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Comparison of dominant hand range of motion among throwing types in baseball pitchers
Human Movement Science xxx (2013) xxx–xxx
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Human Movement Science journal homepage: www.elsevier.com/locate/humov
Comparison of dominant hand range of motion among throwing types in baseball pitchers Lin-Hwa Wang a,⇑, Li-Chieh Kuo b,1, Sheng-Wen Shih c, Kuo-Cheng Lo d,2, Fong-Chin Su e,3 a
Institute of Physical Education, Health & Leisure Studies, National Cheng Kung University, 1 University Rd, Tainan 701, Taiwan Institute of Occupational Therapy, National Cheng Kung University, 1 University Rd, Tainan 701, Taiwan c Master Program of Physical Education, National University of Tainan, 33, sec. 2, Shu-Lin St., Tainan 700, Taiwan d Office of Physical Education, Kun Shan University, 949, Da Wan Rd., Tainan 710, Taiwan e Department of Biomedical Engineering, Medical Device Innovation Center, National Cheng Kung University, 1 University Rd, Tainan 701, Taiwan b
a r t i c l e
i n f o
Article history: Available online xxxx psycINFO classification: 3700 Keywords: Biomechanics Pitching Wrist Finger Baseball Kinematics
a b s t r a c t Previous research on baseball pitchers’ wrists, elbows, and should joints contributes to our understanding of pitchers’ control over delicate joint motion and ball release. However, limited research on forearm, wrist, and hand joints prevents full comprehension of the throwing mechanism. The present descriptive laboratory study quantifies angular performances of hand and wrist joints while pitching breaking balls, including fastballs, curveballs and sliders, among pitchers with different skill levels. Nineteen baseball pitchers performed required pitching tasks (10 from university and 9 from high school). A three-dimensional motion analysis system collected pitching motion data. The range of joint motion in the wrist and proximal interphalangeal (PIP) and metacarpophalangeal (MP) joints of the index and middle fingers were compared among fastballs, curveballs and sliders. Thirteen reflective markers were placed on selected anatomic landmarks of the wrist, middle and index fingers of the hand. Wrist flexion angle in the pitching acceleration phase was larger in fastballs (20.58 ± 4.07°) and sliders (22.48 ± 5.45°) than in curveballs (9.08 ± 3.03°) (p = .001). The flexion angle of the PIP joint was significantly larger in curveballs (38.5 ± 3.8°) than in fastballs (30.3 ± 4.8°) and sliders (30.2 ± 4.5°)
⇑ Corresponding author. Tel.: +886 6 2757575x31631; fax: +886 6 2095626. E-mail addresses: [email protected] (L.-H. Wang), [email protected] (L.-C. Kuo), [email protected] (S.-W. Shih), [email protected] (K.-C. Lo), [email protected] (F.-C. Su). 1 Tel.: +886 6 2353535x5908. 2 Tel.: +886 6 2727175x230; fax: +886 6 2095626. 3 Tel.: +886 6 2757575x63422; fax: +886 6 2343270. 0167-9457/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.humov.2013.01.003
Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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(p = .004) of the middle finger. Abduction angle of MP joint on the middle finger was significantly larger in curveballs (15.4 ± 3.6°) than in fastballs (8.9 ± 1.2°) and sliders (6.9 ± 2.9°) (p = .001) of the middle finger, and the abduction angle of index finger was significantly larger in sliders (13.5 ± 15.0°) than in fastballs (7.2 ± 2.8°) (p = .007). Hand and wrist motion and grip types affect the relative position between fingers and ball, which produces different types of baseball pitches. A larger extension angle of the wrist joint and the coordination of middle and index fingers are crucial when pitching a fastball. Abduction and flexion movement on the MP joint of the middle finger are important for a curveball. MP joint abduction and flexion movement of the index finger produce sliders. Understanding the control mechanism in a throwing hand can help improve training protocols in either injury prevention or performance improvement for baseball pitchers. Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction Upper-limb extremities play an important role in pitching breaking balls, improving strike zone control, and enhancing ball rotation. Ball spin may affect pitching quality and ball traction sharpness in the strike zone. Ball spin is generated from friction between the fingers and ball surface and seams. Control of the wrist and fingers determines ball spin quality, accuracy, and sharpness (Hore, Watts, & Martin, 1996). Breaking ball control is mainly produced by the distal segment of upper extremities (Barrentine, Matsuo, Escamilla, Fleisig, & Andrews, 1998). Unfortunately, literature that addresses the kinematics of the distal part of the upper limb is scant, and only some reports indicate