Clin Sports Med 23 (2004) 531–544Biomechanics and developmen.docx

Clin Sports Med 23 (2004) 531–544
Biomechanics and development of the elbow in
the young throwing athlete
Mark R. Hutchinson, MD*, Shawn Wynn, MD
Sports Medicine and Human Performance Center, Department of
Orthopaedics,
University of Illinois at Chicago, 270 MSB, M/C 844, 835
South Wolcott, Chicago, IL 60612, USA
Biomechanics is a complex study of function and demands,
including struc-
ture, motor power and acceleration, and angular forces and
loads. Regarding the
elbow, the study of biomechanics includes: the
flexion/extension motion;
pronation/supination motion; motor power and acceleration
related to the biceps,
brachialis, triceps, brachioradialis, supinator, and pronator teres
muscles; struc-
tural shapes and interactions of the distal humerus/proximal
radius/proximal ulna;
and the forces related to a variety of demands, ranging from

lifting to throwing.
The biomechanics of throwing is particularly complex, and
relies not only on the
function of an isolated segment such as the elbow, but on the
performance and
function of an entire kinetic chain of segments, including the
foot-ground surface,
hip and core power and rotation, scapular mobility and stability,
shoulder motion
and function, and hand and wrist position at ball release. The
throwing motion
has been studied in youth, adolescent, and adult pitchers at all
levels of com-
petition [1–14]; however, most biomechanical studies have been
performed
on the skeletally mature athlete, with closed physes, with years
of throwing
experience, and usually involved in competition at some level.
There is less
biomechanical information available on the developing child at
different stages of
growth, physeal age, and throwing levels.
The complexity of the study of biomechanics is magnified in the
skeletally

immature athlete, due to the dynamic changes occurring during
the devel-
opmental phases of youth. The forces and torques of throwing
with open physes
have been associated with adaptational changes in the growing
bone. As long
bones lengthen with physeal growth, moment arms are altered,
changing any
force calculation. The maturing neuromuscular system is
progressing with in-
0278-5919/04/$ – see front matter D 2004 Elsevier Inc. All
rights reserved.
doi:10.1016/j.csm.2004.06.005
* Corresponding author.
E-mail address: [email protected] (M.R. Hutchinson).
M.R. Hutchinson, S. Wynn / Clin Sports Med 23 (2004) 531–
544532
creased muscle mass and power. The pace of muscular
maturation mirrors, but is
not directly correlated to, advancing maturity of the neurologic
system that
controls coordination, proprioception, quickness, and control.
Each segment of

the kinetic chain matures at a different pace, requiring the
young thrower to make
continuous, subconscious modifications to account for the
changes and still
successfully perform the task or demand. Indeed, although
young throwers may
develop the normal sequence of throwing—including windup,
cocking, accel-
eration, and follow-through—by the age of 8, the coordination
of movement and
power develops gradually over the next several years.
This article reviews basic adult elbow kinematics and
biomechanics, and
introduces the unique ways in which the skeletally immature
and developing
elbow might be affected in comparison. To accomplish this task,
the authors also
review normal physical development and growth in children
specifically in-
volving the elbow, including adaptive changes that can occur
with repetitive
overuse. The discussion of motor skill development in children
emphasizes

the developmental phases of throwing to a mature adult
throwing mechanic. The
effect of abnormal mechanics in relationship to injury patterns
of the skeletally
immature should support the premise that we must be careful to
not overthrow
these young athletes and to teach them proper mechanics.
Basic elbow anatomy and kinematics
The elbow is a complex joint that serves as an important link to
position the
hand in space and transmit forces along the kinetic chain. The
elbow possesses
two degrees of freedom: flexion-extension and supination-
pronation. Normally,
elbow flexion ranges from 08, or slight hyperextension, to about
1508 of flexion.
Forearm rotation averages from 758degrees of pronation to 858
of supination. The
elbow has a relative valgus alignment, called a carrying angle,
that measures
about 108 to 158 in men and about 58 greater in women [15,16].
The carrying
angle is measured when the elbow is in extension; interestingly,
as the elbow is
full-flexed, the arm/forearm angle changes to 258 of varus
secondary to the
obliquity of the elbow joint [17]. An electromagnetic tracking

device that allows
three-dimensional measurement of active elbow motion reveals
the amount of
potential varus-valgus laxity with intact ligament restraints that
occurs during
elbow flexion averages about 38 [18].
Stability of the elbow joint is accomplished by the congruity of
the bony
articulation, the capsule and ligaments, and the muscle tendon
units that cross the
joint. The primary stabilizer for varus stability is the
articulation of the ulno-
humeral joint. The medial collateral ligament is the primary
stabilizer versus
valgus stress, and the most important stabilizer for the throwing
motion.
O’Driscoll et al [19] have also documented the importance of
the lateral ulnar
collateral ligament to elbow joint stability, and in particular to
posterolateral
rotatory instability of the elbow. The flexor-pronator muscle
group serves as a
secondary stabilizer to medial elbow instability.

