Download Biomechanical Comparison of Baseball Pitching and Long

[
research report
]
GLENN S. FLEISIG, PhD1 • BECKY BOLT, MS2 • DAVE FORTENBAUGH, MS3
KEVIN E. WILK, DPT4 • JAMES R. ANDREWS, MD5
Biomechanical Comparison of Baseball
Pitching and Long-Toss: Implications
for Training and Rehabilitation
F
ollowing a shoulder or elbow injury or surgery, a baseball
pitcher or position player must progress through a
multiphase rehabilitation program to return to competition.
Such programs often begin with exercises to restore range
of motion and strength of the affected joint, followed by more
functional and aggressive rehabilitation exercises. The latter
phases incorporate functional exercises, such as plyometrics and highspeed training, to prepare the player
TTSTUDY DESIGN: Controlled laboratory study.
TTOBJECTIVES: To test for kinematic and kinetic
differences between baseball pitching from a
mound and long-toss on flat ground.
TTBACKGROUND: Long-toss throws from flat
ground are commonly used by baseball pitchers
for rehabilitation, conditioning, and training. However, there is controversy over the biomechanics
and functionality of such throws.
TTMETHODS: Seventeen healthy, college baseball
pitchers pitched fastballs 18.4 m from a mound
to a strike zone, and threw 37 m, 55 m, and maximum distance from flat ground. For the 37-m and
55-m throws, participants were instructed to throw
“hard, on a horizontal line.” For the maximumdistance throw, no constraint on trajectory was
given. Kinematics and kinetics were measured
with a 3-dimensional, automated motion analysis
system. Repeated-measures analyses of variance,
with post hoc paired t tests, were used to compare
the 4 throw types within pitchers.
TTRESULTS: At foot contact, the participant’s
shoulder line was nearly horizontal when pitching
The interval throwing program starts skeletally mature
players at a throwing distance of
45 ft (14 m) and progressively increases it to 180 ft (55 m).3,22 For
all flat-ground throws, the player is verbally instructed to use
“crow-hop” footwork, to throw
SUPPLEMENTAL
VIDEO ONLINE
to throw. An interval long-toss
“on a line” (a hard throw with a
throwing program is the halllow trajectory), and to use proper
mark of the return-to-activity phase.28,29 mechanics.3,22,28,29 The use of proper mechanics—the mechanics used by healthy
players—is a critical aspect of the interfrom a mound and became progressively more
val throwing program. It has been suginclined as throwing distance increased. At arm
gested that pitching coaches and sports
cocking, the greatest amount of shoulder external
biomechanists provide a valuable service
rotation (mean  SD, 180°  11°), elbow flexion
on a rehabilitation team to ensure proper
(109°  10°), shoulder internal rotation torque
mechanics.22 Thus an understanding of
(101  17 Nm), and elbow varus torque (100  18
Nm) were measured during the maximum-distance
healthy throwing mechanics is essential
throws. Elbow extension velocity was also greatest
for the rehabilitation of an injured player.
for the maximum-distance throws (2573°/s 
If the player is a pitcher, the flat-ground
203°/s). Forward trunk tilt at the instant of ball
throwing phases of the rehabilitation
release decreased as throwing distance increased.
program are followed by throwing off
TTCONCLUSION: Hard, horizontal, flat-ground
the mound. During the off-the-mound
throws have biomechanical patterns similar to
throwing phase, a pitcher progresses
those of pitching and are, therefore, reasonable
from partial-effort to full-effort pitches.
exercises for pitchers. However, maximum-distance
Theoretically, the progression of throwthrows produce increased torques and changes in
ing phases allows an injured athlete
kinematics. Caution is, therefore, advised in the
to gradually recover his arm flexibility,
use of these throws for rehabilitation and training.
arm strength, and proper throwing meJ Orthop Sports Phys Ther 2011;41(5):296-303,
chanics. 3,22,28,29 Interval throwing proEpub 5 January 2011. doi:10.2519/jospt.2011.3568
grams have been utilized to effectively
TTKEY WORDS: crow-hop, elbow, interval throwing
return pitchers and position players to
program, kinematics, shoulder
baseball.28
Research Director, American Sports Medicine Institute, Birmingham, AL. 2Biomechanist, American Sports Medicine Institute, Birmingham, AL. 3Biomechanist, American Sports
Medicine Institute, Birmingham, AL. 4Associate Clinical Director, Champion Sports Medicine, Physiotherapy Associates, Birmingham, AL. 5Medical Director, American Sports
Medicine Institute, Birmingham, AL. This study was approved by the Institutional Review Board of St Vincent’s Health System, Birmingham, AL. The authors have no financial
affiliation (including research funding) or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript. Address
correspondence to Dr Glenn S. Fleisig, Research Director, American Sports Medicine Institute, 833 St. Vincent’s Drive, Suite 100, Birmingham, AL 35205. E-mail: [email protected]
1
296 | may 2011 | volume 41 | number 5 | journal of orthopaedic & sports physical therapy
41-05 Fleisig.indd 296
4/20/2011 2:15:19 PM
Flat-ground throwing is also used
to improve strength and conditioning
of healthy baseball players, especially
pitchers. Theoretically, long-distance
flat-ground throwing would require the
pitcher’s arm to generate greater force,
torque, range of motion, and speed than
pitching would. Therefore, long-distance, flat-ground throwing may be used
to train a pitcher to have greater arm
strength, arm flexibility, arm speed, and
ultimately pitch speed. Throwing programs for healthy players vary greatly.