kinematic differences of the wrist joint among different pitch types (Floyd & Thompson, 2004). Deviation of pitching quality might relate not only to the wrist, but also to grasping and controlling patterns of the fingers in different types of breaking ball throws. Previous studies of baseball pitchers’ wrist, elbow and shoulder joints contribute to our understanding of pitchers’ control over delicate joint motion and ball release (BR). However, limited research on forearm, wrist, and hand joint motion precludes thorough comprehension of the throwing mechanism. Observing eight collegiate pitchers throw the fastball, curveball, and changeup, Barrentine et al. (1998) found that the wrist joint mainly extended in either the arm-cocking or acceleration phase. They observed slight flexion of about 3 ± 11° at the wrist joint in the release phase. Previous studies indicated that the wrist joint maintains the neutral posture with little flexion during a fastball throw. Nissen et al. (2007) analyzed the fastball pitches of 24 adolescent pitchers with the kinematic and kinetic parameters of their wrist joints, finding elbow moments relatively larger than those for the wrist. The maximum wrist extension moment was 2.4 ± 1.9 N m after BR and rapid wrist supination exposed the elbow to high valgus moments. When inexperienced pitchers with incorrect techniques perform frequent pitches, the risk for injury increases. The fingers can flex and extend at the metacarpophalangeal joints, where the intrinsic hand muscles also control abduction and adduction (Chikenji et al., 2010; Langer, Fadale, & Hulstyn, 2006; Loftice, Fleisig, Zheng, & Andrews, 2004; Nassab & Schickendantz, 2006; Sakurai, Ikegami, Okamoto, Yabe, & Toyoshima, 1993). Disability of complicated hand functions occurs when coordination of these muscles is lacking (Chikenji et al., 2010). Investigating how precisely the central nervous system (CNS) dominated finger muscle contraction during skill movements, Hore, Watts, Martin, and Miller (1995) found that time differences in ball release did not change with variations in target distance. Hore et al. (1996) used the magnetic-field search-coil technique to measure pitching fingers’ movement and the timing of ball release and finger initiation. Finger flexion occurred only after the ball was off the fingers.
Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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Using force transducers, researchers analyzed finger kinematics to see whether reaction forces, caused by balls of different weights to fingers, would result in finger kinematics variation. The study found that different ball weights had little to do with finger extension, and finger flexors exerted larger torques to compensate for the larger reaction forces during finger extension (Hore, Watts, & Tweed, 1999). The central nervous system anticipates the different reaction forces from different ball weights, adjusting finger flexor torques in accordance to ball weights. Hore, Watts, Leschuk, and MacDougall (2001), however, claimed that the ball’s reaction forces on the finger increased throughout an over-arm throw, while grip force progressively increased in opposing correspondence. These forces balance accurately for fairly constant finger-opening amplitude between each pitch during ball release. Finger-joint opening is faster when ball velocity increases, and proximal interphalangeal (PIP) joint extension range remains unchanged at different ball velocities during pitching (Hore & Watts, 2005). Previous studies indicated that proprioceptive feedback of pitching precision control did not come from the elbow joint. Throw speed, not timing scheme, dominated finger-opening velocity (Hore & Watts, 2005). During fast arm movements, finger control over ball release and finger flexion or extension before ball release is composed of small, speedy movements. Even pitchers themselves cannot describe the process in detail (Bahill & Baldwin, 2007). Finger and wrist motion in different baseball pitching types remains unexplored. This study quantifies the kinematics of wrist, index and middle fingers motion during the acceleration phase of pitching, comparing the difference between fastballs, sliders, and curveballs. Kinematic parameters may allow pitching learners to find tips of control in the wrist and fingers and to better understand the pitching mechanism’s effect on distal segments of upper extremities among these types of pitching. This study hypothesizes that there are differences of kinematic performances in the wrist joint, index and middle fingers during acceleration phase among the fastball, slider and curveball. In other words, the movement characteristics of the wrist joint, index and middle fingers among the three pitching patterns are statistically different.
