-
Biomechanics of theTennis Groundstrokes:Implications for
StrengthTrainingE. Paul Roetert, PhD,1 Mark Kovacs, PhD, CSCS,1
Duane Knudson, PhD,2 and Jack L. Groppel, PhD31United States Tennis
Association, Boca Raton, Florida; 2Department of Health and Human
Performance,San Marcos, Texas; and 3Human Performance Institute,
Lake Nona, Florida
S U M M A R Y
THE PURPOSE OF THIS ARTICLE
WAS TO SUMMARIZE RECENT RE-
SEARCH RELATED TO THE BIO-
MECHANICS OF TENNIS
TECHNIQUE IN GROUNDSTROKES
AND THEN TO RECOMMEND SPE-
CIFIC STRENGTH AND CONDI-
TIONING EXERCISES THAT WOULD
TEND TO IMPROVE TENNIS PER-
FORMANCE AND PREVENT INJURY.
BASED ON THE AVAILABLE
RESEARCH, IT WAS DETERMINED
THAT TRAINING EXERCISES
SHOULD EMULATE THE SEQUEN-
TIAL COORDINATION INVOLVED IN
GROUND STROKE PRODUCTION,
AS WELL AS STABILIZING MUS-
CULATURE THAT MIGHT BE IN-
VOLVED IN DEVELOPING FORCE
OR IN PROTECTING BODY PARTS
FROM STRESSFUL ACTIONS. SPE-
CIFIC EXERCISES BASED ON THE
FINDINGS IN THE RESEARCH LIT-
ERATURE WERE THEN OFFERED.
INTRODUCTION
The game of tennis has changeddramatically in the past 30years.
This is probably most
evident in groundstroke techniqueand strategy. Modern players
oftenhit aggressive high-speed ground-strokes to overpower their
opponent.
This strategy places extra stress on theplayers body that
strength and condi-tioning professionals should considerin
designing training programs. Thisarticle will summarize recent
researchrelated to the biomechanics of tennistechnique and propose
specific condi-tioning exercises that logically wouldtend to
improve performance and re-duce the risk of injury in tennis.
CHANGES IN TECHNIQUE
Traditional tennis groundstrokes werehit from a square or closed
stance witha long flowing stroke using simulta-neous coordination
of the body. Themodern forehand and even the back-hand
(particularly the 2-handed back-hand) are more often hit from an
openstance using sequential coordination ofthe body. Elite tennis
always had these2 styles of groundstrokes (1), but sincethat time,
there has been a reversalfrom primarily simultaneous to sequen-tial
groundstroke technique. Thischange in the coordinated use of
thekinetic chain suggests that the load-ing and injury risk to
major segmentsof the body may have changed intennis (11).
It is not possible to uniquely track thetransfer of mechanical
energy in a 3-dimensional movement of the humanbody, but it is
generally accepted thatmost of the energy or force used
toaccelerate a tennis racket is transferred
to the arm and racket from the largermuscle groups in the legs
and trunk(5,15,21). While it is believed thatoptimal use of the
kinetic chain willmaximize performance and reduce therisk of injury
(6,11), the transfer of forceand energy to the small segments
andtissues of the upper extremity do placethem under great stress.
For example,medial elbow pain is on the rise intennis players most
likely because ofthe transfer of energy from the legsand trunk in
forehands and serves. Thisfocuses stress on the medial elbowregion
in the bent-arm sequential co-ordination in these strokes. The
nextsections will summarize recent re-search on technique issues
specific toeach groundstroke that are importantto consider when
planning condition-ing programs. Several reviews of thebiomechanics
of tennis are available forinterested readers (5,15,18).
FOREHAND
Vigorous extension of the lower ex-tremity in classic closed
stance fore-hands creates greater axial torques torotate the pelvis
and hips than notusing the legs (9). While this transfer ofenergy
has not been tested in open
KEY WORDS :
kinetic chain; tennis-specific training;technique analysis
Copyright National Strength and Conditioning Association
Strength and Conditioning Journal | www.nsca-lift.org 1
-
stance forehands, it is logical thatvigorous leg drive also
transfersenergy to trunk rotation. Knudsonand Bahamonde (16)
reported non-significant differences in racket pathand speed at
impact between open andsquare stance forehands of tennisteaching
professionals. As stated byRoetert and Reid (20), there are 2things
to remember related to theseforehand stances: (a) open stances
areoften situation specific and (b) bothstances use linear and
angular momen-tum to power the stroke. Situation-specific forehands
refer to the need toproduce different types of forehandsdepending
on where the player is in thecourt, the purpose of the shot
(tactics),amount of preparation time available,as well as where the
opponent is duringthe same scenario. Tennis players needto create
differing amounts of force,spin, and ball trajectories from a
varietyof positions, and this has resulted inadaptations of stroke
mechanics andstances. The most common situationswhere open stance
forehands areapplied include wide and deep ballswhen the player is
behind the baselineor requires greater leverage to producethe
stroke.