544 533
Although excessive forces commonly lead to failure in the
ligaments and
tendons of mature throwers, children add to the complexity
secondary to their
open growth plates and apophyses. The growth plates frequently
yield before
failure of ligaments or mature bone. Overuse can lead to
adaptational or chronic
pathological changes in the skeletally immature elbow,
including medial epi-
condyle apophysitis or avulsion, radial head hypertrophy, or
avascular changes in
the capitellum (osteochondritis dissecans). The etiology of
adaptational changes
in the elbow are similar to those seen in the shoulder. The
rotational adaptation of
humeral head retroversion seen in elite adult throwers has been
correlated with
the torque forces placed across the proximal humeral physis in
young pitchers
[20]. When evaluating the developing throwing athlete, it is
helpful to know the

normal progression of the appearance and closure of the primary
and secondary
centers of ossification [21]. Comparative radiographs can also
reveal significant
side-to-side differences.
Biomechanics of throwing
Throwing is an integral component of many sports, and has been
associated
with more overuse problems about the elbow than any other
single mechanism.
The biomechanics of the throwing motion is dependent on a
coordinated se-
quence of events along a kinetic chain from the ground reaction
force, up the leg
and through the hips and torso (core), across the shoulder
through the elbow, and
down to the hand and ball release [22]. Coordinated human
motion, energy, and
momentum are transferred and increased through successive
body segments,
which allows the ultimate outcome of speed or distance to
occur. The coor-
dination of the sequence is important to prevent overload and
overuse injuries,

especially in the more terminal segments about the shoulder and
elbow [23,24].
The six stages of the pitching motion are well known (Fig. 1)
[7,25–28].
Briefly, they include the windup, stride, arm cocking, arm
acceleration, arm
deceleration, and follow-through [7,14]. The windup starts with
the pitcher on the
mound, and ends when the throwing hand leaves the glove and
the front leg
Fig. 1. Four of the six phases of the adult throwing mechanic:
wind up, arm cocking, acceleration,
follow-through.
544534
strides toward home plate. The stride phase ends when the foot
contacts the
mound. The cocking phase begins when the front foot contacts
the mound, and
ends when the arm is brought into maximum external rotation.
The arm
acceleration phase begins when the arm is in maximum external
rotation, and
ends right before the ball is released. The arm deceleration

phase begins with ball
release, and ends when the shoulder has reached maximal
internal rotation.
Follow-through begins with the shoulder in maximal internal
rotation, and ends
when the pitcher has reached a stable fielding position [14].
Each of the six phases has a unique biomechanics about the
elbow. During the
windup, the forearm is slightly pronated and the elbow is
flexed. During the
stride or early cocking phase, the elbow is extended slightly,
but very few
significant forces cross the elbow. During late arm cocking, the
forearm is fully
pronated and the elbow extended to about 908, and the shoulder
is cocked onto
external rotation. Valgus forces across the elbow begin to rise
in late cocking, but
increase exponentially during acceleration, resulting in loads
that approach the
ultimate failure strength of the medial collateral ligament.
During acceleration to
ball release, the elbow extends from 908 to 110 8of flexion to
208 to 358 of
extension. In late cocking and acceleration, the energy of the

forward stride and
the energy from pelvic and upper torso rotation are transferred
more distally
along the kinetic change to the upper extremity. In professional
pitchers, the hand
can accelerate to 100 miles per hour in the matter of 50
milliseconds. Internal
torque forces on the humerus approach 14,000 in-lbs before ball
release [29].
This motion has been described as the fastest in all sports.
Shoulder internal
rotation maximum velocity is between 6000 and 75008/s [6,30].
Maximum
velocity at the elbow in professional baseball pitchers is about
23008/s; during the
football throw it is slightly slower at about 17608/s. The forces
to create this
Fig. 2. Valgus forces associated with throwing lead to
compressive forces on the lateral aspect of the
elbow and tension forces over the medial aspect of the elbow.
544 535
powerful acceleration are developed sequentially along the
kinetic chain, with
some contribution of triceps contraction during acceleration.