2. Methods 2.1. Subjects Nineteen baseball pitchers recruited in this study were voluntary practitioners (10 from university and 9 from high school). All of these participants had at least five years of baseball practice experience. The university players played in Taiwan’s first-division college league, and the high-school players were in the senior baseball league. Before testing, all participants were informed of the detailed procedures and signed an informed consent form describing the possible risks and benefits of participation. Potential participants were excluded from the study if they were judged to have inferior pitching technique – that is, if they could not perform at least two pitching types – presented upper extremity injuries or had undergone an upper extremity surgery within the last three months.
2.2. Instruments For kinematic analysis, thirteen reflective landmarks were attached to the index finger (fingertip of index finger, distal interphalangeal joint, proximal interphalangeal joint, metacarpophalangeal joint, midpoint of metacarpal bone), middle finger (fingertip of index finger, distal interphalangeal joint, proximal interphalangeal joint, metacarpophalangeal joint, midpoint of metacarpal bone) and the wrist (ulna styloid processes, radial styloid processes, dorsal wrist) (Fig. 1). A three-dimensional eight-camera motion-analysis system (Motion Analysis Corp., Santa Rosa, CA, USA) collected the throwing motion data of the hand and wrist joints with a sampling frequency of 500 Hz. At least two cameras monitored each reflective marker. The retro-reflective markers were spherical balls with 9.0 mm diameter covered by 3 M reflective tape. A digital video camcorder captured the throwing motions and quantified the total successful numbers. A foot switch (MA-136, Motion Lab Systems, Inc., USA) defined the pitching phase, functioning synchronously with motion analysis systems to Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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Fig. 1. Placement of reflective markers on the dorsum of wrist, index and middle finger. Index finger – G (fingertip of index finger); H (distal interphalangeal joint, DIP); I (proximal interphalangeal joint PIP); J (metacarpophalangeal joint, MP); K (midpoint of metacarpal bone). Middle finger – L (fingertip); M (distal interphalangeal joint, DIP); N (proximal interphalangeal joint, PIP); O (metacarpophalangeal joint, MP); P (midpoint of metacarpal bone); wrist – Q (radial styloid processes); R (dorsal wrist); S (ulna styloid processes).
determine maximum shoulder external rotation at leading foot contact (Fleisig et al., 2006). A Radar gun (Decatur Electronics Inc., Decatur, IL, USA) was used to measure the ball speed in each pitch trial.
2.3. Procedures An L-shaped frame established a global coordinate system in the testing space. Before motion data collection, the participants warmed-up and practiced pitching in the testing environment. Participants were first asked to stand still in an anatomically neutral position to collect reference frame data. All participants used the dominant hand (right hand) for pitching and wore a fielding glove on the opposite hand. The mound and cleats were unavailable for pitching motion data collection in our laboratory environment. Three static data and five pitching trials of each style were collected for three seconds (Fig. 2). The visual focus was on the center of the standing target, which was necessary to compute arm translation. Successful pitches must land within a specified 30-by-30 square-centimeter area (3 m away from participants and at eye level for each participant) locating at the front of a net. Pitchers threw the types of pitches that they routinely used during competition (Fig. 3). The initial pitch was determined according to the ball’s trajectory and then a specific pitch sequence was assigned. Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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Fig. 2. Pitching motion data collection from acceleration phase to ball release.
Fig. 3. The wrist, index finger (blue line), and middle finger (red line) specifically produce the fastball (left), slider (center) and curveball (right) before ball release. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
2.4. Data processing Kinematic parameters include the major action of MP joint (abduction/adduction, flexion/extension) at the middle and index fingers, PIP joints (flexion/extension), and wrist joints (flexion/extension, ulnar/radial deviation) during the pitching motion. Previous studies defined abduction angle at the MP joint from static data (neutral and closed fingers), relating the vectors between fingertip and MP joint for middle and index fingers to dynamic motion during pitching (Fig. 4). They calculated flexion angle of the PIP and MP joint from two vectors by dot product (since there was only one degree of freedom on a hinge joint) (Fig. 5). For the wrist joint, previous studies used the Euler angle to describe the orientation of a distal segment coordinate system relative to a proximal segment coordinate system (Elliott, Grove, Gibson, & Thurston, 1986). The joint subsequently rotated in the order X-Z0 -Y00 . 2.5. Data analysis Acquiring parameters from kinematic data of the body segments during experiments requires further analysis. Three-dimensional marker trajectory data were collected at 500 Hz and filtered using a low-pass fourth-order Butterworth’s filter with the cutoff frequency set at 6 Hz. EVaRT 4.2 software Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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Fig. 4. (1) MP joint diagram for abduction angle at middle and index finger. (2) Static position of middle and index finger.
