Efficient Deceleration - The Forgotten Factor in Tennis-Specific Training

Efficient Deceleration: The Forgotten Factor in Tennis-Specific Training Mark S. Kovacs, PhD, CSCS,1 E. Paul Roetert, PhD,1 and Todd S. Ellenbecker, DPT, CSCS2 1 Player Development, United States Tennis Association, Boca Raton, Florida; 2Physiotherapy Associates, Scottsdale, Arizona

SUMMARY EFFICIENT DECELE EFFICIENT DECELERATION RATION IS PARAMOUNT TO ALLOW FOR FAST AND EXPLOSIVE CHANGES OF DIRECTION. BECAUSE MOST TENNIS POINTS HAVE BETWEEN 3 AND 7 CHANGES OF DIRECTIONS, THE DEVELOPMENT OF THE COMPONENTS IN CHANGE OF DIRECTION MOVEMENTS IS A MAJOR COMPONENT OF COMPETITIVE PLAY. TRAINING TRAINI NG FOR TENNIS REQUIRES REQUIRES A STRONG UNDERSTANDING UNDERSTANDING NOT ONLY OF THE ACCELERATION ASPECTS OF MOVEMENT BUT ALSO THE NEED FOR TENNIS TENNIS-SPECI -SPECIFIC FIC DECELERATION. IN THIS ARTICLE, WE REVIEW TENNIS MOVEMENTS FROM BOTH AN UPPER- AND LOWER-BODY PERSPECTIVE AND DESCRIBE DESCRI BE THE IMPORTA IMPORTANT NT COMPONENTS OF TENNIS-SPECIFIC DECELERATION WITH PRACTICAL EXAMPLES OF DECELERATION TRAINING IDEAS.

INTRODUCTION

or com compet petiti itive ve ten tennis nis pla player yers, s, exce ex cept ptio iona nall mo move veme ment nt is a  requiremen requi rementt to achie achieve ve succe success ss in junior tournaments as well as at the collegiate or professional level. Acceleration focused training is common in strength stren gth and cond condition itioning ing prog programs rams forr te fo tenn nnis is pl play ayer ers; s; ho howe weve ver, r, le less ss emphas emp hasis is is som someti etimes mes giv given en to the importance that effective deceleration trai tr aini ning ng pl play ayss in bo both th up uppe perr- an and d

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lower-body movements of the tennis athl at hlet ete. e. The lo lowe werr bo body dy ne need edss to perform large decelerations to prepare for and reco recover ver aft after er grou groundst ndstroke rokess and an d vo voll lley eys, s, as we well ll as du duri ring ng th thee follow-through and landing phase of  thee se th serv rvee (2 (29) 9).. The up uppe perr bo body dy,, particularly the muscles of the upper back ba ck an and d po post ster erio iorr as aspe pect ctss of th thee shoulder, shoul der, feature feature the majo majorr musc muscles les that help decelerate the upper limbs afterr ball con afte contact tact in serve serves, s, grou groundndstroke str okes, s, an and d vol volley leyss (30 (30). ). As suc such, h, decelera dece leration tion need needss to be cons consider idered ed a vit vital al co compo mponen nentt of a co compe mpetit titive ive tennis ten nis pla playe yer’s r’s tra traini ining ng ro routi utine ne to achieve peak tennis performance. To explor exp loree the co compl mplex ex na natur turee of deceleration, a deterministic model has been be en us used ed to sh show owca case se th thee mu mult ltiifaceted nature of deceleration and the manyy co man compo mponen nents ts tha thatt ne need ed to be traine tra ined d to suc succe cessf ssfull ullyy ex execu ecute te the correct corr ect move movement ments. s. A det determin erministic istic mode mo dell is a sy syst stem emat atic ic mo mode dell th that at is use used d to ana analyz lyzee an and d eva evalua luate te an important component component of a skill, which provides an approach that is based on a hie hiera rarch rchyy of fac factor torss tha thatt ar aree dependent on the result or outcome of  the pe perfo rforma rmanc ncee (22 (22). ). Fi Figur guree 1 describes a deterministic model for deceleration that can help the strength and conditioning specialist highlight areas that need to be trained during  the pha phases ses of a per period iodize ized d tra traini ining  ng  prog pr ogra ram. m. At th thee si simp mple lest st le leve vell of  analysis, anal ysis, decelerati deceleration on is the fine interplay between musculoskeletal, neural,, an ral and d tec techni hnical cal co compo mpone nent nts. s. To

develop effective deceleration capabilities in tennis athletes, it is important thatt the str tha streng ength th and con condit dition ioning  ing  program includes ample time on all 3 of these broad areas of training. PLYOMETRIC PLYOMETRI C MOVEMENTS

