. West Point, -;-"'Y, all data for analysis. \\";,,'m l:p Protocols Attempts were made to control potentially confounding variables. For example, la) testing occurred at 6 A1>1 S" ,,,r:;,, executed the warm up sessions in small groups each day, with subjects advised not to eat or drink any\1:' l:1<:primary investigator leading the DWU (Table 11 thing other than water before testing; ib) subjects were aI', : .::1 '--l~sociateinvestigator (BHi leading the SWU ITaqueried for injuries. illness, or excessive fatigue each day; b!. The order in which the subjects performed the 3 I c) subjects were reminded of the importance of maximal \\': ,":1 up conditions was counterbalanced to avoid poteneffort each day before testing: I d) graders were either tic ',i"sing effects associated with test sequence. Each physical therapists or physical therapy assistants with at \1 ,'up session lasted 10 minutes. Subjects scheduled least 1 year of experience collecting performance mea1',,,,';\\T' rested in an area adjacent to the testing site. surement data for another study; and Ie) graders received P"j'!ol'mance Testing a standardized orientation to the measurements required :\1 ""Cl'nt investigations of pre-exercise stretching have for the study. 11,,·rtical jump tests as the measure of performance, Ten subject>; were remon,d from the study after comT: n'Sl'nt investigation used other performance meapleting the' orientation: 2 suhjects fllr ('xces'"iw fatii,'U£' ,-' Tahl(, 31 in order to evaluate ai!ility as \I'ell as a from cadet physical requireIn('!1ts tht: pre\'ious da.", 2 suh1>, "f"'pt:ctrum ofwsks requiring power. Care lIas takjects from injuries n:latl'd to military tf"aining'. and Ei suh,"oid tasks that would induce fatigue. hecausl' fa:jects for mis~('d testing sessions, :'-:<l 'suhjects ~I'('n' injun'd .'..:,_~ '_;'!'''_lJ!'.l.'n--::;.hD __ ~'.:.r:, _JQ....biJJdJ.:J: Jnc,HL.Dl\k"(:lllaL---I2('.I·1.0f"--_........d.llri.0i!.._t~':'. -p"I'fo,T.r...nanCl' nf..0.tl"!.('':..,--,-f~lb __ '' \I':lI·n1....~1 p ct.J.I.ld i=-. ",~pl'ciall.l, fll!' t<.lsks that in\'o!n' th(, stretch-short-lion . ; Of"pel'formancl' l(',.;ting, 'ubjects had ma,,:ered the techniques for the pedor'-'e measures. the" repeated each of the 3 events until ':.'scores no long~r i~proved. Rest between trials of ':'-drilllasted approximately 2 minutes. Rest between t, . " of the 5-step jump and medicine ball throw for di3t, 'l' was at the subject's discretion. but generally of 3013 -c·conds' duration. Subjects were encouraged to take as j, '_':1S necessary to recover from the previous effon.
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opposit.l'
side,
I.i" nil th,· 1,,1'1 silk. t:l'Ilsi' 1Ill' ril~hl Illlld,' or 1'001 wilh t.IH· right hllIH\. l'lilllh,' ri::loI 1" .•. II"wllrd IIH' Illlt.l""\,,, ,,1,,1 Ih,· II,i::11 J'('"rw:ml '1'1", ril,.loI tllll~h ""'y 1)1' fnrlh('\' ,·xlI·I"It·d wit.h pJ'('ssUJ'(' fmlll t.h,· 1t-1\.l'ool.. J{,·!W"t. 0" till' oppllsil,' sid,', Do IIUt. pull th" heel Iilrr •. l'tilly to 1.11,' 1"01I.,,,'k, "Sl'" ,'j"I1,\ il' 11"'re is disCll,nf(lrl in t.he knee joinL. In this case. achieve a h"npficial st.rdch hy allowing the knel' t.o st.raight.en slightly "lid pull 111('
Idlll'l'p"
'l'l'tlll
li"'IV"rd
sid,· 111'11", forwllrd
r"isillg
,SlIpi'H'
t.o Ih •. r"ar. i'osit.ioll.
