Data based interval throwing programs for collegiate softball players

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J Athl Train. 2002 Apr-Jun; 37(2): 194–203. PMCID: PMC164345

Copyright © 2002, National Athletic Trainers' Association, Inc.

Data-Based Interval Throwing Programs for Collegiate Softball Players

Michael J. Axe, Thomas C. Windley, and Lynn Snyder-Mackler

University of Delaware, Newark, DE
Michael J. Axe, MD, contributed to conception and design; acquisition and analysis and interpretation of the data; and critical revision and final
approval of the article. Thomas C. Windley, MPT, contributed to conception and design; acquisition and analysis and interpretation of the data;
and drafting and final approval of the article. Lynn Snyder-Mackler, ScD, PT, ATC, SCS, contributed to conception and design; acquisition and
analysis and interpretation of the data; and critical revision and final approval of the article.
Address correspondence to Lynn Snyder-Mackler, ScD, PT, ATC, SCS, 301 McKinly Lab, University of Delaware, Newark, DE 19716. Address
e-mail to Email: smack@udel.edu

This article has been cited by other articles in PMC.

Abstract

Objective: To construct interval throwing programs followed by a simulated game for collegiate softball
players at all positions. The programs are intended to be used as functional progressions within a
comprehensive rehabilitation program for an injured athlete or to augment off-season conditioning
workouts.

Design and Setting: We collected data over a single season of National Collegiate Athletic Association
softball at the University of Delaware and Goldey Beacom College. We observed 220 half-innings of play
and 2785 pitches during data collection.

Subjects: The subjects were collegiate-level softball players at all positions of play.

Measurements: We recorded the number of pitches for pitchers. For catchers, we recorded the number of
sprints to back up a play, time in the squat stance, throws back to the pitcher, and the perceived effort and
distance of all other throws. We also collected the perceived effort and distance of all throws for infielders
and outfielders.

Results: Pitchers threw an average of 89.61 pitches per game; catchers were in the squat stance 14.13
minutes per game; infielders threw the ball between 4.28 times per game and 6.30 times per game; and
outfielders threw distances of up to 175 feet.

Conclusions: We devised the interval throwing programs from the data collected, field dimensions, the
types of injuries found to occur in softball, and a general understanding of tissue healing. We designed
programs that allow a safe and efficient progressive return to sport.

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Keywords: simulated game, college softball conditioning, rehabilitation for softball, softball injuries

College softball and women's collegiate sport participation have seen incredible growth over the last 2
decades. The number of female National Collegiate Athletic Association (NCAA) athletes has more than
doubled over this time period. During the 1998–1999 academic year, 14 943 of the 145 832 NCAA female
1,2
athletes were softball players. Serious injuries in collegiate softball rarely happen, but less serious
injuries, which may cause time loss from sport, occur frequently. From NCAA Injury Surveillance System
(ISS) data over the last 13 years of softball, the average practice injury rate was 3.3 per 1000 athlete-
3
exposures, and the average game injury rate was 5.0 per 1000 athlete-exposures. An athlete-exposure is
defined as one athlete participating in one practice or game in which she is exposed to the possibility of
athletic injury. Of the injuries sustained, the most common type of injury was sprains (25%), followed by
contusions (24%) and strains (13%). In addition, during the 1999 season, 28% of injuries resulted in 7 or
3 4
more days of time loss. Powell and Barber-Foss studied sex-related injury patterns in high school sports.
They found that 22.9% of softball injuries were classified as forearm, wrist, or hand injuries, while 16.3% of
softball injuries were to the upper arm or shoulder. They also noted that throwing accounted for 28.1% of
4
practice injuries and 12.2% of game injuries.

Very little research has been conducted differentiating fast-pitch softball players from baseball players. The
available literature groups the athletes together as throwing athletes and does not account for differences in
the games. In contrast to NCAA baseball, NCAA softball contests are played on a smaller field, with a larger
5,6
ball, in fewer innings of play. Softball players are injured more frequently than baseball players. Powell
4
and Barber-Foss noted differences in injuries over the course of a season between baseball and softball
4
players at the high school level. Softball players had a 27% higher injury rate than baseball players.

