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Relationship of Biomechanical Factors to Baseball Pitching Velocity: Within Pitcher Variation

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To reach the level of elite, most baseball pitchers need to consistently produce high ball velocity but avoid high joint loads at the shoulder and elbow that may lead to injury. This study examined the relationship between fastball velocity and variations in throwing mechanics within 19 baseball pitchers who were analyzed via 3-D high-speed motion analysis. Inclusion in the study required each one to demonstrate a variation in velocity of at least 1.8 m/s (range 1.8-3.5 m/s) during 6 to 10 fastball pitch trials. Three mixed model analyses were performed to assess the independent effects of 7 kinetic, 11 temporal, and 12 kinematic parameters on pitched ball velocity. Results indicated that elbow flexion torque, shoulder proximal force, and elbow proximal force were the only three kinetic parameters significantly associated with increased ball velocity. Two temporal parameters (increased time to max shoulder horizontal adduction and decreased time to max shoulder internal rotation) and three kinematic parameters (decreased shoulder horizontal adduction at foot contact, decreased shoulder abduction during acceleration, and increased trunk tilt forward at release) were significantly related to increased ball velocity. These results point to variations in an individual's throwing mechanics that relate to pitched ball velocity, and also suggest that pitchers should focus on consistent mechanics to produce consistently high fastball velocities. In addition, pitchers should strengthen shoulder and elbow musculature that resist distraction as well as improve trunk strength and flexibility to maximize pitching velocity and help prevent injury.
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Biomechanical Factors and Pitching Velocity
1
1
JOURNAL OF APPLIED BIOMECHANICS, 2005, 21, xx-xx
© 2005 Human Kinetics Publishers, Inc.
1
Kinesiology Div., 214 Eppler South, Bowling Green State University, Bowling Green,
OH 43403;
2
Dept. of ??????????, American Sports Medicine Institute, 1313 13th St. South,
Birmingham, AL 35205;
3
Dept. of ????????; Southwestern University, \\which one?\
Au: need full mailing address of co-authors\
Relationship of Biomechanical Factors
to Baseball Pitching Velocity:
Within Pitcher Variation
David F. Stodden
1
, Glenn S. Fleisig
2
, Scott P. McLean
3
,
and James R. Andrews
2
1
Bowling Green State University;
2
American Sports Medicine
Institute;
3
Southwestern University
To reach the level of elite, most baseball pitchers need to consistently produce
high ball velocity but avoid high joint loads at the shoulder and elbow that
may lead to injury. This study examined the relationship between fastball ve-
locity and variations in throwing mechanics within 19 baseball pitchers who
were analyzed via 3-D high-speed motion analysis. Inclusion in the study re-
quired each one to demonstrate a variation in velocity of at least 1.8 m/s (range
1.8–3.5 m/s) during 6 to 10 fastball pitch trials. Three mixed model analyses
were performed to assess the independent effects of 7 kinetic, 11 temporal,
and 12 kinematic parameters on pitched ball velocity. Results indicated that
elbow flexion torque, shoulder proximal force, and elbow proximal force were
the only three kinetic parameters significantly associated with increased ball
velocity. Two temporal parameters (increased time to max shoulder horizontal
adduction and decreased time to max shoulder internal rotation) and three
kinematic parameters (decreased shoulder horizontal adduction at foot con-
tact, decreased shoulder abduction during acceleration, and increased trunk
tilt forward at release) were significantly related to increased ball velocity.
These results point to variations in an individual’s throwing mechanics that
relate to pitched ball velocity, and also suggest that pitchers should focus on
consistent mechanics to produce consistently high fastball velocities. In addi-
tion, pitchers should strengthen shoulder and elbow musculature that resist
distraction as well as improve trunk strength and flexibility to maximize pitch-
ing velocity and help prevent injury.
Key Words: throw, kinetics, trunk, shoulder, elbow
Stodden, Fleisig, McLean, and Andrews2
The ability to consistently maximize fastball velocity is an important factor
for most baseball pitchers. Theoretically, an individual’s maximum pitching ve-
locity potential is a product of optimal pitching mechanics. The notion of optimal
pitching mechanics for anyone is a concept that is difficult to address due to the
dynamic and complex nature of the movements involved in throwing and the in-
herent differences in the anatomical, neuromuscular, and physiological makeup of
each individual. A pitchers maximal velocity is indicative of kinematics, kinetics,
and relative timing of segmental interactions that lead to effective transfer of mo-
mentum to the baseball. Slight changes in a pitchers mechanics may result in
higher or lower ball velocity.
Many studies have compared mechanics between pitchers in an attempt to
understand variables related to pitched ball velocity (Elliott, Grove, & Gibson,
1988; Fleisig, 1994; Fleisig, Barrentine, Zheng, Escamilla, & Andrews 1999;
Matsuo, Escamilla, Fleisig, Barrentine, & Andrews 2001). However, the study of
within-pitcher variability has been limited, due in part to previous studies which
stated that mechanics within pitchers were remarkably consistent and showed little
variability among pitches (Feltner & Dapena, 1986; Pappas, Zawacki, & Sullivan,
1985). Stodden, Fleisig, McLean, Lyman, and Andrews (2001) addressed variabil-
ity within individual pitching motions and indicated that they may not be as con-
sistent as previously reported. Theoretically, increased pelvis and upper torso
velocities would allow more momentum to be transferred from the trunk to the
throwing arm, and ultimately to the ball, leading to increased pitch velocity.
