Abstract
Background:
Pitching velocity is one of the most important metrics used to evaluate a baseball pitcher’s effectiveness. The relationship between age and pitching velocity after a lighter ball baseball training program has not been determined.
Purpose/Hypothesis:
The purpose of this study was to examine the relationship between age and pitching velocity after a lighter ball baseball training program. We hypothesized that pitching velocity would significantly increase in all adolescent age groups after a lighter baseball training program, without a significant difference in magnitude of increase based on age.
Study Design:
Cohort study; Level of evidence, 2.
Methods:
Baseball pitchers aged 10 to 17 years who completed a 15-week training program focused on pitching mechanics and velocity improvement were included in this study. Pitchers were split into 3 groups based on age (group 1, 10-12 years; group 2, 13-14 years; group 3, 15-17 years), and each group trained independently. Pitch velocity was assessed at 4 time points (sessions 3, 10, 17, and 25). Mean, maximum, and mean change in pitch velocity between sessions were compared by age group.
Results:
A total of 32 male baseball pitchers were included in the analysis. Mean/maximum velocity increased in all 3 age groups: 3.4/4.8 mph in group 1, 5.3/5.5 mph in group 2, and 5.3/5.2 mph in group 3. While mean percentage change in pitch velocity increased in all 3 age groups (group 1, 6.5%; group 2, 8.3%; group 3, 7.6%), the magnitude of change was not significantly different among age groups. Program session number had a significant effect on mean and maximum velocity, with higher mean and maximum velocity seen at later sessions in the training program (P = .018). There was no interaction between age and program session within either mean or maximum velocity (P = .316 and .572, respectively).
Conclusion:
Age had no significant effect on the magnitude of increase in maximum or mean baseball pitch velocity during a velocity and mechanics training program in adolescent males.
One of the most coveted aspects of a baseball pitcher’s skill set is pitch velocity. Study of the mechanical complexity of the overhead pitch has demonstrated intrinsic and acquired traits that contribute to pitch velocity, including age, height, stride length, strength, and technique. 3 The desire to maximize pitch velocity has given rise to a variety of training programs focusing on modifiable factors, including increased strength and improved throwing technique with the ultimate goal of increasing pitch velocity. 14 However, studies of the musculoskeletal and biomechanical factors associated with injury subsequent to overhead pitching have identified pitching velocity as a primary risk factor for injury. 2,9,10,13,16
Baseball pitchers have traditionally focused on improving strength with a combination of resistance exercises and pitching-specific programs. 3,4 Several studies have demonstrated that nonspecific strength training increases velocity in several sports, including baseball, golf, water polo, and cricket. 3 Escamilla et al 6,7 established that various baseball-specific training programs improve throwing velocity in youth baseball players, though the authors did not demonstrate that one specific resistance training program was more effective than the others.
Similarly, several studies have investigated a variety of kinematic correlates with pitch velocity, though few have focused on important demographic data such as age. 1,5,6,8,11,12,17 –19 Sgroi et al 16 showed that each year of pitcher age is associated with an increase in pitch velocity of 1.5 ± 0.1 mph (mean ± SD), contributing to 66% of pitch velocity variance among 420 youth and adolescent overhead pitchers (mean age, 14.7 ± 2.6 years). Riff et al 15 demonstrated a significant increase in pitch velocity with age in 295 youth pitchers studied at a single time point. However, there have been no studies focusing on absolute and percentage improvement of pitch velocity based on age. While older players throw faster, it is unclear if they will see a more significant percentage increase in their pitching velocity than younger players over the course of a velocity training program. The purpose of this study was to examine the relationship between age and pitching velocity after a lighter ball baseball training program. We hypothesized that pitch velocity would significantly increase in all adolescent age groups, without a significant difference in magnitude of increase based on age.
Methods
Study Design
Male baseball pitchers between the ages of 10 and 17 years were eligible to participate in the velocity training program. Players were excluded if they were currently injured or had recent surgery and were not cleared to return to throwing at the start of the program. A history of an injury that was resolved at the time when the program began did not exclude pitchers from taking part in the program. All players who participated (and their legal guardians) assented/consented to participate in the program and to have their data analyzed. All data were collected by the facility where the program was run as standard of care and was de-identified before sharing for analysis. Therefore, this study was deemed exempt by the institutional review board. The velocity-based training program was designed and monitored by one of the authors (T.R.A.), who is a former professional baseball pitcher. A total of 37 pitchers met these criteria and agreed to participate.