The fourth and fifth
phases come after ball release, and involve a quick deceleration
and follow-
through. Just after ball release, the biceps and brachialis fire
powerfully to avoid
hyperextension of the elbow. The biceps contraction also assists
in slowing fore-
arm pronation. If the biceps and triceps are delayed or weak,
posterior impinge-
ment occurs.
In the adult, the throwing motion can place extreme forces
across the elbow
that, if unbalanced or uncontrolled, can lead to injury. During
late cocking and
acceleration, tension forces across the medial elbow jump to
about 300 N (Fig. 2)
[31]. During deceleration, the elbow compressive force jumps
over 800 N [4,31].
When the tension forces or chronic changes of the capitellum or
radial head
secondary to the compressive loads are left unbalanced or
unaccounted for, it is
not surprising that athletes can develop failure of the medial
collateral ligament.

Fleisig and colleagues [8,22,32] noted that a single throw in
elite baseball players
approaches the ultimate tensile strength of the medial collateral
ligament.
The skeletally immature thrower
Although the fundamental concepts of throwing biomechanics
apply to the
developing elbow, a number of factors make it difficult to
directly translate the
forces and specific mechanics of the adult thrower to the
skeletally immature
thrower. The creation of forces is dependent on a mature versus
immature
throwing mechanic, the age of the athlete, the weight of the
athlete, the height and
stride length of the athlete, the length of each kinetic segment
(forearm, arm, and
so on), the strength in each muscle group along the kinetic
chain, and a
coordination of the activation and firing of those muscle groups.
Much has been studied and written about the general
developmental
milestones in the pediatric population (eg, crawling, walking,
talking). Less is

known about the development of a throwing motion in children.
Wild [33,34]
first described the developmental sequences for bhard
overhandQ throwing.
Thirty-two children were filmed while throwing forcefully at
multiple times from
age 2 to age 12. She studied how the children, at different ages,
recruit different
parts of their body to achieve a forceful throw. Wild and others
initially were
describing what is now known as the btotal-body phenomenonQ
to the devel-
opmental throwing sequence [33–37]. Further research into the
development of
an overhead throwing motion has led to a bcomponent
approachQ [38–40].
Roberton and Halverson [41] published the developmental
sequences for
components of the overarm throw for force, which include the
developmental
sequences for three body parts involved in the overarm throw:
the trunk (pelvis-
spine), the humerus, and the forearm.
The developmental throwing milestones are a consistent
sequence of events

that maturing children progress through when developing a
normal throwing
mechanic (Fig. 3) [33,34]. The first few stages begin with the
young athlete
Fig. 3. (A–C) The first three developmental phases of throwing
include a push, cocking or trunk
rotation, and a step in the direction of the target but all with the
body facing the target. (D,E) The final
developmental phases of throwing are heralded by a body turn
to perpendicular to the target, followed
by a gradual progression to a mature throwing mechanic.
544536
Fig. 3 (continued).
544 537
facing the target, torso parallel. First the young child simply
pushes the ball (age
2–3). Next, she learns to cock her arm with some torso rotation
to gain
momentum (age 3–5). In an attempt to make the ball go farther
in Stage III, she

learns to take a step toward the target (age 5–6). This usually
begins with an
awkward ipsilateral step before adding coordination and
stepping with the
contralateral leg. The next major development occurs when the
young athlete
begins the sequence with her torso facing perpendicular to the
target (age 7 and
above). This allows for a more mature development of windup,
stride, cocking,
acceleration, and follow-through. Very few injuries happen to
children in the
early stages of a developing throwing mechanic. In each stage
in which the child
begins parallel and not perpendicular to the target, it is difficult
if not impossible
to create enough torque and force development along the kinetic
chain to
negatively affect the ligaments or growth plates. As the
sequence of throwing
approaches a more mature throwing mechanic, peak velocity
improves and the
timing of ball release associated with peak arm velocity
improves [41]. Before a

mature throwing mechanic is achieved, children are unlikely to
throw hard
enough or frequently enough to exceed the limits of their
structure.
Various authors [42–44] have reported that the pace of
developing a mature
throwing mechanic may be delayed in females compared with
age-matched males
[Fig. 4]. Indeed, Jones in 1961 [45] may have been the first to
show that
Fig. 4. The percentage of mature throwing patterns by grade and
gender. From left to right the
percentage of both males and females with those patterns
increases from kindergarten to eighth
grade, with intermediate decreases in some years; however,
females remain delayed throughout
the age progression. (Data from Butterfield SA, Loovis EM.
Influence of age, sex, balance, and
sport participation on development of throwing by children in
grades K–8. Percep Mot Skills 1993;76:
459–64.)