Some programs limit throws to a specific
distance (55 m, for example), while others include maximum-distance throws.
Some programs require the players to
throw on a line, while others recommend
throwing on an arc.
Flat-ground throwing has been part
of baseball rehabilitation and conditioning for decades. Recently, however, some
have asked whether flat-ground throwing might be ineffective or even harmful
for baseball pitchers and position players. There has also been controversy over
limitations on throwing distance. While
pitching biomechanics has been studied
extensively, little is known about longtoss throwing biomechanics. In the only
previous study on long-toss baseball
throwing, Miyanishi et al20 compared
the kinematics of 24 college baseball
players throwing a ball on a horizontal
line as fast as possible against throwing a ball as far as possible. No previous
study has compared the biomechanics
of flat-ground throwing and pitching.
Therefore, it is still not known whether
baseball pitchers use similar kinematics and kinetics during long-toss and
pitching. Thus, the theoretical benefits
of long-toss for pitchers remain unsubstantiated. The purpose of this study
was to compare the biomechanics of
pitching and long-toss throwing. The
present study tested the hypotheses
that there are kinematic (motion) and
kinetic (torque and force) differences
in the throwing shoulder and elbow
between pitching and throwing various
flat-ground distances.
FIGURE. (A) Collection of long-toss data. (B) Collection of pitching data.
METHODS
P
itchers from 3 college baseball
teams were recruited for the study.
Players who had been injured during
the previous 12 months and those who
pitched with sidearm or “submarine” mechanics were excluded. Seventeen baseball pitchers met the criteria and agreed
to participate. All participants were experienced with long-toss, as all 3 colleges
used long-toss in their conditioning and
warm-ups. Each participant completed
an informed consent form and provided
medical history, physical information,
and baseball background. The pitchers
were (mean  SD) 20.6  1.2 years of age
and 186  6 cm in height, and had a mass
of 89  10 kg. The study was approved by
The Institutional Review Board of St Vincent’s Health System, Birmingham, AL.
Each participant was tested during 2
sessions. For each session, 21 reflective
markers (10 mm in diameter) were attached to the participant. This included
markers attached bilaterally to the distal
end of the third metatarsal, lateral malleolus, lateral femoral epicondyle, greater
trochanter, lateral superior tip of the acromion, lateral humeral epicondyle, and
journal of orthopaedic & sports physical therapy | volume 41 | number 5 | may 2011 | 297
41-05 Fleisig.indd 297
4/20/2011 2:15:21 PM
[
research report
]
TABLE 1
Comparison of Position Data Among Throws*
Fastball Pitch (18.4 m)
37-m Throw
55-m Throw
Maximum-Distance Throw
(80 ± 9 m)
Differences
Foot contact
Elbow flexion
78  17
79  18
79  18
86  20
Shoulder external rotation
53  30
56  28
60  28
58  26
Shoulder abduction
96  10
98  10
99  10
98  9
Shoulder horizontal abduction
21  11
19  12
19  11
21  11
Upper trunk tilt
6  7
13  9
15  8
24  8
Pelvis angle
37  12
37  11
39  11
40  11
Front knee flexion
47  9
46  8
44  7
42  6
Stride length, % participant's height
80  4
79  6
80  6
80  7
Foot position, cm
25  12
16  14
13  15
5  18
c,e,f†
a,b,c,d,e,f†
b,c,d,e†
a,b,c,d,e,f†
Arm cocking
Maximum elbow flexion
101  11
103  10
104  11
109  10
c,e,f†
Maximum shoulder external rotation
174  10
174  10
176  10
180  11
c,d,e,f†
17  6
18  7
18  7
17  7
Maximum shoulder horizontal adduction
Ball release
Shoulder abduction
88  7
89  9
89  9
88  8
Forward trunk tilt
34  8
27  8
25  7
18  8
Lateral trunk tilt
25  8
24  8
24  8
26  7
Front knee flexion
37  13
36  12
33  13
31  12
a,b,c,d,e,f†
b,c,d,e,f†
*Values are mean  SD degrees, except where otherwise indicated.
