Effect of Wrist and Forearm Training on Linear

Journal of Strength and Conditioning Research, 2006, 20(1), 231–240 q 2006 National Strength & Conditioning Association

EFFECT OF WRIST AND FOREARM TRAINING ON LINEAR BAT-END, CENTER OF PERCUSSION, AND HAND VELOCITIES AND ON TIME TO BALL CONTACT OF HIGH SCHOOL BASEBALL PLAYERS DAVID J. SZYMANSKI,1 JOSEPH S. MCINTYRE,2 JESSICA M. SZYMANSKI,1 JOSEPH M. MOLLOY,1 NELS H. MADSEN,2 AND DAVID D. PASCOE1 Departments of Health and Human Performance and 2Mechanical Engineering, Auburn University, Auburn, Alabama 36849.

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ABSTRACT. Szymanski, D.J., J.S. McIntyre, J.M. Szymanski, J.M. Molloy, N. H. Madsen, and D.D. Pascoe. Effect of wrist and forearm training on linear bat-end, center of percussion, and hand velocities and on time to ball contact of high school baseball players. J. Strength Cond. Res. 20(1):231–240. 2006.—This study examined the effects of 12 weeks of wrist and forearm training on linear bat-end velocity (BV), center of percussion velocity (CV), hand velocity (HV), and time to ball contact of high school baseball players. Forty-three baseball players were randomly assigned by a stratified sampling technique to 1 of 2 training groups. Group 1 (n 5 23) and group 2 (n 5 20) performed the same full-body resistance exercises while training 3 days a week for 12 weeks according to a stepwise periodized model.

Group 2 also performed wrist and forearm exercises 3 days a week for 12 weeks. Wrist and forearm strength were measured pre- and posttraining. Linear BV, CV, HV, and time to ball contact were recorded pre- and posttraining by a motion-capture system. A 3 repetition maximum (RM) parallel squat and bench press were measured at baseline and after 4, 8, and 12 weeks of training. Both groups showed statistically significant increases (p # 0.01) in linear BV, CV, and HV (m·s21 6 SD) after 12 weeks of training; however, there were no differences between the 2 groups. Both groups statistically increased wrist and forearm strength (p # 0.05). Group 2 had statistically greater increases (p # 0.05) in 10 of 12 wrist and forearm strength measures than did group 1. Both groups made statistically significant increases in predicted 1RM parallel squat and bench press after 4, 8, and 12 weeks of training; however, there were no differences between groups. These data indicate that a 12-week stepwise periodized training program can significantly increase wrist and forearm strength, linear BV, CV, and HV among high school baseball players. However, increased wrist and forearm strength did not contribute to further increases in linear BV, CV, or HV. KEY WORDS. bat speed, grip strength, strength, resistance training

INTRODUCTION at swing velocity significantly contributes to the characteristics of a good hitter (1). Most baseball coaches and hitting instructors believe that hitting a baseball with increased bat swing velocity requires strong forearms, wrists, and hands. It can be difficult and sometimes confusing for coaches to select a conditioning program that will maximize their players’ ability to hit a baseball. Enhancing a player’s ability to hit requires not only the development of good eye-hand coordination and sound hit-

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ting mechanics (1, 6, 17, 27) but also the integration of strength training and sport-specific resistance training in a comprehensive periodized program. According to Stone et al. (22), periodization can be described as a progressive method of controlling training variables, such as volume and intensity, to increase the possibility of enhancing specific performance goals.

Researchers have indicated that resistance training can increase bat swing velocity. Schwendel and Thorland (18) concluded that, among men, power resistance training for 7 weeks was more effective than traditional resistance training in increasing bat velocity. Furthermore, Gilligan (12) indicated that resistance training per se did not improve bat velocity, but the combination of resistance training and swinging a heavy bat improved bat swing velocity. DeRenne and Okasaki (8) showed that bat swing velocity could be increased by using a commercial Power Swing (air-resistance device) or a special heavy weighted bat (34 oz). Sergo and Boatwright (19) reported that swinging a bat of any weight 100 times per day, 3 days per week, for 6 weeks would significantly improve bat velocity. DeRenne et al. (7) concluded that bat swing velocity could be increased by swinging heavy-weight (31–34 oz), light-weight (27–29 oz), and standard-weight (30 oz) baseball bats in a periodized sequence for 12 weeks. Szymanski et al. (23) found no significant differences in bat velocity after female collegiate softball players swung balanced or unbalanced weighted softball bats for 4 weeks. Most recently, Hughes et al. (13) demonstrated that 6 weeks of additional forearm and grip strength training did not contribute to further improvements in instantaneous bat velocity.

Even though researchers have reported different ways to improve bat velocity, many baseball coaches are reluctant to implement these different forms of training into their team’s training because they may be unaware of the information, are skeptical that the program will not yield the claimed results, or may not want to change the way they are training their players. Because implementing additional wrist and forearm exercises into an existing strength program would be relatively easy, the purpose of this study was to evaluate the effect of wrist and forearm training on linear bat-end velocity (BV), center of percussion velocity (CV), hand velocity (HV), and time to ball contact of high school baseball players.

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METHODS

TABLE 1. Mean (6SD) baseline descriptive data for groups.

Experimental Approach to the Problem

Many baseball coaches believe that strong forearms, wrists, and hands are important to bat swing velocity. As a researcher and strength coach, the lead author has had many conversations with baseball and strength coaches addressing this topic. However, not much research exists, and much of the information regarding wrist and forearm training is anecdotal.