544538
bthrowing like a girlQ represented simply an immature throwing
mechanic and not
a specific gender-related anatomic or physiologic finding.
Historically, when
evaluating ball velocity, gender has been a reasonable predictor;
however, if the
athletes are grouped by stages of development, gender explains
no more then 2%
additional variance [46]. The concept that gender alone causes
an abnormal
throwing mechanic should be discarded. What is witnessed is
more likely an
immature throwing mechanic.
Tullos and King [47] recognized that by early adolescence
young Little
Leaguers had developed a similar sequential pattern of throwing
to that of adults.
Campbell and colleagues [48,49] have documented a mature
throwing mechanic
by the age of 8 to 9 in some Little Leaguers. Fleisig and
coworkers [7] performed
a kinematic and kinetic study to compare pitching biomechanics
among various
levels of competition, in order to see if proper mechanics were

taught and learned
early in a pitcher’s career. Two hundred and thirty-one male
baseball pitchers
were included in the study (23 youth, 33 high-school, 115
college, and 60 pro-
fessional level athletes). Kinematic (position and velocity),
kinetic, and temporal
parameter were calculated and compared among the four levels.
All velocity and
kinetic parameters increased with competition level. Only 1 out
of the 17 position
and temporal parameters showed a significant difference. The
increases in joint
forces and torques in the higher level athlete were due to
increased strength and
muscle mass. Therefore, it seems that the biomechanics between
the different
544 539
levels of competition were not significant, except for the
velocity parameters,
which increase as the athlete’s strength increases and the body
matures [7].

Although the sequence appears normal, it is not possible for
immature
throwers to develop the same levels of forces across their
elbows as seen in adult
throwers. Humerus and forearm length are less than the mature
adult, implying a
shorter moment arm to develop torque. Muscle mass, as shown
by Fleisig et al [7]
is smaller in the young athlete. Muscle strength and quickness
continue to
advance as the young athlete matures, but muscles are not as
powerful or agile as
in the adult athlete. These facets, as well as the relative low
pitch count in the
youngest of throwers, may explain why injuries are less
commonly seen in the
8- to 11-year-old throwers. Relatively speaking, however, the
protective concepts
of shorter moment arm, reduced muscle mass, and reduced
motor power remain
true for the 12- to 14-year-old pitchers, who are the most
common age group to
develop overuse injuries to their elbows. Why does this occur?
Biomechanics and elbow injuries in the skeletally immature
throwing athlete

Elbow pain in young baseball pitchers is associated with many
factors,
including age, weight, height, number of pitches thrown during
a season,
satisfaction with performance, lifting weights, and playing
outside of the league
[50]. Age and the timing of the child’s growth spurt appear to
be important
factors, because the physis appears to be at increased risk of
injury during active
phases of growth. The athlete’s increased height implies longer
moment arms in
the kinetic chain to transfer for forces. The athlete’s higher
weight implies more
potential energy to be transferred along the kinetic chain during
forward stride.
The total pitch count gradually increases as the child thrower
matures. By age 11
to 14, young athletes have begun to separate themselves out as
position players,
leaving those determined to be pitchers to have an increased
total number of
throws. Increased practice with parents and coaches, and the
increased demands

and total innings that come with success, further increase the
total pitch count.
The energy and forces across the maturing elbow grow with the
total number of
pitches, and are magnified by a gradual increase in the speed of
the ball thrown
from relative low speeds to 45 to 55 miles per hour by age 11 or
12. Andrews and
Fleisig [51] performed a survey of US baseball to determine
recommendations for
pitch counts, and came up with 52 F 15 pitches per game at age
8 to 10, 68 F 18
pitches per game for 11 to 12 year olds, and 76 F pitches for 13
to 14 year olds.
Lyman et al [52] noted a 35% increased risk of elbow pain if
young athletes were
throwing 75 to 99 pitches per game and over 600 pitches per
season. The impact
of pitch type has received special focus in the literature on
young throwing athlete
[53–56].
Historically, coaches and physicians have discouraged young
pitchers from
throwing curve balls, for fear of increased forces across the
medial elbow and