This idea is supported by Fleisig et al.’s (1999) finding that more advanced
pitchers (college and professional) generally achieved higher upper torso veloci-
ties than their less-developed counterparts (youth and high school). College level
pitchers also showed increased pelvis velocities over both high school and youth
pitchers. Matsuo et al. (2001) found that kinematic parameters early in the pitch-
ing movement influenced pitch velocity. Specifically, lead knee movement, maxi-
mum external rotation, and forward trunk tilt at release were associated with
differences in pitching velocity between high and low velocity groups. Additive
effects of trunk angular velocities and anthropometric factors were also suggested
to be related to group velocity differences. Increases in momentum transfer from
proximal to distal segments may imply a demand for increased kinetics at the
shoulder and elbow during arm acceleration.
Changes in temporal parameters may indicate that momentum was trans-
ferred in a more effective manner, thus limiting the demand for joint kinetics to
produce high ball velocities. This alternative argument is supported by Herring
and Chapman (1992), who used a three-segment computer model that simulated
the throwing motion in a sagittal plane. Their study indicated that variations in the
timing of torque reversal at the shoulder, elbow, and wrist produced variations in
ball velocity. The purpose of the present study was to examine the relationship
between fastball velocity and variations in kinematic, kinetic, and temporal pa-
rameters within individual pitchers.
Methods
Participants
The current study utilized the same group of 19 healthy male baseball pitchers as did
Stodden et al. (2001). Participants had an average age of 20.9 ± 2.1 years, height of
Biomechanical Factors and Pitching Velocity
3
185.4 ± 5.1 cm, and mass of 83.0 ± 6.8 kg. To be considered for the study, pitchers
were required to throw a fastball pitch at least 33.5 m/s (75 mph) during testing. In
addition, they were required to have at least 1.8 m/s (4 mph) of variation in ball
velocity among their maximal effort pitch trials. A 1.8 m/s variation in velocity
was chosen because it represents a variation in ball velocity that is considered by
many in baseball to be large enough to affect the pitchers performance. Fleisig et
al. (1999) also showed a difference of 2.0 m/s between college and elite pitchers.
Procedure and Design
After completing informed consent and history forms, each participant was tested
with a procedure previously described (Escamilla, Fleisig, Barrentine, Zheng, &
Andrews, 1998; Fleisig, Escamilla, Andrews, et al., 1996). Each one completed
his warm-up and stretching routine in accordance with his individual preference
and was then asked to complete 10 maximal effort throws from a pitching mound.
Some pitchers used more than one type of pitch within their 10 maximal effort
throws (e.g., curve, slider, change-up). Since only fastball throws were used for
data analysis in this study, each pitcher had a total of 6 to 10 fastball trials that
were used in the analysis. Ball velocity was recorded with a Jugs Tribar Sport
radar gun (Jugs Pitching Machines Co., Tualatin, OR) from behind home plate.
The radar gun was accurate to ± .22 m/s (0.5 mph).
Each participant was marked with retroreflective 2.5-cm diameter balls bi-
laterally on the distal end of the third metatarsal, lateral malleolus, lateral femoral
epicondyle, greater trochanter of the femur, lateral tip of the acromion, and lateral
humeral epicondyle. A reflective band wrapped around the wrist on the throwing
arm was used to mark the joint center of the wrist. A reflective marker was also
placed on the ulnar styloid of the glove hand. Participants wore spandex shorts and
no shirts so as to limit movement of the markers from their anatomical landmarks
during the pitching motion. The reflections of these markers were tracked indi-
vidually by four electronically synchronized 200-Hz charged-coupled device (CCD)
cameras (Motion Analysis, Corp., Santa Rosa, CA). Three-dimensional marker
locations were calculated with Motion Analysis ExpertVision 3D software, utiliz-
ing the direct linear transformation (DLT) method (Abdel-Aziz & Karara, 1971).
The locations of the midhip, midshoulder, elbow joint center, and shoulder joint
center were calculated (see Figure 1) in each frame as described by Dillman, Fleisig,
and Andrews (1993). In each frame, local reference frames were calculated at the
shoulder (R
s
), the elbow (R
e
), and the trunk (R
t
).
Kinematic Parameters
Angular displacements of the “shoulder” (i.e., glenohumeral joint), elbow, and
trunk were calculated as described by Fleisig et al. (1996) (see Figure 2a). Twelve
kinematic parameters were calculated from front foot contact to ball release (see
Table 1). Figure 3 depicts each stage of the pitching motion and instances separat-
ing the phases. Stride foot contact was defined as the time when velocity of the
lead ankle joint marker decreased to less than 1.5 m/s. These parameters were
chosen because they define important segmental positions during critical moments
within a pitch. Angular velocities of the pelvis and upper torso were calculated
with a method published by Feltner and Dapena (1989) (see Figure 2f). Angular
Stodden, Fleisig, McLean, and Andrews4
velocity of the pelvis was the cross-product of the pelvis vector and its derivative.
Angular velocity of the upper torso was the cross-product of the upper torso vector
and its derivative.
