Softball first began in 1887 as an indoor sport at the Chicago Farragut Boat Club. Originally it was called kittenball, pumpkin ball, or mush ball (15,29). The term “softball” was coined subsequently in 1926 by W.A. Hakanson. Shortly afterward, the game moved outside, and in the 1930s, the national governing body, the Amateur Softball Association (ASA), was formed (15). Since then, the game has grown tremendously in popularity. Currently, both fast pitch and slow pitch softball are played competitively by athletes of both genders and various ages.
The ASA is the largest softball governing body in the United States, overseeing more than 80,000 teams annually within their youth program. This encompasses approximately 1.3 million athletes on fast pitch and slow pitch teams (3). At the high school level, the National Federation of State High School Associations (NFSHSA) reported that during the 2010 to 2011 school year 1,548 boys and 389,455 girls competed on either fast or slow pitch teams. During that year, fast pitch softball was the fourth most popular sport in girl’s high school athletics (1). At the National Collegiate Athletic Association (NCAA) level, 950 women’s fast pitch teams, with a total of 17,154 participants, were competing in 2007 to 2008 (24).
One unique aspect of softball is the tremendous number of adult athletes who participate in the sport. The ASA adult programs encompass more than 170,000 teams with 2.5 million participants annually (2). The significant increase in participation numbers at the adult level can be attributed partially to the increased participation of male athletes. Within the armed forces, softball is considered one of the most popular recreational activities, although no accurate participation data are available (13).
Now softball is played year round across the United States. Competitive youth softball has returned to its roots, as it moves indoors in cold weather environments. During these months, teams participate in conditioning as well as games. The indoor game fields may be limited in overall field dimensions and are commonly covered in turf. In addition to team play, pitchers often work on technique and developing new pitches between competitive seasons. The opportunity to play indoors has resulted in a decrease in rest time for athletes. Therefore there is now no longer a true “off season” for most competitive softball players.
Softball versus Baseball
Although softball and baseball are very similar, there are several distinct differences between the games. Softball is commonly played for fewer innings and on a smaller field. The bases are 60 ft apart in softball and 90 ft apart in baseball. In softball, the pitcher throws from a flat pitching circle as opposed to a raised mound in baseball. As of the 2010 to 2011 academic year, the NFSHSA increased the high school pitching rubber distance from 40 to 43 ft, which is the same distance as the college game. The baseball pitching distance was 46 ft at the youth level and eventually increased to 60 ft 6 inches. Either an 11- or 12-inch circumference softball is used, depending on the level of competition. The softball weight ranges between 6.25 and 7 oz, which is heavier than the standard 5-oz baseball. However one of the most important differences between softball and baseball is the pitcher’s delivery. The underhand pitching technique is commonly described as a windmill pitch.
Windmill pitching can be divided into six phases as described by Maffet et al. (19) (Fig. 1). Phase 1 is the windup, then phases 2 through 5 reflect the movement of the arm like a hand moving on a clock, and phase 6 is the release. Because of the mechanical differences in throwing techniques, it traditionally was thought that the windmill pitch put the throwing arm at minimal risk for injury compared with the overhand pitching technique. In 1992, this view was challenged when Loosli et al. (17) documented that windmill pitchers participating in the 1989 NCAA tournament championship reported a significant number of time-loss injuries. This study brought to light that the windmill pitching technique placed pitchers at significant risk of suffering a throwing-related injury.
Since then, biomechanical studies have demonstrated that the windmill pitch and the overhand baseball pitch both place significant stress on the pitcher’s body. Barrentine et al. (5) demonstrated distraction stresses of 70% to 98% body weight at the elbow and shoulder joints of collegiate level windmill pitchers. At the youth softball level, Werner et al. (35) demonstrated stresses of 46% to 94% body weight at the elbow and shoulder joints. These throwing arm torques are comparable with what baseball pitchers experience. For example, Werner et al. (36) also performed a kinematic study on professional baseball players. This kinematic study revealed the average maximum shoulder distraction forces of 108% ± 16% body weight. The ground reaction forces on the stride leg also are similar, if not greater, for softball pitchers despite throwing from a flat surface (18,36). However a key difference between the overhand throw and windmill pitching styles is in the biceps brachii muscle activity. Windmill pitchers have been shown to have significantly higher biceps brachii muscle activation than baseball pitchers. This is because softball pitchers flex the elbow during the delivery, while baseball pitchers extend the elbow. The peak of activation is shortly before ball release. Here, the elbow is flexed minimally and the biceps is contracted eccentrically (28,30).