subsequent increased risk of injury. In a recent study [52], 476
pitchers ranging in
age from 9 to 14 were prospectively studied. Nearly 7% of all
pitching ap-
544540
pearances resulted in elbow pain, and 28% of pitchers admitted
to having elbow
pain at least once during the season. In studying pitch types,
including the slider,
the curveball, and the change-up, it was found that only the
slider had a
significant relationship to elbow pain, and that it had an overall
86% increased
risk of elbow pain among the pitchers who threw it. The use of
the change-up was
associated with 12% risk reduction for the development of
elbow pain. Albright
et al [57] noted that the elbow injury rate was higher in
pediatric throwers with
poor technique (52%) as opposed to those who used proper
technique (9%). In
their study, side arm motion was implicated; however, the effect

of throwing a
curve ball on the skeletally immature elbow remained unproven.
Seventeen to forty-five percent of preadolescent and adolescent
baseball
pitchers aged 9 to 14 years have elbow discomfort while
pitching [16,58–61].
The presence of a mild flexion contracture occurred in 4% to
12%, and valgus
deformity in 3% to 37%. Radiographic changes may be seen in
28% to 100% of
young pitchers. Radiographic changes include hypertrophy,
separation, and frag-
mentation of the medial epicondylar physis; osteochondrosis,
flattening or frag-
mentation of the capitellum; radial head hypertrophy or
fragmentation; olecranon
physeal widening or spurring; or asymmetric valgus alignment
of the elbow. The
etiology of these findings is directly related to overuse and the
biomechanics of
the throwing motion [62]. The cocking and acceleration phases
create a medial
tension stress over the medial collateral ligament that
chronically pulls on the

medial epicondyle. The same valgus load creates chronic
compressive forces over
the capitellum and radial head, leading to hypertrophic
compensation or vascular
compromise. The compressive forces across the capitellum and
radial head
continue during the deceleration phase, as the biceps and
brachialis fire to slow
extension and decelerate the forward motion of the arm. The
olecranon is loaded
during active extension of the elbow, and may impinge in the
olecranon fossa
during cocking and during follow-through. Campbell and
colleagues [48,49]
performed some interesting studies comparing pitchers in four
age groups: 9 to
12 years old, 13 to 16 years old, collegiate, and professional.
They discovered
that younger athletes had slower ball velocity, less angular
velocity of the upper
torso, less elbow extension, less shoulder internal rotation, less
shoulder internal
rotation torque, and less shoulder anterior force, even when
compensated for

body weight. The elbow in the youth pitcher’s elbow did have
increased varus
torque forces in the acceleration phase compared with the adult
thrower.
So with all of these forces, why doesn’t a pitcher destroy his
elbow with every
pitch? The answer lies in the coordinated, balanced, progression
of forces trans-
ferred in a carefully sequenced pattern up the kinetic chain.
Timing and coor-
dination are important for pitch accuracy, especially the timing
of ball release
with peak velocity [63,64]. Some flaws may reduce the forces
across the elbow
and reduce the risk of injury. Backward lean in the balance
position and early ball
release were associated with a decreased risk of elbow pain
[52]; however, if the
athlete tries to throw with the same speed with poor push-off or
core rotation, he
must make up the momentum somewhere, and the shoulder or
elbow usually
suffer. The distal segment velocity is directly related to the
efficiency of the

544 541
proximal/distal segment articulation and the proximal segment
angular velocity
[65,66]. The timing of muscle firing and coordination of
movement along the
kinetic chain is a developed skill. If the kinetic sequence and
transfer of forces are
coordinated, balanced, and smooth, the athlete can throw at the
same speed with
less detrimental forces across the joints.
Biomechanical concepts for injury prevention
The best time to correct improper biomechanics, and thereby
prevent elbow
injury and pathology, is at the beginning of a pitcher’s career,
which usually starts
during youth or Little League baseball. The two primary targets
of intervention
are overuse and technique. Current Little League rules advise
limiting young
throwers to six innings per week with 3 days rest between
outings [67]. Total
pitch counts have been implicated, and should be monitored

carefully. Little
Leaguers and their parents have dreams of playing professional
baseball. Care
must be taken to include total practice pitches at full speed and
with different
teams when evaluating total throwing exposure. In reviewing
major league
pitching staffs, it became apparent that most pitchers began
pitching at age 15 and
began throwing breaking pitches at age 17. No Little League
All-Star pitcher has
become a professional level pitcher [68].
The second target of prevention is optimizing technique.
Children should not
be allowed to throw as hard as they can until a mature throwing
mechanic is
documented. Poor coordination or weakness at any segment
proximally in the
kinetic chain will directly influence the forces seen at more
distal segments. If
balance is poor and the sequence is uncoordinated, excessive
forces will be
placed at the weak links in the chain. For young developing
throwers, the weak