The purpose of the present study was to examine 3 major questions: Would performing additional wrist and forearm exercises contribute to significantly greater increases in linear BV, CV, and HV during a 12-week period? Furthermore, would 12 weeks of additional wrist and forearm exercises significantly contribute to a decrease in time to ball contact? Finally, is there a relationship between improvements in strength (bench press, parallel squat, wrist, forearm, and grip) and improvements in linear BV, CV, HV, and time to ball contact?

For 2 years before this study, the lead author had used the 6 wrist and forearm measures without injury with reproducible test results with the university baseball team he previously trained. Furthermore, all players in this study were shown and verbally told how to properly perform each exercise during the initial meeting before the study began. During the familiarization session and the pre- and posttraining testing sessions and throughout the 12-week study, players were continually told and observed by the lead author and his assistants to perform the exercises properly according to the guidelines described in this study.

Previous research has used photosensing computerized timers (7, 8, 19), a Quick Bat (18), or SETPRO Rookie (13) to measure bat velocity. For the photosensing computerized timers, only the portion of the bat that passes through the timer’s 2 light beams (most likely the bat’s center of percussion) can be recorded. Thus, the same location on the bat cannot possibly be recorded for every swing for every participant. This means the recorded bat velocities could be from different locations on the bat, which may produce slight variations in the bat velocities.

When a participant swings the test bat past the detection zone of the Quick Bat housing unit, the 2 detectors sense light bouncing off of the reflective pad placed on the end of the bat. By measuring the time to travel from one detector to the next, the Quick Bat housing unit provides a reading of the bat swing velocity. Depending upon how far apart the 2 detectors are between the detection zone of the housing unit of the Quick Bat speed meter and the space over home plate for the electronic timing device, velocities may not be accurately recorded. Also, bat swing velocities could be under- or overestimated because the Quick Bat used by Schwendel and Thorland (18), was calibrated at a speed of only 30 mph (48.3 km·h21). This was much slower than the reported 90–100 mph (40.2–44.7 m·s21) bat swing velocities. The SETPRO Rookie has 2 sensors placed 4 in. apart that detect a reflector placed on the end of each participant’s bat. When the bat is swung in front of the sensors, bat velocity is recorded.

According to Hughes et al (13), the SETPRO Rookie was calibrated by the manufacturer; however, the authors did not test the unit for reliability. To control for these variations and provide greater reliability of data, a motioncapture system was used for this study. This system al-

Group 1 (n 5 23) Group 2 (n 5 20)

Age (yr)

Height (cm)

Weight (kg)

Body fat (%)

15.3 (1.2)

176.6 (7.8)

72.3 (13.4)

10.5 (5.6)

15.4 (1.1)

179.0 (5.0)

72.1 (7.9)

10.1 (5.0)

lows any location on the bat to be recorded and measured at any point in time of the swing. Furthermore, the same location on the bat can be evaluated for every swing and for every participant. In addition to linear BV, linear CV was measured and calculated and compared with the velocity results of other studies that used the photosensing computerized timer.

Subjects

Forty-six male high school baseball players between the ages of 14 and 18 years volunteered for this study. All volunteers and parents completed a written informed consent in accordance with University’s Institutional Review Board’s guidelines before the volunteers were allowed to participate in this study.

Players answered a modified Physical Activity Readiness Questionnaire (PAR-Q), which the lead author immediately evaluated to exclude those who might be at risk of injury. The PAR-Q consisted of questions addressing potential cardiovascular, muscular, bone, joint, and medication concerns. If a contraindication for participating in an exercise program was noted, the player was not allowed to participate. Players also completed a Descriptive Data Questionnaire, which described their playing and exercising experiences. Three players did not complete the study for reasons unrelated to the project.

Players were separated by academic grades (freshman, sophomore, junior, and senior) and body-mass categories (45.4–58.6 kg, 59.1–72.3 kg, 72.7–85.9 kg, 86.41 kg), which were modified from boys’ wrestling weight classifications used by the Alabama High School Athletic Association (3), and then randomly assigned to 1 of 2 training groups by a stratified sampling technique to control for selection bias to internal validity. Group 1 (n 5 23) and group 2 (n 5 20) both performed a stepwise periodized full-body resistance-exercise program 3 days a week for 12 weeks. Group 2 performed additional wrist and forearm exercises 3 days a week for 12 weeks. The players had to attend 90% (n 5 33) of the total 36 exercise sessions to be included in the study. Players could not miss on subsequent days or they would be dropped from the study. Players’ descriptive data are listed in Table 1.

Familiarization Sessions

During the first week of the study, before assessment of 3 repetition maximum (RM) parallel squat and bench press, players underwent 2 low-resistance (5 3 5RM) strength-training sessions. The lead author conducted these sessions to familiarize the players with the exercises and to have them practice proper lifting and spotting techniques. Players were constantly supervised and verbally reminded about these techniques on a daily basis.

Procedures

Pre- and posttesting for height, body mass, body composition, linear BV, CV, HV, time to ball contact, muscular

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TABLE 2. Training protocols.* Weeks 5–8

Weeks 1–4 Sets Groups 1 and 2 Core Assistance Group 2 Forearm†

Sets

Weeks 9–12

Reps

% 1RM

2 WU 3

10 10

45, 50 65, 70, 75

3

10

3

8

3

6

2

12

2

10

2

8

2 WU 3

Reps

% 1RM

10 8

45, 50 70, 75, 80

Sets 2 WU 3

Reps

% 1RM

10 6

45, 50 75, 80, 85

* Adapted with modifications from Baker et al. (5) and Stone et al. (22). Reps 5 repetitions; RM 5 repetition maximum; WU 5 warm-up. Groups 1 and 2 trained with predicted 1RM values based on load assessments by Wathen (26). Rest time between all sets 5 90 seconds. † Resistance was heavy enough so that the last 2 repetitions of each set were difficult.

strength, and grip strength were conducted on 1 day. The sequence of tests, protocols, and rest periods for the posttest was consistent with that of the pretest. For control of outside influences, all players were instructed to consume a normal diet and abstain from additional resistance training and from taking ergogenic aids (e.g., creatine, amino acids) during the testing period. Players recorded pre- and posttesting food and drink consumption the day before and the day of strength testing in a diet log to ensure that their normal diet was maintained.

