A systematic review on dry-land strength and conditioning training on swimming performance

A systematic review on dry-land strength and conditioning training on

swimming performance

Article  in  Science & Sports · September 2018

DOI: 10.1016/j.scispo.2018.07.003 CITATIONS 0 READS 625 6 authors, including:

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Instituto Politécnico de Leiria

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Instituto Politécnico de Leiria

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Universidade da Beira Interior

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REVIEW

A

systematic

review

on

dry-land

strength

and

conditioning

training

on

swimming

performance

Effets

de

l’entraînement

de

force

à

sec

sur

le

performance

de

nage

:

une

revue

systématique

N.M.

Amaro

,

P.G.

Morouc

¸o

,

M.C.

Marques

,

N.

Batalha

,

H.

Neiva

,

D.A.

Marinho

a_{LifeQualityResearchCentre,PolytechnicInstituteofLeiria,RuaDr.JoãoSoares,2400-448Leiria,}

Portugal

b_{ResearchCenterinSportsSciences,HealthSciencesandHumanDevelopment,CIDESD,QuintadePrados,}

5001-801VilaReal,Portugal

c_{CentreforRapidandSustainableProductDevelopment,PolytechnicInstituteofLeiria,RuadePortugal,}

2430-028MarinhaGrande,Portugal

d_{UniversityofBeiraInterior,DepartmentofSportSciences,ConventodeSantoAntónio,6200-001Covilhã,}

Portugal

e_{UniversityofÉvora,R.ReguengosdeMonsaraz,n}◦_{14,7000-727Évora,Portugal}

Received16June2017;accepted8July2018

KEYWORDS Swimmers; Performance; Starts; Turns; Plyometric Summary

Objectives.—Theobjectiveofthisreviewwastoexaminetheeffectsofdry-landstrengthand conditioning(S&C)trainingonswimming,andstartsandturnsperformances.

News.—S&Ctrainingisacommonpracticeinswimmingaimingtoenhanceperformanceorto preventinjuries.However,studiesregardingtheeffectsofS&Conswimmingperformanceare scarce;theinfluenceofage,genderorcompetitivelevelisevenscarcer.

Prospectsandprojects.—After astructured literaturesearch,sixteenstudieswere included in the current review. Of those,seven did not report any positive or negative effects on swimming performance. Contrarily,moststudies withpositive effects wereconducted with olderswimmerswhereasmaximalstrengthwasthemosteffectivemethodologyforimproving swimmingperformance.S&Cplyometrictrainingissuggestedtobethemosteffectivemethodto

∗_{Correspondingauthor.CentreforRapidandSustainableProduct}

Development,PolytechnicInstituteofLeiria,RuadePortugal, 2430-028MarinhaGrande,Portugal.

E-mailaddress:pedro.morouco@ipleiria.pt(P.G.Morouc¸o).

https://doi.org/10.1016/j.scispo.2018.07.003

2 N.M.Amaroetal.

improvestartsandturns.FutureRandomizedControlledTrialsshouldbeconductedtoexplore theeffectsofS&Cinducedbyageandgender,ondifferentswimmingdistancesandtechniques, andlong-termtrainingeffects.

Conclusion.—ItisrecommendedthatS&Ctrainingshouldbebasedonmaximalstrength,ranging fromsixtotwelveweeksof2to4sessionsperweek(approximately24sessionsaltogether).In eachsession,coachesshouldvaryfrom2to3setsand3to5repetitions,accordingtoprescribed intensity.Restintervalsshouldrangebetween2to5minutesandtheintensityshouldbefrom80 to90%of1RM.Particularlyregardingimprovingstartsandturns,aS&Ctrainingregimeranging from6to8weeksandwith2sessionsperweekissuggested.Ineachsession,swimmersshould performbetween1and6setsand1and10repetitions,accordingtotheestablishedintensity. Restbetweensetsshouldrangefrom60to90seconds.Theswimmersintheincludedstudies aremostlymenwhichdonotallowtosayiftherecommendationsmadearegender-dependent. ©2018ElsevierMassonSAS.Allrightsreserved.

MOTSCLÉS Nageurs; Performance; Départs; Virages; Plyométrique Résumé

Objectifs.—L’objectifdecetterévisionaétéd’examinerleseffetsdel’entraînementdeforce àsecsurlesperformancesdenage,départsetvirages.

Actualités.—L’entraînementdeforceàsecestunepratiquecommuneennatationetapourbut d’augmenterlaperformanceoudeprévenirlesblessures.Pourtant,lesétudessurleseffetsde cetyped’entraînementsurlaperformancedenagerestentencorepeunombreux;l’influence del’âge,legenreouleniveaucompétitifsontdesquestionsencoremoinsabordées.

Perspectivesetprojets.— Àlasuited’unerecherchestructurée,quinzeétudesfurentincluses danscetterévision.Parmicelles-ci,septconcluaientl’absenced’effet,positifounégatif,sur la performancedenage.Enrevanche, encequiconcernelesétudes quimettentenavant leseffetspositifssurlaperformance,l’entraînementdeforcemaximumfûtlaméthodologie laplusperformante,pourlaplupart,chezlesnageurslesplusexpérimentés.L’entraînement plyométriqueapparaîtcommelaméthodologielaplusperformantepouraméliorerla perfor-mancedesdépartsetdesvirages.Lesétudesfuturesdevraientêtremenéespourexplorerles effetsdel’entraînementdeforceinduitsparl’âgeetlesexe,surlesdifférentesdistanceset techniquesdenatationetleseffetsd’entraînementàlongterme.

Conclusion.—Ilestconseilléquel’entraînementdeforceàsecreposesurlaforcemaximum, durantunepériodevariantentre6et12semainesavec2ou4sessionshebdomadaires.Pour chaquesession,lesentraîneursdoiventréaliserentre2ou3sériesetentre3ou5répétitionspar série,toutenrespectantl’intensitérequise.Lesintervallesderécupérationdoiventavoirune duréevariablequisesitueentre2et5minutes,tandisquel’intensitédevraientsesituerentre les80etles90%de1RM.Concernantl’améliorationdesdépartsetdesvirages,ilestsuggéréque l’entraînementdeforceàsecvarieentreles6etles8semainesavec2sessionshebdomadaires. Aucoursdechaquesession,lesnageurssonttenusderéaliserentre1et6sériesetentre1et 10répétionsparsérie,toutenrespectantl’intensitérequise.Lesintervallesderécupération doiventavoiruneduréevariablequisesitueentre60et90secondes.Lesnageursdesétudes contempléessontenmajoritédehommesauxquelsondéfenddediresilesrecommandations faitesvarientselonlesexe.

©2018ElsevierMassonSAS.Tousdroitsr´eserv´es.

1.

Introduction

Theabilitytoapplyforceinwateriscrucialincompetitive swimming[1—5],particularlyinshortdistancesevents[6,7]. Aswellashighvaluesofstrengthandpower,mostlyinthe upperbody,havebeenidentifiedasadeterminantfactorfor successincompetitiveswimming[8—10].Dry-landstrength andconditioning(S&C)trainingcanimproveswimming

per-formance[1,8,9,11—15],increasetetheredswimmingforce

[8,16] and technicalparameters such asincreased stroke length[11,14]andstroke rate[14].Therefore,S&C train-ingiscommoninswimmingprescription[17],beingdry-land

S&Canalternativetoin-waterprocedures,evenifits speci-ficityisquestioned[18].