Vigorous axial hip and upper-trunkrotation allow for energy
transfer fromthe lower extremity to the upperextremity in the
square stance fore-hand. The upper trunk tends tocounter-rotate
about 90 to 100 fromparallel to the baseline and about 30beyond the
hip in the transverse plane(22) in preparation for the
stroke.Forward axial torque to rotate the hipsachieves its peak at
the initiation ofthe forward stroke (8). Forward rota-tion of the
upper trunk coincides witha lag in the upper extremity resisted
byeccentric muscle actions and large peakshoulder horizontal
adductor andinternal rotation torques (3). Well-coordinated
sequential rotations upthe kinetic chain through the trunkand upper
extremity take advantage ofthe stretch-shortening cycle of
muscleactions.
The forearm flexors and grip muscula-ture are also important in
the tennis
forehand. Not because these musclescreate a great deal of joint
rotation toaccelerate the racket (4) or becausegrip forces increase
ball impulse (13),but because the energy from the lowerbody and
trunk must be transferred tothe racket in the later stages of
thestroke. In fact, the preferred style ofgrip and height of the
ball at impactused by the player significantly affectsthe potential
contribution of thehand/wrist rotation to racket speed(4). The main
kinetic chain motionsthat create racket speed in the fore-hand are
trunk rotation, horizontalshoulder adduction, and internal
rota-tion (4). Modern forehand technique(typically utilizing grips
ranging be-tween eastern and western grips)clearly involves
sequential coordina-tion that takes advantage of stretch-shortening
cycle muscle actions.Training exercises should, therefore,emulate
this sequential coordination,as well as stabilizing
musculature.Following impact in all tennis strokes,the racket and
arm retain the vastmajority of the kinetic energy frombefore
impact, so the eccentricstrength of the musculature active inthe
follow-through should also betrained. Eccentric strength both inthe
upper and in the lower body canassist in maximizing tennis
perfor-mance as well as to aid in the pre-vention of injuries (12).
Particularly, thecatching phase of the medicine ball(MB) tosses in
Figures 47 helps inimproving both upper- and lower-body eccentric
strength.
Figure 1ac show the preparationphase of the open stance
forehand.The players weight transfer from hisright leg to his left
leg (he is lefthanded) shows the horizontal linearmomentum used to
preload the left legfor a stretch-shortening cycle action
toinitiate the stroke. Some of the energystored in this leg is
converted topredominantly upward (vertical linear)momentum but also
forward (horizon-tal linear) momentum. This leg driveutilizes
ground reaction forces and iscritical for linear to angular
momentumtransfer and the development of high
racket speed. In Figure 1df, we can seethe forward swing. The
pronouncedhip and shoulder rotation from Figure1cf is evidence of
the use of angularmomentum. Energy from the left legis transferred
as the hips open up first,followed by the shoulders. The
com-pletion of the swing shows a follow-through in the direction of
the targetuntil well after contact is made fol-lowed by the racket
swinging backover the head as a result of the forcefulrotational
component of the swing.This follow-through, where the
racketactually finishes over the head, is anadaptation that many
players haveimplemented, and although the follow-through is
initially still toward thetarget (Figure 1e), the overall pathwayof
the stroke (Figure 1f ) ending upover the shoulder allows the
playerto impart greater spin on the ball.This adaptation is
partially the resultof technology changes in the tennisracket and
strings allowing for morepower and spin generation resultingin more
margins for error on thestrokes.