link is likely to be the tension medial side of their elbow or the
lateral
compression side of their elbow. Attention to these issues of
biomechanics in the
young throwing elbow can help to reduce the overall risk of
injury in these
developing athletes.
References
[1] Barrentine SW, Matuso T, Escamilla RF, Fleisig GS,
Andrews JR. Kinematic analysis of the
wrist and forearm during baseball pitching. J Appl Biomech
1998;14:24–39.
[2] Dillman CJ, Fleisig GS, Andrews JR. Biomechanics of
pitching with emphasis upon shoulder
kinematics. J Orthop Sports Phys Ther 1993;18:402–8.
[3] Escamilla RF, Fleisig GS, Zheng N, Barrentine SW,
Andrews JR. Kinematic comparisons of
1996 Olympic baseball pitchers. J Sports Sci 2001;19(9):665–
76.
[4] Feltner M, Dapena J. Dynamics of the shoulder and elbow
joints of the throwing arm during
a baseball pitch. International Journal of Sports Biomechanics
1986;2(4):235–59.

[5] Fleisig GS, Andrews JR, Dillman CJ, Escamilla RF.
Kinematics of baseball pitching with
implications about injury mechanisms. Am J Sports Med
1995;23:233–9.
[6] Fleisig GS, Escamilla RF, Andrews JR, Matsuo T,
Satterwhite Y, Barrentine SW. Kinematic and
kinetic comparison between pitching and football passing. J
Appl Biomech 1996;12:207–24.
544542
[7] 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:
1371–75.
[8] Fleisig GS, Escamilla RF, Barrentine SW. Biomechanics of
pitching: mechanism and mo-
tion analysis. In: Andrews JR, Zarins B, Wilk K, editors.
Injuries in baseball. Philadelphia7
Lippincott-Raven; 1998. p. 3–22.
[9] MacWilliams BA, Choi T, Perezous MK, Chao EY,
McFarland EG. Characteristic ground
reaction forces in baseball pitching. Am J Sports Med

1998;26:66–71.
[10] Pappas AM, Zawacki RM, Sullivan TJ. Biomechanics of
baseball pitching. A preliminary report.
Am J Sports Med 1985;13:216–22.
[11] Pappas AM, Morgan WJ, Schulz LA, Diana R. Wrist
kinematics during pitching. A preliminary
report. Am J Sports Med 1995;23:312–5.
[12] Sakuri S, Ikegami Y, Okamoto A, Yabe K, Toyoshima S. A
three-dimensional cinematographic
anaylsis of upper limb movement during a fastball and curveball
pitches. J Appl Biomech 1993;
9:47–65.
[13] Vaughn RE. Three dimensional kinematics of the baseball
pitch. In: Terauds J, Barham JN,
editors. Biomechanics in sports, vol. II. Del Mar (CA)7
Academic Press; 1985. p. 72–8.
[14] Werner SL, Fleisig GS, Dillman CJ, Andrews JR.
Biomechanics of the elbow during baseball
pitching. J Orthop Sports Phys Ther 1993;17:274–8.
[15] Stroyan M, Wilk K. The functional anatomy of the elbow
complex. J Orthop Sports Phys Ther
1993;17(6):279–88.

[16] Yocum Y, Dryer RF, Thambyrajah K, Flat AE, Sprague BL.
Biomechanical analysis of forearm
pronation-supination and elbow flexion-extension. J Biomech
1979;12:245–55.
[17] DaSilva MF, Williams JS, Fadale PD, Hulstyn MJ, Ehrlich
MG. Pediatric throwing injuries
about the elbow. Am J Orthop 1998;27(2):90–6.
[18] An KN, Morrey BF. Biomechanics of the elbow. In: Morrey
BF, editor. The elbow and its
disorders. Philadelphia7 WB Sanders; 1985. p. 45–7.
[19] O’Driscoll SW, Bell DF, Morrey BF. Posterolateral
rotatory instability of the elbow: clinical and
radiographic features. J Bone Joint Surg 1991;73A:440–6.
[20] Chant CB. Rotational adaptation: humeral head
retroversion in throwing athletes. Biomechanics
2003;10(4):22–32.
[21] Hutchinson MR, Ireland ML. Overuse and throwing
injuries in the skeletally immature athlete.
Instr Course Lect 2003;52:25–36.
[22] Fleisig GS, Barrentine SW, Escamilla RF, et al.
Biomechanics of overhand throwing with
implication for injuries. Sports Med 1996;21(6):421–37.

