Training With Lighter Baseballs Increases Velocity Without Increasing the Injury Risk

Background: Pitch velocity has become an increasingly popular metric by which pitchers are graded and compared. Training programs that utilize weighted balls have been effective in increasing velocity but at the cost of an increased injury risk. No studies have evaluated training with lighter baseballs with regard to increasing pitch velocity and the injury risk. Purpose/Hypothesis: The purpose of this study was to determine whether a training program utilizing lighter baseballs could increase fastball velocity without increasing the injury risk to participants. We hypothesized that a training program with lighter baseballs would increase fastball velocity but not increase the injury risk. Study Design: Case series; Level of evidence, 4. Methods: All baseball pitchers who participated in a 15-week program at a single location, with the same coaches, and aimed to improve pitching mechanics and increase velocity were included. The training program was broken down into 3 phases, and each participant went through the same program. Lighter baseballs (3 and 4 oz) and standard baseballs (5 oz) were utilized as part of the training program. Weighted (heavier) balls were not used. Velocity was measured at 4 time points throughout the program with the pitcher throwing 5 fastballs using a standard 5-oz ball at maximum velocity (sessions 3, 10, 17, and 25). Injuries for all players were recorded throughout the entire program. Results: A total of 44 male pitchers aged 10 to 17 years (mean age, 14.7 ± 1.8 years) completed the training program and were available for analysis. No pitcher sustained a shoulder or elbow injury during the course of the training program. Fastball velocity increased by a mean of 4.8 mph (95% CI, 4.0-5.6 mph) (P < .001). Overall, 43 of 44 players (98%) had an increase in fastball velocity over the course of the program. Conclusion: A 15-week pitching training program with lighter baseballs significantly improved pitching velocity without causing any injuries, specifically to the shoulder or elbow. Lighter baseballs should be considered as an alternative to weighted baseballs when attempting to increase a pitcher’s velocity.

Injury rates in baseball players of all levels have been on the rise in recent years. 2,[4][5][6]8,14 Many injury prevention programs focused on modifiable risk factors have been implemented in an effort to quell this rise in injury rates and include an emphasis on pitch count limits, minimum number of days of rest between starts, and many other factors. 4,7,13 Unfortunately, one of the most significant risk factors for an injury in baseball players is also a metric that is used to measure and evaluate a pitcher. This risk factor is pitch velocity. 3 Pitch velocity is one of the most commonly measured and valued pitching performance metrics in all of baseball. Since the introduction of the radar gun to baseball in the 1960s, pitch velocity has become an integral part of evaluating pitching talent. As such, many pitchers strive to continually increase their fastball velocity in an attempt to pitch more effectively. There are many ways that pitchers attempt to increase their velocity. One of the most common methods that pitchers have used to increase their velocity in recent years is the use of weighted (heavier) baseballs. 1,10,12 A standard, regulation baseball weighs 5 oz, and many velocity enhancement programs have utilized weighted (heavier) baseballs up to 32 oz in an attempt to increase fastball velocity. 1,11 Heavier baseballs are theoretically thought to enhance throwing mechanics, as well as arm strength and speed, thereby leading to enhanced pitch velocity. While pitch velocity is a kinetic chain phenomenon that begins from the ground up, enhancing upper extremity mechanics may have a significant role in increasing velocity. While many of these weighted baseball programs have been effective in increasing fastball velocity, some have also caused a significant number of injuries to the pitchers participating in the programs. 12 Interestingly, none of these programs have critically evaluated the use of lighter baseballs in regard to the injury risk and as a means of increasing pitching velocity. Velocity is determined by the distance that an object travels, divided by the time that it takes to progress through that distance. Theoretically, if training can focus on increasing the speed of the arm and not be affected by a small increase in the weight of the ball from 3 or 4 oz to the standard 5 oz, the velocity of the ball can be increased.
Therefore, the purpose of this study was to determine if a pitching training program utilizing lighter baseballs could increase fastball velocity without increasing the injury risk. We hypothesized that a training program with lighter baseballs would increase fastball velocity without causing injuries to the participants.