†
Analysis of variance revealed significant difference among throws (P<.01). Post hoc t tests indicated significant differences between (a) pitch and 37-m throw,
(b) pitch and 55-m throw, (c) pitch and maximum-distance throw, (d) 37-m and 55-m throws, (e) 37-m and maximum-distance throws, and ( f ) 55-m and
maximum-distance throws.
ulnar styloid. Additional markers were
placed on the medial humeral epicondyle, radial styloid, and dorsal surface of
the hand on the throwing extremity. Four
markers were attached to a baseball hat
on the front, back, top, and right sides
of the head. The reflective markers were
tracked with an 8-camera automated motion capture system (Eagle System, Motion Analysis Corporation, Santa Rosa,
CA). Ball velocity was measured by a
Stalker Sport radar gun (Stalker Radar,
Plano, TX).
For the first testing session, the motion capture system was set up in the
outfield of a college baseball field. The 8
cameras were arranged in a ring around
a designated throwing area. Because the
motion capture system could not properly filter out sunlight, data collection
for this session occurred at night under
artificial stadium lighting (FIGURE). Pilot
testing confirmed that the marker track-
ing in this outdoor setup was reliable and
the calibration coefficients were similar
to values recorded during indoor testing.
Distances were measured and marked
from the throwing area. The x-axis was
the direction of throwing, the z-axis was
the vertical axis, and y was their cross
product (z × x). Participants wore tight
shorts, socks, and cleats. Reflective markers were attached to a pair of participants,
who, by throwing to each other, took as
much time as they needed to warm up.
The pair started by throwing close to each
other and progressively increased their
distance apart, until they were throwing near their maximum distance. Each
participant was then tested for five 37-m
(120-ft), five 55-m (180-ft), and 5 maximum-distance throws to a coach. Each
pitcher completed a total of 15 throws (5
throws at 3 distances), which provided a
sufficient sample of data, without allowing the second pitcher in the pair to cool
down while waiting his turn to be tested.
Each participant was allowed to use the
crow-hop footwork that he was comfortable with, as there is no description of
crow-hop footwork in the published literature, and coaches, physical therapists,
and athletic trainers have given varied
opinions. While most agree that crowhop footwork is a sequence of steps of the
front foot, back foot, then front foot, there
is no consensus on whether the back foot
steps behind, in front, or next to the front
foot. The participant was instructed to
throw “hard, on a horizontal line,” when
performing the 37-m and 55-m throws.
The participant was told to get the maximum distance on his final 5 throws, with
no constraints on trajectory.
The second testing session took place
in an indoor biomechanics laboratory.
The 8 cameras were mounted on the walls
surrounding a portable pitching mound
(FIGURE, ONLINE VIDEO). A home plate strike
298 | may 2011 | volume 41 | number 5 | journal of orthopaedic & sports physical therapy
41-05 Fleisig.indd 298
4/20/2011 2:15:22 PM
TABLE 2
Comparison of Peak Velocity Data Among Throws*
Maximum-Distance Throw
Fastball Pitch (18.4 m)
37-m Throw
55-m Throw
(80 ± 9 m)
Differences
Pelvis angular velocity, °/s
568  67
586  69
602  73
621  84
a,b,c,d†
Upper trunk angular velocity, °/s
1120  99
1141  100
1153 99
1179  98
a,b,c,d†
Shoulder internal rotation velocity, °/s
7640  1173
7590  1214
8139  1609
80401211
Elbow extension velocity, °/s
2480  255
2492  204
2540  176
2603  164
37  2
37  2
37  2
36  2
Ball velocity, m/s
b,c†
*Values are mean  SD.
†
Analysis of variance revealed significant difference among throws (P<.01). Post hoc t tests indicated significant differences between (a) pitch and 55-m throw,
(b) pitch and maximum-distance throw, (c) 37-m and maximum-distance throw, and (d) 55-m and maximum-distance throw.
zone was placed 18.4 m (60.5 ft) from the
pitching rubber. Participants wore tight
shorts, socks, and athletic shoes. Reflective markers were attached to each participant, and each was allowed the time
he needed to warm up. The participant
then threw 10 maximum-effort fastball
pitches for data collection. Because players warmed up individually before testing,
there was no risk of a warmed-up player
cooling down while waiting to be tested.
Twenty-five parameters (16 position, 5
velocity, and 4 kinetic values) were calculated for each trial, according to methods
previously described.5-10,14,16,17,19,25 Nine position parameters were measured at the
instant of foot contact: elbow flexion,
shoulder external rotation, shoulder abduction, shoulder horizontal abduction,
upper trunk tilt, pelvis angle, front knee
flexion, stride length, and foot position.
Upper trunk tilt was defined as the angle
between a line through the 2 shoulder
joints and the horizontal plane. Pelvis angle was the angle between a line through
the 2 hips and the x-axis. Stride length
was the distance between the rear ankle’s
location when the front leg was lifted to
its maximum height and the front ankle’s
location when the front foot landed. (For
a right-handed pitcher, his “rear ankle”
is his right ankle.) Foot position was the
distance between the back ankle when it
was against the pitching rubber and the
front ankle at the time of foot contact, in
the y direction. Three position parameters were calculated when the arm was
cocked back: maximum elbow flexion,
maximum shoulder external rotation,
and maximum shoulder horizontal adduction. The other 4 position parameters
were measured at the time of ball release:
shoulder abduction, forward trunk tilt,
side trunk tilt, and front knee flexion.
