A Narrative Review of Softball Pitching Workload and Pitch Counts in Relationship to Injury

Abstract

Context:

Fastpitch softball is a popular women’s sport in the United States, and participation rates are increasing. There is growing concern about the prevalence of overuse injuries in softball pitchers at all competitive levels. Pitching workload in softball may be a modifiable risk factor and will be discussed in this narrative review.

Evidence Acquisition:

A review of softball injury research related to workload available in electronic databases, including PubMed, Medline, and EBSCO.

Study Design:

Clinical review.

Level of Evidence:

Level 4.

Results:

There is a paucity of research evaluating workload (inclusive of internal and external risk factors) including pitch counts in women’s softball. In particular, research has shown that pitchers report increasing fatigue and pain over a game and weekend tournament, and that the number of pitches thrown by pitchers varies widely. One study showed that pitchers throwing >85 pitches per game had an increased risk of injury over the season. As of 2023, no established pitch count restrictions exist in the United States or Canada. Further research, particularly at high school and collegiate levels, is needed.

Conclusion:

Softball pitchers are at an increased risk of overuse injury and further research is needed to recommend specific workload interventions such as pitch counts.

Strength-of-Recommendation Taxonomy (SORT): B.

Fastpitch softball (hereafter “softball”) is the fifth most popular female sport in the United States, with a significant number of athletes participating at both the high school and collegiate levels during the 2021 to 2022 academic year. Specifically, approximately 340,923 female high school athletes, constituting 10.5% of all high school female athletes, engaged in the sport.^38,40 Moreover, 21,477 collegiate softball players also dedicated themselves to competing in this sport during the same period.^38,40 The growth in popularity of softball has increased opportunities for girls, with >25 countries now offering Little League softball programs to approximately 300,000 female athletes aged 4 to 16 years. ²⁹ Although all genders play softball, the vast majority of softball is played by female athletes.

A sharp rise in club sports has mirrored the increase in participation across all sports.^33,49 These opportunities for participation beyond school sports are focused on competitive environments that emphasize performance and elite skill development. Consequently, athletes frequently engage in year-round play and early specialization, sometimes as early as middle school. ¹³ Recent literature has raised concerns about the effects of year-round competition and specializing in a single sport, as it has been associated with high rates of overuse injuries.^{4,26,33,36,45,48} This trend is especially concerning for athletes in sports such as in softball that require repetitive motions. For instance, middle-school-aged softball pitchers who compete year-round without adequate offseason rest are significantly more likely to experience reduced stamina and multiple overuse injuries by the time they graduate from high school. ¹⁵

Across all female sports, evidence indicates that softball athletes are more inclined to specialize in their sport. ³ Specialization implies year-long participation and training in a single sport at the exclusion of other sports and activities. ²⁵ In addition, it has been observed that softball has some of the highest rates of overuse injuries. ⁴⁵ Specifically, an epidemiologic study of injuries has shown that 50.4% of shoulder injuries and 48.9% of elbow injuries in softball athletes are categorized as chronic or overuse injuries. ⁴³ This underscores the urgent need for further investigation into the physical demands placed on softball pitchers in all levels of competition. Considering the repetitive nature of softball movements and the increasing prevalence of year-round play and single-sport specialization, it is crucial to provide athletes, parents/caregivers, coaches and sports administrators with better recommendations for managing workloads to mitigate the heightened risk of overuse injury. This focused review aims to initiate this effort by defining workload for softball pitchers and explaining how an increased workload could potentially contribute to overuse injury. It is important to emphasize that the assumption exists that increased workloads are a primary factor in injuries. However, there is a significant lack of research examining the relationship between lower workloads and throwing-related injuries in softball and other throwing sports.