Plyometric exercises Plyometric exercises typic typically ally are incorporat corp orated ed into an athle athlete’s te’s progr program am by th thee st stre reng ngth th an and d co cond ndit itio ioni ning  ng  specialist to improve explosive movements men ts by imp improv roving ing pow power er out output putss (21). Plyometric movements involve an eccentric loading immediately followed by a co conc ncen entr tric ic co cont ntra ract ctio ion n (1 (14) 4).. Plyometric Plyom etric train training ing enha enhances nces athle athletic tic performa perf ormance, nce, typic typically ally by impro improving  ving  power pow er out output putss as mea measur sured ed by con con-centr ce ntric ic con contra tracti ctions ons.. How Howeve ever, r, the benefit of plyometric training also aids in the tra traini ining ng of ada adapta ptatio tions ns in the sensorimotor system that enhances the athlet ath lete’s e’s abi abilit lityy to bra brake, ke, som someti etimes mes referred to as the ‘‘restrain ‘‘ restrain mechanism’’ (35,36). In addition, plyometric training  aids in the correction of mechanically disadvantageous jumping and change of direc direction tion movements. movements. Anothe Anotherr added benefit ben efit wit with h res respec pectt to dec decele elerat ration ion traini tra ining ng is the lan landin dingg com compon ponent entss after aft er a ply plyome ometri tricc typ typee mov moveme ement. nt. Because Beca use plyo plyometri metricc movem movements ents producee gre duc greate aterr pow power er out output puts, s, as the resu re sult lt of th thee gr grea eate terr us usee of st stor ored ed potential poten tial energ energy, y, than nonply nonplyometr ometric ic KEY WORDS:

acceleration; deceleration; movement; quickness; speed; tennis

Figure Figu re 1.   Deterministic model of deceleration.

Figure Figu re 2.   Lower body deceleration after a tennis stroke.

movements moveme nts (33) (33),, the these se gre greate aterr for forces ces require req uire gre greate aterr dec decele elerat ration ion abil abilitie ities. s. Therefore, training with the use of plyometric movements not only improves

power and exp power explosi losive ve move movemen ments ts but also al so re resul sults ts in tra traini ining ng ad adap apta tatio tions ns durin du ringg th thee lan landi ding ng or de dece cele lera rati tion on phase of these movements. The need

to de deve velo lop p thi thiss im impr prov oved ed ab abili ility ty to ‘‘brake’’ and improve the restrain mechanism will be the major focus of the remainder of this article.

Efficient Deceleration

Figure Figu re 3.   Upper and lower body deceleration after a tennis serve.

LOWER-BODY DECELERATION 

Although training acceleration is vital to help an athlete become become faster, this improve impr oved d acc accele elerati ration on abil ability ity may nott tra no transf nsfer er int into o imp impro rove ved d te tenn nnis is performance if the athlete does not have ha ve the ab abili ility ty to de dece cele lera rate te the faster fas ter vel veloci ocities ties in the app approp ropria riate te timee fra tim frame me an and d un unde derr the ne need eded ed control con trol to mak makee opt optimum imum con contac tactt with the tennis ball. The ability to

effectively decelerate effectively decelerate is also important while transitioning into a recoveryy mo er move veme ment nt tha thatt wi will ll all allow ow the athl at hlet etee to be in po posi siti tion on fo forr th thee next ne xt st stro roke ke in th thee ra rall llyy. Fi Figu gure re 2 demonstrates the body position and importance importa nce of appro appropriate priate strength, balance bala nce,, and coo coordi rdinat nation, ion, first to acce ac cele lerat ratee int into o the fo fore reha hand nd,, an and d secon sec ond d to de dece celer lerat atee ra rapid pidly ly af afte terr contact with the ball has been made.

Figure Figu re 4.  Four major deceleration components.

An ath athlet lete’s e’s abi abilit lityy to dec decele elerat ratee is a trainable biomotor biomotor skill and, as such, needs to be included in a well-rounded, tennis-spe tenn is-specific cific train training ing prog program. ram. An athlete who can decelerate faster and in a shorter distance is an athlete who will not only be faster but will also have greatt body control grea control durin duringg the tennis stroke. This greater control during the stroke will result in a greater level of  dynami dyn amicc bal balanc ancee (Fi (Figur gures es 1 and 4), which translates into greater power of  the strokes, and more solid racket and balll con bal contac tact, t, whi which ch res result ultss in mor moree effective execution. A major influence on a tennis player’s ability to decelerate is mo mome ment ntum um.. Mo Mome ment ntum um is th thee product of the mass of a moving athlete and an d his/ his/her her vel veloci ocity ty.. As an ath athlet lete’s e’s velocity increases, momentum is amplified, requiring greater forces to decelerate the fast moving tennis player. A la larg rger er te tenn nnis is pl play ayer er (i. (i.e. e.,, gr grea eate terr mass ma ss)) ha hass a mo more re di diffi fficu cult lt ti time me decelerating and, if the coach focuses the

Figure Figu re 5.  Deceleration and requirement of eccentric strength during a forehand stroke.