METHODS
Male baseball pitchers aged between 10 and 17 years were eligible to participate in the velocity training program. Players and parents were asked about injury history, current injury status, and prior surgery by the coach running the program (T.R.A.). They also underwent a brief screening examination by 1 author (B.J.E.) before participation. Players were excluded if they were currently injured or had undergone recent surgery and were not cleared to return to throwing at the start of the program. An injury that was resolved at the time that the program began did not exclude pitchers from taking part in the program. All players (and their legal guardians) signed an assent/consent form 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 were deidentified before sharing for analysis. The study was considered exempt from institutional review board approval. The velocity-based training program was designed and monitored by one of the authors (T.R.A.), who is a former professional baseball pitcher.
The program was divided into 3 phases (a total of 25 training sessions, which will be referred to as "sessions") and was run out of a single facility, with all players going through the same scheduled sessions. The program is detailed in Appendices 1 to 6. The training sessions took place in the winter months. Players were asked after each session if they had sustained any injury to any body part. An injury was defined as any issue that caused the player to miss time participating in the program (to leave a session early or miss a session). The total duration of the training program was 15 weeks. All participants were divided into 3 groups based on age: group 1, 10-12 years; group 2, 13-14 years; and group 3, 15-17 years. Only 1 group trained on a given day, such that players in an age group trained together. Group 1 trained on Mondays and Fridays, group 2 trained on Tuesdays and Saturdays, and group 3 trained 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 exact routine. No group had more than 2 sessions per week during the program. All groups went through the same routine at each session.
Pitch velocity was tested at 4 time points during the program using a radar gun (JUGS Sports): sessions 3, 10, 17, and 25. Pitchers were instructed to throw 5 fastballs at maximum effort after having warmed up. Pitch velocity was recorded for each pitch.

Statistical Analysis
For each time point, mean velocity was calculated using the 5 velocity measurements obtained. Data normality was evaluated using the Kolmogorov-Smirnov test, and parametric and nonparametric tests were used as appropriate depending on data normality. Velocity data for each time point were compared with baseline using the paired Student t test and related-samples Wilcoxon signed rank test. All analyses were performed with Excel 16 (Microsoft) and SPSS 25 (IBM).

RESULTS
In total, 48 players were involved in the program. There were 4 players who were excluded from the analysis: 1 because no baseline velocity data were available, as he did not attend the initial session; 1 because he did not complete the program, as he sustained a broken ankle while playing basketball at home; 1 because he moved before completion of the program; and 1 because he experienced biceps tendon soreness after participating in back-to-back showcases before the training program was completed against recommendations. Hence, 44 male pitchers aged 10 to 17 years (mean age, 14.7 ± 1.8 years) completed the training program and were available for analysis. No player sustained a baseball-related injury during the training program.
Velocity significantly and sequentially increased over baseline at all time points (Table 1). The mean change in velocity by the end of the program was 4.8 mph (95% CI, 4.0-5.6 mph) (P < .001). By the end of the program, velocity was increased for all but 1 player; that is, velocity increased for 43 of 44 or 98% of players ( Figure 1).