Training Protocols

Training for both groups was performed 3 days a week for 12 weeks according to a stepwise periodized model similar to previous research (5, 21, 22, 24). Training loads for the core strength exercises (parallel squat and bench press) were preceded by 2 warm-up sets of 10 repetitions to prepare the players for the more demanding 3 working sets. Set workloads were progressively increased every 4 weeks during the study after having 3RM parallel squat and bench press reassessed. Additionally, various assistance exercises (stiff-leg deadlift, bent-over rows, shoulder press, biceps curls, and triceps extensions) were performed to make the training more comprehensive and realistic to the off-season training programs of high school baseball players. Furthermore, players in group 2 performed additional wrist and forearm exercises 3 days a week for 12 weeks. Details of the training protocols and schedule of exercises are found in Tables 2 and 3.

Linear Velocities and Time to Ball Contact

Players reported to the motion-capture laboratory twice to record bat swing velocities. The first visit was used to determine players’ pretraining linear BV. The mean velocity of 6 recorded swings represented the pre- and posttraining linear BV, CV, and HV for each player. Linear BV was defined as the maximum BV of the test bat immediately before ball contact. Linear CV was defined as the maximum sweet spot of the bat velocity, 4 in. from the bat end. Linear HV was defined as the maximum mean hand-position velocity recorded during the swing.

Time to ball contact was defined as the distinct change of the bat’s path, known as the slope of the swing, in the opposite direction to ball contact.

The lead author demonstrated proper bat swing technique and verbally explained the bat swing warm-up protocol. Each hitter performed stretches of his choice for 5 minutes outside the laboratory. After stretching, each hit-

TABLE 3. Schedule of exercises.

Exercise Groups 1 and 2 Parallel squats* Stiff-leg deadlift† Barbell bench press* Bent-over row† Barbell shoulder press† Lying triceps extension† Barbell biceps curl† Group 2 Straight-bar wrist curls‡ Straight-bar reverse wrist curls‡ Standing plate squeeze‡ Standing radial deviation‡ Standing ulnar deviation‡ Seated pronation/supination‡

Tuesday Thursday

Sunday

X X X X X X X

X X X X X

X X X X X X X

X

X

X

X X X X X

X X X X X

X X X X X

* Core exercise. † Assistance exercise. ‡ Forearm exercise.

ter took 2 sets of 10 warm-up swings with a baseball bat of his choice (33 in. 30 oz or 32 in. 29 oz) before going into the laboratory. The height of the batting tee was adjusted to the height of the hitter’s pubic arch, which represented the location of a pitched baseball in the center of each hitter’s strike zone.

At the batting-tee station, each hitter performed 4 practice swings and 6 recorded swings with a modified test bat of the same weight and length as the warm-up bat he used outside the laboratory. The lead author held a 182.9-cm pole with a reflective marker on the end, which was placed on top of the foam ball resting on the batting tee so the computer could identify the ball’s location (x, y, and z coordinates) in 3-dimensional (3D) space. This allowed the lead author to identify the frame (point in space) just before the hitter made contact with the ball. When the lead author’s assistant gave the command ‘‘Ready, Set, Go!’’ the lead author removed the pole with the reflective marker and the hitter swung the modified test bat. After he hit the foam ball off the tee into the catch net, the hitter had 20 seconds of rest before taking the next swing.

Instrumentation

Nuance Motion Capture software (Biomechanics Systems Inc., Atlanta, GA) was used to record and measure linear

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BV, CV, and HV in the motion-capture laboratory. The motion-capture system (Biomechanics Systems Inc.) was designed and constructed to provide a convenient, flexible, accurate, and noninvasive means of assessing human and animal movement. The system includes 4 shuttered, synchronized 60-Hz video cameras. A spotlight was mounted on each camera and directed along the camera axis. Reflective markers (3M Corp., Minneapolis, MN) on each player’s bat produced ‘‘bright spots’’ in the video images. The video images were digitally processed. A thresholding system was used to identify the location and number of bright spots (markers) in each image. By correlating the camera image and exploiting previous fields, the bright spots were associated with particular markers (tracking of markers). The location of these markers in 3D space was determined according to the camera positions and orientations. Each player’s position and configuration was then determined by an optimization approach that exploited these 3D locations, knowledge of how the markers were attached to the player’s bat, and knowledge about the possible movements of the player. A scaled 3D computer-graphics model of each player’s test bat was then displayed and manipulated according to the player’s bat position and configuration.

The motion-capture system’s reliability was validated in several ways. The accuracy of the location measurement for the 2 markers was checked by physically measuring the distance between them and comparing that with the motion-capture system distance computations for the same markers. The lead author also watched each swing. The computer animations were then checked for variances from the observed swing path.

The system was calibrated by determining the accuracy with which 3D marker locations in space can be determined to a fixed global coordinate system. For example, if the position and orientation of the bat (system variables) were known and the location of the markers on the bat (local coordinate) were given, the motion-capture system would be able to evaluate the location of the markers relative to the global system (predicted position).

Thus, the system variables were determined as those values that minimize the sum, over all the markers, of the squared distances between the global position of the marker and its predicted position (based upon system variables and local coordinates). Because these system variables so determined depend upon all the marker coordinates, their sensitivity to errors in any single marker coordinate was reduced (14). Also, the optimization approach provided a system accuracy measure that reflected the overall performance of the system. Therefore, recorded linear velocities and the measurement of time (time to ball contact) were determined to be sufficiently accurate.