What Is Workload

According to the International Olympic Committee consensus statement on load in sport, workload in sport has been defined as the amount of physical and mental strain placed on athletes in relation to their involvement in sports activities. This strain can vary in terms of duration, frequency, and intensity. ⁵³ Extensive research has been conducted in the field of sport and exercise to explore the impact of workload on injury risk, injury prevention, and performance in lower extremity sports such as soccer/football and rugby.^7,24,27 More recently, there has been a growing interest in studying the effects of workload and implications for injury in baseball players and pitchers.^2,17,61 However, there are limited data available regarding workload and its implications for overuse injury risk in softball pitchers. While 1 study found that softball pitchers who pitch high volumes and on consecutive days account for a significant proportion (>82%) of total pitches thrown, that study did not investigate the association with injury. ⁵⁴ Furthermore, although previous studies have indicated that high workloads or undertraining are linked to injury in various sports,^7,24,27 it is essential to gather further data to accurately determine workload and its relationship to overuse injury risk among softball pitchers.

One of the difficulties in accurately determining workload in any throwing athlete has been integrating all of the relevant internal and external factors. For example, in baseball, pitch counts have been synonymous with workload. ² However, it is important to note that pitch counts alone do not reflect a comprehensive picture of an athlete’s workload.^6,17 Workload also includes effort, fatigue, pitch velocity, and other internal and external factors.^{5,9,10,16,59-61} Some internal risk factors include age, skeletal age, skill level, history of previous throwing-related injuries, physical readiness to participate in sport, and height. Examples of external factors include (but are not limited to) pitch volume, sport specialization, participation in multiple teams at the same time, and training months per year.^34,35 A recent study assessing youth softball windmill pitchers indicated increased shoulder fatigue, pain, and weakness when pitching on consecutive days during a weekend tournament. ⁵¹ Given that further data have indicated increased fatigue from fastpitch softball pitching in gluteal and scapular musculature, determining fatigue and effort levels as part of a workload management plan would be an advisable approach. ¹² Figure 1 summarizes factors that contribute to arm health in softball pitchers. All internal and external risk factors contribute to the extent of arm health in softball pitchers.

Figure 1.

Summary of factors that contribute to arm health in softball pitchers. All internal and external risk factors contribute to the extent of arm health in softball pitchers.

Impact of Increasing Workload

Despite studies finding suboptimal performance alterations with increasing workload, softball lacks any pitch count or rest day regulations. ²³ Softball pitchers report significantly higher levels of pain and fatigue after a competitive softball season compared with their preseason values. ⁵⁸ In addition, a study analyzing pain and fatigue during a weekend tournament revealed that pitchers experienced increased pain and fatigue at the end of each day, with higher values on both Saturday and Sunday compared with their baseline values on Friday. ⁵¹ Yang et al ⁵⁸ tracked high school softball pitchers throughout a season and found that both early and late in the season, the postgame pain and fatigue scores were significantly higher than the pregame scores. In addition, pregame pain and fatigue scores in the late season (final week) were significantly higher than those in the early season (first week), and pitchers who participated in more games exhibited greater pregame fatigue scores in the late season.

Though not directly assessed, the increased reported fatigue and pain may be a confounding variable in the observed decrease in shoulder and hip strength reported in the literature with increased workload.^{12,14,23,41,51,58} Due to its full-body involvement, the windmill pitching technique has been associated with decreased strength in both the upper and lower extremities in softball pitchers over a single day, tournament, and season. ⁵¹ In addition, increased workload has been found to affect hip and shoulder range of motion.^14,23,58 Similar to baseball, hip range of motion has consistently been shown to decrease postgame and throughout a competitive season.^11,23,62 However, the relationship between shoulder range of motion and workload is not as clear in softball pitchers. Typically, overhead athletes present with increased dominant shoulder external rotation and decreased internal rotation. ⁵⁷ However, research suggests that softball pitchers may not follow this typical adaptation. In collegiate softball pitchers, it was found that dominant shoulder internal rotation increased throughout a season, with no change in external rotation. ²³ In addition, in the examination of a simulated double header, it was found that there was a decrease in both dominant and nondominant internal rotation and a decrease in nondominant shoulder external rotation. ¹⁹ In a descriptive study comparing shoulder range of motion between youth softball pitchers and positional players, it was noted that pitchers had less dominant shoulder external rotation compared with positional players. ²¹ These varying results highlight the need for further research in this area and caution against applying previously established risk factor criteria for shoulder range of motion in baseball to softball pitchers.