Coaches have prescribed S&C training programs for

decades to enhance swimming performance and/or

pre-vent injuries [19—22]. Despite being a common practice,

some coaches assume that S&C training can negatively

affect the swimmer’s technical ability and consequently

increase drag forces [5]. This is mostly due to the

muscular hypertrophy and the decrease in flexibility

commonly associated with S&C training. Nevertheless,

several improvements were associated with S&C

andmuscular enduranceand optimizationof performance

[5,23].

Studiesexamining theeffectsofS&Conswimming per-formancehavebeenconductedoverthelast30years,butits overallimpactremainsinconclusive[16,18,24].Whilesome

oftheseinvestigationsshowedimprovements inswimming

startsandturns,and25m,50m,400mfreestyleswimming races[1,8,9,11—15],othersdidnot[10,16,18,24—27].The transferability of dry-land S&C gains to swimming

perfor-manceremainsunclearand itissuggested tobeacrucial

factorfortheabsentofpositiveresults.

ThesuccessofaS&Cprogramdependsonseveralfactors suchasthetypeoftraining,methods,materials,

periodiza-tion,andswimmers’maturationor competitivelevel.The

optimalcombination ofthesefactorsrequires clarification andfurtherinvestigation.Infact,fewstudieshavefocused

onyouthswimmers[1,9,10,13,16,26], perhapsbecauseof

ethicalissues [28]. Nevertheless, S&C and in waterpower

outputseemtohaveadeterminantinfluenceonyouth

swim-mers’performanceandshouldbepartoftheirtraining[29].

Hence, scientific researchhasnotreached aconsensus

onthemethodologiesandbenefitsofS&Ctrainingprograms inswimming.Thevariabilityofresearchdesigns(e.g.

proto-cols,outcomesselected,swimmingevents,andswimmers’

competitive level)makes itdifficult tocompare data and

cometopracticalconclusions.Therefore,thepurposeofthe presentstudywastoexaminepossibleeffectsofS&C train-ingonswimmingperformance,aswellasonstartsandturns

performances.Asystematicreviewwasdone,summarizing

evidencerelatedtotheeffectofS&Ctrainingonswimming

performance. We are awarethat the reduced number of

studiesconductedwithinthissubject,associatedtothelack of investigationswithboth sex, differentages,aswell as

moreswimmingtechniques anddistance couldbeanissue

toclearlystateahypothesis.Nevertheless,wehypothesized thatS&Ctrainingwillhelpswimmerstoimproveswimming velocityandstartsandturnsperformance.

2.

Methods

2.1. Literaturesearch

An extensive literature search was conducted to identify

studies fromJanuary1st,1985 untilDecember31st,2017

inwhichS&Ctrainingprogramseffectsonswimmingwere

investigated. This was done through computer searches

(ISIWebof Knowledge,PubMed,Scopusand SPORTDiscus)

using the keywords ‘‘swimming’’, ‘‘swimmer’’, ‘‘swim’’,

‘‘strength and conditioning’’, ‘‘strength’’, ‘‘strength

training’’, ‘‘weight training’’, ‘‘resistance’’, ‘‘dry-land’’, ‘‘performance’’and‘‘longitudinal’’,withmultiple combi-nations.Inaddition,thebibliographiesofthelocatedstudies wereextensivelysearchedandcross-referenced.Those arti-cleswithrestrictedfulltextonlinewerefoundinhardcopy forminlibraryarchives.

Studies selected for this review fulfilled the following selectioncriteria:

• thestudieswerewritteninEnglish;

• theywerepublishedinapeer-reviewedjournal;

• theycontainedresearchquestionsontheeffectsofS&C

trainingprogramsoncompetitiveswimming;

• themainoutcomereportedwasaperformancemeasure

(e.g.timeorvelocity);

• healthyhumanparticipantswereused.

Review articles (qualitative review, systematic review, andmeta-analysis)werenotconsidered.Theincluded stud-iesfocusedonlongitudinalinterventionsinS&Ctrainingon

competitiveswimming.Studiesbasedonotherpopulations

(e.g.paralympicswimmers)wereexcluded.Studiesthatdid notpresentacompletedescriptionoftheirmethodsand/or resultswereexcluded.

Ourinitialsearchidentified361studies.Afterreadingthe titlesandabstracts,sixteenarticleswerechosenforfurther analysis(Tables1and2).Ofthese,fourstudiesfocusedon theeffectsofS&Ctrainingprogramsinterventionsonstarts

andturnsperformanceandtwelvestudiesonoverall

swim-mingperformance.Thosethatwereclearlynotrelevantor

didnotmeetinclusioncriteriawereeliminated(Fig.1).

3.

Results

Tables 1 and2 show the purpose, sample characteristics, S&Ctrainingprogram,swimmingperformancemeasuredand

relevant findings. Several investigations showed

improve-mentsin25m[14],50m[1,11,14,15]and400m[8]freestyle swimmingperformance,instrokelength[11,14],instroke rate[14],instarts[9]andturns[13]performance.

Concerning samples, 8 in 16 studies did not randomly

allocate subjects to group [8,10,12,14,18,24—26]. Other

investigations did not include a control group [12,27].

Samples size ranged from 7 [1] to 38 subjects [26],

with the age of participants being around 16 years old

(16.4±3.1 years).Seven studies assessedadolescent

sub-jects [2,9,13—16,27], six studies were conducted with

young adults [8,11,12,18,24,25] and only three studies

assessed prepubescent swimmers [1,10,26]. In terms of

gender,onlyonestudyfocusedexclusivelyonfemale

swim-mers [24], while nine studies evaluated male swimmers

[1,9,12,14,16,18,24,25,27].Theremainingwereconducted

with mixed samples, coupling male and female subjects

[2,8,10,13,15]andonlyonecomparedthegendereffect[8].

The intervention programs varied between four and

twenty-four weeks, with six weeks being the most

cho-senlength(n=4).Thefrequencyofsessionsperweek was

between2 and4,and from30to60min per session.

Vol-umepersessionvariedbetween10and36repetitions.Sets variedfrom2 to3 sets persession. In studies using time insteadofnumberofrepetitions,thelengthofexercise exe-cutionvariedfrom10to120seconds,with2to6setsper session.Intensitywasexpressedasa%of1RM,rangingfrom

30to100% of1RM+1kg. Somestudies reportedan

inten-sityofexercisesfrom1to7kgwhileothersdidnotpresent intensitiesatall.

Weight lifting equipmentwasthe most common

mate-rialused[2,8,10—12,15,18,25,27].Freeweightswereused

inthreestudies[14,18,24]andbodyweightexerciseswere

usedinsevenstudies[1,2,9,10,12,13,15,26].Other materi-alssuchasmedicineball[1,10],ergometerbicycle[27]and ahydroisokineticergometer[16]werealsoused.

