The Relationship Between Concentric Only Half Squat Strength and Pop up Time in Baseball Catchers ______

THE RELATIONSHIP BETWEEN CONCENTRIC ONLY HALF SQUAT STRENGTH AND POP UP TIME IN BASEBALL CATCHERS ______

A Thesis

Presented to the

Faculty of

California State University, Fullerton ______

In Partial Fulfillment

of the Requirements for the Degree

Master of Science

Kinesiology ______

Stratton Kim

Thesis Committee Approval:

Jared W. Coburn, Department of Kinesiology, Chair Derek Pamukoff, Department of Kinesiology Pablo Costa, Department of Kinesiology

Spring 2018

ABSTRACT

The ability to quickly and accurately throw a runner out at second base has been found to be one of the catcher’s most important attributes to make it to the next level of play. The purpose of this study was to determine the relationship between concentric only half squat (COHS) strength, absolute and relative, and pop up time in baseball catchers.

Twenty-nine male baseball catchers (age: 21.5 ± 3.2 years, height: 1.8 ± .05 m, mass:

90.6 ± 12.6 kg) participated in this study. The catcher’s pop up time (initial phase of the overall pop time) was recorded and then a 1RM test was performed in the COHS. The results indicated there were no significant correlations between absolute COHS (r

= -.339, p = .072) or relative COHS (r = -.332, p = .078) and pop up time. More research needs to be done in evaluating various measures of strength and power and any phase of the pop time in baseball catchers.

TABLE OF CONTENTS

ABSTRACT ...... ii

LIST OF TABLES ...... iv

LIST OF FIGURES ...... v

ACKNOWLEDGMENTS ...... vi

Chapter 1. INTRODUCTION ...... 1

2. REVIEW OF LITERATURE ...... 3

Strength Training for Performance ...... 3 The Squat ...... 4 Baseball Catching Mechanics ...... 6

3. METHODS ...... 9

Participants...... 9 Procedures ...... 10 Instrumentation ...... 12 Data Analysis ...... 12 Statistical Analyses ...... 12

4. RESULTS ...... 13

5. DISCUSSION ...... 15

REFERENCES ...... 21

iii

LIST OF TABLES

Table Page

1. Level of Baseball ...... 10

2. Correlation Between Absolute and Relative COHS 1RM Values and Pop Up Time ...... 13

3. Means and Standard Deviations of Pop Up Times, Absolute COHS 1RM, and Relative COHS 1RM by Level of Baseball ...... 13

LIST OF FIGURES

Figure Page

1. Sequence of the COHS ...... 5

2. Phases of the throwing motion ...... 7

3. Scatterplot showing the relationship between absolute COHS 1RM and pop up time ...... 14

4. Scatterplot showing the relationship between relative COHS 1RM and pop up time...... 14

ACKNOWLEDGMENTS

I would like to thank Fullerton College, Hope International University, Orange

Coast College, Cypress College, California State University San Bernardino, and

California State University Fullerton for allowing their catchers to participate in this study. I would also like to thank my chairman, Dr. Jared Coburn, for all of the help and guidance during the process of the study as well as the rest of my committee. Also, thank you to my co-author, Kevin Choe, for all of his help throughout the duration of the study.

Lastly, I would like to thank all the coaches, friends, and family helping in the subject recruitment for this study as well as for your support throughout the process.

vi 1

CHAPTER 1

INTRODUCTION

In recent years, baseball has begun to see the use of strength and conditioning as a means to improve performance and keep athletes healthy throughout the duration of a season. The pitcher and catcher positions are thought of as the two most physically demanding positions on the field, with catching being the single most demanding due to the amount of throws on a daily basis and the constant squat position held by catchers

(10, 24, 25). Throwing, more specifically throwing out a potential base stealer, is considered by many scouts as one of the most important skills of a catcher, and is crucial in making it to the next level of competition (10). However, limited research has been done on the catching position (10, 15, 24-27, 29, 38) and none have examined the effects of resistance training on a catcher’s ability to throw a runner out at second base.