C1'OSS
1hI' It,n kIll'"~ toward
1'''1'1 I' i\IIlI'(' 10 tl,,· quadruped
'\-
:--:tn'lch
II,,· right.
lilt' c1wst posit.ioll,
"nklt[{ep"al then
over
t.h" It'ft t.high,
on till' cont.inue
pns:-:ively fh~x(~d. 1':lrt:J.: ;\,10\'" 10 tlw 1'1'011" posit.ion, I'•.rforrll t.h" prone 'I'll<' I highs ,Itld p"lvis J'('st. '"1 till' 1~J'(l\III<I, I{"I", lh"
opposit.e rearward
Cr"splh,'
righl
kn,',·
wit.\1 hot.\1 h,,"ds
and
pull
it towal'lls
t.\,,' 1•. 1'1 sllo,iI,!t-t'
wl,il"
side, t.o sit. hack
IInlo
lhl'
Ipg's whil,·
Iw,'ping
the
al'ln5
l'xt.end"d
t.o lhe
1"'''"1, 'I'hl'
1"",,1
1"l'1ll:1ill:-'
I
point In LIlt' rear.
pn'ss hark
lip I'rom "it.l1t'r "nd abdolllill,,1
till' 1;II'I'arl11 '''' hands. 1I11'''c1,'s wllil,' Ill'aring
d"pending on jlldividw<l the bodyw"igltt t.hrouglt
fl,',ihilily ",,,I ('011<1"1'1, t.\,,' st.raii:ltl "I'II1S, '1'"""
TABLE
warm
UD
Performance on each dependem variable based on conditions .Y = 30 Data are mean:: SD. ,',
4.
:'ledicine ball throw fo:distance \m I Control (~~'U) SWL: m\T
9.77 9.69 9.56
= 0.8:2 = 0.85 = 0.79"
9.47 9.34 9.79
= 2.89 = 2.87 = 3.017
i)-step jump 1m)
9.51 9.78 10.06
= 1.14+ = 1.172+ = 1.23+
'" X\VU = no warm up; swr = static-stretching warm up; D\vL; = dynamic warm up. -;-Denotes significam difference from the other 2 warm up conditions r p < O.Oll. + Denotes significam difference between all 3 warm up conditions I p < o.on
used to evaluate the effect of warm up conditions on the 3 performance measures. Tukey's honestly significant difference (HSD) was used for post hoc analysis. Statistical significance was set at p :s 0.05. RESULTS
Descriptive statistics representing the performance on each dependent variable based on warm up conditions are presented in Table 4. Repeated measures ANOVA re~ealed neither a significant' main effect nor interaction for gender; therefore, data were collapsed for post hoc testing. The main effect for wann up protocol was significant. Pair-wise comparisons using Tukey's HSD revealed that subjects scored better after the DWU than after the NWU or SWU on all 3 performance tests (p < O.Oll. There were no significant differences between the 8WU and NWU for the medicine ball throw and the T-drill; however, subjects scored better after the S\VU than after the NWU on the 5-step jump (p < 0.01). DISCUSSION
The purpose of this study was to compare the effects of D\\'U, S\VU, and l'<"WU on selected measures of power and agility. Results indicate that the DWU conferred a modest performance enhancement for all 3 measures of power and agility relative to the SWU and NWU. These results are consistent with Bishop's review of the literature. indicating that an active warm up of moderate intensity is likely to significantly improve short-term performance on a range of tasks as long as fatigue is not induced (4). Although static-stretching warm up exercises have been shown to decrease power and one-repetition maximum strength tasks (21, 371, our results show no significant difference between the SW1.J and NWU for the T-drill and the medicine ball throw for distance. The 8\v1] was a significant improvement over NWU for the 5-step jump. In a review of the warm up literature. Bishop cites several reasons why an active warm up such as the DVv'1.J used in this study might improve short-term performance I·a :Ylost factors are related to temperature and include decreaiied stiffness of the muscles and joints: increased -t-l'flftSHt-i-ss-i 0 n r a-te-of-nt >;'V-l!i m ~}\-I1,;p-,;-,,,,·.n"Hl f{e",i.1+trw...for~ __ "elocity relationship: and increased glvcogpnolysis. gly· colysis. and high-ener::,~' phosphatL' degradation. In addition to these temperature-related changes, ~ neul'Omu,,l'ular phl'nonwna possibl,' actinltpL! h\' the ])We could potentiall\' enhance power and agilitv l)('rfcll'Il1ance. I'ost;ll'ti"al ion potent iation 'PAl': an increas,· in l11usck
t'.'.i:ch force dj~:nning cc po"....·r and ril;~j('rers to stc,mtractic ml",1sured il cn;..lbie a n1