4 N.M.Amaroetal.

Table1 SummaryofthestudiesconcerningtheinfluenceofS&Cprogramsonswimmingperformance. References Sample Characteristics Dry-landS&C intervention Swimming performance Findingsinexperimental group

Manningetal.[27] Nationallevel( )

Experimentalgroup

(n=7,16.49±0.81

years)

Nocontrolgroup

Powertraining(weight

lifting)

9weeks(3

sessions/week)

2sets×highestrepsin

1min Weeks1—3:30%;weeks 4—6:40%;weeks7—9: 50%1RM 11exercises 50,100and200yard freestyle 50yardtime:−0.98s 100yardtime:_−0.06s 200yardtime:−1.30s Strass[14] Competitive swimmers (n=17 ;n=2 ) Experimentalgroup (n=10,16.6±1.2 years) Controlgroup(n=9, 17.8_±3.9years) Heavyexplosive

trainingwithfree

weights 6weeks(4 sessions/week) 3sets_×3repsat90% of1RM 2sets_×2repsat95% of1RM 1repat100%of1RM 1repattemptedat 100%of1RM+1kg Exercise:elbow extensions 25and50mfreestyle Strokerate Strokelength 25mv:1.83_±0.1to 1.91±0.1m.s−1** 50mv:1.77±0.08to 1.81±0.08m.s−1** 25m:55±4to 53.5_±3.4cycles.min−1* 50m:56.7±3.2to 54.7_±3.6cycles.min−1* 25m:2.01±0.24to 2.16±0.26m** 50m:1.88±0.1to 2.01±0.24m**

Tanakaetal.[18] Collegiatelevel( )

Experimentalgroup (n=12,19.17_±0.32 years) Controlgroup(n=12, 19.50±0.26years) Generalstrength

training(weightlifting

andfreeweights)

8weeks(3

sessions/week)

3sets×8to12reps

Exercises:dips,

chin-ups,latpull

downs,elbow

extensions,bentarm

flys 22.9mfreestyle 365.8mfreestyle Strokelength Novaluesreported Nodifferencesbetween

groupsforanymeasure

Trappe&Pearson[24] Collegiatelevel

( ;n=10,20.1±1.2

years)

Weightassisted

traininggroup—WAT

(n=5)

Freeweighttraining

group—FWT(n=5)

Generalstrength

training(weightlifting

andfreeweights)

6weeks(2

sessions/week)

WAT:1set_×noweight,

1set×13.6kg,1

set_×22.7kg(until

failure)

Exercises:dipsand

pull-ups

FWT:3

sets/exercise_×8—12

reps

Exercises:elbow

extensionandflexion,

latpulldowns,bent

armflys,quadriceps

extension,hamstring flexion 22.9mfreestyle 365.8mfreestyle Strokerate Strokelength Nodifferencesbetween

groupsforfreestyle

velocityin22.9mand

365.8m

Noobservedchangesin

strokerateandstroke

Table1(Continued) References Sample Characteristics Dry-landS&C intervention Swimming performance Findingsinexperimental group

Giroldetal.[2] Regional/national level (n=21;10 ,11 ) Strengthgroup:S (n=7,16.5±2.5 years) Assisted-sprintgroup (n=7) Controlgroup(n=7, 16.5±1.5years) Maximalstrength (weightlifting) 12weeks(2 sessions/week) Sgroup 3sets×6repsat80% to90%of1RM Exercises:press,

pull-up,drawwith

barbells,abdominal,

squatandplyometric

jumps 50mfreestyle Strokelength Strokerate Strokedepth 50mtime:−2.8±2.5%* 1.61_±0.11to 1.59±0.09m 48.9_±4.98to 50.7±3.71cycle.min−1 0.86±0.05to 0.83±0.05m*

Hong-SunSongetal.[12] Nationallevel( )

Experimentalgroup

(n=10;18.50±2.07

years)

Nocontrolgroup

Maximalstrengthand

power(weightlifting

andfreeweights)

1stcycle—18weeks(4 sessions/week):10 weeksmax. strength+8 weeks-power endurance 2ndcycle—20weeks (4sessions/week):12 weeksmax. strength+8 weeks-power endurance

Swimmingrecords 1stcycle:10personal

records,4Korean

records,2Asianrecords

2ndcycle:8personal

records,4Korean

records,2Asianrecords

Aspenesetal.[8] Competitivelevel

Experimentalgroup (n=11,6 ,5 ; 17.5±2.9years) Controlgroup(n=9,2 ,7 ;15.9±1.1 years) Maximalstrength (weightlifting) 11weeks(2 sessions/week)

3sets×5max.reps

Exercises:latpull

downs 50mfreestyle 100mfreestyle 400mfreestyle Strokelength Strokerate 50mv:1.73±0.12to 1.75±0.11m.s−1 100mv:1.59±0.1to 1.61±0.1m.s−1 400mv:1.38±0.16to 1.4±0.08m.s−1* 1.68_±0.17to 1.73±0.16m 0.953_±0.090to 0.930±0.074Hz

Garridoetal.[10] Competitivelevel

Experimentalgroup (n=12,8 ,4 ; 12.0_±0.78years) Controlgroup(n=11, 6 ,5 ; 12.18±0.75)

Powerandgeneral

strength Weightlifting 8weeks(2 sessions/week) 2—3sets_×6—8repsat 50to75%of6RM Exercises:leg extension;CMJ;CMJto

box;medicineball

throws(1kg);bench press 25mfreestyle 50mfreestyle 25mv:6.95%m.s−1** 50mv:4.77%m.s−1** Controlgroup 25mv:6.44%m.s−1* 50mv:3.16%m.s−1*

Giroldetal.[11] Nationallevel

Strength(S)group (n=8,4 ,4 ; 21.1±1.4years) Controlgroup(n=8,4 ,4 ;24.2±4.6 years) Maximalstrength (weightlifting) 4weeks(3 sessions/week) 3sets×6repsat80to 90%of1RM

Exercises:pull-ups;lat

pulldowns;drawswith

pulleys 50mfreestyle Strokelength Strokerate 50mv:2_±1.3%* 2.05±0.01to 2.11_±0.01m* 54.7±4.1to 55.9±2.7cycle·min−1

6 N.M.Amaroetal. Table1(Continued) References Sample Characteristics Dry-landS&C intervention Swimming performance Findingsinexperimental group

Sadowskietal.[16] Competitivelevel( )

Experimentalgroup

(n=14;14.0±0.5

years)

Controlgroup(n=12;

14.1±0.5years)

Power(hydroisokinetic

ergometer) 6weeks(3 sessions/week) 6sets×50secondsof work Exercises:hydro isokineticergometer 25mfreestyle Strokelength Strokerate 25mv:1.3% Performance:5.98% Performance:−4.3%

Westonetal.[15] Nationallevel

Experimentalgroup (n=10,5 ,5 ; 15.7±1.2years) Controlgroup(n=10, 5 ,5 ;16.7±0.9 years) Generalstrength 12weeks(3 session/week) 2—3 sets×30—120seconds hold 10—30 repetitions×3—7kg load Exercises:prone

bridge;sidebridge;

birddog;legraise;

overheadsquat;sit

twist;shoulderpress

50mfreestyle 50mtime:_−2.0%;4.2to

1.1

90%confidenceinterval

Amaroetal.[1] Nationallevel( )