Another unique aspect of softball is the volume of pitches that are thrown. Unlike in youth baseball, the majority of softball pitchers do not have pitch count regulations. Little League Softball is one of the few governing bodies to enforce pitching limitations. Since 2011, they restrict innings pitched and mandate rest days for softball pitchers between ages 9 and 11 years. In other leagues, softball pitchers will commonly pitch double headers and throw on back-to-back days. It also has been documented that pitchers may throw 1,200 to 2,000 pitches within a single 3-d tournament weekend (5,11,36,37). Collegiate level pitchers traditionally master five pitches: fastball, rise, curve, drop, and a change-up. The off-speed pitches are usually most effective and therefore are thrown more commonly (8). Different ball grip and styles of release can be used to throw the off-speed pitches.
NCAA Injury Surveillance System data collected from 1988 to 1989 through 2003 to 2004 provided a longitudinal look at injury rates across Divisions I, II, and III fast pitch women’s softball. Across all divisions and seasons, the game injury rate was 4.30 per 1,000 athlete exposures (AE), and the year-round practice injury rate was 2.67 per 1,000 AE. Of note, preseason practice injury rates were significantly higher with 3.65 per 1,000 AE compared with the in-season practice injury rate of 1.68 per 1,000 AE (P < 0.01). Injuries to the lower extremity (42%) and upper extremity (33%) were common in both games and practices. Frequently reported game injuries included ankle ligament sprains, knee internal derangements, upper leg strains, contusions, and throwing shoulder strains. The majority of game injuries (51.2%) were due to contact with the ground, the ball, or an object such as a wall. Sliding injuries were considered separately and made up 23% of all game injuries (20).
The National High School Sports-Related Injury Surveillance system was used to collect longitudinal injury data for high school softball during the 2005 to 2008 school years. These data demonstrated a higher injury rate for games (1.74 per 1,000 AE) compared with practices (0.742 per 1,000 AE) (33). The same online injury surveillance system was used to document severe injuries during the 2005 to 2006 school years. Severe injuries were defined by a loss of sports participation for >21 d. The severe injury rate was 0.30 per 1,000 AE for games and 0.12 per 1,000 AE for practices. The knee (30.7%) and ankle (19.2%) were the most common severely injured locations. Fractures (41.3%) and ligament injuries (33.3%) were the most common severe injuries. Contact with bases (21.3%) was the most common mechanism for suffering a severe injury (7).
Fortunately catastrophic injuries in softball are rare. Between 1982 and 2007, the National Center for Catastrophic Injury Research reported four catastrophic injuries, including one fatal injury due to a blow to the head by a ground ball (34). Another mechanism for suffering a severe or catastrophic injury is head-first sliding. This places the athlete at risk for suffering cervical cord injuries as well as head trauma.
See Table for a comprehensive list of softball-related injuries.
Injuries unique to softball are associated mainly with the windmill pitching technique. These include biceps tendinitis, forearm stress fractures, and ulnar neuritis.
Proximal Biceps Tendinitis
Because most softball injury data does not break down shoulder tendinitis into specific categories, it is difficult to determine the frequency of rotator cuff overuse injuries versus proximal biceps tendinitis. Since the overhand throwing technique is identical in baseball and softball, rotator cuff problems such as tendinitis, strains, and impingement are still commonplace. However windmill pitchers seem to be at increased risk of developing biceps tendinitis due to the high levels of biceps brachii muscle activation that occurs near the end of the delivery (28,30). Athletes will complain of pain through the bicipital groove in the anterior aspect of the proximal humerus. It will be most painful just before or during ball release, and the pain may extend distally into the biceps musculature.