majori majo rity ty of mo move veme ment nt tr trai aini ning ng on accelerat acce leration ion witho without ut focu focusing sing ample time on deceleration, it will result in an athlete who has a faster initial velocity but who may not be able to control the body to slow down fast enough before and/or after making contact with the ball.l. Th bal This is wil willl res result ult in red reduce uced d oncourt performance and may result in the increased likelihood of injury. It has been proposed in the literature that the caus ca uses es of th thee ma majo jori rity ty of at athl hlet etic ic injuries are the result of inappropriate deceleration abilities of athletes and an overemphas overe mphasis is of acce accelerat leration-f ion-focuse ocused d (concentri (conc entricc speci specific fic movem movement) ent) exercises both on and off-c off-court ourt (11,26).

degrees relative to the body (abduction). In this position, large forces are gene ge nera rate ted d by th thee in inte tern rnal al ro rota tato torr muscle mus cless suc such h as the lat latissi issimus mus dor dorsi si and pectoralis major to accelerate the arm and racquet head forward toward an explosive ball impact. Immedi Imme diat atel elyy af afte terr ba ball ll im impa pact ct,, th thee muscles in the back of the shoulder, including the scapular stabilizers (infraspinatus, teres minor, serratus anterior, trapezius and rhomboids [27]), have to

work ecc work eccent entric ricall allyy to dec decele elerat ratee the arm as it continues to internally rotate. Flei Fl eisig sig et al al.. (9 (9)) re repo port rted ed an ante teri rior or translational forces during the acceleration and follow-through phases of the overhead throwing motion to approximately 13  body weight in the glenohumeral humer al joint joint.. The posterior rotator cuff muscle–tendon units are responsible for mai mainta ntaini ining ng joi joint nt sta stabili bility ty by resisting resist ing this ante anterior rior tran translatio slation/dis n/dis-tractional force to prevent injury to the

UPPER-BODY DECELERATION 

In the upper extremity, the body uses eccentric contractions after ball impact in virtually all strokes to decelerate the upper-extre upper -extremity mity kinet kinetic ic chain chain.. The These se contra con tracti ctions ons are of vit vital al imp import ortan ance ce around the shoulder and scapular area  beca be cause use th they ey he help lp to ma main inta tain in th thee critic cri ticall allyy imp import ortant ant sta stabili bility ty tha thatt is need ne eded ed to bo both th pr prev even entt in inju jury ry an and d enhance enhan ce perf performan ormance. ce. For examp example, le, during the serve (Figure 3), the upper arm is elevated approximately 90–100

Figure Figu re 6.   Length–tension curve before and after eccentric exercise. Adapted from Brughelli and Cronin (3).

Efficient Deceleration

glenoid labrum and other structures in the shoulder (9). This deceleration is critical criti cal for injur injuryy preve prevention ntion because the ina inabil bility ity to dis dissip sipate ate the these se lar large ge forces by the muscles in the back of the shoulder and scapular area can lead to injury inj ury (Fi (Figur guree 3). Sim Simila ilarr res result ultss are seen in tennis movements and require appropriate training (7). In addition to the high levels of activity identified during the serve, the same rotator cuff and scapular muscles work  to decelerate the arm on the forehand duri du ring ng th thee fo follo lloww-th thro roug ugh h ph phas ase. e. Training these important muscles provides important muscle balance to the tennis player. Players are deficient in these impor important tant dece decelera lerator tor muscle muscless (5,16, (5, 16,31) 31) and do not und unders erstan tand d the importanc impor tancee of train training ing these muscles by inc incorp orpora oratin tingg dec decele elerat ration ion typ typee traini tra ining ng pro progra grams ms int into o the their ir nor normal mal training regimens.

Figure Figu re 7.  90/90 prone plyometric exercise.

TRAINING SPECIFICITY

It ha hass be been en sho shown wn in th thee sc scie ient ntifi ificc literature liter ature that linea linearr acce accelerat leration ion and linear maximum velocity are separate qualities qualit ies from multid multidirect irectional ional movemen me nts th thaat re requ quir iree a cha han nge of  direct dir ection ion and and/or /or a de decel celera eratio tion n of  movement (43). Young Young et al. (43) found that straight-ahead sprinting, such as a 100-m sprint in track and field, does not transfer directly to the movements typically seen on a tennis court. This result is caused by the differences in moveme mov ement nt mec mechan hanics ics,, mus muscle cle firi firing  ng  patt pa tter erns ns,, an and d mo moto torr le lear arni ning ng sk skil ills ls required to perform straight line sprinting versus tennis play that require start and sto stop p mov moveme ements nts and num numero erous us changes of direction in every point. As a res result ult,, tra traini ining ng for ten tennis nis-sp -speci ecific fic accelerat acce leration, ion, dece decelerat leration, ion, and reco recovvery movements (change of direction) requires movement patterns, distances, and energy system focus that resembles competitive tennis play. Because tennis is an untimed competition, it may last anywhere from 30 minutes to 5 hours (17). However, from a practical standpoint, we know that high-level competi pe titi tive ve te tenn nnis is ha hass so some me ty typi pica call patter pat terns ns tha thatt oc occur cur dur during ing mat matche chess

Figure Figu re 8.  Prone horizontal abduction plyometric exercise.