Sets/repsgroup(Gr1) (n=7,12.7_±0.8 years) Sets/timegroup(Gr2) (n=7,12.7±0.8 years) Controlgroup (n=7.12.6±0.8 years) Power 6weeks(2 session/week) Gr1:3sets×6—18reps Gr2:3 sets×10—25seconds Exercises:medicine

ballthrowdown(1kg);

CMJtobox(30cm); dumbbellflys(1.5kg); Russiantwist(3kg); push-ups 50mfreestyle 50mtime:33.43±2.83 to1.65±2.53s*** ␩␳2=0.616

:male; :female;v:velocity;max:maximal;CMJ:countermovementjump;_␩␳2_:effectsize. * _{IndicatesP<0.05.}

**_{IndicatesP<0.01.} *** _P<0.001.

TheseS&Cprogramswereimplementedandtheireffects onswimmingweretestedbyanalyzing25yards[18,24],25m

[10,13,14,16],50yard[27],50m[1,2,8,10,11,13—15],100 yard [27], 100m [8], 200yard [27],400 yard [18,24]and 400m [8,13] freestyle(front-crawl stroke) swimming

per-formances.Onlyoneinvestigationanalyzed theeffectson

otherswimmingtechniques[12](Tables1and2).

4.

Discussion

4.1. EffectsofS&Conswimmingperformance

accordingtoage

Most investigations until now have been conducted with

adolescentsandyoung adults.Infact,only two

investiga-tions[1,10]focusedonprepubescentswimmers.Themost

recent studyreportedimprovementsof 2.21%inthe50 m

front-crawl swimmingtime (*).Instead, noimprovements

werefoundinthepreviousstudy[10]beingreportedsimilar

improvements in swimmingvelocitygains between

exper-imental and control group (4.8 vs. 3.2%, respectively).

The lack of studies may be due to financial and ethical

issues [29] or the assumption by coaches that technical

trainingismoreimportantthanS&Ctraining[8,10,28,30].

Coaches usually assume that muscular hypertrophy and

consequent decreases in flexibility may affect the

swim-mer’s ability and increase drag forces [5]. Nevertheless,

during theprepubescentstage,muscle hypertrophyis not

believed to be the primary factor in strength

improve-ment [31], with neuromuscular adaptations identified as

the main explanation for strength gains [32,33]. It is

indeedrecommendedthatyoung athletesengagein

Table2 SummaryofthestudiesconcerningtheinfluenceofS&Cprogramsonswimmingperformance(startsandturns). References Sample Characteristics Dry-landS&C intervention Swimming performance Findingsin experimental group Cossoretal.[26] Competitivelevel

( ) (n=38;11.7_±1.16 years) Experimental group Controlgroup (n=19) Plyometric 20weeks(3 sessions/week) 2sets×10—15 reps 15exercises(not described) 2.5mroundtrip 5mroundtrip 50mfreestyle 2.5mtime: 3.58±0.39to 3.32_±0.42s 5mtime: 7.45±0.72to 6.94±0.67s 50mtime: 38.46_±3.36to 37.51±2.9 Nodifferences betweengroups

foranymeasure

Breed&Young[25] Non-competitive

( ) n=23;18.9years (s=1.5) Experimental group(n=12) Controlgroup (n=11) Generalstrength

andpower(weight

lifting) 9weeks(3 sessions/week) 2—5sets×4—10 repsof 5RM—10RM 14exercises Flightdistance Take-offvelocity Take-offangle Totalhorizontal Imp HorizontalImpof hands Noimprovements TS:3.42±0.3to 3.48±0.3m.s−1* TS:−13.3±7.4to −10.1±5.6** TS:198±35.2to 221_±39.0N.s* TS:65.6±32.7to 94.0±41.2N.s**

Bishopetal.[9] Competitivelevel

Experimental group(n=11; 13.1±1.4years) Controlgroup (n=11;12.6±1.9 years) Plyometric 8weeks(2 sessions/week) 1—4sets×1—5 reps Intensity:low(3 weeks);medium (3weeks);high(2 weeks) 19exercises

Angleoutofblock

Distancetohead

contact

SwimBlockStart

velocity Timetohead contact Angleofentry Timeto5.5m 26.7±7.10to 34.5±6.43*** 1.70_±0.19to 1.83±0.19m*** 1.29_±0.18to 1.48±0.15m.s−1*** 1.32±0.09to 1.24±0.06s* 42.3±7.33to 47.5±3.95* 3.88±0.48to 3.29_±0.47s***

Potdevinetal.[13] Competitive

swimmers Experimental group(n=12,5 , 7 ;14.3±0.2 years) Controlgroup (n=11,5 ,6 ; 14.1_±0.2years) Plyometric 6weeks(2 sessions/week) 1—6sets×1—10 reps Intensity:height jumpfrom0.21to 1m 15exercises Glidingvelocity Gliding acceleration 50mfreestyle 400mfreestyle 2.28±0.19to 2.41_±0m.s−1* ␩␳2=0.26 6.80±1.12to 4.81±0.90m.s−2** ␩␳2=1.99 1.29_±0.15to 1.25±0.18m.s−1* ␩␳2=0.1 0.96±0.09to 0.92_±0.10m.s−1* ␩␳2=0.15

:male; :female;CMJ:countermovementjump;Imp:impulse;TS:trackstart;␩_␳2:effectsize. * _{IndicatesP<0.05.}

** _{IndicatesP<0.01.} *** _P<0.001.

performance, but also to prevent sports-related injuries

[32,33].

Studies conducted with adolescent swimmers showed

that the effects of S&C training may not be as clear as

thought. Positive effects were reported in four studies

[2,14,15,27] and no influence was reported in one study

[16]. Within the adolescent age group,caution must

pre-vailwhenanalyzingresults.Biologicalmaturityisrelatedto

chronologicalage,andhasamajorimpactonthephysical

8 N.M.Amaroetal.

Figure1 Flowofinformationthroughthedifferentphasesof

paperselectionforthesystematicreview.

performance may be influenced not only by training but

alsobygrowthandmaturation[35],whichcancause

mor-phological and neural changes [36]. Maturity status was

notprovidedintheaforementionedinvestigations.

There-fore,with subjects ranging from13 to19 years old,and

morphologicalcharacteristics beingconsidered one ofthe

mainreasonsforthedifferencesinenergeticprofilesafter puberty[37],theresultsmaynotbeasclearasexpected.

Three studies conducted withswimmers after puberty

reported positive effects [8,11,12] and no effects were

reportedintwootherstudies[18,24].Inbothinvestigations

wherenopositiveeffectwasreported,theswimmers

com-petedincollegiate teams.The lowercompetitive levelof

theseswimmerscouldinfluencetheresults,sincethe ener-geticandbiomechanicalprofilesofswimmersweredifferent

[28].Swimmingperformancedependsonthegood

relation-shipbetweenbioenergeticsandbiomechanicalparameters

[38].Thus,thetransferabilityofdry-landstrengthgainsto

swimmingperformancecoulddependontheinteractionof

severalparameterssuchasstrength(dry-landandin-water) andbiomechanics(kinematicsandkinetic)[38],determined bycompetitivelevel.

Investigationshave,sofar, focusedonadolescenceand

early adulthood. Investigations with age group swimmers

must be conducted as a means of potentially enhancing

swimmingperformancenotonlyintheshortterm,butalso

inthelong-term,andatdifferentcompetitivelevels.