ONE-HANDED AND TWO-HANDEDBACKHAND
Training the wrist extensors is partic-ularly important for
tennis playersusing a 1-handed backhand. Torquesabout the wrist in
1-handed backhandsare greater than direct force loading(14) and can
create a rapid stretch ofthe wrist extensors that is more
pro-nounced in players with a history oftennis elbow (17). This is
strongretrospective evidence that trainingof the wrist extensors
and grip maybe useful to reduce the risk of thecommon overuse
injury of the lateralepicondyle.
There are differences in the use of thelegs, trunk, and upper
extremity be-tween the 1- and 2-handed backhands.One-handed
backhands have the hit-ting shoulder in front of the body andrely
less on trunk rotation and moreon coordinated shoulder and
forearmrotations to create the stroke (Figure2af ). Front-leg
extensor torques arelarger in the 1-handed backhandthan the
2-handed backhand (19).
VOLUME 0 | NUMBER 0 | MONTH 20092
Biomechanics of the Tennis Groundstrokes
-
Two-handed backhands have largerextension torques in the rear
leg, whichresult in larger axial torques to rotatethe hips and
trunk than 1-handedbackhands (2,10,19). Greater upper-trunk
rotation has been observed in2-handed backhands than in
1-handedbackhands (19). Note the hip and trunkrotation in the
2-handed backhand(Figure 3af ).
Despite these differences, skilled play-ers can create similar
levels of racketspeed at impact in 1- and 2-handedbackhands (19).
In general, there are2 styles of coordination in 2-handedbackhands.
One essentially involvesstraight arms and 4 major kinetic
chainelements (hips, trunk, shoulder, and
wrist), while the other adds rotationsat the elbow joints
(7,19). Whateverthe technique adopted, the strengthand conditioning
professional shouldwork with the tennis coach to custom-ize
training programs for the specifictechniques used by players.
EXERCISES
Examples are described for forehands(right-handed players), but
they shouldalso be performed on the opposingside to mimic movements
required forbackhand strokes.
MEDICINE BALL DEEPGROUNDSTROKE
The purpose was to train the athlete tomove efficiently to deep
balls behind the
baseline and to be able to producegreater energy transfer from
openstance position that will translate intogreater weight
transfer, trunk rotation,and more effective stroke productionfrom
deep in the court (Figure 4).
The athlete starts on the center servicemark and the
coach/trainer throws theMB about 3 to 5 feet behind and to
theright. The athlete will need to moveback and across quickly to
catch theMB (loading phase) and then whilemaintaining dynamic
balance producea forceful hip turn and throw that willmimic the
muscle contractions andmovements required for a deep de-fensive
forehand stroke (for a right-hander).
Figure 1. (af ) Forehand groundstroke(ac) illustrates the
preparation phase of the open stance forehand, while (df )
illustratesthe forward swing.
Strength and Conditioning Journal | www.nsca-lift.org 3
-
MEDICINE BALL SHORTGROUNDSTROKE
The purpose was to train the athlete tomove forward and in a
balanced fash-ion transfer energy from the lowerextremities (open
or square stance) toweight transfer and hip/trunk rotationfor more
effective stroke production(Figure 5). In Figure 5, the athlete
isdemonstrating a closed stance catchingposition. This movement can
also beperformed using an open stance catch-ing position.
The athlete starts on the center serviceline and the
coach/trainer throwsthe MB about 3 to 5 feet in front andto the
athletes right. The athlete will
need to move forward and acrossquickly to catch the MB
(loadingphase) and then while maintainingdynamic balance produce a
forcefulhip and trunk rotation to throw theMB. This will mimic the
movementand muscles used during a short at-tacking forehand.
MEDICINE BALL WIDE
The purpose was to train the athleteto move sideways and to be
able toproduce greater energy transfer froman open stance position
(Figure 6).This position will produce greaterweight transfer, trunk
rotation, andmore effective stroke production onwide balls.
The athlete starts on the centerservice line and the
coach/trainerthrows the MB about 5 feet to theright of the athlete.
The athlete willneed to move laterally (utilizing eitherthe shuffle
or the crossover step) tocatch the MB (loading phase) and thenwhile
maintaining dynamic balanceproduce a forceful hip and trunkrotation
to throw the MB. Thismovement sequence will mimic themovement and
muscles used in a wideforehand.
MEDICINE BALL WALL OPENSTANCE
The purpose was to develop rotationalhip and core strength in
movement
Figure 2. (af ) One-handed backhand groundstroke(ac) illustrates
the preparation phase of a 1-handed closed stance backhand,while
(df ) illustrates the forward swing.
