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Summary: Baseball throw vs. tennis serve injuries

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  • Summary: Baseball throw vs. tennis serve injuries

    Here is a summary of the responses we got to our question concerning the
    differences in injury rates between baseball pitching and tennis
    serving. This question was posted to experts who are not biomch-l
    subscribers as well as the biomch-l list. We are posting all responses
    here. Thanks to everybody who responded.

    Here is the question again:

    "[A friend] has noticed that the frequency of shoulder injuries among
    elite tennis players is way less than that of his elite pitchers, even
    though they all have the same kinematic sequence (serving and pitching
    are virtually the same) and their practice number of serves equals that
    of the pitchers pitch counts. He feels that this may be due to the
    simple fact that the tennis player does not let go of the racquet and
    the pitcher lets go of the ball? Does this explain the stress to the
    arm or is there another main reason? "

    ======================summary or responses=============================

    >From Roger Fredericks:

    I would think that the reason baseball pitchers have more problems than
    tennis players is because ALL of the baseball pitchers throws are
    overhand with the arm being elevated vertically, with much more
    frequency than the tennis player. Yes, the tennis player's serve is
    also overhand (with the arm vertical), but they get more balance from
    the repetitive stress because they're also hitting millions of balls
    with the sidearm motion that they employ in their ground games. I would
    think that as a result of doing both overhand and sidearm motions with
    the shoulder girdle, the tennis player would have less repetitive stress
    on the shoulder girdle than the baseball pitcher, who isn't constantly
    just making overhand deliveries. In either case, I still believe that
    their hips - along with their shoulders - have to become "tamed" after
    their sessions to restore the muscles back to function,

    That's my theory.

    >From David Ostrow:

    I wonder if it has something to do with the centrifical vs. centripetal
    force differences that holding a racquet and releasing of a
    there any data on these forces on the rotator cuff at the moment of
    release or impact? Somehow, that seem to me to be the plausible
    explanation. There could be extra long axis stress on the rotator cuff
    via the distraction of the humerus, that I envision upon releasing a
    ball vs. the recoil and weight that a racquet puts on the shoulder in
    terms of centripetal forces....

    I suppose high speed filming could help visualize if there were more LAD
    on the humerus with pitching vs. tennis.

    Is it also possible that even though the kinematic sequences are the
    same that the actual motion and loading are not...

    >From Peter Mackay:

    Initially it seems that the release of the ball requires more eccentric
    counter-force with the rotator cuff but let's look a little deeper!

    >From Mike Boyle:

    1- Tennis players are not going downhill ( the mound and the downhill
    action increases the loads and correspondingly increases the eccentric
    force needed to decelerate.
    2- Tennis players hit backhand as well as forehand. This may act to
    strengthen the posterior musculature in a way that a pitcher could not.

    Just two thoughts.

    >From Randy Myers:

    Does the weight of the racquet equal the weight of a baseball? I'm not
    sure, but all of the tennis pros I trained had well developed shoulder
    muscles on their serving arm - I assumed it was because they were
    carring around a racquet and overtime it served a like a light weight
    and got them stronger.

    Baseball pitchers develop skills at a similar age, but aren't lifting a
    racquet (weight) overhead on a frequent basis. I also think he's onto
    something with releasing the ball. Although the shock of hitting a
    tennis ball may increase the stability of the shoulder joint. Just some
    of my thoughts.

    >From Ramsay McMaster:

    I think it has a lot to do with position of the cervical spine and head
    righting reflexes
    ps plus triceps proprioceptive conrtol

    >From Dr. Byrd:

    For pitchers, the difference may be the mound. Adding the gravity force
    of the body to the velocity pushes the shoulder close to the point of
    breakdown (or beyond... oops!). That is partly why they need four days
    to recover between outings, unless they see limited pitches as a
    reliever. Every day position players may have shoulder problems more
    comparable to what is seen in tennis. I am not sure, but I could check
    the stats with some of the ATP docs, if you like.

    The idea of less deceleration is intriguing. Since the time interval
    for deceleration is much shorter than acceleration, the force curve is
    much steeper, explaining some of the rotator cuff injuries that occur
    due to tensile failure during the deceleration phase of throwing, as it
    contracts eccentrically to slow the arm. In tennis deceleration is
    largely accomplished by contact with the ball. Of course, it is not
    that simple, but may be partial plausible reasoning on the subject.