After 12 weeks of training, players were retested by the same protocol and rest periods as the pretest. This visit allowed the lead author to determine if linear BV, CV, HV, or time to ball contact improved after 12 weeks of stepwise periodized resistance training.

Dynamic Wrist and Forearm Strength

Wrist Barbell Flexion. Each player sat on a flat bench with his forearms supinated slightly less than shoulder width apart resting on the flat bench. A neoprene wrap was secured together around the cubital fossa (upper part of the anterior forearms just below the elbow joint) and flat

bench so that his arms were isolated and he could use only the flexor carpi radialis, flexor carpi ulnaris, and palmaris longus.

Next, a goniometer was lined up with the midline of the radius and the extended first metacarpal of the flexed wrist to record each player’s full, flexed position. Then, players were instructed to follow the same procedures used to perform the 10RM wrist barbell flexion test found in Szymanski et al. (24).

Wrist Barbell Extension. Each player sat on flat bench with his forearms pronated slightly less than shoulder width apart resting on the flat bench. A neoprene wrap was secured together around the brachioradialis (upper part of the posterior forearms just below the elbow joint) and flat bench so that his arms were isolated and he could use only the extensor carpi radialis longus, extensor carpi radialis brevis, and extensor carpi ulnaris.

Next, a goniometer was lined up with the midline of the ulna and the extended fifth metacarpal of the extended wrist to record each player’s full, extended position.

Then, players were instructed to follow the same procedures used to perform the 10RM wrist flexion test found in Szymanski et al. (24).

Forearm Supination. Each player’s dominant hand was measured first. The player’s arm and shoulder were placed in the neoprene sleeve and tightly secured to his torso. With the player’s shoulder adducted and neutrally rotated, elbow flexed at 908, the assistant wrapped and secured a neoprene band around the upper arm and opposite side of the upper torso so that the player’s arm was held tightly to his side. This isolated the use of the supinators (biceps brachii and supinator) and brachioradialis. The player then sat in a standard chair (46 cm high) with his right elbow resting on a table, forearm in neutral position (08), and the wrist between 0 and 158 of ulnar deviation.

A goniometer was lined up with the vertical line (08) formed by the extended fingertips and the horizontal line (80–1008) formed by the extended fingertips after pronating the wrist through a full range of motion (ROM). Then each player was instructed to hold an Olympic plate-loaded dumbbell vertically (08) by the handle in his hand. The vertical line formed by the second flexed knuckles (second proximal interphalangeal joints) surrounding the dumbbell was at 08. After pronating to the player’s full ROM (80–1008), the player supinated the dumbbell to the starting neutral (08) position for the repetition to be successfully recorded. For a complete description of 10RM forearm supination test procedures, see Szymanski et al. (24).

Forearm Pronation. Each player’s dominant hand was measured first. The player’s arm and shoulder were secured by the same procedure as for forearm supination.

His shoulder and elbow position were also the same as the forearm supination. This isolated the use of the pronators (pronator teres and pronator quadratus) and flexor carpi radialis. The player sat in a standard chair (46 cm high) with his shoulder adducted and neutrally rotated, elbow flexed at 908 and resting on a table, forearm in neutral position (08), and wrist between 0 and 158 of ulnar deviation.

A goniometer was lined up with the vertical line (08) formed by the extended fingertips and the horizontal line (80–1008) formed by the extended fingertips after supinating the wrist through a full ROM. Then each player held an Olympic plate-loaded dumbbell vertically (08) by

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the handle in his hand. The vertical line formed by the second flexed knuckles (second proximal interphalangeal joints) surrounding the dumbbell was at 08. After supinating to the player’s full ROM (80–1008), the player pronated the dumbbell to the starting neutral (08) position for the repetition to be recorded. Players followed the same procedures as the forearm supination 10RM test found in Szymanski et al. (24).

Wrist Radial Deviation. Each player’s dominant hand was tested first. The player’s arm and shoulder were placed in the neoprene sleeve and tightly secured to his torso with his shoulder adducted, wrist medially rotated, and elbow fully extended at 1808. Next, the first of 2 neoprene bands was wrapped and secured around the upper arm and opposite side of the upper torso. The other was wrapped and secured around the lower arm (just below the elbow) and opposite side of the hip so that the player’s entire arm was held tightly to his side. This isolated the use of the flexor carpi radialis, extensor carpi radialis longus, and extensor carpi radialis brevis.

To measure each player’s full ROM, a goniometer was lined up over the ulnar styloid process (blunt, bony end of the lateral wrist) parallel to the third extended metacarpal (08) and the angle (40–608) formed by the player’s radial deviated wrist at the third extended metacarpal.

The player held an Olympic plate-loaded dumbbell below the bottom collar in his hand with the dumbbell pointing in front of him. Then the goniometer was lined up over the ulnar styloid process and the parallel third knuckle (interphalangeal joint) of the third metacarpal surrounding the dumbbell (08). The player was instructed to raise (radial deviate) the dumbbell to the previously recorded angle formed without the dumbbell for the repetition to be recorded. Players followed the same procedures as the forearm supination 10RM test found in Szymanski et al.

(24).

Wrist Ulnar Deviation. Each player’s dominant hand was measured first. The same procedures for securing the player’s arm used for wrist radial deviation were followed.

When players performed the ulnar deviation, these procedures isolated the use of the flexor carpi radialis, extensor carpi radialis longus, and extensor carpi radialis brevis.