While the differences between baseball and softball encompass players of all positions, the largest
difference is in pitching style. Fast-pitch softball players use a windmill style, which is accomplished with the
humerus remaining in the plane of the body. Baseball pitchers throw overhead from an abducted
7,8
position. The power in the windmill pitch comes from adduction of the arm across the body. Baseball
pitchers generate power during internal rotation of the humerus. While the power is attained through
different motions, the same muscle, the pectoralis major, is responsible for most of the power in both
7–9
pitches. The eccentric follow-through phase of the baseball pitch demonstrates high activity of the
10
external rotators to slow the arm down. In contrast, the role of the posterior rotator cuff (external rotators)
in the windmill pitch is lessened as the forearm strikes the lateral thigh at ball release, dissipating the
7,8,11
energy. Most high-level baseball pitchers throw a high percentage of fastballs. This is not the case in
softball. Pitching at the collegiate level of softball usually involves the mastery of 5 different pitches (fastball,
rise, curve, drop, change-up). The fastball is not as effective as the other pitches and, therefore, is not
12
thrown as often as it is in baseball.

A common assumption prevalent in softball is that the pitching style used by softball pitchers does not place
significant stress on the athlete. The result is pitchers throwing too many pitches without the benefit of rest.
13,14 15
They may pitch in consecutive games and batting practice. Loosli et al observed injury patterns in
collegiate softball pitchers from 8 college teams ranked in the top 15 teams in the country in 1989. Nearly

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half (11 of 24, or 45%) of the players contracted a time-loss injury (modified or missed activity) at some
point during the season. Of the 11 time-loss injuries, 9 involved the upper extremity. Also, the pitchers with
grade I and II injuries (had pain or complaints but continued to play) averaged more innings per season
15
than those who were uninjured.

The conventional exercises for shoulder rehabilitation focus on strengthening and endurance training of the
dynamic stabilizers of the shoulder in order to decrease the stress placed on the passive structures of the
joint. Treatment programs include capsular stretching (especially the posterior capsule in overhand
throwers), rotator cuff strengthening, multidirectional strengthening, dynamic stabilization techniques,
13,16–26
plyometrics, open and closed kinetic chain exercises, and concentric and eccentric exercises. While
these traditional therapies are necessary, the only way to imitate the forces and torques placed on the joints
21
of the upper extremity and trunk during softball is by pitching and throwing.

Conventional rehabilitation exercises used for the injured throwing athlete should include a structured
throwing program. The purpose of an interval throwing program (ITP) is to return an injured player to
preinjury status through a step-wise functional progression without overstressing the healing tissues.
21
Throwing too much too soon goes against this principle and may cause an athlete to heal more slowly.
13,16,21,27–29
Few examples of ITPs exist in the literature. Most are based merely on how quickly the authors
21,29
believe an athlete should return to play. Axe et al have developed 2 ITPs based on data that consider
the stresses placed on the athlete during a game situation as well as the type of injury a player has
incurred. One of these programs is devised for Little League (9- to 12-year-old) baseball pitchers, and the
21,29
other was designed for baseball pitchers at all other levels (Senior Little League to professional). We
found no published data-based ITPs for fast-pitch softball players. In addition, we found no published
data-based ITPs designed for position players other than the pitcher for baseball or softball at any level.

The culmination of an ITP is a simulated game. A true simulated game is derived from game-specific data
of athletes at a particular level of competition (ie, college). The injured athlete must complete this simulated
game before being cleared to return to competition. No descriptions of data-based simulated games have
30
been published for softball players at any position. Coleman et al reviewed data collected from 3
professional baseball seasons in order to determine an injured pitcher's readiness for return to play. They
used a simulated game that included number of pitches per inning, innings pitched per game, time between
30
innings, and preinjury pitch mix utilized by the player in question. While the simulated game is excellent
for testing a pitcher for game worthiness, it does not include a step-wise progression building toward the
21
simulated game.

The purpose of our study was to develop data-based ITPs followed by simulated games for collegiate
fast-pitch softball players at all positions. These ITPs are based on the game data collected, rules of the
game at the collegiate level, and the type of injury sustained.

METHODS

Data Acquisition
We collected pitching data for the pitcher's throwing program over 220 half-innings and 2785 pitches of
NCAA softball during a single season. We recorded number of pitches per inning and per game. We used

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5
these data and NCAA softball rules (eg, innings per game, pitcher to home plate distance) to construct the
pitcher's throwing program.