DISCUSSION
Fastball velocity is an important metric used by many to evaluate and grade baseball pitchers. While velocity itself is a risk factor for injuries, velocity enhancement programs have also been implicated in injuries because of the use of weighted (heavier) baseballs. Our hypotheses were confirmed, as the use of lighter baseballs (3 and 4 oz) was effective in increasing fastball velocity but did not cause any injuries in the pitchers who participated in the program.
The use of weighted (heavier) baseballs to enhance pitching velocity has become a subject of debate in the baseball community among players, coaches, training staff, and team physicians. 1,9 Some authors have found a significant increase in pitching velocity when using weighted (heavier) baseballs to train their pitchers, while others have seen no change in velocity. 10,12 Fleisig et al 9 conducted a study to evaluate the kinetics and kinematics of weighted baseball exercises. The authors included 25 high school and collegelevel pitchers and had the participants use 4-, 5-, 6-, and 7-oz baseballs that they threw off a mound and with a flatground crow hop. The participants also performed flatground hold exercises with 14-and 32-oz balls. The authors found no difference in arm and trunk velocities between throwing a standard 5-oz baseball and a lighter 4-oz baseball. However, arm and trunk velocities steadily decreased as the ball's weight increased from 5 to 32 oz. Furthermore, while arm torque and forces decreased as the ball's weight increased, elbow flexion torque increased as the ball's weight increased. The increase in elbow flexion torque is concerning for the use of weighted balls, as this could increase the risk of injury to the elbow.
Okoroha et al 11 conducted a study to evaluate medial elbow torque with the use of weighted baseballs in 19 youth baseball pitchers with an average age of 11.8 years (range, 9-14 years). The authors found that, for every 1-oz increase in the ball's weight, velocity decreased an average of 2.0 mph (P < .001), medial elbow torque increased 0.92 NÁm (P ¼ .02), and arm speed decreased 8.52 rpm (P ¼ .02). This biomechanical analysis adds to the data that weighted baseballs may increase the injury risk by placing increased loads on the medial elbow.
Interestingly, the authors asked pitchers which ball (based on weight of 3, 4, 5, and 6 oz) they preferred the most and then asked a separate question of which ball they disliked the most. The majority of pitchers preferred the 3-oz ball the most, and a majority of pitchers disliked the 6-oz ball the most. Given the results of these studies, it may be that lighter baseballs train the arm to move faster by allowing for higher shoulder and elbow angular velocities. This in turn can lead to an increase in arm speed and ultimately an increase in ball velocity.
While previous studies have demonstrated an increase in torque placed on the elbow with weighted baseballs, these studies did not evaluate the injury risk or ball velocity. Caldwell et al 1 performed a systematic review of the literature to determine if weighted baseballs increased a pitcher's velocity and increased the risk of injuries. The authors included 10 articles in their analysis but unfortunately noted that the majority of studies were heterogeneous and found it difficult to draw significant conclusions. It did appear that weighted balls were effective and increased velocity, although the types of weighted balls varied greatly between studies (6-32 oz). Reinold et al 12 randomized 38 youth male baseball pitchers (average age, 15.3 years) into a control group (only using standard 5-oz baseballs) and an experimental group, which participated in a 6-week weighted ball program 3 times per week using balls ranging from 2 to 32 oz. Both groups participated in a strength training program. The authors found a 24% injury rate in  the experimental group (all were elbow injuries) compared with a 0% injury rate in the control group. Reinold et al did not randomize pitchers to a lighter ball training program. The current available literature suggests a potential increase in ball velocity with weighted baseball training programs but at the cost of an increased risk of sustaining an elbow injury. The lighter ball training program in this study achieved the goal of increasing velocity but without causing any injuries during the training program. Theoretically, a light ball allows the pitcher to focus on training for increased speed of his arm movement, which can then be used to increase the velocity of the arm when throwing the regulation-sized 5-oz ball. Consideration should be given to a training program utilizing lighter baseballs to enhance pitching velocity in an effort to mitigate the injury risk while at the same time increasing velocity.
One additional difference between this program and others is that this training program was longer (more weeks) than some training programs in previous studies. 12 The pitchers in this study did not begin throwing on a rope until after the 10th session. Hence, this delay in throwing while working on mechanics may be a good way to ready a player's arm for more intensive throwing. To date, the ideal duration of a velocity training program has not been defined. As none of the players who participated in this throwing program were injured, consideration may be given to a longer training program with more days of rest to potentially decrease the injury risk. Future studies randomizing pitchers to velocity programs of varying durations will help elucidate the ideal training program duration.

Limitations
While this study is the first to critically evaluate a training program with lighter baseballs, it is not without limitations. The pitchers included in this study ranged in age from 10 to 17 years. Therefore, it is unclear if these results, either in the velocity increase or injury risk, are translatable to pitchers who are younger or older. This study did not have a control group of pitchers who used weighted balls, as we do not believe that these programs should be used based on current evidence showing significant increases in injury rates for players. This study included a relatively small group of pitchers, which will be expanded to include more pitchers in future studies. Finally, this study did not determine a "ceiling effect" in which the pitchers reached a certain velocity and neither additional training nor time to train led to further increases in velocity. While there were no injuries during the course of the training program, there was no control group of pitchers who did not participate in the training program for comparison. When this program is instituted in following years, the goal will be to follow the participants throughout the subsequent season to determine if their injury risk is the same, lower, or higher than their peers who did not participate in the training program.

CONCLUSION
A 15-week pitching training program with lighter baseballs significantly improved pitching velocity without causing any injuries, specifically to the shoulder or elbow. Lighter baseballs should be considered as an alternative to weighted baseballs when attempting to increase a pitcher's velocity. This phase focuses on continued core strengthening and mechanics but adds in quick twitch movements. Lighter balls are introduced during this phase of the program. The pull-downs are the throws during the session in which the lighter balls are used. These throws are the highest effort throws of the session, designed to increase velocity by increasing momentum before the throw and then translating that momentum from the ground up the kinetic chain during the throw. 75. Active warm-up þ stretching routine a. Before your group starts 76. Velocity program throwing routines a. Precatch routine: 5 repetitions per exercise i. Hip hinge routine: 20 repetitions b. Long toss i. 10 throws 77. Final pull-down evaluation: will be using data from this evaluation to calculate overall improvement with these drills a. 5 (5 oz) þ 5 (4 oz) þ 5 (3 oz) þ 5 ( 5 oz

Description of Light Medicine Ball Routine
This routine uses 2-and 4-lb medicine balls to execute "over-the-head" throws with both arms. These drills are great for building velocity because the arm is not carrying the workload, whereas most velocity programs place all the stress on the arm, which leads to overuse and a higher potential for injuries. The drills in this routine involve the feel of the concepts from the heavy medicine ball routine and the strength gained with each concept in those drills, with an emphasis on acceleration instead of power. The lighter ball combined with the power development from the heavy medicine ball routine will be used to teach the body to be the primary accelerator for motion while the arm remains in a healthier position for a longer period of time and does less work.