Forward trunk tilt was the angle between
the spine (measured as the line from the
mid-hips to the mid-shoulders) and the
z-axis, projected in the xz-plane. Lateral
trunk tilt was the angle between the spine
and the z-axis, projected in the yz-plane.
Maximum values of pelvis angular velocity, upper trunk angular velocity, elbow
extension velocity, shoulder internal rotation velocity, and ball velocity were computed. Pelvis and upper trunk velocities
were measured by their rotations in the
global reference frame. Elbow and shoulder velocities were computed as the rate
of change of the joint angle.
Maximum values for elbow and shoulder kinetics were computed. Values were
reported as the force, or torque, applied
by the proximal segment onto the distal
segment at the joint. Though this convention was the opposite of that reported in a
few previous papers,2,23,26 it was consistent
with most studies.1,5-9,14-19,25,30 Maximum
values were reported for elbow varus
torque and shoulder internal rotation
torque when the arm was cocked, and for
elbow flexion torque and shoulder proximal force near the time of ball release.
For each participant, mean values
were computed for each throw type:
pitching, 37 m, 55 m, and maximum distance. The differences among mean val-
ues for the 4 throw types were analyzed
for each parameter with a repeatedmeasures analysis of variance (ANOVA).
When the ANOVA revealed a significant
difference, post hoc paired t tests were
performed among the throw types. To
protect against type I error, an alpha level
of .01 was used for all statistical analyses.
RESULTS
T
he mean  SD value for the maximum-distance throw among the 17
participants was 80  9 m (262 
30 ft) and the range was 65 to 96 m (213315 ft). Differences in position parameters
are shown in TABLE 1. There were 4 significant differences at the instant of foot
contact: elbow flexion was greatest for the
maximum-distance throw, and, as throwing distance increased from pitching to
maximum distance, upper trunk tilt increased, while front knee flexion and foot
position decreased. When the arm was
in the cocked position, elbow flexion and
shoulder external rotation were greatest
for the maximum-distance throw. At the
time of ball release, as throwing distance
increased, both forward trunk tilt and
front knee flexion decreased.
Differences in velocity parameters are
shown in TABLE 2. The pelvis and upper
trunk rotational velocities were greatest for the maximum-distance throw.
They were also significantly greater in
the 55-m throws compared to the pitch.
The elbow extension velocity was significantly greater for the maximum-distance
journal of orthopaedic & sports physical therapy | volume 41 | number 5 | may 2011 | 299
41-05 Fleisig.indd 299
4/20/2011 2:15:23 PM
[
research report
]
TABLE 3
Comparison of Joint Forces and Torques Among Throws*
Fastball Pitch (18.4 m)
37-m Throw
55-m Throw
Maximum-Distance Throw
(80 ± 9 m)
Differences
Arm cocking
Elbow varus torque, Nm
92  19
90  18
95  19
100  18
a,b,c†
Shoulder internal rotation torque, Nm
94  18
92  17
96  18
100  18
a,b,c†
Ball release
Elbow flexion torque, Nm
47  5
47  8
47  8
48  8
Shoulder proximal force, N
1172  159
1087  184
1139  202
1092  129
*Values are mean  SD.
†
Analysis of variance revealed significant difference among throws (P<.01). Post hoc t tests indicated significant differences between (a) pitch and maximumdistance throw, (b) 37-m and 55-m throws, and (c) 37-m and maximum-distance throws.
throws compared to both the pitch and
the 37-m distance throw. No significant
differences were detected among throw
types in ball velocity.
Differences in joint forces and torques
are shown in TABLE 3. Peak elbow varus
torque and peak shoulder internal rotation torque were both greater in the maximum-distance throw than in the fastball
pitch and 37-m throw. These torques
were also greater in the 55-m throw than
in the 37-m throw.
DISCUSSION
T
he data supported the hypotheses that there are kinematic and
kinetic differences among the 4
throw types tested: pitching (18.4 m)
from a mound, flat-ground throwing on
a horizontal line at relatively short (37
m) distance, flat-ground throwing on a
horizontal line at medium (55 m) distance, and flat-ground throwing at long
(maximum) distance. As throwing distance increased, the player used a more
inclined (more upward trunk tilt) position at foot contact. Also, as throwing distance increased, the player seemed to rely
less on rotation in the sagittal plane (less
forward trunk tilt and less knee flexion)
and more on rotation in the transverse
plane (greater pelvis angular velocity,
upper trunk angular velocity, elbow flexion, and elbow extension velocity). Longer throws also produced greater elbow
and shoulder torques in the arm-cocked
position. The greater rotations in the
transverse plane might have been caused
by the greater arm-cocking torques; but
this cause-and-effect relationship was beyond the focus of the current study. There
were a greater number of significant differences between the maximum-distance
throws and the other throws.