We collected catcher data over 219 half-innings. We recorded time in the squat stance, throws to the
5
pitcher (43 ft [13.11 m]), throws to base (throws involving an attempt to put out an opposing runner),
distance of throws to base, the intensity (percentage effort) of throws to base, and sprints to first or third
5
base (60 ft [18.29 m]). We then assessed the time in the squat stance, throws to the pitcher, throws to
base, and sprints by number per inning and number per game. We calculated the mean distance of throws
and intensity of throws. Intensity of throws was estimated by the observer based on the game situation (eg,
5
live plays were always recorded as 100%). We used these data and NCAA softball rules to construct the
catcher's throwing program.

We collected the infielder and outfielder data over 219 half-innings. We recorded number of throws,
distance of throws, and intensity of throws for each position. We calculated the mean distance of throws
and intensity of throws and assessed the number of throws per inning and per game. We then constructed
5
the infielder and outfielder throwing programs from these data and NCAA softball rules.

Data Management
In order to construct the ITPs, we considered dimensions of the collegiate-level softball field, the data we
collected, the types of injuries found in collegiate softball players, and a general understanding of tissue
healing times and properties. We developed separate programs for the catcher and pitcher because the
stresses placed on these players during a game situation vary greatly from those placed on infielders and
outfielders. In addition, we constructed one program for the infielders and one for the outfielders. These
programs reflect the maximums of all infielders and outfielders, respectively. This type of design allows an
infielder to be cleared for play at any position in the infield and the outfielder to be cleared for play at any
position in the outfield. We used the ranges, instead of means, to devise the throwing programs because in
any given contest, the athlete may have to perform at the maximum level. Therefore, the simulated games
represent the maximums at each position.

RESULTS

Pitchers
During data collection, no pitchers were removed from a game due to injury, and no other pitching changes
were noted within games. However, in all recorded cases, pitchers were replaced between doubleheaders.
The pitchers averaged 12.7 pitches per inning and 89.6 pitches per game. The range of pitches was 60 to
141 per game; 2785 pitches were recorded. We recorded no pick-off attempts during data collection
because, unlike baseball, the runners in softball are not allowed to lead off.

Catchers
We found the catchers to be in the squat stance for an average of 14.1 minutes. They threw to the pitcher
an average of 52.6 times per game. Live throws, or throws to base, were made an average of 3.2 times per
game at an average distance of 65.7 ft (20.03 m) and an average effort of 97.65%. In addition, we
calculated 1 sprint of approximately 60 ft (18.29 m) for each game (Tables 1 and 2).

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Table 1. Softball Catchers' Data (Throws to Base Not Included)

Table 2. Softball Fielders' Data

Fielders
The shortstops averaged the most throws per game (6.3). The highest average effort of throws (93.1%)
was exhibited by the third basemen, who only threw the ball an average of 4.3 times per game, while the
second basemen averaged the lowest average effort per throw (80.6%). The longest throws (average, 63.8
ft [19.45 m]) were from the third basemen, while the shortest throws (46.2 ft [14.08 m]) were made by the
second basemen. Even though they averaged the shortest throwing distances, the first and second
basemen had the largest ranges (10 to 110 ft [3.05 to 33.53 m] and 10 to 130 ft [3.05 to 39.62 m],
respectively) (see Table 2).

The left fielders averaged the most plays (2.8) per game, and had a low average distance of throws (77.5 ft
[23.62 m]), a small range of distances of throws (10 to 140 ft [3.05 to 42.67 m]), and the lowest average
effort (87.8%). Right and center fielders had larger and more similar average distance of throws (87 and
85.8 ft [26.52 and 26.15 m], respectively) and ranges of distance of throws (25 to 165 ft [7.62 to 50.29 m]
and 20 to 175 ft [6.10 to 53.34 m], respectively) (see Table 2).