The time that it takes the catcher to throw the ball to second base in order to throw out an attempting base stealer is known as “pop time.” Pop time is defined as the time between the moment the ball hits the catcher’s glove to the moment the ball hits the infielder’s glove at second base. More specifically, “pop-up time” is defined as the moment of ball impact in the catchers’ glove until the stride leg foot makes contact with the ground (25, 38). In order to throw a base runner out at second base, a catcher must catch a pitched ball, rapidly rise from the squatted position, and deliver an accurate throw to second base (10, 25). The catcher has approximately 2.0 seconds to throw the ball

2 accurately 127 feet (40m) to second base. This is a highly specific skill that takes years of practice to perfect and may never be mastered, which is why the catcher must find any way possible to get an advantage over the base runner.

Research on catchers is scarce, as only a few studies have examined the topic of throwing to second base (10, 24-27, 29). More specifically, there is a paucity of research on how resistance training or muscular strength affects pop time in catchers. The catcher only uses the concentric portion of the squat when throwing to second base, since they start in the squatted position and then rise up to get into the throwing position. According to the specificity principle, the exercise being used should mimic the kinetics and kinematics of the actual movement used in the sport (30). The squat and half-squat exercise has been suggested to improve vertical jump and athletic performance (1, 3, 4); in this study we will be using the concentric only half squat (COHS) also known as the

Anderson squat. However, the specific relationship between the COHS and pop up time remains to be investigated. Therefore, the purpose of this study was to determine the relationship between the COHS and pop up time in baseball catchers. We hypothesized that individuals with a higher 1RM in the COHS will have a quicker pop up time compared to those with a lower 1RM in the COHS.

CHAPTER 2

REVIEW OF LITERATURE

Strength Training for Athletic Performance

Strength or resistance training is a method of conditioning involving the movement of various external loads against gravity to increase physical performance or increase skeletal muscle mass (32). Improving muscular strength, in particular maximal strength, is a major factor in increasing or improving athletic performance (37). Increases in maximal strength increase the upper limit of the body’s ability to produce force; therefore, higher forces can be produced with less effort. This is important in sports due to the time constraints of sport specific tasks during competition such as running, jumping, throwing, and change of direction (37). Exercises such as the squat (16) deadlift

(8) and power clean (12) utilize multiple muscle groups with the largest cross sectional area (CSA), such as the gluteal and quadriceps muscles. These multi-joint exercises lead to strength adaptations in large muscle groups, and have similarities to sport-specific movements, such as running and jumping and activities of daily living (ADLs) such as sitting, standing, and walking (7).

Elite level athletes have used resistance training to improve athletic performance for years. A study by Wisloff et al. (40) found a strong correlation between maximal strength in half squats and vertical jump height (r = 0.78), 10-m sprint test (r = 0.94), and

30-m sprint test (r = 0.71) in seventeen international male soccer players (40). In a study

4 done by Crewther (4), nine rugby players performed countermovement jumps, sprints, and sled pushes after doing a 3RM back squat. The 3RM back squats were shown to significantly improve vertical jump height (4). This study also states that the potentiating effects of squats may exhibit some degree of movement specificity, being greater for those exercises with similar movement patterns (4). These studies, and others, suggest that resistance training can be utilized to increase athletic performance.

Greater strength leads to the ability to produce more force in the trained musculature, increasing performance (12). An increase in maximal strength reduces the relative force production requirement to accomplish a given task, which reduces the amount of effort and also increasing power. Adams et al. (1) found that a 7-week program of parallel squats significantly increased hip and thigh power, as well improved their vertical jump height by an average of 3.30 cm (1). In a study performed on high school aged males a larger increase in squat strength contributed to a greater increase vertical jump height (3). The squat and the vertical jump use the same primary muscle groups, which is one reason, the squat helps to improve vertical jump (12).

The Squat

The squat is a commonly used movement that is effective in resistance training programs with multiple goals, including performance enhancement, rehabilitation, and general fitness (6, 20). There are many variations of the squat with some of the most common being the front squat (FS), back squat (BS), split squat (SS), and half squat

(HS). All of these variations differ in where the load is placed relative to the neck, foot placement, or range of motion of the squat. Of these variations the back squat is the most common in training programs (6). The squat is a multi-joint movement that requires

5 mobility from the hip and ankle joints, but stability from the knee and lumbar spine. The major muscles being trained in the squat exercise are the hip and knee extensors, gluteal muscles and quadriceps muscles, respectively (12, 16).