To measure each player’s full ROM, a goniometer was lined up over the radial styloid process (blunt, bony end of the medial wrist) parallel to the third extended metacarpal (08) and the angle (20–408) formed by the player’s ulnar deviated wrist at the third extended metacarpal.

The player held an Olympic plate-loaded dumbbell above the bottom collar in his hand with the dumbbell pointing behind him. Then the goniometer was lined up over the radial styloid process and the parallel third knuckle (interphalangeal joint) of the third metacarpal surrounding the dumbbell (08). The player was instructed to raise (ulnar deviate) the dumbbell to the previously recorded angle formed without the dumbbell for the repetition to be recorded. Players followed the same procedures as the forearm supination 10RM test found in Szymanski et al.

(24).

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HIGH SCHOOL BASEBALL PLAYERS 235

most accurate measure of grip strength (15). Grip strength was assessed at baseline and after 12 weeks of training. For a complete description of the grip strength test, see Szymanski et al. (24).

Parallel Squat and Bench Press Strength

According to Baechle et al. (4), many of the players in this study were classified as a beginner or intermediate lifter (,1 year of resistance-training experience). Because of this training status, an estimation of 1RM (the most weight lifted 1 time) was determined by performing 3RM tests (the most weight lifted 3 times) on the parallel squat and bench press with Olympic standard free weights because this procedure is safer (25). Furthermore, 3RM tests were used because the players may not have been accustomed to handling heavy loads and may have had a fear of failing or getting injured (16). For a complete description of the predicted 1RM parallel squat and bench press strength tests, see Szymanski et al. (24). Training protocols and schedule of exercises are displayed in Tables 2 and 3. The lead author used a Weight Training Percentages Table (25) to determine the appropriate resistance (%) of the predicted 1RM for parallel squat and bench press during each training session.

Statistical Analyses

SPSS version 10.0 (SPSS Inc., Chicago, IL) was used for the statistical analyses. Independent-sample t-tests were conducted before the 12-week study to determine if any statistically significant differences existed between the 2 groups. To determine if any statistical differences existed between or within groups, repeated-measure (group 3 trials) analyses of variance were conducted on all variables.

A Pearson product moment correlation test was conducted to examine the relationship between improvements of research variables (wrist and forearm strength, grip strength, and parallel squat and bench press strength) and improvements of linear BV, CV, and HV. For all analyses, significance was set at an alpha level of p # 0.05.

All data are presented as group means 6 SD.

RESULTS Linear Velocities

Independent-sample t-tests demonstrated no statistically significant differences between the 2 groups for linear BV, CV, and HV before the study. Pre- and posttest means for linear BV, CV, and HV for groups 1 and 2 are presented in Table 4. Both groups made statistically significant (p # 0.01) increases in linear BV, CV, and HV after 12 weeks of training; however, there were no statistically significant differences between groups.

Time to Ball Contact

An independent-sample t-test indicated no statistically significant differences between the 2 groups for time to ball contact before the study. There were no statistically significant differences for either group for time to ball contact after 12 weeks of training.

Grip Strength

Dynamic Wrist and Forearm Strength

A Jamar Hydraulic Hand Dynamometer (Sammons Preston, Bolingbrook, IL) set at the second handle position for all players was used to assess grip strength for both hands (dominant and nondominant) because it is the

Independent-sample t-tests revealed no statistically significant differences between the 2 groups for any of the wrist and forearm variables (10RM wrist flexion, 10RM wrist extension, 10RM dominant and nondominant pro-

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TABLE 4. Mean (6SD) linear bat-end, center of percussion, and hand velocities for pre- and posttest and percent (%) change.* Pretest Variable

Posttest

(m · s )

(mph)

(m · s )

(mph)

% Change

BV Group 1 Group 2

29.2 (2.2) 30.4 (2.3)

65.4 (12.0) 68.0 (8.1)

30.3 (2.1) 31.4 (2.3)

67.7 (9.4) 70.3 (5.1)

3.5%† 3.2%†

CV Group 1 Group 2

24.5 (1.9) 25.4 (1.9)

54.8 (10.1) 56.9 (6.8)

25.6 (2.1) 26.3 (2.0)

57.3 (6.8) 58.9 (4.5)

4.3%† 3.4%†

HV Group 1 Group 2

8.8 (0.7) 9.2 (0.8)

19.6 (3.7) 20.7 (2.6)

9.2 (0.8) 9.9 (0.7)

20.6 (2.5) 22.1 (1.6)

4.9%† 6.3%†

1

1

* BV 5 linear bat-end velocity; CV 5 center of percussion velocity; HV 5 hand velocity. † Significant difference within groups at p , 0.01. There was not a statistical difference between groups.

FIGURE 1. For wrist barbell flexion, there was a significant difference (*) within groups (p # 0.01) and (1) between groups (p # 0.05). Group 2 made statistically greater improvements than did group 1.

FIGURE 2. For wrist barbell extensions, there was a significant difference (*) within groups (p # 0.01) and (1) between groups (p # 0.05). Group 2 made statistically greater improvements than did group 1.

nation, 10RM dominant and nondominant supination, 10RM dominant and nondominant radial deviation, and 10RM dominant and nondominant ulnar deviation) before the study. Pre- and posttreatment means for all wrist and forearm strength measures for both groups can be found in Figures 1–6. Both groups showed statistically significant increases in all wrist and forearm measurements except 10RM dominant and nondominant supination for group 1. A statistically significant (p # 0.05) interaction effect between groups was observed. Group 2 had statistically greater improvements in all wrist and forearm variables than did group 1 after 12 weeks of training.

FIGURE 3. For dumbbell forearm pronation, there was a significant difference (*) within groups (p # 0.01) and (1) between groups (p # 0.05). Group 2 made statistically greater improvements than did group 1. G1 5 group 1; G2 5 group 2; Dom 5 dominant hand; N. Dom 5 nondominant hand.