    >From Paul Hurrion:

    Despite the kinematic sequence (serving and pitching being the same) and
    their practice number of serves equals that of the pitchers pitch
    counts, the key issue is how the arm decelerates in order to create the
    power in the throw or delivery. The same situation can be said for
    Javelin (injury prone) and Hammer throwers. Despite the hammer being
    heavier (Hammer 7.5kg - Javelin 800gm) there are no shearing forces at
    play during the activity. It is these shearing forces that rip the body
    apart and do the damage. Hammer throwers release the hammer whilst in
    motion and often air-borne. There are no deceleration forces in the
    shoulder joints during release, hence they can throw and throw and throw
    and do very little damage to there body. However, the Javelin release is
    very similar to baseball, it is the stabilization required to aid the
    deceleration of the shoulder joints that creates the force to propel the
    800gm javelin that creates the strain... A tennis player swings though
    the ball, not at it, again like the Hammer thrower with very little
    deceleration in the shoulder joint. They are often air-borne at the
    point of contact.

    >From Gray Cook:

    A few questions came to mind since it sounds like the work load is the
    same. I wonder about the frequency between pitches and serves. Pitches
    are successive in longer packages than serves. There is also lots of non
    overhead activity between each package of serves. I also wonder about
    arm speeds - are they equal?

    I totally think that Tom's observation has some merit. At first glance I
    thought there might be something else but then I started thinking about
    neurological stuff. Check this out:

    Since the tennis player continues to hold onto the racquet and the
    centrifugal force on the racquet increases in the arc - a few things
    happen that could cause significant "automatic" protection to the
    shoulder of the tennis player that my not be afforded to the pitcher.

    1) The traction created by holding the racquet my create a reflex
    stabilization effect on the scapular stabilizers and cuff muscles. Both
    compression and traction stimulate the joint receptors creating enhanced
    reflex stability within skeletal muscle stabilizers.

    2) The need to hold onto the racquet and the increased traction force on
    the racquet in the arc cause a reflex response in the grip. The reflex
    grip activation my stimulate improved shoulder stability. Over gripping
    is often used in weight training to increase strength and stability
    (atomically). We often see grip strength reduced in compromised shoulder
    positions and assume it is some kind of reflex inhibition. The same
    thing may occur with reflex stimulation of the grip causing some form of
    facilitation in tennis that cannot occur with a pitch.

    3) Basically a complete release (pitching) my be more stressful to the
    shoulder than an incomplete release (tennis). In tennis the load of the
    ball is released but the load of the racquet is maintained and may also
    assist in help with deceleration.

    One or all three of these my serve to help the tennis player - Pardon
    the pun!

    >From Dave Donatucci:

    I have reviewed this question with some of the tennis coaches at the
    academy and have an answer.

    First according to one of the coaches he does not feel the incidence of
    injury is less. He feels there are a lot of overuse injuries on the

    second the motion of the serve (Biomechanic if you will) is differnt
    than a pitcher. The new pattern of serving is similar to throwing a
    baseball or football straight up in the air. Meaning shoulders are on a
    60 degree plane with the lead shoulder facing upward (trophy pose), the
    hand with the racquet is scratching the back of the person, and upon
    hitting the ball the racquet hand is pronated and the racquet is dropped
    downward pinting to the ground. Of course the body moves as well but the
    shoulder movement is again almost an upward motion, with a racquet drop
    at the top and excessive pronation of the hand. The upper arm does not
    create the torque or stress on the Ulnar collateral ligament as that of
    a pitcher because the hand stays above the shoulder and is not bent
    behind the body. The upper arm stays at 90 degrees.

    The main differnce is that the arm in tennis finishes above the head and
    the body lowers it back to the ground, if done correctly. wheras in
    pitching the shoulder musculature has to decelerate the arm.

    >From Rob Mottram:

    Pitching vs tennis shoulder injuries.

    Trying to think about what the differences are between the motions even
    though 3D shows they're fairly similar. Dr. Jobe has EMG activity for about the tennis serve?

    Other thoughts...