To properly perform the squat, the barbell is placed anterior or posterior to the neck, with the knees and hip joints extended. The lifter then flexes their knees, hips, and ankles continuously until a desired depth is achieved, then extends those joints reversing the movement until they reach the starting position (6). When performing the COHS the lifter begins in a squatted position at a desired depth (normally ~90° knee flexion), and then extends the hips, knees, and ankles until they are standing in an erect position (6, 35, 36,

41) (Figure 1).

Figure 1. Sequence of the COHS.

The squat strengthens the hip, thigh, and back musculature, which are important muscles in running, jumping, and lifting, common movements in most sports (6). The squat exercise is effective in increasing athletic performance by improving lower

6 extremity strength and function (6). Strength and performance in the squat are associated with success in sports and positions that involve sprinting and jumping, and therefore, should be incorporated into strength programs for those athletes.

Baseball Catching Mechanics

Catching is one of the most physically demanding positions on the field, yet one of the most under studied positions. In any given game, the starting catcher makes more throws than any other player on the field and many professional scouts believe that a catcher’s throwing ability is their most important skill (10, 15, 25). While a pitcher has essentially an unlimited amount of time to prepare and make a pitch, a catcher must catch a pitched ball from a squat position and deliver an accurate throw nearly 40 m in 2.0 seconds or less to throw a base runner out at second base (10, 25).

Success at throwing a runner out at second base is influenced by many different factors, and all of these factors should be taken into account when assessing a catcher. In a perfect situation, the ball is thrown down the middle of the plate, the batter does not swing, the pitcher delivers the ball quickly, and the catcher’s technique is perfect, resulting in an out at second base. This perfect situation often never occurs so it is a catcher’s job to optimize everything that can be controlled (technique, strength, etc.) in order to be successful (10).

The four phases of throwing for a catcher include a) stride leg foot contact b) maximum shoulder external rotation (MER) c) ball release (BR) and d) maximum shoulder internal rotation (MIR) (25, 26) (Figure 2).

Figure 2. Phases of the throwing motion.

The first phase of the throwing motion begins when catcher catches the ball in a squatted position and it ends when the foot of the stride leg makes contact with the ground (25, 26). The stride leg is defined as the leg that steps toward the target of second base (non-throwing arm side) (25, 26). During this phase the catcher generates energy that produces force in to the ground, propelling the stride leg toward the target (26).

The second phase of throwing, also known as the cocking phase, begins after stride leg foot contact and ends with maximal external rotation of the throwing shoulder

(26, 27). The third phase, known as the acceleration phase, begins after maximal external rotation is achieved and ends after the ball is released (25-27). The final stage of the throwing motion begins when the ball is released from the hand and ends when maximal internal rotation of the throwing shoulder is achieved (25-27).

The throwing motion of the catcher as described above follows the kinetic link theory, which states that force generated from the lower extremities must be correctly and efficiently transferred through the trunk to the upper extremities in order to produce

8 maximal velocity of the ball when throwing (34). Plummer et al. stated that the inability to produce force into the ground correctly at the beginning of the throwing motion would alter the energy transfer as it ascends up the kinetic chain to the hand (26). This can lead to making a bad throw and ultimately more stress on the smaller more distal segments of the body. Therefore, catchers should incorporate exercises that strengthen the entire lumbo-pelvic-hip complex into their training programs including but not limited to squats, bridges, and deadlifts (26).

CHAPTER 3

METHODS

Participants

Twenty-nine male baseball catchers (age: 21.5 ± 3.2 years, height: 1.8 ± .05 m, mass: 90.6 ± 12.6 kg) participated in this study. This number was based on previous literature that found significance among various dependent variables when analyzing

(range of subject numbers) catchers (10, 15, 24-27, 29, 38). Participants varied in levels of baseball played from high school to Major League Baseball (MLB) (as seen in Table

1). All participants were recruited from local baseball teams and organizations.