Kinetic Parameters
Resultant joint forces and torques were calculated at the shoulder and elbow using
kinematic data, documented cadaveric body segment parameters (Clauser,
McConville, & Young, 1969; Dempster, 1955), and inverse dynamics equations
(Fleisig, 1994). The calculations of forces and torques began at the distal end of
the system where the force of the ball and hand, together as one unit, acted on the
wrist. The subsequent masses, forces, and torques associated with the forearm
were used to calculate the forces and torques acting on the elbow, and the subse-
Figure 1 — Markers attached to (1) the leading hip, (2) leading shoulder, (3) throwing
shoulder, (4) throwing elbow, and (5) throwing wrist. Virtual markers calculated at
the mid-hips (MH), mid-shoulders (MS), throwing shoulder joint center (S), and
throwing elbow joint center (E). Unit vectors for the pelvis (P), upper torso (U), and
trunk (T). Reference frames shown for the shoulder (X
S
Y
S
Z
S
) and elbow (X
E
Y
E
Z
E
).
Biomechanical Factors and Pitching Velocity
5
Figure 2 — Definition of kinematic variables: (a) shoulder abduction, (b) horizontal
adduction, (c) external rotation, (d) elbow flexion, (e) trunk tilt, and (f) pelvis angular
velocity and upper torso angular velocity. Adapted from Fleisig et al. (1996) with
permission. \\
Au: Who did you get the permission from?\
quent masses, forces, and torques associated with the upper arm were used to cal-
culate the forces and torques acting on the shoulder.
Eleven kinetic variables were calculated throughout the pitch (see Figure 4).
Force applied to the arm at the shoulder was separated into three components:
anterior-posterior, superior-inferior, and proximal. Shoulder torque was separated
into horizontal abduction-adduction, adduction-abduction, and internal-external
rotation components. Force applied to the forearm at the elbow was divided into
three components: medial-lateral, anterior-posterior, and proximal. Elbow torque
was separated into only two components: flexion-extension and varus-valgus. Forces
were normalized as percent body weight, and torques were normalized as percent
body weight 3 height. Maximum values for 7 of the kinetic variables were used
(see Table 2). Kinetic variables were analyzed between front foot contact and just
after ball release (see Figure 3). This interval has been shown to produce the larg-
est forces and torques at the shoulder and elbow during pitching (Fleisig, Andrews,
Dillman, & Escamilla, 1995).
Temporal Parameters
Eleven temporal parameters primarily related to joint or segment angular and lin-
ear velocities were calculated (see Table 3). These temporal parameters were shown
as relative values where 0% corresponded to stride foot contact and 100% corre-
sponded to the instant of ball release. The specific temporal event times were cho-
Stodden, Fleisig, McLean, and Andrews6
Table 1 Kinematic Parameter Data and Factors Associated With Ball Velocity
(N = 166)
Variable Mean SD
Ball velocity 35.2 m/s 1.6 m/s
Shoulder abduction at SFC 96° 14º
Shoulder horizontal adduction at SFC** –17° 12º
External rotation at SFC 63° 32º
Stride leg knee angle at SFC 131°
Elbow angle at SFC 96° 20º
Maximum shoulder horizontal adduction 21°
Maximum external rotation 173° 11º
Average abduction during acceleration** 99° 10º
Trunk tilt forward at release** 32°
Trunk tilt sideways at release 117° 12º
Elbow angle at release 153° 10º
Shoulder horizontal adduction at release 12°
Note: All parameters were initially entered in the model and then were individually
removed if not significantly contributing to the model. SFC = stride foot contact.
**Significant differences, p < .01
Figure 3 — The six phases of pitching. Images represent the instances separating the
phases: initial motion, balance point, stride foot contact, maximum external rotation,
release, and maximum internal rotation. Modified with permission from Fleisig et al.
(1996). \\Au: same query as #2\\
Biomechanical Factors and Pitching Velocity
7
Figure 4 — Definition of kinetic variables: (a) shoulder forces: superior, proximal,
and anterior; (b) shoulder torques: internal rotation and horizontal abduction; (c)
elbow forces (medial); and (d) elbow torques (varus). Adapted from Fleisig et al. (1996)
with permission. \\
Au: same query as #2\\
Table 2 Kinetic Parameter Data and Factors Associated With Ball Velocity
(N = 166)
Variable Mean SD
Shoulder anterior force (%BW) 45.6 9.4
Shoulder proximal force (%BW)** 118.3 17.8
Elbow proximal force (%BW)** 100.1 14.0
Shoulder horizontal adduction torque (%BW
3H) 6.6 1.8
Shoulder internal rotation torque (%BW
3H) 4.6 0.8
Elbow varus torque (%BW
3H) 4.6 0.8
Elbow flexion torque (%BW
3H)** 3.6 1.0
Note: All parameters were initially entered in the model and then were individually
removed if not significantly contributing to the model.
Significant differences: *p < .05; **p < .01
Stodden, Fleisig, McLean, and Andrews8
sen because they represent “theoretical windows” for the transfer of momentum
from proximal segments to more distal segments during the delivery of the ball.
Total pitch time (SFC to ball release, in seconds) was also reported.
Statistical Analysis
Three separate mixed models (MANOVAs) were used to assess the independent
effects of the parameters within kinetic, positional, and temporal groups since the
data structure included multiple pitch trials for each participant (Stodden et al.,
2001). The initial kinetic, positional, and temporal models were then reduced us-
ing a stepwise modeling procedure, which eliminated nonsignificant variables
without a reduction in model fit. The stepwise regression was a combination of a
backward and forward modeling procedure. The modeling procedure reduced the
full model by the least significant variable (VAR1). The models were then reevalu-
ated and the next least significant variable was removed (VAR2). At this point
VAR 1 was reentered into the model to see if significance was then obtained. If
not, it was dropped again. At each step the overall model significance was then
evaluated to see if there had been a significant reduction in model fit. This contin-
ued until all remaining variables were significant and/or the removal of an addi-
tional variable significantly reduced model fit. Significance at p < .05 and p < .01
are reported. SAS
®
Version 8.0 was used for all analyses.