Figure Figu re 9.  Reverse catch deceleration training exercise.

that can help the strength and conditioning tioni ng prof profession essional al when desig designing  ning  programs. Athletes typically encounter between 3 and 7 directional changes per point, rarely move more than 30 yard ya rdss in on onee di dire rect ctio ion n (1 (16, 6,38 38). ). In additi add ition, on, poi point nt len length gth ave averag rages es are around aro und 6 sec second onds, s, wit with h the maj majori ority ty of points lasting less than 10 seconds, and a typical work-to-rest ratio during  individ ind ividual ual poi points nts and mat matche chess is between 1:2 and 1:5 (15,16,18,19,30). All thes th esee fa fact ctor orss ca can n be us used ed to he help lp develop devel op tenn tennis-spe is-specific cific dece decelerat leration ion training programs. WHAT FACTORS IMPROVE A TENNIS PLAYER’S DECELERATION ABILITY?

Dynamic balan Dynamic balance, ce, ecce eccentric ntric stren strength, gth, powe po wer, r, an and d re reac acti tive ve st stre reng ngth th ar aree 4 major qualities that have a significant influ in fluen ence ce on an at athle hlete te’s ’s ab abil ilit ityy to decelerat dece lerate, e, while main maintainin tainingg appr approopriate pri ate bod bodyy pos positi ition on to exe execut cutee the necess nec essary ary ten tennis nis str stroke oke and the then n recover cov er for the nex nextt str stroke oke (Figure (Figure 4) (41). Although other components do contri con tribut butee to an ath athlet lete’s e’s abi abilit lityy to effectively effec tively decelerate, decelerate, these 4 fact factors ors will be investigated to aid the strength and conditioning conditioning coac coach h in desig designing  ning  effective programs. DYNAMIC BALANCE

Dynami Dyna micc ba bala lanc ncee is pa para ramo moun untt in tennis, specifically during the deceleration movement phase before or after the player makes contact with the ball. Dynamic balance is the ability of the athlete to maintain a stable center of  gravity while the athlete is moving (1). This Th is ab abili ility ty to ma main inta tain in ba bala lanc ncee in a dyn dynami amicc env enviro ironme nment nt all allows ows the athlete to successfully use the segmental summation of muscular forces and movements through the kinetic chain (13). This efficient energy transfer from the ground and up through the entire kine ki neti ticc ch chai ain n wi will ll re resu sult lt in a mo more re efficient and powerful tennis stroke, in addition to faster racket head speeds and ball velocities. velocities. Addit Additional ionally, ly, dynamic balance can refer to the ability duri du rin ng mo move veme men nts of opp ppos osin ing  g  muscle mus cless to wor workk opt optima imally lly tog togeth ether er

Figure Figu re 10.  Tennis-specific reverse catch. A) Start. B) Deceleration phase.

to produce uncompensated movement patterns (1). This is particularly important ta nt in th thee up uppe perr ex extr trem emit ityy wh when en proper muscle balance must be maintained to improve shoulder joint stability. Although experts may not agree on the mechanisms involved in athletespecific balance, the research suggests that th at ch chan ange gess in bo both th se sens nsor oryy an and d motor systems influence balance performance (1). The feedback obtained from plyo plyometri metricc movem movements ents enco encommpasses a number of reflexive pathways that aid muscle and neural adaptations to accommodate unanticipated movements (34). These adaptations are vital for the pre preven ventio tion n of inj injuri uries es dur during  ing  practice and competition.

ECCENTRIC STRENGTH 

Eccentric strength requir Eccentric requires es traini training ng of  the musc muscles les dur during ing the len length gtheni ening  ng  phase of the muscle action. An example would be during the step before and the loading phase of a forehand (Figur (Fi guree 5). Ecc Eccent entric ric str streng engthe thenin ning  g  exercises need to be performed both bilaterally bilate rally and unilat unilaterall erally. y. Nearl Nearlyy all tennis movements require the athlete to load one side of the body more than thee ot th othe her, r, an and d it is pa para ramo moun untt th that at thes th esee un unev even en lo load adin ingg pa patt tter erns ns ar aree traine tra ined d ecc eccent entric ricall allyy as wel welll as con con-centricall cent rically. y. It is know known n that physically trained humans can support approximately 30% more weight eccentrically