Inclusion requirements included male baseball catchers between the ages of 18-29 years old. Participants had at least 5 years of catching experience and must have partaken in competitive catching (high school, travel ball, college- NCAA

DI/DII/DII/NAIA/Junior College, or professional level- minor leagues, independent league, or MLB) within the past 6 months. They participated in lower body resistance training at least twice a week, and were comfortable with the squat exercise and one repetition maximum (1RM) testing. All participants were free from any lower body injuries within the past 6 months.

Table 1. Level of Baseball

Level of Baseball Number of Participants High School- Varsity 4 Junior College 14 NAIA 4 DI 1 DII 2 Independent League 2 Minor League Baseball (MiLB) 1 Major League Baseball (MLB) 1

Procedures

The study required one visit from each participant. Before the testing began, participants read and signed an IRB approved informed consent form and had their height and weight recorded. Pop up time testing began after the participants completed their own pre-competition warm-up (25-27, 34). Upon completion of the warm-up the participant then put on their full catcher’s gear consisting of a chest protector, shin guards, a mask, and a glove. Participants then had their pop up time recorded. Pop up time was determined as the time between the ball reaching a velocity of 2 m/s and lead foot contact on the force plate. The velocity of 2 m/s was defined in pilot testing as zero velocity of the ball. A true zero velocity of the ball was unobtainable, as the impact of the baseball into the catcher’s glove caused some movement. Foot contact was determined as the instant the ground reaction force (GRF) reached a threshold of 20 N. The participant received a pitched ball from a pitcher positioned 5.4 m away. The research team recognizes this is not equivalent to the distance between a pitcher’s mound and home plate (18.4 m). However, the physical limitations of the laboratory in which data

11 collection occurred did not allow for the true distance of 18.4 m. As soon as the ball was caught, the participant stood up as quickly as possible as if he were going to throw the ball to second base. The pitcher was instructed to locate the ball as close as possible to the middle of home plate at the catcher’s chest. If the ball was outside of home plate or outside of the catcher’s body (the catcher had to reach for the ball), the trial did not count and that trial was repeated. Participants had 10 warm up trials to familiarize themselves with the procedure. Then five testing trials were performed and all trials were used for data analysis. A regulation National Collegiate Athletic Association (NCAA) baseball wrapped in retro reflective tape was used for all trials.

The 1RM testing for the COHS was performed on the same day, after the pop up time testing and followed the protocol used by Suchomel et al (35, 36). Each participant performed warm up sets as follows: 5 reps at 30%, 5 reps at 50%, 3 reps at 70%, and 1 rep at 90% of their estimated 1RM COHS. The loads were based on previous findings that the 1RM of the COHS is 1.2 times that of the respective 1RM back squat (35). Two minutes of rest was given in between the 30 and 50% sets and four minutes of rest was given in between the 70 and 90% sets. After the last warm up set the participant performed maximal COHS attempts, with four minutes of rest in between each attempt.

The loads got progressively heavier until a failed attempt occurs or technique breaks down. The primary investigator determined the loads for the maximal attempts. A successful 1RM attempt was considered when the participant reaches a fully erect position with no excessive flexion or extension of the trunk, and the researcher did not observe any obvious frontal plane knee movement relative to the foot. All repetitions for the COHS were performed the barbell resting on the safety pins of the squat rack with the

12 participant starting with a knee angle of approximately 90°, or thighs parallel to the ground. A spotter was used for all 1RM attempts and verbal encouragement was given during all attempts. Any type of belt, knee wraps, weightlifting shoes or lifting straps were not allowed during the 1RM testing.

Instrumentation

Kinematic data were sampled at 240 Hz using a 9-camera Qualisys motion capture system (Gothenburg, Sweden). Kinetic data were sampled at 2400 Hz using an

AMTI force plate (Watertown, MA).

Data Analysis

Raw kinematic and kinetic data were exported to LabVIEW (National

Instruments, USA). A recursive, fourth order, low-pass Butterworth filter with a cut off frequency of 12 and 50 Hz was used to filter kinematic and kinetic data, respectively. A custom LabVIEW program was used to identify previously stated events as ball velocity and initial foot contact onto a force plate determine pop up time.

Statistical Analyses

Pearson correlation coefficients were calculated to determine the relationship between absolute (kg) and relative (kg/kg body mass) COHS strength and pop up time.

An alpha level of 0.05 was used to determine statistical significance.