Program Design
Within a given ITP, an athlete progresses from no throwing to the volume and intensity present in a game
situation. Each program includes long tosses designed to increase endurance and strength throughout the
progression. All long tosses should be thrown with the “crow-hop” method, which employs a hop, skip, and
throw to incorporate the use of the lower extremities and trunk. The “crow-hop” minimizes the risk of
28
improper mechanics and enables the body to gain momentum from the lower extremities and trunk. Total
throwing volume (number of throws × distance × intensity) is progressed slowly throughout each
21
program. During each step and portion of each step of the throwing programs, one of the 3 components
of the total throwing volume is increased, thereby increasing the total throwing volume. For instance, the
total throwing volume of the field practice in step 3 of the infielder's program is (5 × 60 × .75) + (10 × 75 ×
.75) = 787.5, while the total throwing volume of the field practice in step 4 is (5 × 60 × .75) + (5 × 84 × .75)
+ (5 × 120 × .75) = 990. The pitching program consists of 4 phases; the catching program has 3 phases;

5 of 12 9/6/11 9:47 AM


and the infielder and outfielder programs have 2 phases each.

The 4 phases of the pitching program are early throwing, initiation of pitching, intensified pitching, and a
simulated game. We designed these phases to slowly progress the loads applied to the throwing arm. The
program begins with short throws to tolerance (up to 50% effort) as well as long tosses up to 120 ft (36.58
m) to increase arm strength and endurance (early throwing). No pitching is instituted in this phase. The next
phase, initiation of pitching, includes pitching up to 75% effort as well as continuation of the long-toss
component. The intensified pitching stage takes the pitcher from the initiation of pitching to the simulated
game. Off-speed pitches (curve, rise, drop, change-up) and rest intervals, which correspond with a game
situation, are incorporated in this phase. The pitcher chooses the mix of pitches that compare with her
preinjury pitch preference. The final stage of this phase is for the athlete to pitch batting practice. Before
being cleared for return to play, the pitcher pitches a simulated game. The simulated game is based on the
maximums of all inning and game data collected (Appendix A).

Appendix A. Softball Pitcher's Program

The catcher's program has 3 phases: beginning throwing, catching practice, and a simulated game. First,
the catcher throws only up to 50% of perceived effort, with long tosses to 90 ft (27.43 m). This phase
(beginning throwing) allows the catcher to build the strength and endurance that are necessary for
intensified activity. With progression, sprints are incorporated as in a game situation when backing up
throws. Additionally, the athlete simulates throwing to second base as well as throwing the ball back to the
pitcher (catching practice). Eventually, the athlete completes a simulated game before she is cleared for
return to play (Appendix B).

Appendix B. Softball Catcher's Program

The infielder and outfielder programs consist of only 2 phases: throwing and a simulated game. The
infielder's throwing phase begins with short throws at 50% of maximum intensity and long tosses up to 60 ft
(18.29 m). It then progresses, over 5 steps, to throws at 100% effort and long tosses up to 150 ft (45.72 m).

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Fielding practice and sprints are included in the program (Appendix C). Before returning to play, the athlete
must complete the simulated game. The outfielder's throwing program consists of the return-to-throwing
phase and a simulated game. Initially, the fielders only throw up to 50% of maximum effort and up to
distances of only 60 ft (18.29 m). The final stage includes long tosses of up to 180 ft (54.86 m) and throws
of up to 100% effort. Fly and ground balls are included in all stages, and rest intervals correspond with rest
between innings (Appendix D). The final step is for the athlete to complete a simulated game.

Appendix C. Softball Infielder's Program

Appendix D. Softball Outfielder's Program

PROGRAM PROGRESSION

Soreness Rules
21
Axe et al defined soreness rules (Table 3) for baseball pitchers in an ITP. Their rules allow the athlete to
modify progression according to symptoms. Athletes may heal at different rates and, therefore, need to
progress at different paces. The soreness rules are used to prevent overstressing the soft tissues during
progressive return to play. They dictate when an athlete may progress to a higher step, remain at the same
step, or drop down one step. They also help dictate the amount of rest time indicated between throwing
21
days.

Table 3. Soreness Rules

Injuries
In the return-to-play phase of rehabilitation, we use an injury classification scheme to modify the program:

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specifically when to begin throwing, how many days of rest are needed between days of throwing, and how
quickly the athlete may progress through the ITP. The classification is hierarchical. Injuries to body parts
other than the throwing arm require the least modification, followed by injuries to the throwing arm that do
not involve the joints (bruises), mild injuries to the throwing arm that involve the joints (tendinitis), and
injuries to the throwing arm that are severe (postoperative, torn ligament) (Appendices E,F,G,H). Before
initiation of throwing, the physician and any rehabilitation specialist involved must determine that the
21
healing structures are ready to withstand the stresses of throwing. Once throwing has begun, the athlete
can progress as the classification of her injury and the soreness rules allow.