Another aspect related to workload is pitching performance and mechanics. Research has indicated that as workload increased pitch velocity decreased.^18,20 In addition, different pitch types can have varying effects on performance. In the examination of a simulated double-header, Downs Talmage et al ²⁰ found that pitch speed decreased during the fastball, dropball, and curveball from the first to the last inning of the simulated game (100 pitches). However, after a 30-minute break, fastball pitch speed returned to baseline values while the dropball and curveball pitch speeds did not return to baseline. In a similar softball pitching analysis, it was found that pitch volume had an influence on stride length, center of mass position, and trunk flexion. ⁴¹ Specifically, as pitch volume increased, pitchers displayed greater stride length, a more anteriorly shifted center of mass, and increased trunk flexion and rotation. ⁴² The same study also compared trunk kinematics between the first and last inning. The results revealed that pitchers had significantly less trunk rotation toward their pitching arm side in the last inning compared with the first, both at the start of the pitching motion and at the top of back swing.

In summary, research has shown that cumulative workload throughout a game and weekend tournament results in more self-reported pain and fatigue. High pitching workloads have deleterious effects on a pitcher’s kinetics and kinematics, which may affect performance as well as increase injury risk. More research is needed into how to quantify and monitor workload in softball pitching as well as the effects of cumulative workload over time.

Pitch Counts

In baseball, there is a significant relationship between pitch counts and shoulder pain.^30,31,44 Specifically, throwing >75 pitches per game increases the risk of reported shoulder pain among youth baseball pitchers. ³¹ In addition, throwing >100 innings per season has been associated with a higher risk of injury. ⁴⁴ Due to the increasing occurrence of elbow and shoulder injuries in baseball, both the USA Baseball Medical Safety and Advisory Committee and Major League Baseball have published guidelines for baseball pitchers. These guidelines include recommendations for the maximum number of pitches per outing, rest days in between pitching outings, and off-season time off. ⁴⁷ In softball, there is also a growing body of evidence suggesting a relationship between pitch counts and upper extremity pain and injury. Different studies have provided varying estimates of weekend pitch counts ranging from 50 to 75 pitches per game to ≥80.^{22,50,51,52,58} In a weekend tournament, the average pitcher can throw anywhere from 95 to 381 pitches. ⁵¹ More recent studies focusing on high school pitchers have shown that those who report pain typically throw around 429 pitches per week, whereas pitchers who do not report pain throw around 219 pitches per week. ²³ At the professional level, pitchers who experienced injuries reported an average of 967 more pitches per season than noninjured pitchers, indicating a potential link between pitch volume and injuries. ⁴⁶ Furthermore, research has found that softball pitchers throwing >85 pitches per game are more than twice as likely to seek medical attention for an injury and play through pain over the course of the season. ²² Another study involving high-school-aged softball pitchers found that pain and fatigue increased over a season of approximately 12 pitching appearances in 6 weeks. ⁵⁸ Further research will be needed, however, to determine whether is it high chronic loads or rapid changes in load (ie, spikes in pitch counts over a weekend) that are greater contributors to injury. Tracking both acute and chronic loads would help practitioners better understand this link.

As of 2023, there are no established pitch count restrictions in place for USA Softball or the National Federation of State High School Associations. However, it is important to note that the National Council of Youth Sports, in partnership with the American Orthopaedic Society for Sports Medicine, has released a set of recommendations for adolescent pitchers known as the STOP campaign. These recommendations include guidelines for pitch counts by age, limiting consecutive days of pitching, and the importance of proper warm-up. ³⁹ Surprisingly, a recent study showed that <15% of caregivers were aware of these expert consensus guidelines in the context of softball. However, an overwhelming majority of 93% reported that they would adhere to guidelines if they were made available to them. ²⁸