VOLUME 0 | NUMBER 0 | MONTH 20094
Biomechanics of the Tennis Groundstrokes
-
patterns and planes that are most usedduring tennis strokes
(Figure 7).
The athlete starts about 5 to 8 feetfrom a solid wall and loads
the hips
and core while also putting the
oblique muscles on stretch. From
this loading position (Figure 7 demon-
strates an open stance loading
position), the athlete forcefully
rotates the hip and upper body to
release the MB as hard as possible
against the wall.
Figure 3. (af ). Two-handed backhand groundstroke(ac)
illustrates the preparation phase of a 2-handed open stance
backhand,while (df ) illustrates the forward swing.
Figure 4. Medicine ball deep groundstroke drill.
Strength and Conditioning Journal | www.nsca-lift.org 5
-
CABLE ROTATION IN THETRANSVERSE PLANE
The purpose was to develop rotationalcore strength in the
transverse plane(Figure 8).
The athlete grasps the handle of a cablepulley machine at the
height of thewaist. The athlete takes 3 to 5 stepsfrom the machine
to increase thetension and lowers the body intoa quarter squat
position. From thisposition, the athlete slowly rotatesthrough the
transverse plane as far asthe athletes flexibility allows.
Thismovement is then repeated on theway back to the starting
positionfocused on developing decelerationability in this same
plane of motion.
WRIST ROLLER
The purpose was to increase gripstrength and endurance via
forearmflexion and extension (Figure 9).
The athlete grasps the wrist rollerdevice with both hands at
shoulderheight. The athlete flexes and extendsthe wrist to lower
the weight. Once theweight is lowered as far as possible,the
athlete then flexes and extends thewrist to lift the weight back up
to thestarting position.
WEIGHTED FOREARMPRONATION AND SUPINATION
The purpose was to develop forearmstrength and endurance in
pronationand supination (Figures 10).
Figure 5. Medicine ball short groundstroke drill.
Figure 6. Medicine ball wide groundstroke drill.
Figure 7. Medicine ball wall open stance groundstroke drill.
VOLUME 0 | NUMBER 0 | MONTH 20096
Biomechanics of the Tennis Groundstrokes
-
The athlete places their forearmon a table or bench while
graspinga head heavy instrument (a weightedbar and hammer are both
goodoptions). Figure 10a demonstrates
a forearm pronation movement, andFigure 10b demonstrates a
forearmsupination movement. Both thesemovements are used during
tennisgroundstrokes.
SUMMARY AND APPLICATIONSFOR COACHES
The purpose of this article was to helpcoaches recognize the
unique aspectsof tennis groundstrokes, with specificimplication for
how they can train theirathletes. Again, the 2-fold approach ofthis
article was to help practitionersrealize the types of training that
will (a)improve performance by creating moreforce within muscle
groups, improvecoordination between various bodyparts involved in
each stroke, anddevelop overall power in the athletesstroke
production and (b) developstrength in the various body partsand
across joints that would protectthe athlete from injury.
Practical exercises have been offeredthat will emulate the
stroke coordina-tion to improve the efficiency of strokeproduction
as well as exercises that willimprove the athletes ability to
deceler-ate specific body parts to assist inrecovery after the
execution of thespecific stroke. The exercises denotedin this
article are designed to help thecoach with on-court and
off-courttraining so that various training sitescan be utilized for
effectiveness intraining. For example, MB drills areoffered to help
the athlete, not onlymove and get in position properly but
Figure 8. Cable rotation (in the transverse plane) drill.
Figure 9. Wrist roller drill.
Strength and Conditioning Journal | www.nsca-lift.org 7
-
also to execute the form of the stroke inthe proper pattern.
Coordination ofbody weight transfer is discussed as well.
Finally, there is a demonstration ofhow the legs, hips, and
torso shouldmove in synchrony as well as in-struction on how to
develop coordi-nation so the athlete can utilize thekinetic chain
more effectively. It isanticipated that coaches will be able
toprovide a safer yet more productiveand effective strength
training regimenfor their athletes.
E. PaulRoetert isManagingDirector ofCoachingEducation andSport
Science atthe United States
Tennis Association.
Mark Kovacs isSenior Managerof Strength andConditioning/Sport
Scienceat the UnitedStates TennisAssociation.