Table 3 Temporal Parameter Data and Factors Associated With Ball Velocity
(N = 166)
Variable Mean SD
Total pitch time (sec) .145 .03
Maximum pelvis angular velocity (% pitch) 39 17
Maximum mid-pelvis linear velocity (% pitch) 13 19
Maximum upper torso angular velocity (% pitch) 52 12
Maximum mid-upper torso linear velocity (% pitch) 93 5
Maximum trunk tilt angular velocity (% pitch) 93 20
Maximum horizontal adduction angular velocity (% pitch) 50 22
Maximum horizontal adduction (% pitch)* 57 14
Maximum external rotation (% pitch) 81 6
Maximum elbow extension angular velocity (% pitch) 95 11
Maximum internal rotation angular velocity (% pitch)* 104 5
Note: Total pitch time measured in seconds. Other 10 parameters measured from stride
foot contact until particular event, expressed in time or percentage of pitch (where 0%
corresponds to instant of stride foot contact and 100% corresponds to instant of ball
release). All parameters were initially entered in the model and then were individually
removed if not significantly contributing to the model.
*Significant differences, p < .05
Biomechanical Factors and Pitching Velocity
9
Results
A total of 166 pitches were collected from the 19 participants for data analysis.
Total pitches analyzed from a single pitcher ranged from 6 to 10. Means and stan-
dard deviation values for the parameters and ball velocity are shown in Tables 1, 2,
and 3. The average ball velocity in this study (35.2 m/s) was comparable to other
studies involving elite pitchers (Fleisig et al., 1995: 38.3 m/s; Dillman et al., 1993:
38 m/s; Feltner & Dapena, 1986: 33.5 m/s). Results of the kinetic, temporal, and
positional mixed models all indicated strong model fitness (kinetic parameter model,
χ
2
= 129.32; temporal parameter model, χ
2
= 193.79; positional parameter model,
χ
2
= 196.33, all p < .0001).
The analysis of the full kinetic model, with all 7 variables, indicated that
only elbow flexion torque increased as ball velocity increased. However, when the
model was reduced from 7 variables to eliminate nonsignificant variables and to
improve model fit, elbow flexion torque combined with two additional parameters
in separate models did improve the model fit. When introduced into the model
separately with elbow flexion torque, both shoulder proximal force and elbow
proximal force increased the model fit and attained the .05 significance level.
Both shoulder proximal force and elbow proximal force increased with increasing
ball velocities. When introduced together into the model with elbow flexion
torque, neither met the .05 significance level. The use of two separate models can
be rationalized by recognizing that shoulder proximal force and elbow proximal
force are highly correlated (r = .79). When these variables are introduced in the
same model with elbow flexion torque, their contributions to the model are not
independent and thus must be examined in separate models.
Results of the reduced temporal model indicated that as ball velocity in-
creased, time to maximum horizontal adduction and time to maximum internal
rotation velocity were significantly associated with ball velocity. Specifically, as
the pitchers’ velocity increased, time to maximum horizontal adduction increased.
Conversely, time to maximum internal rotation velocity was inversely related to
ball velocity. As ball velocity increased, time to maximum internal rotation veloc-
ity decreased.
The reduced positional model indicated that three variables were signifi-
cantly associated with increased ball velocity: horizontal adduction at stride foot
contact, shoulder abduction during the acceleration phase, and trunk tilt forward at
release. Two parameters were inversely related to ball velocity. As ball velocity
increased, shoulder horizontal adduction at stride foot contact and shoulder abduc-
tion during the acceleration phase decreased. Conversely, as a pitcher’s ball veloc-
ity increased, trunk tilt forward at release increased.
Discussion
The purpose of this study was to examine the relationship between fastball veloc-
ity and variations in throwing mechanics within individual pitchers. Overall, 8 of
30 kinetic, temporal, and kinematic parameters were significantly associated with
increased pitched ball velocity within an individual pitcher.
The complex relationship of the three significant kinetic parameters is im-
portant for discussion of both performance and injury concepts. As pitchers’ ve-
locities increased, elbow flexion torque, shoulder proximal force, and elbow
Stodden, Fleisig, McLean, and Andrews10
proximal force all increased. Increases in these three kinetic variables were re-
quired in order to resist distraction of both the upper arm from the glenohumeral
joint and the forearm at the elbow joint, as well as control the rate of elbow exten-
sion. Increase in shoulder proximal force is provided by the musculature that sup-
ports the glenohumeral joint as well as capsular and ligament structures (Fleisig et
al., 1995). The increase in elbow proximal force is provided by the musculature
supporting the elbow joint as well as the ligaments. The increased proximal force
at both the shoulder and the elbow is directly related to the increase in pelvis and
upper torso rotational velocities (Stodden et al., 2001) and opposes the resultant
increases in centrifugal force acting at both the glenohumeral and elbow joint. The
mass of the forearm, hand, and ball are common aspects of the centrifugal force
acting at both the shoulder and elbow to cause distraction at both joints.
These two forces are at their maximum almost simultaneously (elbow first
and then shoulder) near or at the end of the arm acceleration phase (Fleisig et al.,
1995). Therefore, the proximal forces acting at both joints to resist this centrifugal
force should be highly correlated. In fact, the high correlation between shoulder
and elbow proximal force (r = .79) is the primary reason why a model, which
indicates that both variables nonsignificantly contribute to velocity, does not jus-
tify their practical importance.