FIGURE 4. For dumbbell forearm supination, there was a significant difference (*) within groups (p # 0.05) and (1) between groups (p # 0.05) only for group 2. Group 2 made statistically greater improvements than did group 1. G1 5 group 1; G2 5 group 2; Dom 5 dominant hand; N. Dom 5 nondominant hand.

Grip Strength

An independent-sample t-test indicated no statistically significant differences between the 2 groups for dominant and nondominant hand grip strength before the study.

Both groups showed statistically significant (p # 0.05) increases in dominant and nondominant hand grip strength after 12 weeks of training; however, there were no statistical differences between groups for dominant and nondominant hand grip strength.

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TABLE 5. Mean (6SD) predicted 1RM PS and BP at baseline, and after 4, 8, and 12 weeks of training and percent (%) change.* Variable PS, kg Group 1 Group 2

Baseline

FIGURE 5. For dumbbell wrist radial deviation, there was a significant difference (*) within groups (p # 0.01) and (1) between groups (p # 0.05). Group 2 made statistically greater improvements than did group 1. G1 5 group 1; G2 5 group 2; Dom 5 dominant hand; N. Dom 5 nondominant hand.

FIGURE 6. For dumbbell wrist ulnar deviation, there was a significant difference (*) within groups (p # 0.01) and (1) between groups (p # 0.05). Group 2 made statistically greater improvements than did group 1. G1 5 group 1; G2 5 group 2; Dom 5 dominant hand; N. Dom 5 nondominant hand.

Parallel Squat and Bench Press Strength

Independent-sample t-tests indicated no statistically significant differences between the 2 groups for predicted 1RM parallel squat and bench press before the study.

Pretreatment means for predicted 1RM parallel squat and bench press for groups 1 and 2 are presented under ‘‘Baseline’’ in Table 5.

Mean and percent change after 4, 8, and 12 weeks of training for predicted 1RM parallel squat and bench press for groups 1 and 2 are presented in Table 5. Both groups made statistically significant (p # 0.05) increases in parallel squat and bench press strength after 4, 8, and 12 weeks of training; however, there were no statistically significant differences between groups on any of these testing days.

DISCUSSION Our findings suggest that 12 weeks of wrist and forearm training completed in addition to performing a stepwise periodized resistance-training program does not significantly contribute to further improvements in linear BV, CV, or HV. However, groups 1 and 2 both experienced statistically increased (p # 0.01) linear BV (3.5 and 3.2%), CV (4.4 and 3.4%), and HV (4.9 and 6.3%) after performing our 12-week stepwise periodized resistance-training program. Because no additional resistance training or bat swings were allowed during the 12-week training pro-

% Change Group 1 Group 2

8 wk

12 wk

97.5 (19.3) 117.8 (24.2) 133.4 (24.1) 147.1 (24.9) 99.4 (25.5) 114.6 (24.7) 131.6 (24.7) 143.5 (25.8)

% Change Group 1 Group 2 BP, kg Group 1 Group 2

4 wk

71.8 (16.3) 72.9 (15.4)

17.2%† 13.2%†

26.9%‡ 24.5%‡

33.7%§ 30.7%§

78.2 (15.3) 79.8 (16.8)

83.7 (15.3) 83.9 (15.9)

86.9 (15.4) 86.8 (14.2)

14.2%‡ 13.5%‡

17.4%§ 15.9%§

8.2%† 8.7%†

* RM 5 repetition maximum; PS 5 parallel squat; BP 5 bench press. † Significant difference within groups after 4 weeks of training at p , 0.05. ‡ Significant difference within groups after 8 weeks of training at p , 0.05. § Significant difference within groups after 12 weeks of training at p , 0.05.

gram, the improvements to linear BV, CV, and HV can be attributed to the stepwise periodized resistance-training program. This would suggest that such a program alone is a sound approach to statistically increase linear BV, CV, and HV in high school baseball players.

Our results are supported by Hughes et al. (13), who examined the effect of grip strength and grip-strengthening exercises on instantaneous bat velocity. Two groups of collegiate baseball players participated in their normal baseball practice and strength and conditioning sessions for 6 weeks. Resistance training occurred 3 times per week for 6 weeks for both groups, whereas 1 group performed additional grip- and forearm-strengthening exercises. Results revealed no significant difference between posttest bat velocities for either group. Additionally, there was no significant relationship between grip strength and bat velocity. As with our results, Hughes et al. (13) indicated that performing additional grip and forearm exercises did not contribute to any greater increases in bat swing velocity. Their results suggest that adding gripand forearm-strengthening exercises to increase bat swing velocity is not necessary.

Our results are similar to those found in Schwendel and Thorland (18), who worked with male and female college students who were not skilled baseball or softball players. Even though both male groups (traditional and power resistance training) in their study made significant improvements in bench press (14.5 and 14.7%) and leg press (15.8 and 29.1%) strength, only the male power resistance-training group significantly improved bat velocity (7.9%). The male traditional resistance-training group, who performed 3 sets of 10 repetitions for each exercise for the entire 7-week study, did not make significant improvements in bat velocity. They were instructed to perform the eccentric phase of each repetition with a 4-second count. The male power resistance-training group was instructed to train initially with 80% of 1RM for each exercise and to perform 3 sets of 5, 3, and 1 repetitions during the 4 phases of the training program. Additionally,

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they were instructed to perform both the concentric and the eccentric phases of each repetition within 1 second.