tion.s of mu creu.,:,e mUSt
twpen actin Iv has the E . _\lthoug above were mands of tIsistent witIhancement less I, evidel formed at L recovery (4 present stll< tigue did n( jects. In contr tioned abo\' cise .stretch reLrive to searchers I means by v. motor unit: SWl.; reduc forma nee 01 in this stud vation was measures u In addit increased c, when a forc moment wh tendon, ratl 21 i. Potent: perfc)rmanc· encased. join pJi;,lnce of tl th,ll greate cl'l'ased rar. st rl'lching , sequent reI concept is s L'111warm u 1:0. static S' hcilitation IJjTeases ir ''.l.vnarmc n'-ling stat ,,' :.;"ation i .,'.,,.m up. It is im !"'Lching ("!lc(;::'r.e J a L
,'(·d Llbo\' ;\pply .,:, In f~tt ,.dlce corn "hility': ';"xibilit,
cific nature of fiexibilit::. suggesting that flexibility trair:and rate of force development following a coning might enhance performance in sports that rely on exditil1;1ing contractile activity could theoretically improve tremes of motion for movement. Conversely. decreased Po\\'''!, and agility performance, though the .optimal paflexibility might actually increase economy of movement rameters to exploit PAP are unknown (29). SImIlarly, poin sports such as distance running, where only the midstcontraction sensory discharge (increased neural activity portion of the range of motion is used (14). The evidence mea.;ured in the dorsal roars following contraction) might suggests that flexibility training should be applied, based ena::>:'" a more rapid and forceful response to perturbaon individual needs and the physical demands of the action~ Jf muscle length (8). Active warm up also may detivity. crea"e muscle stiffness by breaking the stable bonds beAlthough the current investigation examined only the twee~ actin and myosin filaments. though stretching likeeffect of warm up parameters on performance, injury prelv nas he same effec (4, 3-1 . , .-\2~hough none of the ph\'siological facrars mentioned vention is cited rourinely as a reason for pre-exercise warm up. As reponed by Shrier (30" the recent epideabo\·.: were measured ciirecr y. we believe that the demiological evidence suggests typical pre-exercise muscle manci,; of the DW1.J used in this study are generally cons retching protocols do not produce meaningful reducsistent with the recommencia io s of Bishop I·n For entions in risk of exercise-related injury. Conversely, basic hancement of short-term performance '10 seconds or 'cience supports the notion that an active warm up might less evidence suggests a warm up of 5-10 minute". per.1'0 ect against muscle strain injury. though clinical reformed at 40-60% of Vo"ma\:. follo\\'ed b.' ;) mi. es 0" search is equi\'ocal on this point (14). Theoretically, warm recowry (4). Although the recovery inten'al sed i e p acti\ities that enhance neural activation will better present study was less than Bishop's recommendation. faprepare muscles to absorb loads that might othenvise be tigue did not appear to be significant in our athle ic subrra smi -ed a other structures such as ligaments, tenjects. cio_s. and the muscie cytoskeleton. This concept is supIn contrast to the benefits of an acb\'e warm p menported by research showing that muscles under active tioned above, there are at least 2 theories why pre-exercor.trac io. absorb significantly more energy than muscise "tretching might decrease subsequent performance cles a- re"t 13. Recently, Olsen et al. were the first to relati\'e to a more dynamic warm up. First. severa reuse a arge. randomized. controJled study to show reduced searchers have cited reduced neural activation as a rates of inj ry in a group performing a dynamic. funcmeans by which repeated stretches reduce the number of tional warm up (24). motor units available for contraction (3, 1L 211. If the The follov,ing factors should be considered when inS\V1; reduced neural activation relative to the DWU, perterpreting the results of the present