The pitching biomechanics of the current study was consistent with previously
published college pitching data.1,11,16,17,26
Flat-ground biomechanics in the current
study showed some of the patterns found
by Miyanishi et al.20 At the time of foot
contact, both studies found significantly
greater (7°) elbow flexion for the maximum-distance throws compared to the
other long-toss distances but no difference in shoulder abduction between the
distances. During the arm-cocking phase,
each study found that maximum shoulder
external rotation significantly increased
as the throwing distance increased. However, the magnitude of this increase was
noticeably greater in the Miyanishi et al20
study than in the current study (13° versus 4°, respectively). At the time of ball
release, each study reported less forward
trunk tilt (15° in the Miyanishi et al20
study and 7° in the current study) for the
maximum-distance throws. In addition,
Miyanishi et al20 also reported that, at
ball release, maximum-distance throws
had less shoulder abduction (24°) and
greater lateral trunk tilt (9°), while the
current study did not find significant differences for these parameters.
Elbow Injury Mechanisms and
Rehabilitation
Previous studies have shown that maximum elbow varus torque in pitching occurs near the time of maximum shoulder
external rotation and that this torque
is associated with maximum tensile
force in the ulnar collateral ligament
(UCL).14,21,27 Repetition of high force
in the UCL associated with high varus
torque can lead to gradual attenuation
of the UCL.2,18 Thus the progression of
throwing phases during rehabilitation
after UCL surgery should allow the athlete to regain his pitching mechanics,
while progressively loading the UCL
graft. Because the greatest elbow varus
torque occurred during maximum-distance throwing, these throws should be
avoided following UCL reconstruction
or at least delayed until the clinician has
found that the UCL graft has adequately
healed. Similarly, caution is advised for
maximum-distance throwing in rehabilitation following chondral defects in
the lateral elbow, as varus torque is associated with compressive force between
the radial head and the capitellum.14,23,27
Osteophytes in the posteromedial elbow
result from varus torque during rapid elbow extension.2,14,27 Because maximumdistance throws exhibited both the
greatest varus torque and the greatest
elbow extension velocity, such throws
should not be used early in rehabilitation after posteromedial osteophyte
removal.
300 | may 2011 | volume 41 | number 5 | journal of orthopaedic & sports physical therapy
41-05 Fleisig.indd 300
4/20/2011 2:15:25 PM
Shoulder Injury Mechanisms and
Rehabilitation
During arm cocking, a pitcher’s shoulder
is abducted, horizontally abducted, and
externally rotated. These motions produce tension in the shoulder’s anterior
capsule.15,27 The current study reported
no differences in abduction or horizontal
abduction among the different throws;
however, there was increased maximum
shoulder external rotation for maximumdistance throws. Maximum-distance
throws also produced the greatest internal rotation torque, which occurred near
the time of maximum shoulder external
rotation. Because of the increased shoulder external rotation and shoulder internal rotation torque, maximum-distance
throwing should be avoided or delayed
in rehabilitation after procedures such as
anterior capsular plication, capsulolabral
repair, or labral repair, until adequate tissue healing has occurred. Excessive external rotation of the abducted shoulder is
also the mechanism for symptoms of internal impingement of the infraspinatus
and supraspinatus.30 Therefore, caution
is advised for use of maximum-distance
throwing in the rehabilitation of infraspinatus injury.
While certain aspects of pitching
mechanics vary among successful pitchers, shoulder abduction is consistently
near 90° at both foot contact and ball
release.9,10,16 Excessive abduction may result in subacromial impingement of the
bursa. Insufficient abduction is also a
risk factor due to misalignment of force
vectors among the deltoid, rotator cuff,
and other shoulder stabilizers. Because
no differences were reported in shoulder abduction among the various throws
in the current study, there is no specific
concern in throw types for rehabilitation
from these injuries.
Fleisig et al14 described the mechanism
of injury for a superior labral anteriorto-posterior (SLAP) lesion as distal force
applied by the long head of the biceps to
the superior labrum. This biceps force is
applied at its origin, near the time of ball
release, when the biceps is contracting to
both resist glenohumeral distraction and
decelerate elbow extension. Burkhart
and Morgan4 proposed an alternate
SLAP lesion mechanism, in which the
biceps tendon “peels back” the anterior
labrum. Shepard et al24 measured in vitro strength of the biceps-labral complex
during both the distal force and peelback mechanisms, and concluded that
SLAP lesions most likely occur from
repetition of both peel-back and distal
forces. Shoulder external rotation and
shoulder internal rotation torque may
be related to the peel-back mechanism
of the cocked arm, and shoulder proximal force and elbow flexion torque may
be related to the biceps pull-out force
near the time of ball release. Although
the current study found no differences in
ball release kinetics (shoulder proximal
force and elbow flexion torque), both
shoulder external rotation and shoulder
internal rotation torque were greatest in
maximum-distance throws. Thus longer distance throwing should be delayed
until the clinician feels that the glenoid
labrum has had adequate time to heal.