4.2. EffectsofS&Conswimmingperformance

accordingtogender

Asit occurswithcompetitivelevel, differencesin

muscu-larstrengthandanthropometricsemergebetweengenders,

particularly after puberty [37,39,40]. However, there are

few studies with samples separated according to gender.

Results with mixed samples (male and female) must be

analyzedwithextracautionduetoapossiblegendereffect.

Even thoughduringprepubescencestrengthimprovements

are quite similar between boys and girls [33], after this

period boys have a tendency to exhibit higher muscle

strengthlevelsthangirls[41,42].Thus,couplingdatafrom bothsexesinresearchfocused onS&Cmaybemisleading. Withintheanalyzedstudies,onlyonestudypresented

sep-aratedresultsbetweenfemalesandthewholegroup(male

plusfemale)[8].However,7outof9subjectswerefemale inthecontrolgroupand5outof11subjectswerefemalein theinterventiongroup,whichmayhaveledtoheterogeneity betweengroups.Forinstance,theauthorsreporteda signif-icantcorrelation(r=−0.975,P<0.01)betweenstrengthand

400mswimmingperformancein thefemalegroupbutnot

in thewholegroupresults. The authorsalsoreported

sig-nificant improvement in tetheredswimmingforce inboth

thefemalegroupandthewholegroup.Ontheotherhand,

in terms of swimmingperformance,only thewhole group

experiencedsignificantimprovementsinthe400mfreestyle

(−4 s mean). In adulthood differences in swimming

per-formance between genders tend tobe greater over short

distancesandlessoverhigherdistances[18].Additionally, throughhavingmorefatmassthanmales,femalescanadopt

abetterbodyposition,therebyincreasingswimming

econ-omy [37]. By contrast, the remaining investigations with

mixedsamplesdidnotpresentseparatedresults,whichmay

leadtomisleadingresults.Yet,improvementsinswimming

timewerereportedinthe50m[2,11,15].Whereasno

sig-nificant differences between sexes were reported in two

investigations[2,11],Westonetal.[15]attemptedto

bal-ancegroups bysex(5malesand5females).However,the

results of the latterpaper werecoupled andso agender

effect could not be determined. The only study that did

not reportpositive effectswasconducted withage group

swimmers[10],wheredifferencesinswimmingperformance

betweenthesexesdonotexistortendtobenon-relevant.

Nevertheless, thestudy ofheterogeneousgroups in

inves-tigationsofswimmingperformancecanleadtoambiguous

conclusions[43,44].

Mostof thesestudies were conducted withexclusively

malesamples [12,14,16,18,24,28]. Of thosealready

men-tioned, only two reported improvements in swimming

performance [12,14]. On the other hand, there were no

investigationsconductedwithanexclusivelyfemalesample uptothedate.Thus,furtherinvestigationswithseparated samplesmustbeconductedinordertodrawconclusionsona possiblegendereffect.Yet,theavailableliteraturesuggests

atendencyforswimmingperformancetoimprovein

inves-tigationsontheeffectsofS&Ctrainingonmixedsamples. Additionally,itisalsocrucialtocrosscompareinformation withageandconsequentlywiththetheoreticalmaturational

developmentofswimmers.

4.3. EffectsofS&Conswimmingperformance

accordingtotrainingprotocol

Maximal strength training is the most regularly applied

methodology in S&C training programs. Furthermore, all

investigations that have used maximal strength reported

improvements of between 2 and 4% in swimming

SixweeksofS&Ctrainingwith4sessionsperweekusing intensitiesfrom90to100%of1RMshowedgainsofbetween 20and40%ofdry-landmuscularstrength[14].These mea-surementsoccurredinisometricconditionsthatmaynotbe

relatedtoswimmingactions.Swimmingactionsaredynamic

and isometric testing may therefore represent a lack of

specificity [45]. Nonetheless, dry-land muscular strength

gainsallowedsignificantimprovementsinswimming

perfor-manceover25and50m(4.4and2.1%,respectively).Inthis

investigation, only the upper bodywas exercised through

elbow extension exercises and the use of free weights

throughmaximalstrength S&Cmethodologies.Weight

lift-ing equipment was used in the remaining investigations

[2,8,11,12].

S&Ctraining(S)basedonmaximalstrengthwasapplied

for twelve weeks (2 sessions per week) and compared

to resisted and assisted-sprint (RAS) training [11]. These

authors found improvements in the 50m time of the S

(2.8±2.5%) and RAS (2.3±1.3%)groups comparedto the

controlgroup(0.9±1.2%).Improvementsinmusclestrength weremoresignificantintheSgroupthanintheRASgroup. Incontrast,theRASgrouppresentedanincreaseinstroke rateintheir50mfreestyleperformance.Itwassuggested thattheapplicationofSorRAStrainingwasmoreeffective thanswimmingtrainingalone.Theseresultswerethen cor-roboratedbyother researchers[8,11].Afterelevenweeks (2sessionsperweek)ofcombiningmaximalstrength

train-ing and high intensity interval swimming training (HIIT)

the results were positive in strength, tethered swimming

force and 400m freestyle performance [8]. However, no

improvementsoccurredinshortdistanceperformance(50m

or 100m) and biomechanical variables(stroke length and

stroke rate). Withthe ability to exert force in the water adecisivefactorovershortdistances[6,7,17],itwouldbe of greatimportancetoclarify the lack of effectin sprint distances.Moreover,thepositiveeffectsontethered

swim-ming and 400m freestyle were correlated in the female

subjectsoftheinterventiongroup.Theseresultsappeared tosuggestthatin-waterforceexertionmaybeimportantin

middleswimmingdistancesforfemaleswimmers.However,

it wasnot determinedifthe positiveeffectsin swimming

performancewerearesultofthecombinedmethodologies

or ifa crossoverbetweenHIIT andS&Csessionsoccurred. HIITsessionswerecomposedof 4×4minof highintensity intervaltraining.Theseeffortsanddurationsmaybebetter

associatedwiththe400mimprovements.

AninvestigationcomparedtheeffectsofaS&Cprogram (S)withthoseofanelectricalstimulation(ES)program,both

combinedwitha swimmingprogram,over four weeks,on

adultswimmers[11].Additionally,theauthorstriedtoverify iftrainingeffectslastedfourweeksafterthetrainingperiod ended.The S&Ctrainingsessionswereperformed 3 times

per week. The authors reported an increase in swimming

velocityforbothSandESgroup(2%and1.7%,respectively), attheendofthefour-weekintervention.Strokelengthwas

increasedonlyfortheSgroup.Improvementsinswimming

velocityweremaintainedfourweeksafterthe endof the

program inboth groups andnodifferences werereported

between male and female swimmers.It seems that both

methodsweremoreefficientinimprovingswimmingvelocity

thanswimmingtrainingalone.However,electrical

stimula-tiondemandsahigherinvestmentfrommostswimmingclubs

thana S&Cprogram. Yet,thisinvestigation only analyzed sprintperformance(50mfreestyle)inhigh-levelswimmers.

Furtherinvestigationsmustbeconductedwithmiddleand

longswimmingdistancesaswellaswithswimmersoperating atdifferentcompetitivelevelsandwithvaryingamountsof

swimmingexpertise.