Efficient Deceleration

strengthening strengthen ing to optim optimize ize the lengt length h tension relationship. High-inten Highintensity sity and highe higherr volum volumee eccentric ecce ntric exercise result in grea greater ter shifts in optim optimum um leng length th   Eccentr Eccentric ic muscl musclee actio actions ns at long longer er leng le ngth thss re resu sult lt in gr grea eate terr sh shif ifts ts in optimum length   It It ma mayy be po poss ssib ible le to pr prod oduc ucee a  sustai sus tained ned shif shiftt in opt optimu imum m len length gth after 4 weeks of eccentric exercise   Excessive muscle damage may not need to be induced for this shift in opti op timu mum m le leng ngth th to oc occu curr wi with th eccentric exercise From the muscle physiology literature, we know that after eccentric exercise, the athlete’s cytoskeletal proteins, such as desmin and titin, are disrupted and degra de gradat dation ion occ occurs urs (10 (10), ), pos possibl siblyy as high hi gh as 30 30% % af afte terr a si sing ngle le bo bout ut of  eccentric ecce ntric exercise (37 (37). ). This process then results in a protective adaptation that strengthens the cytoskeletal proteins tei ns and prevents prevents the them m fro from m bei being  ng  damaged in the future. This is one of  the major theorized mechanisms as to why eccentric strengthening is important for injur injuryy preve preventio ntion, n, espec especially ially during movements that require rapid decelerat dece leration. ion. Most muscle-r muscle-relate elated d in juries occur when they are actively lengthened (11). From the literature, it appears that neural control of eccentric actions is unique from control of concentric cen tric act action ionss (25 (25). ). Th Thee cen centra trall ner nervous vous system adjusts motor unit recruitment, activ ac tivati ation on lev level, el, dist distrib ributi ution on of tha thatt activation, and afferent feedback duringg ec in ecce cent ntri ricc mu musc scle le ac acti tion onss (8 (8). ). Therefor The refore, e, speci specificity ficity of muscle contraction mode (i.e., eccentric, isometric or co conc ncen entr tric ic)) du duri ring ng tr trai aini ning ng is important. 

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Figure Figu re 11.   External rotation at 90 degrees with elastic tubing. A) Start. B) Finish.

than conc concentr entrically ically (6,23,4 (6,23,40). 0). The Thererefore, eccentric focused strength training needs to be incorporated into an athlete’s athle te’s perio periodized dized program to successfully maximize his or her athletic improvement. A second major benefit of tr trai ainin ningg ec ecce cent ntric ric str stren engt gth h is to aid ai d in th thee pr prev even enti tion on of in inju juri ries es (2,26). A large portion of injuries to tenn te nnis is pl play ayer erss is at attri tribu buta tabl blee to in in-suffici suf ficient ent ecc eccent entric ric str streng ength th bot both h in the upper body during the deceleration of th thee ra rack cket et af afte terr se serv rves es,, gr grou ound nd-strokes, and volleys, as well as in the lower body durin duringg the deceleration deceleration of  the body bef before ore planting planting the fee feett to esta es tabli blish sh a st stab able le ba base se fo forr ef effe fect ctiv ivee stroke production. Eccentric strengthening exercises have a positive effect on altering the length–

tension relationship of muscle (3). The optimum length of peak tension occurs at longer lengths, therefore, shifting the curve to the right (Figure 6). Length–tension curves for single fibers (sarcomeres), whole muscle, and single  joints all have different shapes (3). As the result of these different shapes, it is vital for the athlete to be trained at a  variety of angles and torques to stimulatee ada lat adapta ptatio tions ns in as man manyy mus muscle cle fibers as possible to capture the greatest effect effe ct on alter altering ing the lengt length–ten h–tension sion relationship, specifically during eccentricc dom tri domina inant nt mov moveme ements nts.. A gre great at review of the eccentric exercise literature tu re by Br Brug ughe hell llii an and d Cr Cron onin in (3 (3)) devise dev ised d som somee ten tentat tative ive con conclu clusio sions ns that should be helpful when designing  prog pr ogra ram ms fo focu cuse sed d on ecc ccen entr tric ic

POWER

Power for the ten Power tennis nis player player is wha whatt directly direc tly tran translates slates into grea greater ter rack racket et head hea d spe speed ed and ball vel veloci ocity ty.. Mo Most st forms for ms of ply plyome ometri tricc exe exerci rcise se mov moveements men ts are gea geared red tow toward ard imp improv roving  ing  muscular power. Plyometric exercises aree vi ar vita tall fo forr th thee de deve velo lopm pmen entt of  great gre at de decel celera eratio tion n abi abilit lities ies thr throug ough h a number of separate, yet interrelated

Figure Figu re 12.   Romanian deadlift (RDL). A) Start. B) Finish.

mechanisms. Plyom mechanisms. Plyometric etric move movements ments inducee neuro induc neuromuscul muscular ar adap adaptatio tations ns to thee st th strret etcch re refle flex, x, as we well ll as th thee elasticity of muscle and Golgi tendon organs (GTOs) (39). The stretch reflex  is initiated during the eccentric loading  and an d re resu sult ltss in gr grea eate terr mo moto torr un unit it recruitmen recru itmentt durin duringg the ensui ensuing ng concentric contraction. GTOs have a protect te ctiv ivee fu func ncti tion on ag agai ains nstt ex exce cessi ssive ve tensile loads in the muscle; however, plyometric training results in a degree of dese desensitiz nsitization ation of the stretch refle reflex, x, which allows the elastic component of  muscle mus cle to und underg ergo o a gre greate aterr str stretc etch h (12). The combined adaptations results in a mor moree pow powerf erful ul con concen centri tricc con con-traction which, in tennis, would result in gr grea eate terr po powe werr an and d sp spee eed d in recovering from hitting one stroke to the next. It is thought that a large portion of muscu muscular lar perf performan ormance ce gains after plyometric plyom etric movem movements ents are attr attributed ibuted to neural changes rather than morphological (39). This improved neuromuscular function directly influences influences the major components needed for effective deceleration ability (Figure 1). REACTIVE STRENGTH 