CHAPTER 4

RESULTS

There was no significant correlation between the absolute COHS and pop up time

(r = -.339, p = .072). There was also no significant relationship found between the relative COHS and pop up time (r = -.332, p = .078).

Table 2. Correlation between Absolute and Relative COHS 1RM Values and Pop Up Time

Pop Up Time Sig. Absolute COHS 1RM -.339 .072 Relative COHS 1RM -.332 .078

Table 3. Means (SD) of Pop Up Times, Absolute COHS 1RM, and Relative COHS 1RM by Level of Baseball

Pop Up Absolute COHS Relative COHS 1RM Level of Baseball N Time 1RM (kg) (kg/kg bw) 0.60 High School 4 137.5 (42.42) 1.70 (0.54) (0.08) 0.56 College 21 146.32 (28.20) 1.62 (0.26) (0.09) 0.52 Independent Ball 2 160.23 (43.39) 1.73 (0.61) (0.02) 0.64 Milb/MLB 2 156.82 (3.21) 1.51 (0.09) (0.09) All Participants 0.57 29 146.79 (29.35) 1.63 (0.32) Combined (0.09)

Figure 3. Scatterplot of the correlation between the absolute COHS 1RM and pop up time. The relationship between the variables was not statistically significant (p = 0.072).

Figure 4. Scatterplot of the correlation between the relative COHS 1RM and pop up time. The relationship between the variables was not statistically significant (p = 0.078).

CHAPTER 5

DISCUSSION

To our knowledge, this is the first study to examine the relationship between a metric of lower body strength and any phase of the pop time in baseball catchers. The overall pop time (glove to glove) of a catcher is thought to be one of the catcher’s most important abilities when attempting to reach the next level of play (10, 15). Theoretically, the quicker and more accurately a catcher can deliver the ball to second base to throw out a base runner, the greater the chance his team has to win the game (15). However, few studies have been done on the position of catcher and none on the effects of strength training on any phase of the pop time (10, 15, 24-27, 29, 38). Our hypothesis was that greater COHS 1RM strength would have a significant negative correlation with pop up time. However, the findings of this study indicated there was not a significant correlation between absolute or relative COHS 1RM strength and pop up time in baseball catchers.

While no other studies have specifically examined the relationship between strength and pop up time in catchers, some studies have investigated the effects of different warm up protocols and strength training on bat velocity in baseball players (11,

22, 28, 39). For example, Reyes et al. reported a significant relationship between lower body strength (1RM back squat) and bat speed (r2 = 0.406, p = 0.008) (28). One possible reason for the discrepant findings between the present study and that of Reyes et al. is that the 1RM back squat may have an increased neural drive when compared to the 1RM

COHS due to the eccentric component of the exercise. This could have more of a carry over to a swing due to the ballistic nature of the swing and the strength required to overcome the force of the ball at the contact point. The baseball swing is generated from the ground up and as the batter transfers this force from the back leg to the front leg, ground reaction forces are as high 140% of the batters weight (13). This requires large amounts of strength to control these forces and efficiently transfer it to upper extremities, and it could require more strength than the pop up of a catcher. This may be one reason why the squat has a significant correlation with a swing rather than the pop up time. More research needs to be done to fully understand why 1RM strength correlates with bat speed but not pop up time.

Previous studies have been done showing the importance of strength on throwing velocity in baseball players (2, 5, 9, 17, 33, 34). For example, a study done by Escamilla et al. examined the effects of three baseball specific 6-week training programs on maximum throwing velocity. One group used dumbbells and elastic tubing and performed slower controlled movements; the second group used Keiser Pneumatic equipment, which kept the resistance constant throughout the whole range of motion; a third group performed plyometrics, using medicine balls or elastic tubing to perform explosive movements. This study showed that all three types of training were effective at increasing throwing velocity (9). The study had a subject pool of 68 subjects, and 58 were included for analysis. This is a significantly larger subject sample than the 29 subjects in the current study. This may at least partially explain why they found significance across all three training programs and the current study did not. Also, they required their subjects be to be untrained for at least three months prior to the study,

17 whereas in the current study the subjects were required to be performing resistance training at least two times per week. Future studies may also want to examine resistance training and playing experience as factors influencing various components of baseball performance.