Trunk Throw
Start on your knees with your body square to the target (feet, hips, shoulders), checking to make sure that you have a straight line from your knees to your shoulders. The ball should be sitting slightly above and behind your head with the elbows bent and arms loose. This is not a high-effort throw. The torso will generate the movement forward to start the throw with your arms following. Your elbow should follow your chest, allowing your throwing arm to rotate externally. Your hands will come through last, and as you release, you need to focus on feeling your throwing hand pronate (hand rotates thumb in and down). This is not a high-effort throw, and the torso is still what you are using to get the arms moving.

Back Leg Drive þ Front Foot Stabilization þ Trunk Throw: With Stop
Start with both feet pointing forward (feet, hips, and chest facing forward toward your target), with the plant foot slightly in front of the drive foot and both arms above your head with elbows bent and the ball sitting slightly above and behind your head. Starting from the drive foot, you will drive your hips forward with your plant foot extending. Once your drive foot drags, you will plant and stabilize your front foot/leg and hold this position. Your plant foot should be ahead of your knee with your leg almost straight, and your torso should be chest up and sitting slightly behind your belt buckle with your arms in the same position as when you started. If your positioning is off, then you will fix it. Once you are in a good stable position, you will drive with the back foot and extend your trunk to initiate the throw as you "push the earth down" with your lead leg. You want to try and create an explosive move with your torso on this drill, with increasing intensity as you improve with the drill.
Do not worry about finishing in a "perfect position" with this drill; simply allow your body to react to the momentum of your torso, generating power with a strong front leg.
Back Leg Drive þ Front Foot Strike þ Trunk Throw:

One Motion
The starting position and the details from the previous drill are the same for this drill. The only difference is that you will not stop motion at front foot strike. The goal here is to delay the throw until your drive foot drags and you feel front foot strike. Do not worry about finishing in a perfect position with this drill; simply allow your body to react to the momentum of your torso, generating power with a strong front leg.

Hip/Shoulder Separation Throw: With Stop
Start with both feet pointing forward (feet and hips facing forward toward your target), with the plant foot slightly in front of the drive foot. Your shoulders should be perpendicular to your hips (starting with hip/ shoulder separation) and the ball sitting above your throwing shoulder and behind the ear with both hands on the ball and elbows bent with arms loose. Starting from the drive foot, you will drive your hips forward with your plant foot extending and your torso "riding the back leg" and maintaining hip/shoulder separation. Once your drive foot drags, you will plant and stabilize your front foot/leg and hold this position. Check to see that you are maximizing hip/shoulder separation before you start the throw. You will initiate the throw by driving with your back leg and leading your front shoulder forward and down as you push the earth down with your lead leg. Your trunk should rotate to extension with your arms following into the throw. You want to create velocity with your trunk and legs and will again add intensity as you improve with this drill. Do not worry about finishing in a perfect position with this drill; simply allow your body to react to the momentum of your torso, generating power with a strong front leg.

Hip/Shoulder Separation Throw: One Motion
The starting position and the details from the previous drill are the same for this drill. The only difference is that you will not stop motion at front foot strike. The goal here is to delay the throw until your drive foot drags and you feel front foot strike. Do not worry about finishing in a perfect position with this drill; simply allow your body to react to the momentum of your torso, generating power with a strong front leg.

Squat Throw: With Contralateral Trunk Rotation
Start with your body (feet, hips, shoulders) perpendicular to your target. Your feet should be about shoulder width apart, and you want to feel like you are sitting on your heels with a slight bend in both knees (similar to being halfway into a squat in the gym); the ball should be in the same position that your glove would be. You will initiate drive, trying to keep your back heel and back knee from rotating immediately. As you drive forward and extend your lead foot, you will load your hands and ball to the same loaded position as the previous drills. During motion, your hips will start to release into the front leg as you force the shoulders to rotate slightly closed (contralateral trunk rotation) while keeping your body loaded over your back hip (ride your back leg). The goal is to delay the throw until your front leg stabilizes, increasing hip/shoulder separation. Again, the throw and the velocity are coming from the legs and your trunk as it extends over a strong front leg. Allow your momentum to lead you into your finish.