    1. Tennis players don't ONLY serve... whereas pitchers repeatedly do
    the same motion. So, I would guess it's a frequency - over use issue.
    2. Does striking the tennis ball with a racquet help slow the arm down,
    vs the stress and strain of the deceleration of the arm after releasing
    the ball, making it lighter, being hard on the posterior shoulder?

    3. How about throwing down hill from a mound vs the tennis player being
    off the ground and swing slightly upward...making it not gravity


    The following responses are from BIOMCH-L - the biomechanics and
    movement sciences listserve

    Arnel Aguinaldo MA ATC
    Director, Center for Human Performance
    Assistant Professor, Biomechanics
    Department of Exercise and Nutritional Sciences San Diego State

    This is a very interesting question that I've been asked many times.
    Although we've studied hundreds of pitchers, we have yet to study the
    tennis serve so my answer here is partially anecdotal and is my no means

    As you mentioned, the kinematic sequences between the tennis serve and
    baseball pitch are very similar. In fact, you can make the argument that
    most athletic movements that require a sequence of bodily rotations (ie,
    soccer kick, football pass, tennis serve, baseball pitch, etc.) have one
    common denominator, which is the transfer of momentum from one segment
    to another is needed to produce a net effect (ie, throw the ball, serve
    the racquet). Some have quoted the "summation of speed" principle to
    describe this behaviour, albeit a bit oversimplified, in my opinion.

    However, in observing the tennis serve vs. a baseball pitch, there are a
    couple ofvmechanical differences, despite their similarities, which
    could explain thevdiscrepency in injury rates. One obvious difference is
    the mound on which avpitcher has to throw the ball. The regulation mound
    is 10"
    off the ground
    and can play significant role in influencing potentially injurious
    stresses at the shoulder and elbow. Although there is currently limited
    data on the relationship of joint stress vs. mound height, it is
    theoretically possible that raising the height and slope at which the
    player delivers a pitch can cause higher rotational torques compared to
    that of flat-ground throwing.
    The kinematic sequence surronding a pitch is initiated by front foot
    contact, in which the reaction force created by the front leg landing on
    the front of the mound either from the wind-up or the stretch kicks
    start the chain of angular momentum transferring up the body through the
    pelvis, trunk, arm, and ultimately, the ball. Since this reaction force
    is the net sum of gravitional and transient forces, the height at which
    the pitcher "falls" down the mound will partially define the potential
    energy that kicks starts this kinematic sequence.

    Another notable difference is that the axis about which the trunk and
    the arm rotates during a pitch differs to that of the tennis serve. For
    the sake of argument, most pitchers with a 3/4 arm slot or lower rotate
    their trunks about an axis perpendicular to the transverse plane whereas
    tennis players serving primarily rotate about an axis perpendicular to
    the sagittal plane. In our most recent MLB study, we found that players
    with lower arm slots (ie, sidearm deliveries) exhibited higher valgus
    loads at the elbow, even with less elbow flexion, compared to those with
    3/4 or overhand arm slots. As a side note, it's been previously
    suggested that pitchers who kept their arms "straighter" typically were
    less prone to elbow valgus injuries. While it would seem that less elbow
    flexion would reduce the moment arm about the long axis of the humerus
    (and perhaps subsequently minimize elbow valgus loading), the moment arm
    about the trunk's axis of rotation as it squares up increases with elbow
    extension, causing a bending moment at the arm that peaks in the early
    part of acceleration, particularly in deliveries with lower arm slots.
    Since a tennis player would be less likely to serve in the same plane of
    rotation as a pitcher, I imagine he/she would be less prone to the same
    stresses, both in magnitude and loading rate, at the arm as a baseball
    pitcher. (And I played on my JV tennis team in high school so I would
    know!). However, it would be interesting to comparatively study the
    mechanics of the two to substantiate or refute this notion.


    >From John Dewitt:

    I don't think that tennis players snap their wrists like a pitcher
    throwing a curveball - this snapping motion should place more stress on
    the elbow and shoulder

    From: Maggie Mae Zerger:

    Tennis players hit forehand and backhand. This allows for posterior
    development that is lacking in throwing overarm athletes. Overarm
    athletes have imbalanced shoulders caused by hyper anterior development
    and weak posterior development.