Maximum-distance throws may create
the largest peel-back forces and should be
avoided, or at least delayed, after SLAP
repair.
Near the time of ball release, a large
proximal force is produced at the shoulder to resist distraction. The combination of this proximal force and the rapid
internal rotation velocity at the shoulder may produce a grinding of the humeral head against the anterior glenoid
labrum.14 The current study found no
differences in proximal force or internal rotation velocity among throw types.
However, because maximum-distance
throws were identified in the current
study as being the most stressful to the
anterior labrum during arm cocking,
caution is advised for use of maximumdistance throws after any anterior labrum injury.
Training
It has often been hypothesized that
long-distance throwing is beneficial to
the throwing athlete for increasing flexibility, ball speed, arm strength, and endurance. A previous comparison of adult
pitchers with high versus low ball velocity
demonstrated 3 kinematic differences.19
Namely, pitchers with high ball velocity
had greater maximum shoulder external
rotation, forward trunk tilt at the time
of ball release, and lead knee extension
velocity. For longer throws, the current
study found greater maximum shoulder
external rotation but less forward trunk
tilt. Furthermore, the current study found
no differences in ball velocity for various
throw distances, and approximately 10°
of knee extension from foot contact to
ball release for all throws. Thus the current study did not find greater similarity
between particular distances of throws
and the pitching mechanics of pitchers
with high ball velocity.
In another study investigating changes within individual pitchers, several
characteristics correlated with greater
ball velocity.25 Kinetic values near the
time of ball release (elbow flexion torque,
shoulder proximal force, and elbow proximal force) increased with pitch velocity.
For pitches with higher ball velocity, at
the time of ball release, pitchers displayed
decreased shoulder horizontal adduction, decreased shoulder abduction, and
increased forward trunk tilt. The current study showed no differences among
throw types in ball velocity, kinetics at the
time of ball release, shoulder horizontal
adduction, or abduction. Forward trunk
tilt decreased with throwing distance.
Thus, the current study did not indicate that particular throwing distances
were superior in training to increase ball
velocity.
The current study did find greater
range of motion (maximum shoulder
external rotation), speed (angular velocities of the pelvis, upper trunk, and
elbow), and arm torque (elbow varus and
shoulder internal rotation) in long-toss,
which indicates that these throws may
be beneficial in training. However, longdistance throws also produced changes in
throwing mechanics at foot contact (up-
journal of orthopaedic & sports physical therapy | volume 41 | number 5 | may 2011 | 301
41-05 Fleisig.indd 301
4/20/2011 2:15:26 PM
[
hill trunk tilt and foot position) and at
ball release (forward trunk tilt and front
knee flexion). Furthermore, maximumdistance throws produced the greatest
elbow and shoulder torques, without any
change in ball velocity, making these the
least efficient throws, as they produced
the most torque for comparable ball velocity. The benefits or detriments of longtoss cannot truly be determined without
prospective studies comparing performance and safety between groups trained
with and without long-toss.
Limitations and Future Direction
The current study’s findings suggest that
the 55-m distance may be a good choice
for the longer throw on a line, as all participants were able to throw this distance
without increasing the ball trajectory.
With unconstrained trajectories, all participants threw 65 m or greater. However,
the fact that only 3 distances (37 m, 55
m, and maximum distance) were tested
for flat-ground throws was a limitation
of the current study. Also, the effects of
throwing distance and trajectory were
not separated. Studying players with a
variety of crow-hop techniques and proficiency would also be valuable. Data from
throws for a greater variety of players and
distances, with different trajectories and
throwing techniques, are needed to determine optimal long-toss throwing distances for college pitchers.
The current study used only healthy
pitchers, even though flat-ground longtoss is relevant for injury rehabilitation.
As stated above, players in rehabilitation
throwing programs are instructed to use
proper throwing mechanics, and the current study provides proper throwing data
based upon a sample of healthy college
pitchers. Future studies of player rehabilitation would be helpful to determine
whether certain injuries lead to mechanical compensations and adjustments in
throwing mechanics.
The current study included baseball
players from only 1 level (college) and
1 position (pitcher), which was also a
limitation. To enhance our understand-
research report
]
ing of throwing biomechanics, data are
needed for baseball players from a range
of levels, various positions, and more
distances. Skeletally immature throwers
may require specific consideration due to
poor mechanics and open growth plates.
On the other end of the spectrum, professional players may require specific consideration due to their strength, length
of season, and abilities to generate ball
velocity, ball distance, and joint torque.
Both clinical and longitudinal studies would prove valuable. Clinical studies
could be designed to compare baseball
success of groups of athletes after various
long-toss programs. Longitudinal studies
could measure throwing biomechanics at
various time intervals for players involved
with various rehabilitation or training
protocols.