There are also no established pitch count guidelines for collegiate softball. According to in-season rules set by the National Collegiate Athletic Association (NCAA), athletes are limited to a maximum of 4 hours per day or 20 hours per week of required practice or mandatory strength and conditioning activities. ³⁷ In addition, during the playing season, all athletes are guaranteed 1 calendar day off per week. It is important to mention that these daily and weekly hour limitations do not apply during the preseason. Interestingly, recent NCAA surveillance data has shown an increase in preseason injury rates, which may suggest a lack of workload regulations during that time, ⁵⁵ although it should be noted that one should consider inappropriately prescribed offseason training programs (such as year round practice without adequate time devoted to athletic development or rapid increases in training load) as possible contributing factors. In comparison with baseball, softball pitchers tend to have significantly more NCAA game appearances and innings pitched per season. ¹ It is worth noting that only 7.35% of collegiate baseball pitchers throw >100 innings in a season, compared with a much larger proportion (43%) of softball pitchers. Further investigation into pitch counts, injury risk, performance, and burnout in collegiate softball is necessary, as injury rates are significantly higher than those at the high school level. ⁵⁶ Moreover, a larger proportion of practice-related overuse pitching injuries are seen at the collegiate and professional levels, as compared with high school.^46,56 Research suggests that unrestricted pitching in high school level may not lead to higher rates of pitching-related injuries until athletes reach their 20s and enter the collegiate and professional levels. This is likely the result of the cumulative overuse of pitching for many years during adolescence, as well as the lack of a holistic training program designed to improve physical qualities that eventually result in injury in college and beyond. Thus, it is crucial to continue studying and monitoring softball pitching workloads to ensure the wellbeing of softball pitchers throughout their playing careers. We believe education and guidelines are needed to promote monitoring arm health, adequate rest, proper warm-up, and adherence to strengthening programs rather than strict pitch counts.

Future Directions

It has been proposed that numerous factors comprise workload. These factors include, but are not limited to, pitch counts, batters faced per game, recovery between pitching outings, intensity and volume of throws in preparation for a game, fastball velocity, and workload progressions.^2,8,17,32,35 Furthermore, all factors should be accounted for when monitoring a pitcher’s arm health. In softball, it has been shown that youth softball pitchers experience fatigue over the course of a game, a weekend, and a season. In addition, data from collegiate and professional softball pitchers indicates a high prevalence of overuse injuries, suggesting that the cumulative effect of high workloads may be detrimental for dominant pitchers at the youth levels. As a result, there is a clear need for research in softball and workload monitoring to determine a “safe” workload for softball pitchers of all ages.

In our opinion, softball is a sport that should be prioritized for workload monitoring research using all available technology and validated research methods that may lead to injury prevention. Furthermore, like other sports, consistent workload monitoring is crucial in reducing the prevalence of overuse throwing injuries. Targeting youth pitchers and engaging their parents/coaches with the National Council of Youth Sports STOP campaign recommendations for game pitch limits and rest days is recommended. In addition, collegiate coaches should recognize the need for adequate rest, particularly in the preseason, where injury rates have increased.

Conclusion

Softball pitchers require their own set of workload guidelines and recommendations that are distinct from baseball pitchers. Although pitch counts are an important factor, other aspects of workload monitoring should be considered. These include such factors as batters faced, the level of effort exerted during games and practices, emotional stressors, the amount of rest in between outings, and the pitcher’s historical workload. All of these may contribute to the risk of overuse injury. Thus, based upon the evidence presented, it would be beneficial for organizations like the NCAA, National Professional Fastpitch Association, and youth sports associations (such as Little League Baseball and Softball) to consider prioritizing workload management in an attempt to promote the overall health of softball pitchers and reduce their risk of overuse throwing injuries.

Strength-of-Recommendation Taxonomy (SORT)

• The prevalence of participation as well as overuse pitching injuries in fastpitch softball is rising in all levels of sport though there is a lack of research evaluating workload in comparison to baseball ([SORT] B).

• Fastpitch softball pitching workload may be a modifiable risk factor and requires further study through evidence-based research ([SORT] B).

• Further research in softball is critical to improve the treatment algorithms of all throwing-related softball players ([SORT] B).