The amount of improvements in leg strength in both studies may be a reason for the improved bat velocity. The greater leg strength improvement made by the male power resistance-training group (29.1%) was very similar to the results of groups 1 and 2 in the current study (33.7 and 30.7%). Strength and power development are interrelated. An increase in power results from either an increase in strength, an increase in speed, or both. Therefore, an increase in strength, measured via predicted 1RM parallel squat or leg press, could result in an increased power output (i.e., bat velocity) as long as speed is maintained.

The results of the current study are in agreement with unpublished data by Adams (2), who evaluated the relationship of leg strength to baseball bat velocity of male collegiate baseball players. He found a positive correlation between total leg strength, measured by a back- and leg-lift dynamometer, and bat velocity (r 5 0.313) and between dual knee extension, measured with a Pacific scientific cable tensiometer, and bat velocity (r 5 0.306).

Furthermore, French (10) evaluated the relationship among trunk rotation strength, leg strength, and the bat velocity of 30 male collegiate freshman baseball players.

He noted a positive correlation (r 5 0.418) between leg strength and bat velocity and recommended that coaches should implement leg strength training into a player’s program to increase bat velocity. There was a positive correlation between parallel squat strength and linear BV for group 1 (r 5 0.431) at the p # 0.05 level and for group 2 (r 5 0.701) at the p # 0.01 level. Furthermore, there was a positive correlation in the current study between bench press strength and linear BV for both group 1 (r 5 0.416) at the p # 0.05 level and group 2 (r 5 0.771) at the p # 0.01 level. However, it must be stated that improvements in parallel squat and bench press strength did not correlate to improvements in linear BV, CV, or HV for either group in the current study.

Neither group in the current study made statistically significant improvements in time to ball contact after 12 weeks of training. Groups 1 and 2 did improve 1.7 and 4.8%; however, only the location of the foam ball placed on the batting tee was controlled and not the players’ bat swing paths. Therefore, players had to hit a ball from the same location pre- and posttesting. It was hoped that all players would maintain the same bat swing path over the course of the study because they were not allowed to take additional bat swings during the research period. In comparison with other research that evaluated time to ball contact, the high school baseball players in our study, in groups 1 and 2, had mean time to ball contact of 0.331 and 0.322 seconds pretraining and 0.325 and 0.306 seconds posttraining. Breen (6) stated that Major League Baseball hitters had a time to ball contact between 0.19 and 0.28 seconds. Some possible reasons for the differences in time to ball contact may be the better talent, more experience, and greater strength of the older, professional baseball players.

To our knowledge, there has not been any other research project evaluating dynamic wrist and forearm strength training. In the current study, 10RM wrist barbell flexion and extension increased 11.0 and 16.4% for group 1 and 27.0 and 24.4% for group 2 after 12 weeks of training. Dominant and nondominant hand 10RM fore-

arm pronation increased 4.8 and 7.4% for group 1 and 12.0 and 11.0% for group 2. Dominant and nondominant hand 10RM forearm supination increased 2.7 and 3.7% for group 1 and 7.5% and 8.5% for group 2. Wrist dominant and nondominant hand 10RM radial deviation increased 19.3 and 16.1% for group 1 and 26.9 and 27.7% for group 2. Wrist dominant and nondominant hand 10RM ulnar deviation increased 24.8 and 22.6% for group 1 and 31.9 and 32.7% for group 2.

In a related unpublished study, Dulchinos (9) evaluated the relationship of wrist strength to bat swing velocity of male collegiate baseball players. The treatment group performed 3 sets of 10 repetitions for wrist flexion and extension 3 days a week for 5 weeks. However, only wrist adduction (ulnar deviation) was measured with a tensiometer pre- and posttraining. The author’s explanation as to why he measured wrist adduction was that wrist adduction was the only action required of the wrist during the swing. Adair (1) is in agreement with Dulchinos’ statement; however, Dulchinos did not train his participant’s using this movement, rather, he used wrist flexion and extension. These 2 movements should have been measured in addition to using wrist adduction in his training program. A Marathon velocity bat, with a builtin speedometer at the top of the barrel, was used to measure bat velocity. Only the best bat velocity was recorded.

In the current study, the mean bat velocity of 6 swings was reported. In the study by Dulchinos (9), mean posttraining bat velocities were 48.0 m·s21 for the control group and 49.7 m·s21 for the treatment group. These data are not similar to any other study evaluating ways to improve bat velocity. Mean posttraining bat velocities in other studies that evaluated collegiate players were 45.4, 43.6, and 44.9 m·s21 (21); 38.0, 37.8, and 36.4 m·s21 (7); and 30.8, 34.3, and 30.9 m·s21 (20). Thus, the velocities recorded with the Marathon bat are questionable. Wrist strength and bat velocity increased after 5 weeks of training for the treatment group, whereas the control group did not make significant improvements. However, in agreement with our research findings, Dulchinos (9) stated that there was not a significant relationship between wrist strength and bat velocity.

In the current study, the mean (6SD) pretraining dominant and nondominant grip strength for male high school baseball players were 50.4 (9.0) and 48.9 (7.9) kg for group 1 and 52.3 (6.3) and 50.4 (7.2) kg for group 2.

According to Mathiowetz et al. (15), the mean grip strength for boys 14–15 years old was 64.4 lb (29.3 kg) for the left hand and 77.3 lb (35.1 kg) for the right hand.

Mean grip strength for boys 16–17 years old was 78.5 lb (35.7 kg) for the left hand and 94.0 lb (42.7 kg) for the right hand. In the current study, the mean grip strength for the male high school baseball players in the 2 groups (mean age 5 15.3 years for group 1 and 15.4 years for group 2) was greater than the means produced in the study by Mathiowetz et al. (15). An explanation for the greater grip strength could be that the high school baseball players were probably stronger than the boys in the Mathiowetz et al. (15) study because they had previous resistance training and playing experience, which would most likely make their grip strength stronger than the average boy of the same age.