DuaneKnudson isChair of thedepartment ofHealth
andHumanPerformance atTexas StateUniversity.
Jack Groppel isco-founder of theHumanPerformanceInstitute.
REFERENCES1. Ariel GB and Braden V. Biomechanical
analysis of ballistic vs. tracking movements
in tennis skills. In: Proceedings of
a National Symposium on the Racquet
Sports. Groppel J, ed. Champaign, IL:
University of Illinois, 1979.
pp. 105124.
2. Akutagawa S and Kojima T. Trunk
rotation torques through the hip joints
during the one-and two-handed backhand
tennis strokes. J Sport Sci 23: 781793,
2005.
3. Bahamonde R and Knudson D. Kinetics of
the upper extremity in the open and square
stance tennis forehand. J Sci Med Sport
6: 88101, 2003.
4. Elliott B, Takahashi K, and Noffal G. The
influence of grip position on the upper
limb contributions to racket-head speed
in the tennis forehand. J Appl Biomech
13: 182196, 1997.
5. Elliott B. Biomechanics of tennis. In:
Tennis. Renstrom AFH, ed. Osney
Mead, Oxford: Blackwell Science, 2002.
pp. 128.
6. Elliott B. Biomechanics and tennis. Br J
Sports Med 40: 392396, 2006.
7. Groppel J. High Tech Tennis (2nd ed.).
Champaign, IL: Human Kinetics, 1992,
107.
8. Iino Y and Kojima T. Torque acting on the
pelvis about its superior-inferior axis
through the hip joints during a tennis
forehand stroke. J Hum Mov Stud
40: 269290, 2001.
9. Iino Y and Kojima T. Role of knee flexion
and extension for rotating the trunk in
a tennis forehand stroke. J Hum Mov Stud
45: 133152, 2003.
10. Kawasaki S, Imai S, Inaoka H, Masuda T,
Ishida A, Okawa A, and Shinomiya K. The
lower lumbar spine moment and the axial
rotation motion of a body during one-
handed and double-handed backhand
stroke in tennis. Int J Sports Med 26:
617621, 2005.
11. Kibler WB. Kinetic chain contributions to
elbow function and dysfunction in
sports. Clin Sports Med 23: 545552,
2004.
12. Kovacs MS, Roetert EP, and Ellenbecker
TS. Efficient deceleration: The forgotten
factor in tennis-specific training. J Strength
Cond Res 30: 5869, 2008.
13. Knudson D. Hand forces and impact
effectiveness in the tennis forehand. J Hum
Mov Stud 17: 17, 1989.
14. Knudson D. Forces on the hand in the one-
handed backhand. Int J Sports Biomech
7: 282292, 1991.
15. Knudson D. Biomechanical Principles
of Tennis Technique. Vista, CA: Racquet
Tech Publishing, 2006. pp. 10.
16. Knudson D and Bahamonde R. Trunk and
racket kinematics at impact in the open and
square stance tennis forehand. Biol Sport
16: 310, 1999.
17. Knudson D and Blackwell J. Upper
extremity angular kinematics of the
one-handed backhand drive in
tennis players with and without
Figure 10. Forearm drill. (a) Pronation (palm down). (b)
Supination (palm up).
VOLUME 0 | NUMBER 0 | MONTH 20098
Biomechanics of the Tennis Groundstrokes
-
tennis elbow. Int J Sports Med 18: 7981,
1997.
18. Knudson D and Elliott BC. Biomechanics
of tennis strokes. In: Biomedical
Engineering Principles in Sports. Hung GK
and Pallis JM, eds. New York, NY: Kluwer
Academic/Plenum Publishers, 2004.
pp. 153181.
19. Reid M and Elliott B. The one- and two-
handed backhand in tennis. Sport Biomech
1: 4768, 2002.
20. Roetert EP and Reid M. Linear and
angular momentum. United States
Tennis Association: High Performance
Coaching Newsletter. 9(3): 58,
2008.
21. Schonborn R. Advanced Techniques for
Competitive Tennis. Achen, Germany:
Meyer and Meyer, 1999. pp. 26.
22. Takahashi K, Elliott B, and Noffal G.
The role of upper limb segment rotations
in the development of spin in the tennis
forehand. J Sci Med Sport 28: 106113,
1996.
Strength and Conditioning Journal | www.nsca-lift.org 9