Training Program
The program was divided into 3 phases (25 training sessions, referred to as “sessions”) and run out of a single facility, with all players going through the same scheduled sessions. The program is detailed in Appendices 1 to 6. Briefly, the training program involved a combination of core strengthening exercises, medicine ball throws, and throws with lighter and regulation weight baseballs. The core strengthening exercise involved front and side planks, deadbugs, glute bridges, crunches, bicycles, and Russian twists. The training sessions took place in the winter months (November-February) over 15 weeks. Participants were divided into 3 groups based on age (group 1, 10-12 years; group 2, 13-14 years; group 3, 15-17 years). Only 1 group trained on a given day such that each age group trained together. Group 1 trained on Mondays and Fridays, group 2 on Tuesdays and Saturdays, and group 3 on Wednesdays and Sundays. Hence, coaches who were training the athletes were able to give each group the same amount of attention and put each group through the same routine. No group had more than 2 sessions per week during the program. Pitch velocity was tested with a radar gun (JUGS Sports) at 4 time points during the program: sessions 3, 10, 17, and 25 (evaluations 1-4, respectively). Pitchers were instructed to throw 5 fastballs at maximum effort after warming up per their own routine. Pitch velocity was recorded for each pitch.
Statistics
Mean and maximum pitching velocity at each evaluation was calculated for each participant by using all 5 recorded velocities. Additionally, individual and mean progress relative to evaluation 1 was calculated at all subsequent evaluations. A repeated-measures analysis of variance for mean and maximum velocity across program sessions was performed with age as a covariate and including the interaction term between program session and age. The effect of age on velocity was determined via the between-participants effects results. The effect of program session on velocity was determined by Roy’s largest root as the within-participants effects results. All analyses were performed in Excel 16 (Microsoft) and SPSS (v 25; IBM).
Results
A total of 37 pitchers enrolled in the lighter ball training program. One (2.7%) participant was excluded owing to a broken ankle sustained in a nonbaseball recreational activity outside the training program. Four (10.8%) participants were further excluded upon analysis because their ages were not listed among the de-identified data set. As a result, 32 pitchers who completed the training program were included in analysis. There were no baseball-related injuries sustained during the training program. Of the athletes, 8 were in group 1, 11 in group 2, and 13 in group 3.
Mean and maximum pitching velocities improved in all 3 age groups across all 4 time points (Table 1, Figure 1). Age had a significant effect on mean and maximum velocity (P < .001 in both cases; observed power, 1.00), indicating that older patients throw harder. Program session number also had a significant effect on mean and maximum velocity (P = .018; observed power, 0.766), indicating that pitchers’ velocity improved throughout the course of the program. However, there was no interaction between age and program session within either mean or maximum velocity (P = .316 and .572, respectively; observed power, 0.244 and 0.156), indicating that the amount of increase in velocity (mean or maximum) did not differ among age groups.
Mean and Maximum Pitch Velocity per Age Group a
a Group 1, ages 10-12 years; group 2, ages 13-14 years; group 3, ages 15-17 years.
Mean pitch velocity (mph) by age group and evaluation number. Mean and maximum pitch velocities improved in all 3 age groups across all 4 time points. Evaluation 1, session 3; evaluation 2, session 10; evaluation 3, session 17; evaluation 4, session 25.
Mean progress and percentage change at each time point relative to Evaluation 1 (session 3) improved within each age group (Table 2). Mean percentage change within and between age groups did not show significance.
Mean Progress and Percentage Change Relative to Evaluation 1
a Evaluation 1, session 3; evaluation 2, session 10; evaluation 3, session 17; evaluation 4, session 25.
Discussion
Pitch velocity is one of the most important metrics used to evaluate a baseball pitcher’s effectiveness. Our hypothesis was confirmed, as mean and maximum pitch velocity significantly increased in all 3 age groups without a significant difference in magnitude of increase based on age. These results demonstrate that during a baseball training program focused on velocity and pitching mechanics, age had no significant effect on the magnitude of change in maximum or mean pitching velocity.
Several studies have investigated a variety of kinematic correlates with pitch velocity, but few have incorporated demographic data such as age in relation to velocity. 1,5,6,8,11,12,17 –19 Sgroi et al 16 performed a multivariate regression analysis on 420 youth and adolescent overhead pitchers (mean age, 14.7 ± 2.6 years) who underwent dual-orthogonal high-speed video analysis while pitching. The study identified 4 factors independently correlated with an increase in pitch velocity: age (P < .001; multivariate R 2 = 0.658), height (P < .001; multivariate R 2 = 0.076), hip and shoulder separation (P < .001; R 2 = 0.027), and stride length (P < .001; multivariate R 2 = 0.016). These 4 factors in combination contributed 78% of pitch velocity variance, while age alone accounted for 66%. 16 The authors suggested the covariance of age and pitch velocity to be due to multiple factors—better pitching mechanics and greater muscle development in older pitchers, for example—and, after correction for remaining variables, associated each year of pitcher age with an increase in pitch velocity of 1.5 ± 0.1 mph. Unlike the current study, however, Sgroi et al evaluated these pitchers at only 1 time point, so it is not clear from the study how age correlates with the magnitude of change in maximum or mean pitching velocity over the course of a training program.