Reactive strength has been defined as the ability to quickly change during the muscle contraction sequence from the eccentric to the concentric phase in the stretch–shortening cycle and is a specific ci fic fo form rm of mu musc scle le po powe werr (4 (42) 2).. A plyometric training program that uses lateral and multidirectional movements while limiting time on the ground will develop reactive strrength st and

Figure Figu re 13.   Box jump. A) Start. B) Finish.

Efficient Deceleration

a weight but rather a piece of elastic tubing to provide the overload for this exercise. The plyo dropping exercises typically use 30-second sets of exercise, whereas the reverse catching exercises use multiple sets of 15 to 20 repetitions to improve local muscular strength and endurance.

Exercise 1 .  Exercise 1 shows the 90/90

Figure Figu re 14.   Lateral hurdle runs with hold.

subseq subs eque uent nt po powe werr ou outp tput utss in th thee muscles and movements that are seen during tennis play. This type of training  directly relates to a tennis athlete in his or her rec recove overy ry seq sequen uences ces bet betwee ween n shot sh otss an and d al also so du duri ring ng th thee ti time mess in a po poin intt wh when en he or she is ‘‘w ‘‘wro rong ng-footed’’ and is in need of rapid change of direction. Increased muscle activity, specifi spe cifica cally lly in the for form m of ecc eccent entric ric loading, will enhance muscle stiffness. This increase in muscle stiffness leads to mor oree for orcce abs bso orp rpttio ion n in the musc mu scul ular ar–t –ten endo don n un unit it ra rath ther er th than an transmitted through the articular structures (32). It has been suggested that muscle activation is a dynamic restraint mechanism mech anism that result resultss in prote protecting  cting  the joints joints suc such h as the shoulder shoulder,, hip hip,, knee, and ankle (32). PRACTICAL APPLICATIONS FOR THE TENNIS ATHLETE

Deceleration is a biomotor skill that is closely close ly linked to agility and multid multidiirectional movement training. As such, it needs to be trained in a multifocused training program with appropriate rest periods and loads that are progressed based bas ed on the ten tennis nis pla player yer’s ’s gro growth wth,, maturation, and training stages. From a tra traini ining ng per perspe specti ctive, ve, the pos poster terior ior muscles of the tennis athlete need to be a fo focu cuss if th thee at athle hlete te is to be beco come me a su succ cces essf sful ul pl play ayer er wh who o ha hass gr grea eatt

deceleration ability. In the lower body, the hip extensors, including the glutes and an d ha hams mstr trin ingg mu musc scle les, s, ne need ed to be trai tr aine ned d sp spec ecifi ifica call llyy in an ec ecce cent ntri ricc manner with progressive increases in resistance. In the upper body, a major focu fo cuss ne need edss to be on th thee po post ster erio iorr aspect of the shoulder region, which will assist in the deceleration of the arm during the tennis serve, groundstrokes, and volleys. Because limited data are curren cur rently tly ava availa ilable ble on dec decele elerat ration ion training guidelines, it is important to monitor monit or train training ing close closely ly beca because use eccentric loading can cause more delayed onset of muscle soreness than similar concentric exercise (23). Because multipl ti plee se sets ts of ex exer erci cise sess ha have ve sh show own n greate gre aterr res result ultss tha than n sin single gle set setss (20 (20), ), decele dec elerat ration ion tra traini ining ng sho should uld be per per-formed forme d using multiple sets with varie varied d repeti rep etitio tion n ran ranges ges bas based ed on the age age,, maturation and training status of the athletes. UPPER-BODY EXERCISES

This section contains 5 upper-extremity plyometric plyomet ric exercises. Each exercise can be st star arte ted d wi with th a sm smal alll ha hand nd-s -siz ized ed plyo pl yome metr tric ic ba ball ll we weig ighin hingg ap appr prox oxiimately 0.5 kg to start with progression to a 1-kg ball as training progresses and comp co mpet eten ency cy an and d to tole lera ranc ncee to th thee exercise is demonstrated by the player. Exerci Exe rcise se 5 (Fi (Figur guree 11) does not use

prone plyometric exercise that places the shoulder and upper arm in a functional position inherent in the serving  motion mot ion.. In thi thiss exe exerci rcise, se, the pla player yer rapidly drops and catches the ball as quic qu ickl klyy as po poss ssib ible le,, wi with th th thee ba ball ll moving mov ing only a few centimet centimeters ers as it leaves the grasp of the player temporarily before being recaught and dropped pe d fr from om th thee re refe fere renc ncee po posit sitio ion n as pictured. Typically, multiple sets of 30 seconds are used in training to foster local muscular endurance (Figure 7).