Interestingly,onlyfourweeksand12sessions(18 repeti-tionspersession)weresufficienttoverifyapositiveeffect inswimmingperformance.Thisvolumewasclearlylessthan thatreportedbyotherstudies:24sessionswith15 repeti-tionsper session [14],24 sessionswith18 repetitionsper session[2],22sessionsand15 repetitionspersession[8], and72sessionsinthefirstcycleofS&Ctrainingand80 ses-sionsinthesecondcycle[12].Thismayindicatethatlower volumesandhighintensityS&Ctrainingmayinduceless

neu-romuscularfatigueandthereforeimprovements,leadingto

subsequentimprovedswimmingperformance.

S&C training for a national team of male swimmers

(18.50±2.07 years) was divided into two cycles applied

accordingto theperiodizationof their main competitions

(JuneandDecember)[12].The firstcycle lastedeighteen

weeks with 4 sessions per week, emphasizing peak

mus-cle strength, power and muscle endurance maintenance.

The second cycle lasted for twenty weeks with 4

ses-sions per week of maximal strength, power and muscle

endurance maintenance. Although several dry-land tests

were performed, no swimming tests were performed to

assesseffectivenessofthisS&Ctrainingprogram.Yet,the authorsreported18personalrecords,8Koreanrecordsand

3 Asian records in those two main competitions.

Never-theless, therewas nostatistical analysis of the influence

of the S&C trainingon swimming performance and there

wasno control group. Authors concluded that S&C

train-ing program enhanced muscular functions and swimming

performance, nevertheless with a significant decrease in

flexibility. Although thiswas the investigation carriedout

over the largest number of weeks, the lack of swimming

tests, some dubious procedures and reports

(contradic-tory information on the number of subjects and weeks

throughout the text)necessitates caution when analyzing

itsconclusions.

Itiscommontousethe1RMmethodologytodefinethe

external load of exercises. However, when analyzing the

influenceof S&Ctrainingin shortdistances,where power iscrucial[6,7,46,47],itisquestionablewhether1RMisthe forceparameterwiththehigherassociationwithpower.For

instance,thevelocitywithwhich exercisesareperformed

atis crucial toincreasingthe specificityof S&C exercises

[48]andoverallpoweroutput.S&Ctrainingbasedonpower (generationofforce overaveryshortperiodoftime)was appliedinthreeinvestigations[10,16,27].However,no

posi-tiveeffectsinswimmingperformancewerereportedbyany

of thoseinvestigations. A S&C training program based on

speedandexplosiveness(power)wasappliedtoadolescent

swimmers(16.49±0.84 years) [26]. Each training session

consisted of 11 exercises (upper and lower body

exerci-tation), performed in 2 sets of the maximum number of

repetitionsduringoneminute.Thiswasperformed3times

aweekovernineweeks,usingweightliftingequipmentand anergometerbicycle.Intensitiesvariedfrom30to50%of

1RMwithaprogressiveincreaseof10%everythreeweeks.

10 N.M.Amaroetal. presentedimprovementsof−0.98s,−0.06sand−1.30sfor

the50,100and200yardtests,respectively.Inswimming,

thesesmallimprovementscanberemarkable,particularly

inshortswimmingdistances.

AS&Cprogramofcircuittrainingoversixweeks(3 ses-sionsperweek),comprising6setsof50sexercitationand 10sofrestonaspecifichydroisokineticergometerdevice eachsession,ledtoimprovedtetheredswimmingpropelling forcebutnotdifferentvaluesof dry-landstrength,stroke

kinematicsand swimming performance (25m front-crawl)

[16].Inspiteoftheefforttomimicunderwatermovement, itwasconcludedthatS&Ctrainingwasnotspecificenough toimproveswimmingperformance.Isokineticconditionsare

not related to in-water actions that are performed with

differentvelocitiesalongthestroke.Itis crucialthatS&C exercisesandtestsstimulatethemusclesusedinswimming

andthatmuscletensionberelatedtoin-water conditions

[19].Inaddition,only3 swimmerswere sprinters(n=26),

whichcouldhaveinfluencedtheresults,asswimming

per-formancewasmeasuredina25mfront-crawltest.

Another study on power training program was applied

on prepubescent swimmers and combined dry-land S&C

training and aerobic swimming training [10]. The

swim-mingtraining programwas complementedwith2 sessions

perweek of S&Ctraining(bench pressand legextension,

medicineball throwing with1kg, countermovementjump

alone and with a 30cm box) over eight weeks. Although

dry-land improvements were reported, no swimming

per-formanceimprovement wasfound. The authorssuggested

thatswimmers’competitivelevelcouldaffectperformance

improvements.Yet,a detrainingperiod(S&Ctraining

ces-sationandmaintenanceofswimmingtraining)ofsixweeks

showedthat,although strength parametersremained

sta-ble,swimmingperformancestillimproved.Itisreasonable

towonderifswimmersbenefitfroman adaptionperiodto

S&C gains, while performing swimming training. The

lit-erature showed that there was norisk of losing strength

and power during shortcessation periods of a S&C

train-ingprogram[49,50],andtheeffectonmaximalpowerwas

smaller thanthat observed for maximal force [51]. So,it

seemsreasonabletoinvestigate whetherspecificin-water

trainingcanbeusefulintakingeffectiveadvantageofS&C

program improvements, after cessation [10]. This

contin-uous stimulation could be the bridge between S&C gains

and swimming performance. In fact, a recent study with

prepubescent swimmers [1] found improvements in 50 m

front-crawl swimming time only 4-week after the end of

S&Ctrainingprogram.Authorsaddeda 6-weekS&C

train-ingprogramtothenormalswimmingtrainingprogram.The

programconsistedon2sessionsperweekofS&C(medicine

ballthrowdown—1kg;CMJtobox—30cm;dumbbellFlys

—1.5kg;Russiantwist—3kg;push-ups)withtwodifferent

methodologies.Onegroupperformedexercisesfollowinga

set/repetitionmethodologywithnorestrictionsonthetime

of execution. The other experimental group followed an

explosivenessmethodology,wheresubjectshadtoperform

asmanyrepetitionsastheycouldinaspecifictime.Although

dry-land improvements were found for both groups, no

swimmingimprovements werereportedat theendofS&C

trainingprogram(6-week). However,authors alloweda

4-weekadaptationperiod,whereswimmershadtheirnormal

swimmingtrainingonly.Afterthisperiod,onlythegroupthat

performedtheS&Ctrainingprogrambasedonexplosiveness

presenteda2.21%improvementin50mswimmingtime.This

factmayreinforcetheimportanceofallowingswimmersto

adapt tonew dry-land strength improvements.

Neverthe-less,furtherinvestigationswithdifferentages,competitive levelsandpost-evaluationperiodizationmustbeconducted toclarifythisissue.