Riff et al 15 collected demographic, anthropometric, kinematic, and pitching history data on 295 youth pitchers (n = 63 [age, 9-12 years]; n = 130 [age, 13-15 years]; n = 78 [age, 16-17 years]; and n = 24 [age, 18-22 years). In regard to observed pitching mechanics, the study determined that as pitchers get older, they generally adopt strategies and movements that may minimize injury risk and increase pitching efficiency, such as maintaining their hand on top of the ball, maintaining closed shoulders at foot strike, leading with their hips, and improving hip to shoulder separation. Importantly, the authors noted a statistically significant increase (P < .001) in pitch velocity with age (49.5 mph [age, 9-12 years]; 62.7 mph [age, 13-15 years]; 71.8 mph [age, 16-17 years]; and 73.5 mph [age, 18-22 years]). While this single-episode cross-sectional study is very useful for its large sample size, breadth of information recorded about each pitcher, and acknowledgment of age as an important contributing factor to pitch velocity, its utilization of only 1 pitching episode does not shed light on the relationship between age and change in pitch velocity over time.
The current study showed that mean progress and percentage change at each time point relative to session 3 improved within each age group, with age and session number having a significant effect on mean and maximum pitching velocity. This indicates that older pitchers threw harder at baseline and maintained this over the course of the training program, as expected. However, as the pitchers progressed through the training program, there was no more significant increase in maximum or mean velocity in older pitchers as compared with younger pitchers. As previous studies have demonstrated that pitchers develop improved muscle strength and mechanics that contribute to increased pitching efficiency and velocity with age, it is interesting that age in this study had no significant effect on the magnitude of change in maximum and mean pitch velocity. 15,16 One possibility is that while older pitchers had a better baseline in strength and mechanics, there was more room for improvement in the younger pitchers; as such, their velocity increased at the same rate as the older pitchers. It is possible that the structure of this velocity and pitching mechanics program enabled all participants to develop age-equivalent muscle strength and throwing techniques that contributed to significant velocity gains with insignificant percentage change differences by age. This would suggest that the baseball training program was equally beneficial in terms of velocity improvement based on age, which is further supported by the finding that session number had a significant effect on velocity across all 4 time points. Future studies evaluating the effects of different types of training programs on velocity, as well as the effect of age, body mass index, and so forth on velocity, will also be helpful to provide information to these athletes. As the number of velocity training programs for baseball pitchers increases in society, this information will be useful to the baseball community to set expectations for these players throughout the course of the program.
Limitations
This study included only healthy pitchers who had no current shoulder or elbow injuries, so there may have been a selection bias. Additionally, while all participants underwent the same training sessions over the 15 weeks, it is not known if any participants were engaged in strength and conditioning programs outside the baseball training program; thus, it cannot be conclusively stated that each participant’s improved pitching velocity was due exclusively to the training program. The purpose of this study was to evaluate age and velocity, not height, weight, and body mass index, as these variables are not used to separate out youth athletes. Essentially, age is the only variable currently used to separate out youth baseball players, and while these other factors likely play a role in velocity, we chose age because this is the most translatable variable to youth baseball. We also did not conduct an a priori power analysis, and so it is unclear whether our study was adequately powered to test differences among age groups. It is possible that this study suffered from type II error given the sample size. It is unknown how velocity would have been affected by simple aging for 15 weeks if these athletes did not complete a training program, as no control group was utilized. Finally, it is unclear if the gains that pitchers made during the program were maintained over time.
Conclusion
Age had no significant effect on the magnitude of increase in maximum or mean baseball pitch velocity during a velocity and mechanics training program in adolescent males.
Footnotes
One or more of the authors has declared the following potential conflict of interest or source of funding: P.N.C. has received educational support from Tornier and Active Medical, consulting fees from Arthrex and DePuy, and royalties from DePuy. M.E.B. has received educational support from Arthrex and Smith & Nephew, grant support from Arthrex, and hospitality payments from Stryker. A.A.R. has received research support from Aesculap/B. Braun, Arthrex, Histogenics, Medipost, Major League Baseball, NuTech, OrthoSpace, Smith & Nephew, and Zimmer; has received consulting fees and speaking fees from Arthrex; has received royalties from Arthrex, Saunders/Mosby-Elsevier, and SLACK; and is a board or committee member for Atreon Orthopaedics. B.J.E. has received educational support from Arthrex, DePuy, and Smith & Nephew. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
Ethical approval for this study was waived by Jefferson University (OHR-19).