With respect to implications for injury, the unique biarticular nature of the
biceps brachii allows this muscle to contribute to both shoulder and elbow proxi-
mal stability during the arm acceleration phase. During the early part of the arm
acceleration phase, the eccentric contraction of the biceps brachii, along with the
other two principal elbow flexors (brachialis and brachioradialis), provides a large
elbow flexion torque to control the rate of elbow extension (Feltner, 1989; Fleisig
et al., 1995). Controlling the rate of extension serves to enhance the effect of the
shoulder internal rotation torque on the velocity of the distal aspect of the forearm/
hand during the rapid internal rotation of the humerus. The secondary function of
the biceps brachii is to resist both distraction of the humerus from the glenohumeral
joint and distraction of the forearm from the elbow joint (Fleisig et al., 1995).
Fleisig et al. (1995) suggested that, with improper mechanics, the loads sustained
by the biceps (shoulder proximal force and elbow flexion torque) might occur
more often, requiring a greater total force by the biceps. This increased load on
the biceps may be one factor leading to the common injury pathology known as a
SLAP lesion (tear to the superior labrum anterior and posterior).
One other interesting interaction between the three variables was that both
shoulder and elbow proximal force were inversely related to elbow flexion torque.
Both correlations were modest, although the relationship does support the argu-
ment that proper timing of elbow extension would serve to limit increases in el-
bow flexion torque and shoulder and elbow proximal force. The dual role of the
biceps brachii is another reason why it is necessary to present two separate models
to elucidate the complexity of shoulder and elbow joint dynamics.
Two kinematic parameters and one temporal parameter provided further evi-
dence of the roles of the trunk and shoulder in the pitch. As an individual pitcher
threw faster, pelvis and upper torso angular velocities increased (Stodden et al.,
2001) and pitchers increased their trunk tilt forward. This combination of move-
ments of the trunk induces a lag effect that can be defined as horizontal abduction
of the humerus relative to the trunk (Dillman et al., 1993; Feltner & Dapena, 1986;
Hong, Cheung, & Roberts, 2001). As pitchers threw faster, they were in a position
Biomechanical Factors and Pitching Velocity
11
of greater horizontal abduction at stride foot contact, which occurred before the
rotation of the upper trunk and before the lag effect.
Greater horizontal abduction at foot contact has been identified to be a sig-
nificant component in why pitchers from certain countries generate greater ball
velocity (Escamilla, Fleisig, Barrentine, Andrews, & Moorman, 2002; Escamilla,
Fleisig, Zheng, Barrantine, & Andrews, 2001). When pitchers began to rotate their
upper trunk, the humerus had to overcome an increased horizontal abduction angle,
which may have led to the increase in time it took to reach maximum horizontal
adduction. Additionally, decreased horizontal adduction at foot contact and in-
creased trunk tilt forward at ball release suggest that the distance the ball traveled
from stride foot contact to release increased as ball velocity increased. The in-
crease in distance traveled in conjunction with the applied muscular forces at the
shoulder would serve to enhance ball velocity.
The increased eccentric loading of the horizontal adduction musculature may
facilitate increased storage and recovery of the elastic energy component in the
stretch-shortening cycle. However, an increase in the forces applied to the throw-
ing arm would not necessarily serve to increase horizontal adduction velocity or
internal rotation velocity, because kinematics are a function of complex interac-
tions of the shoulder, elbow, and wrist, as was discussed in the explanation of
increased kinetics. The influence of the inertial properties of the forearm, hand,
and ball on the humerus, in conjunction with rapid elbow extension, may lead to a
more effective transfer of momentum without showing an increase in the velocity
of the proximal segment (humerus). Neal, Snyder, and Kroonenberg (1991) also
found that highly skilled throwers were able to move the arm segments through a
greater range of motion compared to less skilled throwers.
The average time to reach maximum internal rotation velocity actually oc-
curred just after ball release (104% of total pitch time). As a pitchers ball velocity
increased, maximum internal rotation velocity was reached earlier in the pitch and
closer to the instant of ball release. This result agrees with Matsuo et al. (2001),
who found that faster pitchers reached maximum internal rotation velocity sooner
than slower pitchers.
One positional parameter, shoulder abduction during acceleration, was asso-
ciated with ball velocity. As abduction decreased, ball velocity increased. DiGiovine,
Jobe, Pink, and Perry (1992) showed that the pectoralis major and latissimus dorsi
are most active during arm acceleration. Thus, high activity from these two muscles
might not only create horizontal adduction and internal rotation velocity, but also
reduce abduction. Increasing the time that the internal rotation and horizontal ad-
duction musculature are active would further increase the ball/hand velocity gen-
erated during the rapid internal rotation phase of arm acceleration.
Overall, the data from this study and previous studies indicate that elite pitch-
ers produce large forces and torques at the shoulder and elbow, as well as high
velocities and extensive ranges of motion in the trunk and upper extremity. An
understanding of the kinematics and kinetics of pitching can assist in technique
and strength-training programs that focus on performance enhancement and injury
prevention. Trunk (core) strength is a very important consideration when training
for a complex ballistic movement that demands effective momentum transfer
through the kinetic chain. Additionally, training the rotator cuff and surrounding
musculature of the shoulder and elbow is paramount to maintaining shoulder and
Stodden, Fleisig, McLean, and Andrews12
elbow joint integrity and stabilizing the humeral head within the glenoid fossa as
extreme distraction forces are applied during the pitch.