Finally,three studies basedtheir investigationson dif-ferentprotocolsfromthosealreadydiscussed.S&Ctraining

with weight lifting equipment and free weights was

con-ductedover eightweeks (3sessionsper week) [18].Even

though volumeper sessionwas presented(3 setsof 8—12

repetitions),intensitywasnot.Theauthorsonlyreportedan

incrementof25—35%intheresistanceusedovertheeight

weeks ofS&C. There werenoimprovements in swimming

performanceaftertheS&Ctrainingperiod,possiblydueto theoverloadofacycleofcompetitionsduringtheS&C train-ing.Thepotentiallackofcontroloftheloadandswimming

competitionscouldhavejeopardizedresults.However,the

authorsconcludedthatthelackofspecificityofS&C train-inginrelationtoin-wateractions(swimming)wasthemain reasonfortheabsenceofpositivetransferabilityofstrength

gains. These results were latercorroborated [24]through

thecomparisonof S&Cweightassisted training(WAT)and S&Cfreeweightstraining(FWT).Theinvestigationwas car-riedoutoversixweeks(2sessionsperweek).Ineverysession bothgroupswereinstructedtoreachvolitionalfatigue(WAT) andexhaustion(FWT).Nodifferencesinshort(22.9m)and

medium (365.8m) distance swimming performance were

foundbetweenexperimentalgroups.However,resultsfrom

this study may bemisleading, since therewasno control

groupandgroupswerecomposedofonlyasmallnumberof

swimmers(5ineachgroup).Inaddition,S&Ctrainingwas

implementedoversixweeksoutofatotaloftwelveweeks

follow-up,andtheevaluationwasperformedinweeks4and 12.Theseconfoundingfactorsdidnotallowforaconsistent interpretationofresults.

Recently,aninvestigationtriedtoquantifytheeffectsof anisolatedcore-trainingprogramon50mfront-crawl[15].

A S&C program was implemented 3 times per week over

twelveweeksandincludedexerciseswhichaimedtowork

outthelumbopelviccomplexandupperregionextendingto

thescapula.Eachsessioncomprisedisometric(pronebridge

and side bridge) and dynamic (bird dog; leg raise;

over-head squat;sittwist andshoulder press) exercises. Every

two weeks, volumeper session wasincreased and varied

between60sto360shold;30to90repetitionsand3to7kg ofload.Alargebeneficialeffecton50mswimtime(−2.0%;

90%Confidenceinterval−3.8to−0.2%)wasfoundafterthe

trainingperiod.Good core stabilityis supposed tohave a positiveinfluenceontheefficientrelationshipofforce pro-ductionbetweenupperandlowerlimbs[52].Aquestionto beraisedreliesontheisometricconditionsofmostincluded exercises in S&C training. Swimming actions are dynamic

andsoitwasexpectedthatswimmingspecificitycouldbe

negatively affected.To the bestofour knowledge,this is thefirstinvestigationontheeffectsofS&Ccoretrainingon

swimmingperformanceandfurtherinvestigationisneeded.

In a brief analysis, it seems that maximal strength is

themosteffectivemethodologyforimprovingperformance,

mainly in shortdistances. However, different low-volume

adolescent swimmers, S&C training ranging from six to

twelveweeksandwith2 to4 (approximately 24sessions)

sessionsperweek,issuggestedtoimproveswimming perfor-mance.Inadulthoodandatahighcompetitivelevel,aS&C trainingprogramoffourweeks(3sessionsperweek)is

sug-gestedtoimproveswimmingperformance.Ineachsession,

thevolumeshouldvaryfrom2to3setsof3to5repetitions, according to the chosen level of intensity. Rest intervals

shouldvarybetween2to5minutes.Concerningthe

inten-sities,high velocitiesandloadsranging from80to90%of

1RMareassociatedwithimprovements.Nevertheless,there

shouldbecautionwhenapplyingS&Cprogramsnear compe-titionsoroverhighvolumesofswimmingtraining,inorder toavoid overreachingand overuseinjuries. S&C basedon maximalstrengthrequiresadjustmentsinswimmingtoavoid

overloading of the peripheral and centralfatigue

mecha-nism[53].Mostofthestudiesreportingimprovementsused

weight lifting equipment that may not be affordable for

many swimming clubs due to financial constraints. With

regardtoprepubescentswimmers,therewerecontradictory

resultsregardingeffects inswimmingperformance

associ-atedwithS&Ctrainingprograms.Nevertheless,S&Ctraining

basedonexplosivenessreportedimprovementsinswimming

performanceinthisagegroup.However,conclusionsarenot

easytodrawasmanyconfoundingfactorsseemtoexistin

theavailableinvestigations.

4.4. EffectsofS&Constartsandturns

performance

Startsandturnsareexplosiveactionsusuallyassociatedby

coachesandswimmerswiththestrengthoftheswimmeror

todry-landS&C training,despitethe scarcityofscientific evidence.Theseactionsinswimmingrequirehighvaluesof power output [54,55]. Therefore, explosiveness is usually thoughtofasthemainaimofS&Ctrainingandsupportsthe greateruseofplyometricS&Ctraining.Infact,threeofthe fourinvestigationsanalyzedtheuseofplyometrictraining toimprovestartsandturnsperformance[9,13,26].Positive effectsofplyometrictrainingwerereportedintwostudies

[9,13],whilethethirddidnotfindapositiveresult[26].

A study examined the effects of a plyometric training

programonfreestyletumbleturns,inagegroupmale

swim-mers[26].Thesubjectsperformedfrom300to450ground

contactspersession,3timesperweek,overtwentyweeks.

Therewerenosignificantdifferencesbetweenexperimental

andcontrolgroups,foranymeasure.Despitetheadoption

oflowtomoderateintensities,onecanassumethat

over-loadmayhaveimpairedresults.Moreover,thecontrolgroup

performed90minutesofswimmingtrainingandthe

exper-imentalgroupperformed75minutes,adding15minutesof

S&Ctraining.Althoughtherewerenosignificantdifferences betweentheexperimentalandcontrolgroup,inmostofthe parametersassessed,improvements(%)inthecontrolgroup

werehigherthanthoseintheplyometricgroup.Moreover,

nodifferencesinturningperformancewerefoundbetween

swimmerswho attendedfewer S&Csessions (<49%) when comparedtothosewhoattendedmoreS&Csessions(>75%). Thisraisesquestionsovertheefficiencyofaplyometric

pro-gram,in early ages,andindicates thatswimmingtraining

seemstobeenoughtoimprovefreestyleturns.Moreover,

the authors claimed that some maturational and growth

changes could positively influence performance [35,36],

ratherthanplyometrictraining.

Plyometrictrainingprogramwasalsotestedwithregard to starts, showing some positive results [9,13]. First, an

investigation aimed to identify the effect of plyometric

training,whenaddedtohabitualtrainingregimes,onswim startperformance[9].Significantimprovementswerefound betweenbaselineandpost-evaluationsforplyometric

train-inggroupwhencomparedtothecontrolgroup,inthetime

taken to reach 5.5m (−0.59 s vs. −0.21 s; P<0.01) and velocityof take-offtowatercontact(0.19ms−1vs. −0.07 ms−1; P<0.01). These results can be determinant for a

raceperformance;however,thereshouldbesomecaution

inassessing these effectsas noinformationwasprovided

regarding maturation level or even the sample’s gender.