On examination, the long head of the biceps will be tender to palpation in the bicipital groove. Pain may be noted also when the shoulder is extended with the elbow in a flexed position. Physical examination may reveal a positive Speed’s test (resisted shoulder flexion with elbow flexed 30°) and/or Yergason’s test (resisted supination with elbow flexed).
Treatment of proximal biceps tendinitis consists of decreasing painful throwing, as this is typically an overuse injury. Appropriate strengthening of the entire kinetic chain and assessment for proper throwing mechanics should be performed. Ice and oral nonsteroidal anti-inflammatory drugs may be beneficial. When an athlete is ready to begin pitching, he or she should follow an appropriate return-to-throwing program to gradually increase volume, intensity, distance, and frequency of pitching.
Forearm stress fractures are unique to upper extremity-focused athletes, including windmill pitchers. The ulna seems to be at the greatest risk. An ulnar stress fracture is thought to be associated with the pronation release that some pitchers use to throw a drop ball, although pitching volume alone may play a role. Pain in the ulna is localized usually and presents as a dull ache after practices and games. The pain always will resolve with rest but commonly reoccurs with pitching activity.
On physical examination, the ulna will be painful to palpation in the area of the stress fracture. Plain films may be normal, or they may show a crack in the cortex or periosteal reaction (Fig. 2). If plain films are nondiagnostic, magnetic resonance imaging (MRI) may be used to confirm the diagnosis. T2 images will reveal edema within the bone, and a fracture line may be evident (Fig. 3).
Treatment involves rest from all painful activity, including pitching, for 6 to 8 wk. Upon resolution of symptoms, a return-to-throwing program should be initiated, and proper throwing mechanics should be reviewed.
Ulnar neuritis is another common problem in softball players. Because of the volume of overhand throwing and the forces at the elbow being equivalent between a softball windmill pitcher and a baseball pitcher, the ulnar nerve is at risk for becoming inflamed. Also, windmill pitchers may strike the medial aspect of their throwing elbow on their hip just prior to ball release (22). This direct trauma may result in ulnar neuritis. Most consider striking the elbow against the hip to be a flaw in technique, as it dissipates forces and slows the velocity of the pitch.
Athletes commonly complain of medial elbow pain in or near the ulnar groove. They often will develop burning, numbness, and tingling that can extend down into the forearm and fourth and fifth digit. Symptoms may be exacerbated during sleep if the elbow is held in a flexed position, which stretches the nerve.
On physical examination, the ulnar groove is typically tender to palpation, and a positive Tinel’s sign over the ulnar groove may be present. Decreased pinprick sensation over the hypothenar eminence may occur. Occasionally subluxation of the ulnar nerve out of the cubital tunnel can be visualized medially or palpated as the elbow is moved from flexion into extension.
Treatment includes teaching proper throwing mechanics to reduce the elbow strike on the hip if it is present in pitchers. Avoiding ongoing irritation of the ulnar nerve is crucial, therefore rest from throwing is recommended. Educating patients not to set their elbow on firm surfaces and encouraging them to place an extension splint on the elbow during sleep can be helpful. Icing for pain relief and use of anti-inflammatories also may lessen symptoms.
Sliding is one of the most common mechanisms for softball injury. Studies within high schools, within colleges, and on military bases have found that base sliding injuries account for 21.3% to 45% of all injuries (6,7,20,23). Burnham et al. (6) reported fractures, muscle strains, dislocations, abrasions, internal injuries, concussions, and tendon ruptures as common sliding injuries. Contusions and ankle ligament injuries were the most common in a study of NCAA Division I athletes. Softball sliding injury rates (12.76 per 1,000 slides) have been shown to be higher than baseball (6.2 per 1,000 slides) (10).
One proposed mechanism to reduce sliding injuries involves the implementation of breakaway bases, which cause less force at the ankle compared with standard bases (12). Adoption of breakaway bases has been shown to decrease injury rates in recreational softball and baseball leagues, NCAA baseball, and professional minor league baseball (14,32). Cost is considered the main deterrent in leagues adopting the breakaway bases for use. Head-first sliding technique also has been associated with higher injury rates at the NCAA Division I level compared with feet-first sliding. As one would anticipate, the head-first sliding technique places the athlete at greater risk of suffering a head and neck injury then feet-first sliding (10). Therefore softball players should be taught proper technique and encouraged to slide feet first whenever possible.