One methodological limitation in this study was the inherent error associ-
ated with generating kinetic data from kinematic data. Isolating joint movement
about one axis, summing forces that contribute to arm acceleration (soft tissue
forces, bone on bone forces, and cumulative muscle forces), and identifying the
built-in error of the motion analysis system all suggest a cautious interpretation of
the results. The analysis of an individual’s pitching motion yielded kinematic pat-
terns that were consistent to a certain extent, which supports previous literature.
However, mechanics varied enough within each pitcher such that parameters asso-
ciated with ball velocity could be identified. Because the RMS error in the current
study is larger than typically reported, the likelihood of a Type II error is increased.
Conversely, our chance of making a Type I error would be decreased, suggesting
that the differences we found were real.
In summary, the effects of increased pelvis and upper torso rotational veloci-
ties (Stodden et al., 2001), trunk tilt forward at ball release, increased shoulder and
elbow proximal force, increased elbow flexion torque, decreased horizontal ad-
duction at foot contact, and changes in relative temporal parameters suggest that
when a pitcher increased ball velocity, it was due to a more effective transfer of
momentum in the kinetic chain. The complex interaction of the three increased
kinetic variables suggests that increased elbow flexion torque serves to limit the
increases in shoulder and elbow proximal forces.
When attempting to improve velocity, the notion of “throwing harder” or
“more effort” may not be the correct terms to use with a pitcher who is already
throwing with maximal effort. Avoiding injuries is a high priority with baseball
pitchers, and this study does not address all the mechanisms that are factored into
injury. Slight changes in mechanics taught by knowledgeable instructors, and im-
provements in strength and range of motion of the shoulder, elbow, and trunk may
be a more appropriate strategy for (a) improving momentum generation and trans-
fer within the trunk, (b) protecting the integrity of the glenohumeral and elbow
joints, and (c) producing consistent maximal velocities while limiting increases in
loads at the shoulder and elbow.
References
Abdel-Aziz, Y.I., & Karara, H.M. (1971). Direct linear transformation from comparator
coordinates into object space coordinates in close-range photogrammetry. In ASP
Symposium on Close-Range Photogrammetry (pp. 1-18). Falls Church, VA: Ameri-
can Society of Photogrammetry.
Clauser, C.E., McConville, J.T., & Young, J.W. (1969). Weight, volume, and center of mass
of segments of the human body. Dayton, OH: Wright-Patterson Air Force Base, Aero-
space Medical Research Lab. (AMRL-TR-69-70).
Dempster, W.T. (1955). Space requirements of the seated operator. Dayton, OH: Wright-
Patterson Air Force Base, Wright Air Development Center (WADC-TR-55-159).
Dillman, D.J., Fleisig, G.S., & Andrews, J.R. (1993). Biomechanics of pitching with em-
phasis upon shoulder kinematics. Journal of Orthopaedic and Sports Physical Therapy,
18, 402-408.
DiGiovine, N.M., Jobe, F.W., Pink, M., & Perry, J. (1992) Electromyography of upper ex-
tremity in pitching. Journal of Shoulder and Elbow Surgery, 1, 15-25.
Biomechanical Factors and Pitching Velocity
13
Elliott, B., Grove, R., & Gibson, B. (1988). Timing of the lower limb drive and throwing
limb movement in baseball pitching. International Journal of Sport Biomechanics,
4, 59-67
Escamilla, R., Fleisig, G., Barrentine, S., Andrews, J., & Moorman, C. (2002). Kinematic
and kinetic comparisons between American and Korean professional baseball pitch-
ers. Sports Biomechanics, 1, 213-228.
Escamilla, R.F., Fleisig, G.S., Barrentine, S.W., Zheng, N., & Andrews, J.R. (1998). Kine-
matic comparisons of throwing different types of baseball pitches. Journal of Ap-
plied Biomechanics, 14, 1-23.
Escamilla, R.F., Fleisig, G.S., Zheng, N., Barrentine, S.W., & Andrews, J.R. (2001). Kine-
matic comparisons of 1996 Olympic baseball pitchers. Journal of Sports Science,
19, 665-676.
Feltner, M.E. (1989). Three-dimensional interactions in a two-segment kinetic chain. Part
II: Application to the throwing arm in baseball pitching. International Journal of
Sport Biomechanics, 5, 420-450.
Feltner, M.E., & Dapena, J. (1986). Dynamics of the shoulder and elbow joints of the throwing
arm during baseball pitch. International Journal of Sport Biomechanics, 2, 235-259.
Feltner, M.E., & Dapena, J. (1989). Three-dimensional interactions in a two-segment ki-
netic chain. Part I: General model. International Journal of Sport Biomechanics, 5,
403-419.
Fleisig, G.S. (1994). The biomechanics of baseball pitching. Unpublished doctoral disserta-
tion, University of Alabama at Birmingham.
Fleisig, G.S., Andrews, J.R., Dillman, C.J., & Escamilla, R.F. (1995). Kinetics of baseball
pitching with implications about injury mechanisms. The American Journal of Sports
Medicine, 23, 233-239.
Fleisig, G.S., Barrentine, S.W., Zheng, N., Escamilla, R.F., & Andrews, J.R. (1999). Kine-
matic and kinetic comparison of baseball pitching among various levels of develop-
ment. Journal of Biomechanics, 32, 1371-1375.