Exerci Exe rcise se 2 . Exercise 2 is a prone horizontal abduction plyometric exercise in which the athlete lies prone on a supportive surface with the shoulder abducted 90 degrees with the elbow extended. A small medicine ball is used to repeatedly drop and catch the ball as rapidl rap idlyy as pos possib sible le as des descri cribed bed for exercise 1 previously. By rotating the hand such that the thumb is pointing  upwa up ward rd du duri ring ng th thee dr drop oppi ping ng an and d catching activity (i.e., external shoulder rotation) this exercise has been found to increase activation of the rotator cuff  muscles muscl es (Figur (Figuree 8) (24,28 (24,28). ).

Exercise Exer cise 3 . Exercise 3 shows a reverse catch deceleration training exercise. In thiss exe thi exerci rcise, se, the arm is aga again in pos posiition ti oned ed in 90 de degr gree eess of el elev evat atio ion n (abduction) and 90 degrees of elbow flexion as pictured. A partner stands  just behind the player and throws a sm smal alll 0. 0.55- to 11-kg kg me medi dici cine ne ba ball ll toward the player’s hand (30). Upon catching the ball, the arm moves into intern int ernal al rot rotati ation on unt until il the for forea earm rm is nearly parallel to the ground, just as it is decelerated during the serving motion functionally. The player, after deceleratin at ingg th thee ba ball ll,, ra rapi pidl dlyy fir fires es th thee ba ball ll backwa bac kwards rds tow toward ard the par partne tner, r, pe perrforming a concentric contraction of the

Figure Figu re 15.   A) MB deceleration catch lunge (linear). B) MB deceleration catch lunge (Lateral). C) MB deceleration catch lunge (45 degrees). D) MB deceleration catch lunge (cross-over).

rotator cuff and scapular muscles. Recent research has demonstrated significant increases in eccentric strength in the sho should ulder er of sub subjec jects ts whe when n usi using  ng  these the se typ types es of exe exerci rcises ses in a per perfor for-mance enhancement training program (Figure 9) (4).

Exercise 4 . Exercise 4 shows a variation of the reverse catch exercise where the athlete keeps the elbow straight during  the catching and subsequent release of  the pl plyo yo ba ball ll to sim simula ulate te the servin serving  g  motion and a PNF D2 diagonal pattern. Thee PNF D2 pa Th patt tter ern n is a fu func nctio tiona nall diagonal pattern that closely simulates the move movemen mentt pat patter tern n the upper extremity goes through during the throwing or ser serving ving motion. motion. D2 ext extens ension, ion,

which is per which perfor formed med con concen centri trical cally ly in thiss exe thi exercis rcise, e, incl include udess the pat patter terns ns of  shoulder flexion, abduction, and externall ro na rota tatio tion, n, whe where reas as the ec ecce cent ntric ric action act ion incu incurre rred d in this exe exercis rcisee aft after er the ‘‘catch’ ‘‘catch’’’ of the medicine medicine ball (D2 flexion) flexi on) inc include ludess shou shoulder lder ext extens ension, ion, internal rotation, and slight cross arm adduction. This pattern is chosen for its activation pattern, which closely simulates the funct functional ional throwing or serving  action, as well as its activation of the rota ro tato torr cu cuff ff an and d sc scap apul ular ar mu musc scle les. s. Emphasis is initially on the deceleration of the ball as the arm continues continues forward afte af terr ca catc tchin hingg the ba ball ll the then n rap rapidl idlyy reversi rev ersing ng dire directi ction on to per perfor form m an explosive concentric backward throwing  movement (Figure 10).

Exercise 5 . Exercis Exercisee 5 show showss the exte externa rnall rotatio rota tion n at 90 de degr gree eess ex exer ercis cisee wit with h elastic elas tic tubi tubing. ng. Th Thee tra traditi ditiona onall way of  doing this exercise involves slow controlled internal and external rotation at 90 degrees of abduction. However, to increase increa se the eccen eccentric tric or decele deceleration ration emphasis of this exercise, a plyometric type format can be incorp incorporated orated to add variety. Start with tension on the tubing  with the shoulder shoulder elevat elevated ed 90 degrees degrees in the scapular plane (30 degrees forward from fro m the cor corona onall pla plane) ne) (Fig (Figure ure 11). Thee sho Th should ulder er sho should uld be ex exte tern rnall allyy rotate rot ated d 90 deg degree rees, s, whic which h plac places es the fore fo reaarm in a ver vertic tical al pos positi ition. on. Th Thee athlete then rapidly decelerates forward into internal rotation until the forearm reaches a horizontal position.

Efficient Deceleration

Upon re Upon reac achin hingg th this is po posit sitio ion, n, th thee athlete athle te then explosively returns returns the hand and forearm back to the starting  position with as little pause between the init initial ial len length gtheni ening ng pha phase se of the exercise and the concentric explosive phase as possible. This is repeated for multiple sets of 15 to 20 repetitions (Figure 11).

portio port ion n of th thee lu lung nge. e. Th Thee ca catc tchi hing  ng  aspe as pect ct of th thee mo move veme ment nt lo load adss th thee eccentric portion (Figure 15).