    >From Gordon J. Alderink, PT, PhD:
    Associate Professor
    College of Health Professions
    Program in Physical Therapy
    Grand Valley State University

    Of course, we can speculate "till the cows come home"'s possible
    there are fewer shoulder injuries in tennis because they are generating
    torques with an instrument that has a sizable mechanical advantage.

    >From Glenn S. Fleisig, Ph.D., Smith & Nephew Chair of Research American
    Sports Medicine Institute:

    I am out of the office on vacation, so I am doing this from memory. My
    colleagues and I have compared the biomechanics of the tennis serve to
    the baseball pitch. Here are the citations:

    Elliott B, Fleisig, R, Nicholls R, Escamilla R. Technique effects on
    upper limb loading in the tennis serve. Journal of Science and Medicine
    in Sports 6(1):76-87, 2003

    Fleisig GS, Nicholls RL, Elliott BC, Escamilla RF. Kinematics used by
    world class tennis players to produce high-velocity serves. Sports
    Biomechanics 2(1):17-30, 2003

    As I recall, the tennis serve has greater ball velocity, but less
    shoulder rotational velocity and torque. I believe that the less
    velocity was due to the substantial extra inertia in the distal segment
    of the kinetic chain. In other words, the tennis racquet is, in a
    sense, an extension of the hand. The tennis player has far more inertia
    than the baseball player does in resisting wrist flexion, but the
    increased distance of the segment produces greater linear velocity (of
    the tennis racquet head, compared to the pitcher's finger tips).

    That's the best I can do for now. Happy Holidays,

    - Glenn

    >From Michael Feltner:

    don't know that we have a complete answer to this question based on the
    literature and research. My hunch is that baseball is unique in that
    the pitcher must decelerate his/her arm after release and bring its
    velocity to zero using his/her own musculature, ligaments, etc. In
    volleyball, tennis, or other "overarm" striking sports, the impact from
    the arm/racquet contact with the ball provides a force that slows the
    rotation and velocity of the arm and prevents the muscles/tissues of the
    performer from providing all of the forces necessary to stop the arm's
    movement. While injuries will always be multifactorial in nature, the
    combination of the rapid rates of elbow extension and shoulder internal
    rotation coupled with the need to stop these movements after release
    primarily by eccentric actions of the elbow flexors and external
    rotation muscles at the shoulder, respectively, likely increases the
    injury risk in baseball compared to other sports with a similar movement

    Just my $0.02

    >From Adam J. Bartsch, M.S.
    Cleveland Clinic Spine Research Laboratory:

    One would suppose the much larger weight of the baseball (145g vs. 55g)
    and ball rotation induced by the hand-elbow-shoulder as opposed to
    racquet angle would create more torsional and shearing stress on the
    shoulder and elbow joints to the baseball pitcher.

    One would also question the statement "...even though they all have the
    same kinematic sequence (serving and pitching are virtually the
    same)..." as being valid? It seems as though this might be an overly
    broad statement to apply to two very complicated kinematic operations.


    >From Michael Yessis, Ph.D
    Professor Emeritus, CSUF
    President, Sports Training, Inc.:

    I believe a comparison between the baseball pitch and tennis serve is
    not 100% possible. The same kinetic change is involved for the basic
    body movements, with differences in speed and amount of joint action,
    etc., but the arm actions can be very different.

    For example, in the tennis serve, the arm is extended overhead and is
    fully straightened when contact is made. In baseball pitching, we do
    not see the same position. The ball is usually released with a bent
    elbow or with an extended arm more to the side of the body rather than

    The tennis serve is more limited in regard to wrist and forearm actions,
    usually flexion and pronation, while in the baseball pitch, we see these
    two actions in the fastball. But when throwing other kinds of pitches,
    there may be ulna flexion or variance of wrist flexion (and in some
    pitchers, supination).

    Thus, to determine which actions cause shoulder injury, it is necessary
    to study more closely the exact position and wrist and forearm actions
    that occur. For example, I have found that most shoulder injuries in
    the tennis serve occur when contact is made with a bent elbow. While
    in the baseball pitch, most shoulder/elbow injuries seem to occur when
    slinging the ball more out to the side rather than overhead.

    ===============end of summary======================