investigation. First, formance of power and agility tasks, such as those used due to srudy design and restriction on the availability of in this study, might be diminished. Because neural actisubjects. only 3 repeated measures (one each foHowing vation was not measured, its effect on the performance DW1";, SWl:. and :\\\'L'l were conducted. Therefore, the meas res used in this study is purely speculative. combi ned effect of dynamic and static stretching warm up 1:0 addition, other investigators have suggested that components was not tested. Few studies have examined increase compliance (i.e., the length change that occurs the effect of pre-exercise stretching combined with a dywhen a force is applied) in the tendon results in a brief namic component. Church et al. compared the effect of a mo .c. when muscle force is taking up slack within the general warm up consisting of a 10-minute circuit ofbod)'tencia ... ra her than contributing to gross movement (14, weight exercises with the same warm up paired with ei21,. 0 e _riall)', such an effect could hinder power and ther static-stretching or PNF stretches (6), Vertical jump performance. However, some studies have shown inperformance was limited only by the PNr' stretch warm creased 'oin range of morion without changes in the compliance of the musculotendinous unit (16, 22), suggesting up. The investigators theorized that the increased intensity of the PNF stretching might induce autogenic inhithat )".'Teater stretch tolerance might account for the increast.:d range of motion. Taylor et al. have shown that bition and, therefore. might limit vertical jump performance. stretching and isometric con ractions both result in subsequent relaxation of the muscle-tendon unit (34). This Rosenbaum et al. found that decreased force and rate of force development related La stretching was returned concept is supported by a clinical study in which 3 differto normal after 10 minutes of running i28J. This suggests ent warm up conditions (i.e .. body-weight circuit exercisthat pre-exercise stretching may not hinder power peres, static stretching, and proprioceptive neuromuscular facilitation stretching fPNFJ, each resulted in equivalent formance if followed by dynamic movements that mimic the tasks that follow. Warm up protocols that combine increi1"es in hamstring flexibility <6J. This suggests that a dynamic warm up might increase flexibility from the d.vnamic and static-stretching exercises would add comn'stin;.: state without the potential compromIse of neural paJ'ative value and are encouraged for future investigations. Still. for teams and individuals that arc under time activation associated with an isolated. static-stretchmg warm up._ _ constraints [or warm up. the current body of evidence +-~.;--iI1Ypilf'tailcm-dlsli ngu ish belwel'n--11fl-=-cxercis'e -- suggFSlt.;-tlulCst.atic-.;t rClch ifJ-::~mighT bl'-ulffiectossar',' . .,trdching and flexihility training in general. The perforAnother limiting factor of this stud\' is that physiologman""-rl'!ated issues from pre-eM.'ITise stretching nwnical parameters of thl" warm up protocols wcre not e"tabtJ0nl'[; :1I10v[',especii1l1y reduced neural activation. mii!ht li.,.;hed.Controlling for factors such as Illuscle temppn1turE' ;Ind nx,vgl'n utilizatio[1 would ha\'" alJm\'{,d filr 1-,rreater (;"t ~uply to stretching eXl'ITisL'S pprf(lrmed at other Ilm,,-. In fact. investigation" have noted improved p"!'forIlrl'C'isio[1whl'n descrihing' warm ur paranll'ters, Caution J~lailo.·l' l'IH'J'elated to regular ,.;tretchlng I:lli and increa"ed should be u,,.;edwh'![1 generaiiz!l1g th., n'sults o(t.hls swc!\ Ilt·x!(,iiir.\ ,:3{1 I, c;!l'im l'l. al .. ill a revil'\\ of' thl' literatul'(' iO ottwr population,',. Our SlliJjl'ct" \\'l'I'(' .voung' athll'te~ "n fl,'\iiliiitv and sport.s p,·rt'orm;'Il[,'·. (lOtNl thl' sJJor·t.·sp,·;HTllsl,Ofll('d to \·ig·(Irou ...• athletic ~Ir)(! nlilitary training: t\', i~c:1force
I.