Mark Kovacs is 

the Ma the Mannag ageer of    Spor Sp ortt Sc Scie ienc ncee fo for  r  the Uni United ted Sta States  tes  Tennis Association.

LOWER-BODY EXERCISES

Exer Ex erci cise se 6  .   Ex Exercis isee 6 shows a  Romanian dead Romanian deadlift lift stren strength gth exer exercise cise that works on the muscular developmentt of the ham men hamstr string ings, s, glu glutes tes,, and lower back muscles as force is applied during eccentric muscle actions. Repetition ranges and time under load for this th is ex exer erci cise se sh shou ould ld fo focu cuss on bo both th muscular strength and endurance during the training program (Figure 12).

Paul Roetert is 

the Managing Di-  rect re ctor or of Pl Play ayer  er  Deve De velop lopme ment nt fo for  r  the Uni United ted Sta States  tes  Tennis Association.

Exercise 7 . Exercise 7 shows a traditional box jump with specific emphasis on the landing phase. It is important to have the athlete land in a strong squat positi pos ition, on, whi which ch dev develo elops ps ecc eccent entric ric strength stren gth and rapid deceleration deceleration abilities. A more advanced athlete who has develo dev eloped ped app approp ropria riate te low lower er bod bodyy strength can advance to performing a  depth box jump. However, for younger athl at hlet etes es,, or at athl hlet etes es wi with th li limi mite ted d streng str ength th in the lower body, body, a dep depth th  jump should only be performed after appropria appr opriate te train training ing and lower lower-body -body strengthening exercises (Figure 13).

Exercise Exerci se 9. Med Medici icine ne Ball Dec Decele elerat ration  ion  Catch Cat ch and Lun Lunge ge (Li (Linea near, r, Lat Latera eral,l, 45  ). This exercise Degrees, and Cross-Over ). focuses on the athlete catching a relatively heavy medicine ball during the eccentric portion of the lunge and then rele re leas asin ingg it du duri ring ng th thee co conc ncen entr tric ic

5. Chandler Chandler TJ, Kibler Kibler WB, WB, Stracener Stracener EC, EC, Ziegler AK, and Pace B. Shoulder strength, power,, and endurance in colleg power college e tenni tenniss players.  Am J Sports Med  20: 455–458, 1992. 6. Ellen Ellenbec beckerTS, kerTS, Dav Davies ies GJ, and Row Rowins inski ki MJ. Concentric versus eccentric isokinetic strengthening of the rotator cuff.  Am J  Sports Med  16:   16: 64–69, 1988. 7. Elliott Elliott B and Anderson Anderson J. J. Biomechanica Biomechanicall performance models: The basis for stroke analysis. In:   ITF Biomechanics of  Advanced Tennis. Elliott B, Reid M, and Crespo M, eds. London: The International Tennis Federation, 2003. p. 157–175. 8. Enoka RM. RM. Eccentric Eccentric contract contractions ions require require unique activation strategies by the nervous system.  J Appl Physiol  81:   81: 2339–23346, 1996. 9. Fleisig Fleisig GS, Andrews Andrews JR, JR, Dillman Dillman CJ, and and Escamilla RF. Kinetics of baseball pitching with implications about injury mechanisms. Am J Sports Med  23: 233–239, 1995. 10. Friden Friden J and Lieber Lieber R. Eccentric Eccentric exerciseexerciseinduced injuries to contractile and cytoskeletal muscle fibre components.   171:321–326, 2001. Acta Physiol Scand  171:321–326,

Exercise Exerci se 8. Lat Latera erall Hur Hurdle dle Run Runss wit withh Hold . Thi hiss is a tr trad adit itio iona nall la late tera rallfocused focuse d ply plyome ometri tricc mov moveme ement nt tha thatt work wo rkss on th thee mu musc scle less of th thee lo lowe werr body, from a stretch shortening perspective, but also at the end of each set of 4 hu hurd rdle less th thee at athl hlet etee ne need edss to decele dec elerat ratee and com comee to a com comple plete te stop and hold the lowered center of  mass position for 2 complete seconds before bef ore rea reacce cceler lerati ating ng bac backk int into o the exercise (Figure 14).

shoulder rotators in collegiate baseball players.  J Strength Cond Res  21: 208– 215, 2007.

Todd S. Ellenb Ellenbecke eckerr

11. Garre Garrett tt W. Mus Muscle cle strain strain injuries. injuries. Am J    24: S2–S8, 1996. Sports Med  24:

is th thee Na Nati tion onal  al  Director of Clinical   Research–Physio-  therapyy Assoc therap Associates  iates  and is the Director  Director  of Sports Medicine  Medicine    for the ATP Tour.

12. Hutton Hutton RS and Atwater Atwater SW. SW. Acute and and chronic adaptations of muscle proprioceptors in response to increased use.  Sports Med  14:   14: 406–421, 1992.

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