The Windmill Softball Pitch: Optimal Mechanics and

INJURY PREVENTION &
PERFORMANCE ENHANCEMENT
Jennifer Medina McKeon, PhD, ATC, Report Editor
The Windmill Softball Pitch: Optimal
Mechanics and Pathomechanics of Injury
Gretchen D. Oliver PhD, ATC, LAT • University of Arkansas
F
ast-pitch softball has become increasingly
popular. Over the past two decades, participation in Little League softball in the U.S. has
dramatically increased from 259,080 players
in 1990 to 349,065 players in 2009.1 The
Amateur Softball Association reports over
83,000 youth girls fast-pitch softball teams,
comprising over 1.2 million girls.2 Softball
is similar to baseball, but a higher injury
rate has been reported for girls participating in softball than for
boys participating in
Key Points
baseball.3 When compared to baseball, fastThe muscles of the lower extremity are
pitch softball exhibhighly active during the dynamic moveits some important
ment of the windmill softball pitch.
differences: (a) pitchAdequate pelvis stabilization from the
ing surface, (b) pitchgluteal muscle group is paramount for dising distance to home
sipation of forces.
plate, and (c) number
of pitches delivered
by one pitcher within a short period of time.
In baseball, pitches are delivered from an
elevated mound (approximately 10 inches),
whereas softball pitches are delivered from
a flat surface. The distance from the pitching rubber to home plate in baseball is 18.4
meters, whereas the corresponding distance
in softball is 12.2 meters. Softball pitchers
may pitch in as many as 10 games during a
weekend, which equates to approximately
1,500 to 2,000 pitches within a three-day
period.4,5,6 Because there is no pitch count
restriction in softball, teams typically have a
smaller number of pitchers on their rosters
than baseball teams, which ultimately results
in more innings being pitched per athlete.7
Because the softball pitcher throws from
flat ground, rather than an elevated mound,
the effect of gravity assistance to the pitch follow-though is absent. Instead of a controlled
fall off a mound during the follow-through,
the softball pitcher displays an abrupt stop,
or posting mechanism, by the stride leg upon
ball release. Ground reaction force experienced during the windmill softball pitch
has been reported to be similar or greater
than that experienced by baseball pitchers.7
Softball pitchers have been reported to have
a high incidence of lower extremity injuries,
which may be related to the high ground
reaction force that results from posting of
the stride leg at ball release.8,9
There are many similarities between
softball and baseball. Although the windmill pitching motion is widely perceived
to be more natural and less stressful to the
shoulder than the overhand baseball pitch,
the distraction force at the shoulder while
performing the windmill softball pitch has
been reported to be similar to that of a
baseball pitch.4,6 The torques acting on the
shoulder and the elbow have been reported
to be comparable for both types of pitching,
or even greater for the softball pitch.6 Powell
and Barber-Foss3 reported that softball play© 2010 Human Kinetics - ATT 15(6), pp. 28-31
28  novEMBER 2010
Athletic Therapy Today
ers had a 27% higher injury incidence than baseball
players. Although severe injuries rarely occur,10 less
serious overuse injuries are common.11 Loss of playing
time has been reported for 45% of softball injuries, and
45% of the time-loss injuries involved the shoulder or
the elbow.11 A study of 180 college pitchers found that
72.8% had sustained an injury during the previous
year.8 Among 131 injuries that were reported, 36 were
acute, 92 resulted from chronic overuse, and 3 were
had an unspecified onset.8 Greater attention needs to
be given to prevention of injury to softball pitchers.
Movement efficiency has been associated with
a proximal to distal muscle activation sequence.12
Kibler13 has estimated that the lower extremity contributes 50–55% of the total energy generated by the
body during performance of an upper extremity task.
To transfer energy through the kinetic chain from
the lower extremity to the upper extremity, a softball
pitcher must have good neuromuscular control of the
lower extremity.13,14 Traditionally, analysis of pitching
performance and injury susceptibility has been focused
on the function of the upper extremity; however,
movement of the hips directs movement of the pelvis,
which directs movement of the torso, the scapula, and
the shoulder.15 The pelvis has been described as the
platform for the scapula, and the scapula has been
described as a platform for the shoulder.14,16,17 To serve
as a platform, the pelvis must exhibit stability during
functional movement, just as the scapula must maintain stability for the humerus to be effectively elevated.
Although some studies have analyzed the softball
pitching motion,4,6,7,18,19 the available information is far
less than that for baseball pitching. Understanding of
the pathomechanics of common overuse syndromes
is limited by a relative lack of quantitative information
about the joint displacements and the corresponding muscle activation patterns that occur during the
softball pitching motion. On the basis of available
evidence,4,6-11,19 a description of the softball pitching
motion is provided, with a recommended approach
to injury prevention.