[23] Feltner M, Dapena J. Dynamics of the shoulder and elbow
joints of the throwing arme during
a baseball pitch. International Journal of Sports Biomechanics
1985;5:420–50.
[24] Dillmam CJ. Proper mechanics of pitching. Sports
Medicine Update 1990;5:15–8.
[25] DiGiovine NM. An electromyographic analysis of the
upper extremity in pitching. J Should
Elbow Surg 1992;1:15–25.
[26] Feltner ME, Dapena J. Three-dimensional interactions in a
two-segment kinetic chain: part I:
general model. International Journal of Sports Biomechanics
1989;5(4):403–19.
[27] Moynes DR, Perry J, Antonelli DJ, Jobe FW.
Electromyography and motion analysis of the
upper extremity in sports. Phys Ther 1986;66(12):1905–11.
[28] Sisto DJ, Jobe FW, Moyes DR, Antonelli DJ. An
electromyographic analysis of the elbow in
pitching. Am J Sports Med 1987;15:260–3.
[29] Gainor BJ, Piotrowski G, Puhl J, et al. The throw:
biomechanics and acute injury. Am J Sports
Med 1980;8(2):114–8.
[30] Pappas AM, Zawacki RM, McCarthy CF. Rehabilitation of

the pitching shoulder. Am J Sports
Med 1985;13:223–35.
[31] Werner SL, Fleisig GS, Dilman CJ, et al. Biomechanics of
the elbow during baseball pitching.
J Orthop Sports Phys Ther 1993;17:274–8.
[32] Fleisig GS, Dillman CJ, Escamilla RF, et al. Kinetics of
baseball pitching with implications about
injury mechanisms. Am J Sports Med 1995;23:233–9.
544 543
[33] Wild MR. The behavior pattern of throwing and some
observations concerning its course of
development [dissertation]. Madison (WI)7 University of
Wisconsin at Madison; 1937.
[34] Wild MR. The behavior pattern of throwing and some
observations concerning its course of
development in children. Res Q 1938;9:20–4.
[35] Hanson SK. A comparison of the overhand throw
performance of instructed and non-instructed
kindergarten boys and girls [thesis]. Madison (WI)7 University
of Wisconsin at Madison; 1961.
[36] Leme S, Shambes G. Immature throwing patterns in normal

adult women. Journal of Human
Movement Studies 1978;4:85–93.
[37] Seefeldt V, Reuschlein S, Vogel P. Sequencing motor skills
within the physical education
curriculum. Report to the National Convention, American
Association for Health, Physical
Education, and Recreation. Houston, TX, April, 1972.
[38] Roberton MA. Stability of stage categorizations across
trials: implications for a bstage theoryQ on
over-arm throw development. Journal of Human Movement
Studies 1977;3:49–59.
[39] Haywood K, Getchell N. Life span motor development. 3rd
edition. Champaign (IL)7 Human
Kinetics; 2001.
[40] Langendorfer SJ, Roberton MA. Invidual pathways in the
development of forceful throwing. Res
Q Exerc Sport 2002;73(2):245–56.
[41] Roberton MA, Halverson LE. Developing children—their
changing movement: a guide for
teachers. Philadelphia7 Lea and Febiger; 1984.
[42] Butterfield SA, Loovis EM. Influence of age, sex, balance
and sport participation on
development of throwing by children in grades K–8. Percept

mot skills 1993;76:459–64.
[43] Seefeldt V, Haubenstricker J. Patterns, phases, or stages:
an analytical model for the study of
developmental movement. In: Kelso JA, Clark JE, editors. The
development of movement
control and coordination. New York7 Wiley; 1982. p. 309–18.
[44] Nelson KR, Thomas JR, Nelson JK. Longitudinal change in
throwing performance: gender
differences. Res Q Exerc Sport 1991;62(1):105–8.
[45] Jones F. A descriptive and mechanical analysis of throwing
skills of children [thesis]. Madison
(WI)7 University of Wisconsin at Madison; 1961.
[46] Roberton MA, Konczak J. Predicting childrens overarm
throw ball velocities from their
developmental levels in throwing. Res Q Exerc Sport
2001;72(2):91–103.
[47] Tullos HS, King JW. Throwing mechanism in sports.
Orthop Clin North Am 1973;4:709–21.
[48] Campbell KR, Hagood SS, Takagi Y, et al. Kinetic analysis
of the elbow and shoulder in
professional and Little League pitchers. Med Sci Sports Exerc
1994;26(5):S175.
[49] Cosagarea AJ, Campbell KR, Hagood SS, et al.