Plyometric Throw: 3 Hops for Momentum With Throw on Third Hop
Start your stretch in your set position with the ball sitting above your throwing shoulder and behind the ear with both hands on the ball and elbows bent with arms loose. You will hold your balance; then, you will start by sitting slightly onto your heel (hips back, knee steady, heel connected to the ground) and then hopping laterally in a controlled way. When you land, make sure that your back heel gets down and your knee is not rolled in toward flexion as you cushion the landing by sitting slightly onto your heal (repeat). You will initiate the throw by driving and extending your lead foot with your head staying behind your belt buckle and shoulders staying locked onto the target. Again, you are delaying the throw until front foot strike, and the throw should start with your lead shoulder going forward and rotating down as the trunk extends into the throw. Allow your momentum from the throw to carry you into your finish.

APPENDIX 6
Description of Heavy Medicine Ball Routine This routine uses 8-lb medicine balls to execute "chest pass" throws using both arms. The routine involves several progressive drills with work on connection to the ground with the drive foot, the position of the back knee before drive, increasing the output of force and momentum from the drive leg, hip loading and release, front foot strike, front leg stabilization, and hip/shoulder separation. Improvements to these concepts will increase power from the ground through the hips and into the torso.

Back Leg Drive þ Front Leg Stabilization þ Trunk Extension: With Stop
Start with both feet pointing forward (feet, hips, and chest facing forward toward your target), with the plant foot slightly in front of the drive foot and both arms above your head with elbows bent and the ball sitting slightly above and behind your head. Starting from the drive foot, you will drive your hips forward with your plant foot extending. Once your drive foot drags, you will plant and stabilize your front foot/leg and hold this position. Your plant foot should be ahead of your knee with your leg almost straight, and your torso should be chest up and sitting slightly behind your belt buckle with your arms in the same position as when you started. If your positioning is off, then you will fix it. Once you are in a good stable position, you will drive with your back leg, extending your trunk over your stabilized lead leg, and the arms will follow into the throw. Do not worry about your finish looking like you were pitching. If your body falls back because of the lead leg being straight/strong, that is fine.
Back Leg Drive þ Front Foot Strike þ Trunk Extension: One Motion The starting position and the details from the previous drill are the same for this drill. The only difference is that you will not stop motion at front foot strike. The goal here is to delay the throw until your drive foot drags and you feel front foot strike. Again, do not worry about your finish looking like you were pitching. If your body falls back because of the lead leg being straight/strong, that is fine.

Squat Throw: With Stop
Start with your body (feet, hips, shoulders) perpendicular to your target. Your feet should be about shoulder width apart, and you want to feel like you are sitting on your heels with a slight bend in both knees (similar to being halfway into a squat in the gym); the ball should be in the middle of your chest. You will initiate drive, trying to keep your back heel and back knee from rotating immediately. As you drive forward, extend your lead foot while keeping your body loaded over your back hip and preventing your torso from rotating (shoulders are to stay in line with your target). Front foot strike and lead leg stabilization should occur after your back foot rotates and drags. You will hold this position and check to make sure that your front foot is facing the target, your lead leg is stabilized, and you have good hip/shoulder separation. Once positioning is correct, you will initiate the throw by driving and leading your front shoulder forward with the chest rotating to extension and the throw following. You are trying to use your trunk as the power behind the throw. Allow the momentum from the throw to carry you into your finish.

Squat Throw: One Motion
The starting position and the details from the previous drill are the same for this drill. The only difference is that you will not stop motion at front foot strike. The goal is to focus on the details from Appendix 3 while trying to keep your shoulders and trunk loaded during drive and front foot strike so that when you throw, you will be doing so from a position of maximized hip/shoulder separation. The key is to delay the throw for as long as you can and to feel front foot strike before throwing. Allow the momentum from the throw to carry you into your finish.

Plyometric Throw: 3 Hops for Momentum With Throw on Third Hop
Start your stretch in your set position with the ball in the same position that your glove would be. You will hold your balance; then, you will start by sitting slightly onto your heel (hips back, knee steady, heel connected to the ground) and then hopping laterally in a controlled way. When you land, make sure that your back heel gets down and your knee is not rolled in toward flexion as you cushion the landing by sitting slightly onto your heal (repeat). You will initiate the throw by driving and extending your lead foot with your head staying behind your belt buckle and shoulders staying locked onto the target. Again, you are delaying the throw until front foot strike, and the throw should start with your lead shoulder going forward and rotating down as the trunk extends into the throw. Allow your momentum from the throw to carry you into your finish.