Fig. 5. (1) Dot product for calculating the flexion angle of PIP and MP joints. (2) Vectors diagram for calculating angle of PIP and MP joints at middle and index finger.
(Motion Analysis Corporation, Santa Rosa, USA) traced and identified motion-trajectory images. Finally, the self-designed MATLAB program calculated angular-movement and range-of-motion data for each joint. Descriptive statistics indicated the height, weight, pitch type, handedness, and ball speed of participants. For this analysis, the analyzed parameters were the range of motion (ROM, maximum–minimum displacement), the dependent variables were MP joints (abduction/adduction, flexion/ extension) at the middle and index fingers, PIP joints (flexion/extension), and wrist joints (flexion/ extension, ulnar/radial deviation) during the pitching motion. One-way ANOVA was used to compare the kinematic variables of each pitch types from the acceleration phase to ball release (from maximum shoulder external rotation angle to ball release) during pitching. Values of p < .05 were considered to be statistically significant for all the statistical analyses, which were performed with SPSS 14 (the Scientific Package for Social Sciences, version 14, Chicago, IL, USA). Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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3. Results The mean age of the 19 participants was 18.7 ± 2.7 years. Average height was 1.75 ± 0.05 m. Mean body weight was 73.3 ± 14.5 kg. 3.1. Ball speed Pitchers threw the types of pitches that they routinely used during competition. The 19 participants threw one fastball each. Only 14 of the subjects could throw sliders and only 10 of them could throw a curveball; therefore data on only 14 sliders and on only 10 curveballs were collected. Fastball speed (27.16 ± 3.42 m/s) was significantly higher than that of sliders (23.81 ± 2.91 m/s) (p < .05) and curveballs (22.43 ± 2.56 m/s) (p < .05). There was no significant difference between sliders and curveballs. 3.2. Wrist joint During the fastball pitch, the wrist extended approximately 10° before the acceleration phase, reaching a maximum extension angle of roughly 37.82° with an ulnar deviation of approximately 7.32° during acceleration. At ball release, the wrist flexion and ulnar deviation were roughly 0.63° and 8.4°, respectively. The mean extension angle was significantly larger in fastballs (20.58 ± 4.07°) and sliders (22.48 ± 5.45°) than in curveballs (9.08 ± 3.03°). Curveball pitches did not display larger ulnar or radial deviation angles compared with fastballs or curveballs, and the ROM in the flexion and extension angles was significantly smaller than others (p < .05) (Table 1). 3.3. Proximal interphalangeal joint The maximum and minimum flexion angle of the PIP joint at middle and index finger occurred in the acceleration phase of pitch motion. During the fastball pitch, the release timing of the middle and index fingers was almost simultaneous, thus displaying similar angle variation for these two fingers. At the beginning of the acceleration phase, they extended and then flexed rapidly until ball release for both fastballs and sliders (Fig. 6(1) and (2)). For curveballs, the PIP flexion angle at the middle finger (38.5 ± 3.8°) was significantly larger than for sliders (30.2 ± 4.5°) and fastballs (30.3 ± 4.8°) (p < .004); the ROM in sliders and fastballs was significantly less than in curveballs (p = .003) (Table 2). 3.4. Metacarpophalangeal joint The MP joint maintained its extension angle during the late cocking phase, with larger angle variation in the late acceleration phase (Fig. 3 and 4). The mean flexion angle of MP joint at middle and index fingers was larger in curveballs (middle: 42.9 ± 5.4°, index: 25.6 ± 15.5°) and sliders (middle:
Table 1 Comparison the mean value of wrist joint angle and ROM during acceleration phase in three types of pitch. Movement
Angle (°) Flexion()/Extension(+)
Pitch types
Comparison
Fastball (n = 19)
Slider (n = 14)
Curveball (n = 11)
p
20.58 ± 4.07
22.48 ± 5.45
9.08 ± 3.03
.001
Ulnar(+)/Radial() deviation
5.33 ± 5.89
4.18 ± 13.57
4.02 ± 3.79
.970
ROM Flexion()/Extension(+) Ulnar(+)/Radial() deviation
34.12 ± 7.46 32.1 ± 21.86
14.7 ± 19.76 10.0 ± 13.52
9.3 ± 11.0 8.5 ± 10.4
.068 .653
FA > CU SL > CU
Mean ± SD; p < .05.
Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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(1)
MER
BR
45
flexion(-)/extension(+) adduction(-)/abduction(+)
40
Joint angle(degree)
35 30 25 20 15 10
BR
MER
50
MF PIP flexion(+)/extension(-) MF DIP flexion(+)/extension(-)
40
Joint angle(degree)
(3)
30 20 10 0 -10
5 0
-20 0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
Cycle%
50
60
70
80
90
100
Cycle%
(2)
BR
MER
(4)
45
MER
BR
50
MF PIP flexion(+)/extension(-) MF DIP flexion(+)/extension(-)
40
flexion(-)/extension(+) adduction(-)/abduction(+)
40
Joint angle(degree)
Joint angle(degree)
35 30 25 20 15 10
30 20 10 0 -10
5
-20
0 0
10
20
30
40
50
60
70
80
90
0
100
10
20
30
40
50
60
70
80
90
100
Cycle%
Cycle%
Fig. 6. (1) Comparison PIP joint at middle and index finger of fastball during acceleration phase (BR: ball release; MER: maximum shoulder external rotation). (2) Comparison PIP joint at middle and index finger of slider during acceleration phase (BR: ball release; MER: maximum shoulder external rotation). (3) Comparison MP joint at middle and index finger of fastball during acceleration (BR: ball release; MER: maximum shoulder external rotation). (4) Comparison MP joint at middle and index finger of slider during acceleration phase (BR: ball release; MER: maximum shoulder external rotation). Table 2 Comparison the mean value of MP joint, PIP joint angle and ROM at middle finger and index finger during acceleration phase in three types of pitch. Abbreviations: FA, Fastball; SL, Slider; CU, Curveball; NS, No Significance. Angle (°)
Slider
Curveball
p
Comparison
0.4 ± 15.5
21.0 ± 14.9
25.6 ± 15.5
.004
Index Finger_Abduction/adduction Middle Finger_Flexion/extension
7.2 ± 2.8 7.5 ± 17.3
13.5 ± 15.0 30.9 ± 10.9
8.1 ± 4.1 42.9 ± 5.4
.007 .002
Middle Finger_Abduction/adduction
8.9 ± 1.2
6.9 ± 2.9
15.4 ± 3.6
.001
CU > FA SL > FA SL > FA SL > FA CU > FA CU > FA, SL
ROM at MP joint Index Finger_Flexion/extension Index Finger_Abduction/adduction Middle Finger_Flexion/extension Middle Finger_Abduction/adduction
22.7 ± 3.7 20.4 ± 4.7 27.6 ± 7.2 25.4 ± 10.3
13.7 ± 5.2 19.0 ± 8.0 17.2 ± 10.1 23.9 ± 8.8
27.6 ± 8.1 19.0 ± 3.7 14.8 ± 4.3 15.4 ± 7.3
.005 .89 .24 .19
CU > SL NS NS NS
PIP joint Index Finger_Flexion/extension Middle Finger_Flexion/extension
30.3 ± 6.7 30.3 ± 4.8
33.1 ± 8.8 30.2 ± 4.5
22.6 ± 14.1 38.5 ± 3.8
.16 .004
NS CU > SL, FA
ROM at PIP joint Index Finger_Flexion/extension Middle Finger_Flexion/extension
30.2 ± 29.5 19.2 ± 9.7
12.7 ± 12.9 14.6 ± 7.8
56.7 ± 43.0 26.8 ± 13.0
.014 .003
FA > SL CU > FA
MP joint Index Finger_Flexion/extension
Fastball
Mean ± SD; p < .05.