Comparative analysis of throwing kinematics
from Little League to professional baseball pitchers. Med Sci
Sports Exerc 1993;25(5):S131.
[50] Lyman S, Fleisig GS, Waterbor JW, Funkhouser EM,
Pulley L, Andrews JR, et al. Longitudinal
study of elbow and shoulder pain in youth baseball pitchers.
Med Sci Sports Exerc 2001;33(11):
1803–10.
[51] Andrews JR, Fleisig GS. How many pitches should I allow
my child to throw? USA Baseball
News 1996;5:5.
[52] Lyman S, Fleisig GS, Andrews JR, Osinski ED. Effect of
pitch type, pitch count, and pitching
mechanics on risk of elbow and shoulder pain in youth baseball
pitchers. Am J Sports Med 2002;
30(4):463–8.
[53] Dugas JR, Wilk KE. Adolescent shoulder and elbow
injuries. American Orthopaedic Society
for Sports Medicine Sports Medicine Update 2003;(May–
June):4–6.
[54] DeHaven KE, Evarts CM. Throwing injuries of the elbow
in athletes. Orthop Clin North Amer
1973;4:801–8.

[55] Pappas AM. Elbow problems associated with baseball
during childhood and adolescence. Clin
Orthop 1982;164:30–41.
[56] Escamilla RF, Fleisig GS, Barrentine SW, et al. Kinematic
comparisons of throwing different
types of baseball pitches. J Appl Biomech 1995;14:1–23.
[57] Albright JA, Jokl P, Show R, et al. Clinical study of
baseball pitchers: correlation of injury to the
throwing arm with method of delivery. Am J Sports Med
1978;6:15–21.
544544
[58] Torg JS, Pollack H, Sweterlitsch P. The effect of
competitive pitching on the shoulders and
elbows of preadolescent baseball players. Pediatrics
1972;49:267–72.
[59] Adams JE. Injury to the throwing arm: a study of traumatic
changes in the elbow joints of
boy baseball players. Calif Med 1965;102:127–32.
[60] Gugenheim Jr JJ, Stanley RF, Woods GW, Tullos HS.
Little League survey: the Houston study.
Am J Sports Med 1976;4(5):189–200.

[61] Larson RL, Singer KM, Bergstrom R, Thomas S. Little
League study: the Eugene study. Am J
Sports Med 1976;4(5):201–9.
[62] Klingele KE, Kocher MS. Little League elbow: valgus
overload injury in the paediatric athlete.
Sports Med 2002;32(15):1005–15.
[63] Hore J. Motor control, excitement, and overarm throwing.
Can J Physiol Pharmacol 1996;74:
385–9.
[64] Hore J, Watts S, Martin J, et al. Timing of finger opening
and ball release in fast and accurate
over arm throws. Exp Brain Res 1995;103:277–86.
[65] Putnam CA. Sequemtial motions of body segments in
striking and throwing skills: description
and explanations. J Biomech 1993;26(Suppl 1):125–35.
[66] Chowdhary AG, Challist JH. The biomechanics of overarm
throwing task: a simulation model
examination of optimal timing of muscle activations. J Theor
Biol 2001;211:39–53.
[67] Little League International. 1996 Youth Baseball
Handbook. Williamsport (PA)7 Little League
International; 1996.

[68] Chandler J. Youth baseball injuries. Presented at Injuries
in Baseball Course. American Sports
Medicine Institute. Atlanta, GA, January 2003.
Biomechanics and development of the elbow in the young
throwing athleteBasic elbow anatomy and
kinematicsBiomechanics of throwingThe skeletally immature
throwerBiomechanics and elbow injuries in the skeletally
immature throwing athleteBiomechanical concepts for injury
preventionReferences

Clin Sports Med 23 (2004) 531–544Biomechanics and developmen.docx

Recommended

Recommended

More Related Content

Similar to Clin Sports Med 23 (2004) 531–544Biomechanics and developmen.docx

Similar to Clin Sports Med 23 (2004) 531–544Biomechanics and developmen.docx (20)

More from bartholomeocoombs

More from bartholomeocoombs (20)

Recently uploaded

Recently uploaded (20)

Clin Sports Med 23 (2004) 531–544Biomechanics and developmen.docx