Fleisig, G.S., Escamilla, R.F., Andrews, J.R., Matsuo, T.M., Satterwhite, Y., & Barrentine,
S.W. (1996). Kinematic and kinetic comparison between baseball pitching and foot-
ball passing. Journal of Applied Biomechanics, 12, 207-224.
Herring, R.M., & Chapman, A.E. (1992). Effects of changes in segmental values and timing
of both torque and torque reversal in simulated throws. Journal of Biomechanics, 25,
1173-1184.
Hong, D., Cheung, T.K., & Roberts, E.M. (2001). A three-dimensional, six-segment chain
analysis of forceful overarm throwing. Journal of Electromyography and Kinesiol-
ogy, 11, 95-112.
Matsuo, T., Escamilla, R.F., Fleisig, G.S., Barrentine, S.W., & Andrews, J.R. (2001). Com-
parison of kinematic and temporal parameters between different pitch velocity groups.
Journal of Applied Biomechanics, 17, 1-13.
Neal, R.J., Snyder, C.W., & Kroonenberg, P.M. (1991). Individual differences and segment
interactions in throwing. Human Movement Science, 10, 653-676.
Pappas, A.M., Zawacki, R.M., & Sullivan, T.J. (1985). Biomechanics of baseball pitching:
A preliminary report. The American Journal of Sports Medicine, 13, 216-222.
Stodden, D.F., Fleisig, G.S., McLean, S.P., Lyman, S.L., & Andrews, J.R. (2001). Relation-
ship of trunk kinematics to pitched ball velocity. Journal of Applied Biomechanics,
17, 164-172.
... Shoulder horizontal abduction at foot contact has been reported between 17° and 30° in professional pitchers. 3,24 At maximum external rotation and ball release, the literature has ranged from 5° to 14° at maximum external rotation, and 0° to 12° at ball release, comparable with what this study observed. 4,21 Progression through the pitch includes forward arm movement relative to the trunk with increased horizontal adduction, acted on by the anterior deltoid and pectoralis major. ...
... Increased shoulder horizontal abduction and decreased shoulder horizontal adduction have both correlated with increased ball velocity; however, these were reported at foot contact and not maximum external rotation or ball release. 24 Still, the prospect of attaining increased ball velocity with minimized horizontal adduction throughout the pitch can be substantiated. When pitchers begin to rotate their upper trunk, the humerus has to overcome the degree of horizontal abduction a pitcher starts with, which increases the time it takes to reach maximum horizontal adduction. ...
... When pitchers begin to rotate their upper trunk, the humerus has to overcome the degree of horizontal abduction a pitcher starts with, which increases the time it takes to reach maximum horizontal adduction. 24 With greater shoulder horizontal abduction and shoulder external rotation, the pitcher is able to apply an accelerating force to the ball for the longest distance, hence the reason why the cocking process takes 77% to 80% of the pitch, ultimately generating increased ball velocity as a result. 13,21 Excessively adducting the shoulder horizontally, or leading with the elbow, will in effect cause maximal shoulder horizontal adduction to be reached earlier, with less accelerant force placed on the ball. ...
Article
Background Repetitive horizontal shoulder abduction during pitching can cause increased contact between the posterosuperior aspect of the glenoid and the greater tuberosity of the humeral head, theoretically putting baseball pitchers at increased risk of shoulder internal impingement and other shoulder pathologies. Hypothesis Increased shoulder horizontal abduction is associated with increased shoulder anterior force, while increased horizontal adduction is associated with increased shoulder distraction force. Study Design Descriptive laboratory study. Level of Evidence Level 4. Methods A total of 339 professional baseball pitchers threw 8 to 10 fastball pitches using 3D motion capture (480 Hz). Pitchers were divided into 2 sets of quartiles based on maximum shoulder horizontal abduction and adduction. Elbow flexion, shoulder external rotation, and peak shoulder kinetics were compared between quartiles with post hoc linear regressions conducted for the entire cohort. Results At maximum shoulder horizontal abduction, there was no difference in ball velocity between quartiles ( P = 0.76). For every 10º increase in maximum shoulder horizontal abduction, shoulder anterior force decreased by 2.2% body weight (BW) ( P < 0.01, B = −0.22, β = −0.38), shoulder adduction torque decreased by 0.5%BW × body height (BH) ( P < 0.01, B = −0.05, β = −0.19), and shoulder horizontal adduction torque decreased by 0.4%BW × BH ( P < 0.01, B = −0.04, β = −0.48). For every 10º increase in maximum shoulder horizontal adduction, shoulder anterior force increased by 2%BW and ball velocity decreased by 1.2 m/s (2.7 MPH). Conclusion Professional pitchers with the least amount of maximum horizontal adduction had faster ball velocity and decreased shoulder anterior force. Pitchers with greater maximum shoulder horizontal abduction had decreased shoulder anterior force, shoulder adduction torque, and shoulder horizontal adduction torque. To maximize ball velocity as a performance metric while minimizing shoulder anterior force, pitchers can consider decreasing maximum shoulder adduction angles at later stages of the pitch. Clinical Relevance Identifying risk factors for increased throwing shoulder kinetics (ie, shoulder anterior force, shoulder adduction torque) has potential implications in injury prevention. Specifically, mitigating shoulder anterior forces may be beneficial in reducing risk of injury.
... The combined acceleration of all body parts adds ballistic energy to the thrown ball, resulting in the highest velocity at the moment of release. Stodden et al. (2005) also emphasised that the upper torso begins to rotate towards the release of the ball, while the angle of the pelvis remains almost constant, and the rotation slows down. Rotation of the pelvis is the first to begin, followed by the upper body, allowing the trunk to curl. ...