Thelatterinvestigationmentioned[27]corroboratedthese positiveresults[9],presentingeffectsofthematurational

status (Tanner stages of 3 and 4) and finding no

differ-encesbetweengroups.Investigationswerecarriedoutover

eight [9] and eleven [27] weeks, with total volume per

sessionhigherinthemostrecentone[27].Both investiga-tionsincreasedtheintensityfromlowtohigh,increasedthe height,from0.22to0.79m[9],andfrom0.21to1m[27],

andincreasedthenumberofjumpspersessionfrom37to

192[9],andfrom100to264[27].

Improvementsreportedinthe50and400mfront-crawl

velocity [27], suggest a positive influence on starts and

turnswithin overall swimming performance. This positive

influencewas, accordingtothe authors,explainedbythe

significantcorrelationbetweenimprovementsinSquatJump

(SJ)andvelocityin50mfront-crawl.AsSJmechanicaland

muscular requirements are similarto thoseof starts, the

authorsconcludedthat improvements in swimming

veloc-itywereduetothisphaseoftherace.Despitethisideaof ‘‘transferability’’,therewere nospecificresultsonstarts andturnsoftheswimmers.

Onlyonestudyonstartswasfocusedonpowerand

gen-eralstrengthtraining[25].Thegoalwastoimprovevertical

jump ability, on the grab, swing and rear-weighted track

startsinswimming.Forthatpurpose,16exerciseswere

per-formedovernineweeks.Verticaljumpwasemphasized,as

wellasupperandlowerbodystrengthandpower

mainte-nance.The training program consisted of higher volumes

andintensities in the firstand third sessionsof the week

(3sessionsperweek).Adjustmentsweremadeeverythree

weeks,increasingvolumeandintensityonthefirstandthird

sessionanddecreasingonthesecondsessionoftheweek,

untilnineweeks oftraining werecompleted. Despite

sig-nificantimprovementsindry-landstrength(legpowerand

jumpingability),nosignificantimprovementswerefoundfor flightdistancewhenusinganystarttechnique.Theauthors

suggested thatimprovements in jumping ability werenot

transferredtodivingskills.Informationontheperiodization

of different moments of this investigation was not

pro-vided.Itwouldbeofinteresttoknowwhethertheteaching periodofstartsorthestartstrainingwereconcurrentornot tothe S&Cprogram.Nevertheless, theconclusions ofthis

investigationmustbeanalyzedwithcautionasthesample

comprisednon-swimmersubjects.

SummarizingtheevidenceofS&Ctrainingonstartsand turns,wecouldconcludethatplyometrictrainingisthemost

12 N.M.Amaroetal. effectiveinimproving startsandturns.S&Ctraining

rang-ingfromsix toeightweeks andwith2 sessionsper week

issuggestedtoimproveperformance.In eachsession

sub-jectsareallowedtoperformbetween1to6setsand1to

10repetitions, accordingtothe chosen level of intensity.

Restbetweensetsshouldvaryfrom60to90seconds.This

trainingprogram should be progressive,starting withlow

volumesandintensitiestoallowswimmerstoadaptto ply-ometrictrainingspecificities.Moreover,exercisesshouldbe performedinassimilarawayaspossibletoin-water move-ments.ItwouldbeofinteresttoanalyzeS&Ceffectsinolder andmoreskilledswimmers.TransferabilityofS&Cgainsto

swimmingperformanceremainscontroversial.Therefore,it

wouldbeofinteresttocompareplyometrictrainingtoother methodsofS&Ctraining,andthusanalyzetheefficiencyof differentmethods.

5.

Conclusion

S&C training in swimming is a common practice used by

coachesandswimmerstoenhanceperformanceandto

pre-ventinjuries. Nevertheless, there is no consensus onthe

effectivenessofS&Cprogramsonswimmingperformance.

Some limitations were found in the literature regarding

thisissue.Mostinvestigationsinvolvedadolescentandadult

swimmers,andS&Cprogramswithprepubescentswimmers

arescarce anddonotallowfor validconclusions.Younger swimmersshouldparticipateinS&Cprograms,notonlyto

enhance performancebut alsotobuild a solidfoundation

forpreventingsports-relatedinjuries.Moreover,fewstudies

separatedthesamplesandcomparedthegendereffect,and

thosethatdid,gavenoclearresults.Withregardtothetype ofS&Ctraining,maximalstrengthtrainingisassociatedwith

swimmingperformanceimprovements in the oldest

swim-mers,particularlyinrelationtoshortdistance(25and50m) races.However,itis questionablewhether thisis an

ade-quatemethodologytoapplytoyoungerswimmersandthose

atalowercompetitivelevel.Weightliftingequipmentisthe

mostused trainingtool in research,nonetheless we must

beawarethat most swimmingclubs maynot have access

totheseresources. Additionally,young swimmersmaynot

havetheexpertiseandexperiencetousethisequipment.

The influence offorce exertion cannotbedetermined,

astherewerefewinvestigationsanalyzingtechniquesother thanfreestyle.Likewise,theinfluenceofS&Cinswimming

distancesabove200mwasnotdetermined.Onlyone

inves-tigationassesseda middledistance(400m)andpresented

positiveresults.

Based on this review, it is suggested low-volume S&C

training based on maximal strength, ranging from six to

twelveweeksof2to4(approximately24sessions)sessions

perweek, forimprovingswimmers’performances.Ineach

session,coachesshouldvaryfrom2to3setsandwith3to5 repetitions,accordingtoprescribedintensity.Restintervals shouldvarybetween2to5minutesandtheintensityshould varyfrom80to90%of1RM.

Toimprovestartsandturns,aS&Ctrainingrangingfrom

six to eight weeks and with 2 sessions per week is

sug-gested.Ineachsession,swimmersshouldperformbetween

1to6 setsand1to10 repetitions,according tothe cho-senlevelofintensity.Restbetweensetsshouldvaryfrom60

to90seconds.Volumeshouldbeprogressive,suchasraising intensityfromlowtohighwithintheS&Ctrainingprogram. Itisrecommendedtostartwithlowvolumesandintensities toallowswimmerstoadapttoplyometrictraining

specifici-ties.Onlyrecommendationsforadolescentswimmerswere

given,sincenostudieswitholderswimmerswereincluded

inthisreview.

Althoughthereisalackofcoherentscientificevidence,

S&C training remains a commonly prescribed swimming

practice. So, it seems fair to argue that further investi-gationsshouldbecarriedout.To controlforsome gapsin protocolsandtoenablethegeneralizabilityofconclusions,

randomized controlled trials (RCT) should be conducted.

Futureinvestigationsshouldexplorethefollowingtopics: • differences in S&C trainingeffects induced by age and

gender;

• effectsofS&Ctraininginrelationtodifferentswimming techniques;

• effectsofS&Ctraininginmiddleandlongswimming dis-tances;

• effectsofS&Ctrainingexperimentalperiodsovera sea-son,toevaluatelong-termeffects;

• effectsofaswimmingadaptionperiodafterS&Ccessation toallowtransferabilityofstrengthgainstoswimming.

Disclosure

of

interest

Theauthorsdeclarethattheyhavenocompetinginterest.

Acknowledgements

This projectwassupportedby theNationalFundsthrough

FCT — Portuguese Foundation for Science and

Technol-ogy (UID/DTP/04045/2013) — and the European Fund for

regionaldevelopment(FEDER)allocatedbyEuropeanUnion

through the COMPETE 2020 Programme

(POCI-01-0145-FEDER-006969).

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