Proper equipment is paramount to keeping all softball athletes safe on the field both during games and practices. Direct blow from a thrown or batted ball is a common cause of injury. During a 10-year period, the Air Force reported that 20% of all softball-related injuries that presented for medical evaluation were due to being struck by a ball (6). At the NCAA level, being hit by a batted ball accounted for 11.2% of all game day injuries. Specifically head and neck injuries account for 13.4% of all game-related injuries at the NCAA level. When these injuries do occur, they can be severe and result in significant time loss (20). Therefore it is critical that all batters and base runners be protected properly with a National Operating Committee on Standards of Athletic Equipment-approved helmet. In 2006, it became mandatory for a mounted face guard to be present on all batting helmets for high school softball athletes (25). These provide added facial protection from a direct blow while an athlete is at bat and while running the bases. Headgear use for defensive players is considered optional; however the National Operating Committee on Standards of Athletic Equipment currently is developing standards for this at the request of USA baseball, the NCAA, and the NFSHSA. It is anticipated that this headgear will incorporate a face mask for added protection from a thrown or batted ball (31) (Fig. 4).
Softball pitchers should be trained properly from a young age to master the mechanics of pitching. Proper throwing mechanics may minimize the risk of injury. Several studies have demonstrated that softball pitchers eventually learn to progress properly through a proximal (trunk) to distal (hand) segment activation pattern (21,26). This sequential activation of the kinetic chain requires significant neuromuscular coordination that is learned over time. Developing power from the core musculature is key, and strengthening of the gluteal muscle group should be emphasized (27,28). Activation of the gluteal muscles helps stabilize the pelvis. In turn, the power generated through the pelvis and torso is transferred into the segments of the upper extremity from the trunk to the hand. Weakness of the pelvis and trunk musculature may result in poor development of overall power. Pitchers learn to activate effectively the segments sequentially from proximal (trunk) to distal (hand) as they become more skilled. Novice pitchers lack the ability to activate properly segmentally the upper extremity from proximal to distal. This results in a loss of power that was generated from the pelvis and trunk musculature. As a result, it is common to see novice pitchers develop overuse injuries in the shoulder and elbow as they attempt to gain speed by overactivating improperly these upper extremity segments. Oliver et al. (26) also demonstrated that the hand segment provided 62% of the overall ball velocity. Therefore it is important to develop a pitcher by building overall trunk, shoulder, elbow, and hand strength.
Although education on the proper mechanics of windmill pitching is important, the volume of pitching also requires equal attention. At the NCAA level, 25% of all pitchers’ injuries were the result of overuse (9). Recurrence of shoulder injuries such as muscle strains is common in softball (33). Pitchers are at the greatest risk (16). Prospective studies assessing injury risk and pitch counts are needed to better understand how softball pitchers should be monitored and potentially restricted at all levels of play. In general, a pitcher should not throw when they are fatigued. When a pitcher begins to lose ball control or velocity or experiences shoulder or elbow pain, they should be removed from pitching.
Although softball is played frequently year around, precompetitive season conditioning should be encouraged strongly. This should include a neuromuscular education program, core conditioning, and education on proper throwing and sliding mechanics. Pitchers and athletes at other positions with high throwing volume (i.e., catchers) should consider a rest period from throwing at the conclusion of a competitive season. Prospective studies assessing the appropriate length of rest are needed to determine how best to minimize the risk of suffering an overuse injury. For athletes who have taken an extended time away from throwing, a softball-specific interval throwing program should be encouraged strongly (4).
Softball is a unique sport. Male and female athletes of all ages participate in softball across all levels, from youth to adult competitive leagues. Although there are many differences when compared with baseball, similarities can be found. These include the risk of injury associated with pitching and sliding. Reducing the risk of injury from pitching will require future research on pitch counts in softball. Injury prevention should include appropriate preseason conditioning, education on proper throwing and sliding mechanics, and consideration for adoption of pitch counts. Equipment changes that also may reduce injury risk include the use of breakaway bases and defensive headgear.
The author declares no conflict of interest and does not have any financial disclosures.
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