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30.9 ± 10.9°, index: 21.0 ± 14.9°) than in fastballs (p = .004). ROM at the index finger was larger in curveballs than in sliders (p = .005). The abduction angle of the middle finger was significantly larger in curveballs (15.4 ± 3.6°) than in fastballs (8.9 ± 1.2°) and sliders (6.9 ± 2.9°) (p = .001) and the abduction angle of index finger was significantly larger in sliders (13.5 ± 15.0°) than in fastballs (7.2 ± 2.8°) (p = .007). There were no significant differences between these pitch types in the mean range-of-motion value (Table 2).
4. Discussion The main achievement of the current study was the kinematic model: results from the wrist, hand and fingers quantitatively distinguished joint performance among different baseball pitching types. Although the focus of an increasing proportion of baseball pitching studies is shifting from the shoulder and elbow to the forearm and wrist (Barrentine et al., 1998), few studies focus on hand and finger control during pitching. This study analyzes the fastest movement of distal segments (index finger and middle finger). Because of the limited quantitative research on the pitching hand, it is difficult to provide a precise interpretation of the results. Ball speed results in this study are similar to previous reports indicating that the fastball is fastest among different pitch types (Barrentine et al., 1998; Elliott et al., 1986). Compared with previous reports, lower ball speed was anticipated by the authors of this study, as the indoor environment limits pitching performance. Nissen et al. (2009) found significantly higher ROM on wrist ulnar deviation in curveballs (17 ± 7°) than in fastballs (14 ± 5°). Barrentine et al. (1998) also reported higher ulnar deviation at the instant of ball release in curveballs (24 ± 16°) than in fastballs (19 ± 15°). In Barrrentine’s and our own separate studies, with adult participants, there were no significant differences in curveballs and fastballs on mean ulnar deviation angle during the acceleration phase, while studies with adolescent subjects by Nissen did. This could be attributed to the different age of participants in the different studies. In addition, the most obvious differences of kinematic results might result from the different marker setups among these three studies. These different marker placements lead to different establishment of segmental coordinate systems and influence the measurement in the ranges of joint motion and angular representation. The difference might be due to the larger standard deviation among this study’s participants. The larger wrist extension angle during the acceleration phase of fastballs and sliders is related to pitch type and ball speed. Similar motion between these two types of pitching highlights a sagittal plane of motion for the wrist and hand. The trajectory of a pitched ball is determined by rotation velocity, rotation axis and angle of release (Jinji & Sakurai, 2006). Jinji reported the trajectory of pitched fastballs and curveballs, finding that the fastball was back-spun and raised, while the curveball was top-spun and described a parabola (due to the Magnus effect) before dropping into the catcher’s glove (Hore & Watts, 2005). Friction between fingers and ball derives from the hand grip and finger motion. When curveballs were pitched, forearm supination and wrist ulnar deviation at the instant of ball release made the hand and fingers more horizontal compared with the ball surface (Barrentine et al., 1998). To produce the top-spin, therefore, pitchers need to increase the abduction and flexion angles in the MP joint and flexion angle in the PIP joint at the instant of ball release. The angle increases with the decrease of attached surface on the ball. Ball-release sequence follows the pattern of thumb, index, and then middle finger. The last ball-releasing finger has the greatest effect on ball spin and propulsion. Thus, the motion was larger on the MP and PIP joints in the middle finger for curveballs than fastballs. Relative positions between fingers and ball show more differences between fastballs and sliders than in curveballs. The pitcher grips the ball on its back surface by the middle and index fingers and releases them at the same time to pitch a fastball. All participants pitched four-seam fastballs. These two fingers cross the seams and produce friction on the ball; the ball then rotates with a back-spin because it is progressively released from the ventral finger surfaces, finger pads, then finger tips. That limits flexion angle on the MP and PIP joints due to the reactive force of the ball; this plane of motion requires less abduction and adduction. The grip type for a slider is similar to that of