CONCLUSION
B
ased on the results of this
study, a college baseball pitcher
should not be expected to throw
long, flat throws without kinematic and
kinetic differences in his pitching biomechanics. As reported here, the increased
kinetic and kinematic values with increased throw distance support our clinical experience that long-toss too early in
rehabilitation may lead to shoulder and
or elbow soreness. The use of long-toss
in rehabilitation should be under the supervision of a clinician to monitor tissue
healing and joint range of motion. It is
the opinion of the authors that long-toss
throwing on a line is a safe exercise for
rehabilitation and training; however, the
use of long-toss throwing for maximum
distance may not be beneficial. This advice against maximum-distance throwing
is based upon the high magnitudes of elbow varus torque, shoulder internal rotation torque, and upper trunk tilt, and low
magnitude of forward trunk tilt. More
biomechanical data are needed to quantify various long-toss throwing distances,
techniques, and protocols for players of
various ages, skill levels, and health levels. Performance and safety data after
various long-toss throwing programs
may be valuable in determining clinical
efficacy. t
KEY POINTS
FINDINGS: In a comparison of 4 types of
throws (pitching from a mound and
3 long-toss throws from flat ground),
shoulder and elbow angles and torques
increased as throwing distance increased. Differences in leg and trunk
kinematics were also noticed. The greatest number of differences was found
between maximum-distance throwing
and pitching, 37-m throws, and 55-m
throws.
IMPLICATION: Because shoulder and elbow
torques increase with throwing distance,
progression of throwing during rehabilitation should be under the supervision
of a physical therapist or other clinician, to monitor tissue healing and joint
range of motion. While long-toss thrown
on a line seems biomechanically sound
for rehabilitation and training, the use
of long-toss throws for maximum distance may be more harmful than beneficial.
CAUTION: Data were collected solely from
healthy, college-age pitchers.
ACKNOWLEDGEMENTS: The authors express their
gratitude to the coaches and players of the
Samford University, Birmingham-Southern
College, and University of Alabama at Birmingham baseball teams for their participation in this study. The authors also thank
Ryosuke Ito and Andrew Chappell for their
assistance in data processing and literature
review.
REFERENCES
1. A
guinaldo AL, Buttermore J, Chambers H. Effects of upper trunk rotation on shoulder joint
torque among baseball pitchers of various levels. J Appl Biomech. 2007;23:42-51.
2. Anz AW, Bushnell BD, Griffin LP, Noonan TJ,
Torry MR, Hawkins RJ. Correlation of torque and
elbow injury in professional baseball pitchers.
Am J Sports Med. 38:1368-1374. http://dx.doi.
org/10.1177/0363546510363402
3. Axe MJ, Snyder-Mackler L, Konin JG, Strube MJ.
302 | may 2011 | volume 41 | number 5 | journal of orthopaedic & sports physical therapy
41-05 Fleisig.indd 302
4/20/2011 2:15:27 PM
4.
5.
6.
7.
8.
9.
10.
11.
12.
Development of a distance-based interval throwing program for Little League-aged athletes. Am
J Sports Med. 1996;24:594-602.
Burkhart SS, Morgan CD. The peel-back
mechanism: its role in producing and extending posterior type II SLAP lesions and its effect
on SLAP repair rehabilitation. Arthroscopy.
1998;14:637-640.
Chu Y, Fleisig GS, Simpson KJ, Andrews JR.
Biomechanical comparison between elite female
and male baseball pitchers. J Appl Biomech.
2009;25:22-31.
Dun S, Fleisig GS, Loftice J, Kingsley D, Andrews
JR. The relationship between age and baseball
pitching kinematics in professional baseball
pitchers. J Biomech. 2007;40:265-270. http://
dx.doi.org/10.1016/j.jbiomech.2006.01.008
Dun S, Kingsley D, Fleisig GS, Loftice J, Andrews JR. Biomechanical comparison of the
fastball from wind-up and the fastball from
stretch in professional baseball pitchers. Am
J Sports Med. 2008;36:137-141. http://dx.doi.
org/10.1177/0363546507308938
Dun S, Loftice J, Fleisig GS, Kingsley D, Andrews
JR. A biomechanical comparison of youth baseball pitches: is the curveball potentially harmful? Am J Sports Med. 2008;36:686-692. http://
dx.doi.org/10.1177/0363546507310074
Escamilla R, Fleisig G, Barrentine S, Andrews
J, Moorman C, 3rd. Kinematic and kinetic
comparisons between American and Korean
professional baseball pitchers. Sports Biomech.
2002;1:213-228.
Escamilla R, Fleisig G, Barrentine S, Zheng N,
Andrews J. Kinematic comparisons of throwing
different types of baseball pitches. J Appl Biomech. 1998;14:1-23.
Escamilla RF, Barrentine SW, Fleisig GS, et al.