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The throwing ball velocity is one of the most important skill required in numerous sports, such as softball. Throwing can be considered as an essential technique since softball players must implement this skill to prevent opponents from advancing and acquiring more points. The movement of throwing involves the power generated from lower extremities, mediated by trunk rotation, which moves onwards to the upper extremities. Trunk rotation is assumed to play a crucial role in increasing ball velocity through the throwing movement sequence. However, studies that highlight the relationship between trunk rotation and throwing ball velocity remain lacking. This research determines the relationship between trunk rotation strength and throwing ball velocity among female collegiate softball players. 72 female softball players from Universiti Teknologi MARA are selected to participate in this research. All participants are tested using the trunk rotation strength test and throwing ball velocity test. The recorded scores of both tests are analysed using Pearson's correlation coefficient to identify the relationship between the two variables. The result shows the relationship between these two variables is r=.53 indicates that there is strong relationship between the trunk rotation strength and throwing ball velocity (r<.50). Based on this outcome, trunk rotation strength should be included in softball training programs as well as many other sports that require similar throwing movements to successfully enhance the throwing velocity performance.
... Kinetic characterization and injury of the upper extremities, including the shoulder and elbow, are a major focus of research in baseball. In terms of efficient energy transfer, the lower extremity is also an important component during the multiple phases of baseball, including throwing, base running, and hitting [48,49]. Therefore, we investigated the effects of PT on knee muscle strength. ...
... Several studies have performed kinematic and neuromuscular analyses on the three primary types of throws (standing, with run up and jump throws) performed in team handball Ettema, 2009a,b, 2011;Wagner et al., 2010aWagner et al., ,b, 2018van den Tillaar and Cabri, 2012;Skejo et al., 2019). Furthermore, kinematic investigation shows how the main contributors to velocity in an overhead throw are the elbow extension and maximal shoulder internal rotation (Fradet et al., 2004;van den Tillaar and Ettema, 2007), and an increased MER during cocking phase (Stodden et al., 2005;van den Tillaar and Ettema, 2009a). ...
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Background The prevalence of sport specialization in high school athletes continues to rise, particularly among baseball players. Previous research has focused on the incidence of injury among specialized and non-specialized athletes but has yet to examine the level of sport specialization and pitching biomechanics. Hypotheses/Purpose The purpose of this study was to investigate differences in pitching volume and biomechanics between low-, moderate-, and high-level specialized baseball pitchers. It was hypothesized that high-level specialized pitchers would have the most pitching volume within the current and previous years while low-level specialized pitchers would exhibit the least amount. The second hypothesis states that kinematics and kinetics commonly associated with performance and injury risk would differ between low-, moderate-, and high-level specialized pitchers. Study Design Case-Control Study Methods Thirty-six high school baseball pitchers completed a custom sport specialization questionnaire before participating in a three-dimensional pitching motion analysis. Sport specialization was based off current guidelines and categorized as low-, moderate-, and high-level specialized based upon self-reported outcomes. Pitchers then threw ≈10 fastballs from a mound engineered to professional specifications. Data averaged across fastballs was used for biomechanics variables. Key pitching biomechanical and pitching volume variables were compared between low-, moderate-, and high-level specialized pitchers. Results High-level specialized pitchers were older ( p = 0.003), had larger body mass ( p = 0.05) and BMI ( p = 0.045), and threw faster ( p = 0.01) compared to low-level specialized pitchers. Pitching volume and pitching biomechanics were similar across groups. Conclusions Pitching biomechanics were similar across groups, although high-level specialized pitchers threw with significantly higher throwing velocity compared to low-level pitchers. The low amount of pitching volume throughout the season may be responsible for the lack of additional observed differences. Further research should examine the relationship between pitching biomechanics, upper extremity strength and flexibility, and sport specialization. Level of Evidence Level III
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The motion of a body segment is determined by joint torques and by the motions of the segments proximal or distal to it. This paper describes a three-dimensional model that was used to determine the effects of the shoulder and elbow joint torques and of the upper trunk and arm motions on the angular accelerations of the arm segments during baseball pitching. Equations were developed to fractionate the three-dimensional components of the angular acceleration vector of each segment into angular acceleration terms associated with the joint torques made on the segment, and into various “motion-dependent” angular acceleration terms associated with the kinematic variables of the arm segments. Analysis of the values of the various motion-dependent angular acceleration terms permitted the determination of their contributions to the motion of the segment. Although the model was developed to provide further understanding of the mechanics of the throwing arm during baseball pitching, it can be used to analyze any tw...
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Fastball pitches of eight collegiate baseball pitchers were filmed using the Direct Linear Transformation (DLT) method of three-dimensional (3D) cinematography. Coordinate data were obtained, and the model developed by Feltner and Dapena (1989) was used to fractionate the 3D angular acceleration of the upper arm and distal segment (the forearm, the hand, and prior to release, the baseball) of the throwing arm into terms associated with the joint torques exerted on the segments and the kinematic variables used to define the motions of the segments. The findings indicated that the extreme external rotation of the upper arm during the pitch was due mainly to the sequential actions of the horizontal adduction and abduction muscles at the shoulder. The study also found that the rapid elbow extension prior to ball release was due primarily to the counterclockwise angular velocity of the upper arm and trunk (viewed from above) that occurred during the pitch, and not to the elbow extensor muscles.
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