Phases of the Pitch
Maffet et al20 described the windmill pitching motion
in terms of six phases that correspond to intervals on
a clock. For a lateral view of a right-handed pitcher
(Figure 1), Phase 1 (wind-up) consists of counterclockwise downward movement to a 6 o’clock position. Phase 2 corresponds to upward movement from
6 o’clock to 3 o’clock, phase 3 corresponds to upward
movement from 3 o’clock to 12 o’clock, phase 4 corresponds to downward movement from 12 o’clock
to 9 o’clock, phase 5 corresponds to movement from
9 o’clock to ball release, and phase 6 corresponds
to movement from ball release to completion of the
follow-through motion.
During phase 1, the pitcher is generating momentum. Pitchers will often internally rotate the throwing arm and shift weight to the ipsilateral leg. Many
pitchers display very unique wind-up motions, some
of which involve extraneous movements. The wind-up
should be a continuous motion that provides an efficient energy transfer from phase 1 to phase 2. When
the pitcher displays an interruption in the movement
from phase 1 to phase 2, potentially injurious stress
may be created.
During phase 2, the contralateral stride leg undergoes hip flexion and knee extension and the ipsilateral
gluteal muscle contracts to stabilize the pelvis.19 Also
Figure 1 Phases of the windmill softball pitch.
Athletic Therapy Today
novEMBER 2010  29
during this phase, the triceps are activated to control
elbow extension and the scapular stabilizers are activated to prepare for increasing humeral elevation.19
At the 12 o’clock position, the pitcher’s arm reaches
the limit of its movement in a direction opposite to the
direction the ball will be pitched, which is referred to
as top of backswing (TOB). During phase 3, the pitcher
may make ground contact with the stride foot prior
to TOB. Alternatively, stride foot ground contact may
occur after TOB, which separates phase 3 from phase
4. At TOB, the humerus is externally rotated and in the
position that corresponds to full cocking for the baseball pitch. Maffet et al20 reported that posterior deltoid,
infraspinatus, and teres minor are activated at TOB.
The pitcher should stride directly toward home
plate. Often the pitcher will appear to leap during the
stride phase, but the support foot must remain on the
ground for the pitch to be legal. If the pitcher fails to
drag the support foot, the pitch will be ruled illegal.
Leaping allows the pitcher to get closer to the batter
before ball release, which decreases the amount of time
the batter has to react to the pitch. Pitchers who have
a long stride length tend to have higher pitch velocities.4,18,19 Stride length has been reported to average
60 to 70% of the pitcher’s height.9
As the arm accelerates downwardly from TOB to
the 9 o’clock position (phase 4), the gluteal muscle
group, the scapular stabilizers, and the biceps are
active.19 During this phase, the pitcher is “posting” on
the stride leg for ball delivery. As the stride leg begins
to support the body weight, the gluteus medius must
maintain elevation of pelvis on the opposite side to
transfer energy from one foot to the other. The greatest
activation of the biceps occurs during the acceleration
phase, whereas biceps activation is greatest during the
deceleration phase of a baseball pitch.
From the 9 o’clock position to ball release (phase
5), the pectoralis major, subscapularis, and serratus
anterior muscles internally rotate and adduct the
humerus and stabilize the scapula.20 At ball release,
the muscles with the greatest level of activation are
the gluteal group and the triceps.19 The hips move
from a relatively parallel orientation to home plate to a
more perpendicular orientation. Hip rotation coincides
with ball release. Rojas21 has reported that anterior
shoulder pain in the area of the bicipital grove is a
common complaint among windmill softball pitchers. Biceps activation is greatest from the 9 o’clock
position to ball release.9,21 At the 9 o’clock position,
30  novEMBER 2010
the elbow approaching full extension as the arm is
moving forward.
The follow-through motion in softball pitching is not
as pronounced as that for the baseball pitch. Typically,
a baseball pitcher’s body continues to move forward
in the direction of the throw. Due to the “posting” that
occurs at ball release, a softball pitcher’s follow-through
motion is shorter and the pitcher tends to move away
from the direction of the throw.
Muscles Controlling the Kinetic Chain
On the basis of the relatively limited evidence that is
available, identification of injury risk factors for windmill softball pitching is difficult. The gluteal muscle
group and the triceps have been found to maintain
high activation levels throughout the entire pitching
motion.19 Although most injuries affect upper extremity
structures, the efficiency of energy transfer from the
lower extremity to the upper extremity is probably
an important factor influencing injury susceptibility.
Stabilization of the pelvis by the gluteal muscle group
appears to be extremely important in this regard.12,22-24
Conclusion
Kibler22-24 has suggested that the bulk of the energy
generated by the upper extremity is derived from
the lower extremity. Surface electromyography has
demonstrated that the gluteal muscle group is active
throughout the windmill softball pitching motion.17,19,25
Optimal function of the gluteal muscle group stabilizes
the pelvis to efficiently transfer energy from the lower
extremity to the upper extremity, which may decrease
injury risk.17 Therefore, injury prevention efforts should
be focused on development of a high degree of neuromuscular control the hips and pelvis. 
References
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Gretchen Oliver is an assistant professor and Clinical Coordinator of
the entry-level Graduate Athletic Training Education Program at the
University of Arkansas in Fayetteville.
novEMBER 2010  31