Pitching biomechanics as a pitcher approaches
muscular fatigue during a simulated baseball
game. Am J Sports Med. 2007;35:23-33. http://
dx.doi.org/10.1177/0363546506293025
Fleisig G, Chu Y, Weber A, Andrews J. Variability
in baseball pitching biomechanics among
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
various levels of competition. Sports Biomech.
2009;8:10-21.
Fleisig G, Escamilla R, Andrews J, Matsuo T, Satterwhite Y, Barrentine S. Kinematic and kinetic
comparison between baseball pitching and football passing. J Appl Biomech. 1996;12:207-224.
Fleisig GS, Andrews JR, Dillman CJ, Escamilla
RF. Kinetics of baseball pitching with implications about injury mechanisms. Am J Sports
Med. 1995;23:233-239.
Fleisig GS, Barrentine SW, Escamilla RF, Andrews JR. Biomechanics of overhand throwing
with implications for injuries. Sports Med.
1996;21:421-437.
Fleisig GS, Barrentine SW, Zheng N, Escamilla
RF, Andrews JR. Kinematic and kinetic comparison of baseball pitching among various levels of
development. J Biomech. 1999;32:1371-1375.
Fleisig GS, Kingsley DS, Loftice JW, et al. Kinetic
comparison among the fastball, curveball,
change-up, and slider in collegiate baseball
pitchers. Am J Sports Med. 2006;34:423-430.
http://dx.doi.org/10.1177/0363546505280431
Fortenbaugh D, Fleisig G, Andrews J. Baseball
pitching biomechanics in relation to injury risk
and performance. Sports Health: A Multidisciplinary Approach. 2009;1:314-320.
Matsuo T, Escamilla R, Fleisig G, Barrentine
S, Andrews J. Comparison of kinematic and
temporal parameters between different pitch
velocity groups. J Appl Biomech. 2001;17:1-13.
Miyanishi T, Fujii N, Ae M, Kunugi Y, Okada M. A
three-dimensional comparative study of the motions between speed throw and distance throw
in the university baseball players. Japan J Physical Ed. 1995;40:89-103.
Nissen CW, Westwell M, Ounpuu S, et al. Adolescent baseball pitching technique: a detailed
three-dimensional biomechanical analysis. Med
Sci Sports Exerc. 2007;39:1347-1357. http://
dx.doi.org/10.1249/mss.0b013e318064c88e
Reinold MM, Wilk KE, Reed J, Crenshaw K, Andrews JR. Interval sport programs: guidelines for
baseball, tennis, and golf. J Orthop Sports Phys
Ther. 2002;32:293-298.
23. S
abick MB, Torry MR, Lawton RL, Hawkins RJ.
Valgus torque in youth baseball pitchers: a
biomechanical study. J Shoulder Elbow Surg.
2004;13:349-355. http://dx.doi.org/10.1016/
S1058274604000308
24. Shepard MF, Dugas JR, Zeng N, Andrews JR. Differences in the ultimate strength of the biceps
anchor and the generation of type II superior
labral anterior posterior lesions in a cadaveric
model. Am J Sports Med. 2004;32:1197-1201.
http://dx.doi.org/10.1177/0363546503262643
25. Stodden DF, Fleisig GS, McLean SP, Andrews JR.
Relationship of biomechanical factors to baseball pitching velocity: within-pitcher variation. J
Appl Biomech. 2005;21:44-56.
26. Werner SL, Guido JA, Jr., Stewart GW, McNeice
RP, VanDyke T, Jones DG. Relationships between
throwing mechanics and shoulder distraction in
collegiate baseball pitchers. J Shoulder Elbow
Surg. 2007;16:37-42. http://dx.doi.org/10.1016/j.
jse.2006.05.007
27. Whiteley R. Baseball throwing mechanics as
they relate to pathology and performance: a
review. J Sports Sci Med. 2007;6:1-20.
28. Wilk KE, Meister K, Andrews JR. Current
concepts in the rehabilitation of the overhead throwing athlete. Am J Sports Med.
2002;30:136-151.
29. Wilk KE, Obma P, Simpson CD, Cain EL, Dugas JR, Andrews JR. Shoulder injuries in the
overhead athlete. J Orthop Sports Phys Ther.
2009;39:38-54. http://dx.doi.org/10.2519/
jospt.2009.2929
30. Zheng N, Fleisig G, Andrews J. Biomechanics
and injuries of the shoulder during throwing.
Athl Therapy Today. 1999;4:6-10.
@
MORE INFORMATION
WWW.JOSPT.ORG
VIEW Videos on JOSPT’s Website
Videos posted with select articles on the Journal’s website (www.jospt.org)
show how conditions are diagnosed and interventions performed. For a
list of available videos, click on “COLLECTIONS” in the navigation bar in the
left-hand column of the home page, select “Media”, check “Video”, and
click “Browse”. A list of articles with videos will be displayed.
journal of orthopaedic & sports physical therapy | volume 41 | number 5 | may 2011 | 303
41-05 Fleisig.indd 303
4/20/2011 2:15:28 PM