Appendix E. Softball Pitcher's Instructions

Appendix F. Softball Catcher's Instructions

Appendix G. Softball Infielder's Instructions

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Appendix H. Softball Outfielder's Instructions

DISCUSSION

No data-based ITPs developed for collegiate softball players at any position have previously been
published. Furthermore, no published data-based ITPs for positional players other than pitchers have been
developed for baseball or softball. The ITP being suggested is not intended to replace traditional
rehabilitation but instead to augment those treatments. Within rehabilitation programs, it is imperative to
include a functional progression that allows a speedy and safe return to sport.

Despite the cited differences between baseball and softball, the upper extremity injuries found in softball
4,31
players other than the pitcher (overhead throwers) are similar to those of baseball players. The shoulder
7,20,23–26,32
injuries that occur in overhead throwers include, but are not limited to, impingement,
7,8,13,20,23–26 7,8,16,20,23,25,26
instability, undersurface rotator cuff tears, and glenoid labrum
7,8,16,20,23,25,26 33,34
tears. Common elbow problems in overhead throwers are medial epicondylitis, partial or
34 20,26,33,34
complete tearing of the flexor musculature, osteochondral defects of the capitellum, ulnar
20,26,27,33,34 20,26,32,33
collateral ligament laxity or rupture, olecranon osteophytes and loose bodies, and
20,26,33,34
ulnar neuritis.

Softball pitchers do, however, have specific injury patterns linked to the dynamics of the windmill pitch.
13,14
Most of these injuries occur in the shoulder and elbow. Shoulder injuries include instability, rotator cuff
15 14,15 14 14
tendinitis, bicipital tendinitis, subscapularis strain, pectoralis strain, biceps-labrum
13,14 15 13,14
degeneration, and trapezius strain. Elbow injuries include ulnar neuritis, ulnar collateral ligament
14 15
damage, and tendinitis.

The injuries to softball pitchers are a result of the forces and torques imparted upon the upper extremity
during the windmill pitch. The forces, torques, and speed with which the windmill pitch occurs are
14
responsible for the incidence and type of injuries sustained. The athlete must be rehabilitated
successfully to withstand the listed values imparted on the upper extremity during windmill pitching.

Clearing an athlete to begin the ITP is the responsibility of the health care professionals as a team. They
must be sure that the healing tissues can withstand the forces applied to the joints during the early stages
of the throwing program. The athlete's personal healing characteristics, the incurred injury, the treatment
21
being administered, and the player's softball position all dictate the decision of the health care team. The
early stages of the throwing programs only allow the athlete to throw to tolerance but at no greater effort
than 50%. Baseball players are not usually accurate in attempting to duplicate a desired effort level. Fleisig
35
et al studied 27 healthy college baseball pitchers. When requested to throw at 50% effort, the pitchers

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averaged ball speeds of 85% of their maximum and forces and torques of 75% of their maximum. When
35
requested to throw at 75% effort, the ball speeds reached 90% and the forces and torques reached 85%.
These findings indicate the need for early supervision of the program by the rehabilitation professional or
athletic trainer.

Our goal was to develop data-based ITPs for collegiate-level softball players in all positions. We intend
these programs to be used as functional progressions within traditional rehabilitation programs for injured
softball players. In addition, the programs are useful for training and conditioning regimens used during the
off-season and preseason. Our objective is for the programs to be useful for all health care professionals,
coaches, and their respective athletes. The programs are designed to allow the athlete and coach or
athletic trainer to continue the program once formal rehabilitation has ended. The throwing or pitching
athlete is slowly progressed from no throwing to game situation levels of throwing through a gradual
increase in intensity and total throwing volume step by step. The goal we are proposing for the ITPs for
collegiate softball players is to promote efficient and safe return to sport.

ACKNOWLEDGMENTS

We thank Chris Kuchta and Robbin Wickham, MPT, for their assistance.

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Articles from Journal of Athletic Training are provided here courtesy of
National Athletic Trainers Association

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Data based interval throwing programs for collegiate softball players

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Data based interval throwing programs for collegiate softball players