A study done by Lehman et al. (14) investigated the correlation between lower body field tests, such as medicine ball scoop tosses, jump variations, and sprints, and throwing velocity in baseball players. Their study showed that the lateral to medial jump was correlated with high throwing velocities in both left-handed and right-handed throwers. It should also be noted, however, that they used fast and explosive movements and correlated with another fast and explosive movement, namely throwing velocity. In the current study we used a slow 1RM strength movement and correlated it to a fast and explosive pop up time. This may explain why they found a statistically significant correlation between their variables and while we did not.

McBride et al. (19) found that 1RM squat strength was significantly correlated with 40-yard and 10-yard sprint times in football players. A possible reason for the different results between their study and the present study is differences in the complexity of the skills that were measured. In a sprint the athlete knows where they are going and knows that they are sprinting a certain distance. When a catcher performs a throw to second base it requires a complex combination of kinetics and kinematics such as catching the ball, rising from the crouched position, staying out of the way of the batter, and delivering an accurate throw to second base in a short period of time. There are many more factors that go into performing the pop up than in a sprint.

The results of the present study agree with those of Fry et al. (11) who found that

1RM squat strength did not significantly correlate with batted ball velocity. They found that batted ball velocity was significantly correlated with grip strength (r = 0.37) and incline bench press (r = 0.40). Squat strength was not significantly correlated with batted ball velocity, but was correlated with upper body strength (r = 0.55). These results suggest the importance of total body strength in batting performance. Another study found that heavy squats had no correlation with vertical jump height (18). The results of these studies, as well as the present study, suggest that 1RM strength does not always correlate with performance in a dynamic skill such as swinging a bat, performing a vertical jump, or throwing a runner out at second base. For example, rate of force development (RFD) was found by McLellan et al. to be the primary determinant of vertical jump height (21). This may mean that RFD is more important and may have more of an effect when assessing a dynamic skill such as a vertical jump or in the case of this study, pop up time.

The specific strength test (COHS) that was used in this study may also have had an effect on the results. Since the 1RM is measuring maximum strength at a slow velocity, it may not be the best exercise to use as a measure of strength or power performance when assessing catchers and pop time. An exercise with a higher velocity, such as a power clean, may be a better choice. For example the power clean and the squat were both shown to improve vertical jump performance, but the power clean showed a

56% greater improvement than the squat (3). There was also a stronger correlation between the power clean and vertical jump (r = 0.88) than between the squat and vertical jump (r = 0.42).

Another factor that may have affected the results of the present study is the homogeneity and sample size of participants. All of the participants were elite level players and had ample experience as a catcher (minimum of 5 years), and included major league, minor league, and college level players. This may have made it difficult to find statistical significance, as all of the participants were highly skilled with extensive playing experience. Also, with only 29 subjects in a very homogenous subject pool, significance was hard to find (23).

The lab environment did not allow for the full 60 feet 6 inches to throw the ball, which could have affected the catchers timing and therefore the results of the study.

Furthermore, the participants in the present study were instructed to wear shoes that they would go to the gym in because the lab did not allow for metal cleats to be worn. This also could have affected the results of the study due to the fact that this is not standard equipment that they would perform the skill in during a game. They would normally be in a type of cleat on turf or dirt. In a study by Silva et al. (31) that examined the interaction between the cleat and the surface in soccer players found that the footwear had an effect on their performance. Depending on the shoe that was worn and the surface that it was interacting with, the performance of the athlete either improved or decreased.

Future studies are needed to investigate the relationship between strength and pop time in catchers. For example, studies can examine the relationship between an explosive exercise such as the power clean, snatch, kettle bell swing, etc. and pop up time in catchers. As well as investigate the relationship between the whole pop time, including the throw, instead of just one phase of it as the present study did. Also, future studies should aim to have more subjects than the current study. They should also try and

20 perform the testing in their normal environment such as the baseball field such that the environment does not play a role in the study. Other variables should also be observed such as RFD, time to peak force, peak force, bar speed, etc. Another variable to examine would be EMG activity during the pop time to find out what muscles are activated and the timing of their activation. This could help us to choose the best exercises to develop sport-specific strength and power in catchers.

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