Hughes et al. (13) studied the effect of grip strength on instantaneous bat velocity of collegiate baseball players. They stated that pretraining mean grip strength for

WRIST

both hands combined was 56.7 (8.1) kg for the control group and 55.3 (6.2) kg for the experimental group. These data are greater than the pretraining grip strength for the baseball players in the current study, possibly because of greater maturation status, strength, and body mass. Hughes et al. (13) stated that the posttraining mean grip strength for both hands combined was 57.6 (7.2) kg for the control group and 56.4 (6.4) kg for the experimental group. They found no significant increase in grip strength or bat velocity after 6 weeks of training.

One would not expect significant increases in grip strength after only 6 weeks of training, for research has demonstrated that a minimum of 8 weeks is needed to produce significant increases in strength gains. In the current study, the mean posttraining dominant and nondominant grip strength for male high school baseball players was 53.4 (9.2) and 51.4 (8.7) kg in group 1 and 55.3 (6.3) and 52.1 (6.7) kg in group 2.

Giardina et al. (11) evaluated the relationship of grip strength and forearm size to bat velocity in female collegiate softball players. They found no significant relationship between bat velocity and forearm size or grip strength measure. They agreed with Adair (1) that the torque applied by the hands and wrist during the swing was of little contribution to bat velocity. They suggested that increases in either hand’s or both hands’ grip strength beyond what is accomplished from resistance training will not be of further benefit to increasing bat velocity. Furthermore, they stated that performing exercises to increase forearm strength will not have a significant effect on bat swing velocity. The mean grip strength was 84.0 lb (38.2 kg) for the left hand and 90.4 lb (41.1 kg) for the right hand. According to Mathiowetz et al.

(15), the mean grip strength for untrained women 20–24 years old was 61.0 lb (27.7 kg) for the left hand and 70.4 lb (32.0 kg) for the right hand. The mean grip strength for the female softball players (mean age 5 20.3 years) in the study by Giardina et al. (11) was greater. A possible explanation for the greater grip strength could be that the softball players were probably stronger than the women in the Mathiowetz et al. (15) study because they were athletes. The softball players may have had resistancetraining experience and had a minimum of 5-years playing experience. Thus, their grip strength may have been greater because of swinging a softball bat, which is a resistance device.

The percent improvements in predicted 1RM parallel squat and bench press strength are similar to those found by other researchers (5, 18, 28). In the present study, for groups 1 and 2, predicted 1RM parallel squat improved 30.7 and 33.7%, and predicted 1RM bench press strength improved 15.9 and 17.4%. The participants in the Baker et al. (5) study improved 27.7% in parallel squat and 11.6% in bench press strength. In the study by Schwendel and Thorland (18), male college students who performed traditional bench press improved 14.5%, whereas those who performed power bench press improved 14.7%. Willoughby (28) demonstrated that 16 weeks of a linear periodized program, now described as stepwise periodization (22), increased 1RM parallel squat and bench press strength 34.0 and 23.0% for previously resistance-trained participants. The low total training volume performed by participants in the study by Willoughby (28) should have contributed, in part, to the significant gains in parallel squat and bench press because the participants did not

AND

FOREARM TRAINING

AND

HIGH SCHOOL BASEBALL PLAYERS 239

complete any assistance (single-joint) exercises. Also, the greater strength gains could be expected because the participants trained for 4 additional weeks.

The significantly greater (p # 0.05) leg and upperbody strength in the current study, as measured by predicted 1RM parallel squat and bench press, correlated with the increased linear BV and CV. An electromyographic study completed by Shaffer et al. (20) described baseball batting. During the preswing phase, the high level of activity in the hamstrings and gluteus maximus indicated their role in hip stabilization and initiation of power. Vastus medialis oblique activity increased from preswing to middle swing, where it peaked. Thus, the increased leg strength demonstrated in this study could be linked to the increased linear BV, CV, and HV. Furthermore, the triceps, whose strength should have increased from the increase in predicted 1RM bench press in this study, demonstrated an increased activity in early and middle swing (20). Thus, an increase in triceps strength could be associated with the increased linear BV, CV, and HV because the elbows must extend before bat-to-ball contact.

The present study has made initial efforts to indicate the contribution of wrist and forearm strength to bat velocity of high school baseball players. Hughes et al. (13) have evaluated the effect of grip and forearm strength training on bat velocity of collegiate baseball players.

Both studies indicate that increased grip and forearm strength do not contribute to greater bat swing velocity.

Electromyographic (20) and biomechanical (27) research on baseball hitting suggests that hip and torso rotational strength, leg strength, and upper-body strength are more important variables to increase bat velocity for a hitter than are wrist and forearm strength. Future research should examine the contribution of torso rotational strength on bat velocity.

PRACTICAL APPLICATIONS If there is limited weight-room time for high school or collegiate baseball players because of class schedule, practice time, or playing, a baseball or strength coach may elect to focus the player’s training program on core exercises, such as squats, lat pull-downs, bench press, and torso rotational exercises. Although baseball coaches believe that strong wrists and forearms are essential to good hitting, the results of the present study indicate that high school baseball players do not need to perform additional forearm exercises to increase bat velocity. Furthermore, players may not need to focus as much attention on wrist and forearm training because simply holding barbells and dumbbells while performing resistancetraining exercises increases wrist and forearm strength.

However, if a strength coach has a goal of maximizing wrist and forearm strength for any athlete, then wrist and forearm exercises, such as those completed in this study, should be performed.

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Address correspondence to David J. Szymanski, dszyman@ latech.edu.