a curveball, but the wrist motion resembles that of a fastball. The rotation axis of a slider points up and to the left for the right-handed pitcher (Bahill & Baldwin, 2007). Thus, the middle and index finPlease cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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gers, pressing the side and exerting downward force on the ball, produce a bullet-like rotation. The lateral and downward movement creates a large finger-flexion angle. This study found larger flexion and abduction angles of the index finger and larger flexion angle of the middle finger at the MP joint for sliders than for fastballs. The index finger might perform the latest release sequence at the instant of ball release. This study presented hand and finger pitching characteristics through kinematic analysis of the pitching movement. Some studies focused on physics of the ball rotation and deflection through imaging or a wind tunnel (Alaways, Mish, & Hubbard, 2001; Bahill & Baldwin, 2007; Bahill, Baldwin, & Venkateswaran, 2005; Hore & Watts, 2005). Ball performance depends on movement of body segments, forearm control, and wrist and finger control of ball spin. Quantification of ball release was still limited in this study. Future studies should quantify the release sequence from data of the hand and fingers, finger attachment positions on the ball and release angle at the instant of ball release from the fingers. Limitations of this study include the non-standard pitching distance and the lack of a practical pitching environment, like a pitching mound and catcher. Neither did the study take hand anthropometric data into consideration. This may affect hand grip patterns and finger action. The complicated but delicate manipulative and prehensile functions of the hand are possible because of well-coordinated neuromuscular controls on the numbers of extrinsic and intrinsic muscles of the hand. Unlike the rigorous emphasis on shoulder muscular strengthening, pitchers’ training protocols rarely advocate routine exercises on the distal part of the upper limb, especially for the tiny intrinsic muscles inside the hand. This study quantitatively reveals the motion demands of the wrist and hand joints in different pitching types. The flexion and extension of the MP and PIP joints allow speculation on the roles of the flexor and extensor digitorums and the lumbrical muscles while throwing. The interossei muscles of the hand contribute to the abduction and adduction of the fingers that help pitchers control their curve and slider balls. Unfortunately, even professional athletes seldom focus considerably on strengthening and endurance of these muscles so that muscle fatigue might appear after a number of throws. Unlike the rigorous emphasis on shoulder muscular strengthening, pitchers’ training protocols rarely advocate routine exercises of the distal part of the upper limb, and in particular the tiny intrinsic muscles of the hand. EMG data provide direct and detailed information of the involved muscles in a specific task. Unfortunately, the surface electrodes suitable for detecting the hand muscles, especially the intrinsic muscles, are still unavailable for the modern EMG system. This unavailability is due to the fact that the bulkiness of the surface electrode system precludes precise measurement of a delicate ball gripping movement. With the limitation of measurement instruments, the information retrieved from EMG still needs improvement in terms of accuracy and possible extension in the topic’s research ability. 5. Conclusion This study provides a significant new direction in investigating the effect of finger and wrist-joint biomechanics on precision pitching tasks and related ball performance. Hand and wrist motion and grip types affect the relative position between fingers and ball, which produces different types of baseball pitches. Larger extension angle of the wrist joint and coordination of middle and index fingers are crucial when a fastball is pitched. Abduction and flexion movement on the MP joint of the middle finger are important characteristics for a curveball. MP joint abduction and flexion movement of the index finger produce slider pitching. These results may be useful for those wanting to pitch a breaking ball. Understanding the mechanism of the throwing hand could be useful in clinical training to improve muscle strength and motor control among baseball pitchers. Acknowledgments This study is supported by National Science Council grants NSC 98-2410-H-006-107-MY2, TAIWAN, ROC. The author thanks Yen-Sung Liao for technical support. Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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References Alaways, L. W., Mish, S. P., & Hubbard, M. (2001). Identification of release conditions and aerodynamic forces in pitched-baseball trajectories. Journal of Applied Biomechanics, 17, 63–76. Bahill, A. T., & Baldwin, D. G. (2007). Describing baseball pitch movement with right-hand rules. Computers in Biology and Medicine, 37, 1001–1008. Bahill, A. T., Baldwin, D. G., & Venkateswaran, J. (2005). Predicting a baseball’s path. American Scientist, 93, 218–225. Barrentine, S. W., Matsuo, T., Escamilla, R. F., Fleisig, G. S., & Andrews, J. R. (1998). Kinematic analysis of the wrist and forearm during baseball pitching. Journal of Applied Biomechanics, 14, 24–39. Chikenji, T., Toda, H., Gyoku, C., Oikawa, N., Katayose, M., & Tsubota, S. (2010). A comparison of the strength of the abduction of the little and index fingers and palmar abduction and opposition of the thumb between college baseball players and inexperienced sports players. Journal of Musculoskeletal Research, 13, 75–82. Elliott, B., Grove, J. R., Gibson, B., & Thurston, B. (1986). A three-dimensional cinematographic analysis of the fastball and curveball pitches in baseball. Journal of Applied Biomechanics, 2, 20–28. Fleisig, G. S., Kingsley, D. S., Loftice, J. W., Dinnen, K. P., Ranganathan, R., Dun, S., et al (2006). Kinetic comparison among the fastball, curveball, change-up, and slider in collegiate baseball pitchers. American Journal of Sports Medicine, 34, 423–430. Floyd, R. T., & Thompson, C. W. (2004). Manual of structural kinesiology (15th ed.). Boston: McGraw-Hill. Hore, J., & Watts, S. (2005). Timing finger opening in overarm throwing based on a spatial representation of hand path. Journal of Neurophysiology, 93, 3189–3199. Hore, J., Watts, S., Leschuk, M., & MacDougall, A. (2001). Control of finger grip forces in overarm throws made by skilled throwers. Journal of Neurophysiology, 86, 2678–2689. Hore, J., Watts, S., & Martin, J. (1996). Finger flexion does not contribute to ball speed in overarm throws. Journal of Sports Sciences, 14, 335–342. Hore, J., Watts, S., Martin, J., & Miller, B. (1995). Timing of finger opening and ball release in fast and accurate overarm throws. Experimental Brain Research, 103, 277–286. Hore, J., Watts, S., & Tweed, D. (1999). Prediction and compensation by an internal model for back forces during finger opening in an overarm throw. Journal of Neurophysiology, 82, 1187–1197. Jinji, T., & Sakurai, S. (2006). Direction of spin axis and spin rate of the pitched baseball. Sports Biomechnics, 5, 197–214. Langer, P., Fadale, P., & Hulstyn, M. (2006). Evolution of the treatment options of ulnar collateral ligament injuries of the elbow. British Journal of Sports Medicine, 40, 499–506. Loftice, J., Fleisig, G. S., Zheng, N., & Andrews, J. R. (2004). Biomechanics of the elbow in sports. Clinical Sports Medicine, 23, 519–530. Nassab, P. F., & Schickendantz, M. S. (2006). Evaluation and treatment of medial ulnar collateral ligament injuries in the throwing athlete. [Review]. Sports Medicine and Arthroscopy, 14, 221–231. Nissen, C. W., Westwell, M., Ounpuu, S., Patel, M., Solomito, M., & Tate, J. (2009). A biomechanical comparison of the fastball and curveball in adolescent baseball pitchers. American Journal of Sports Medicine, 37, 1492–1498. Nissen, C. W., Westwell, M., Ounpuu, S., Patel, M., Tate, J. P., Pierz, K., et al (2007). Adolescent baseball pitching technique: A detailed three-dimensional biomechanical analysis. Medicine and Science in Sports and Exercise, 39, 1347–1357. Sakurai, S., Ikegami, Y., Okamoto, A., Yabe, K., & Toyoshima, S. (1993). A 3-dimensional cinematographic analysis of upper limb movement during fastball and curveball baseball pitches. Journal of Applied Biomechanics, 9, 47–65.
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Contents lists available at SciVerse ScienceDirect
Human Movement Science journal homepage: www.elsevier.com/locate/humov
Comparison of dominant hand range of motion among throwing types in baseball pitchers Lin-Hwa Wang a,⇑, Li-Chieh Kuo b,1, Sheng-Wen Shih c, Kuo-Cheng Lo d,2, Fong-Chin Su e,3 a
Institute of Physical Education, Health & Leisure Studies, National Cheng Kung University, 1 University Rd, Tainan 701, Taiwan Institute of Occupational Therapy, National Cheng Kung University, 1 University Rd, Tainan 701, Taiwan c Master Program of Physical Education, National University of Tainan, 33, sec. 2, Shu-Lin St., Tainan 700, Taiwan d Office of Physical Education, Kun Shan University, 949, Da Wan Rd., Tainan 710, Taiwan e Department of Biomedical Engineering, Medical Device Innovation Center, National Cheng Kung University, 1 University Rd, Tainan 701, Taiwan b
a r t i c l e
i n f o
Article history: Available online xxxx psycINFO classification: 3700 Keywords: Biomechanics Pitching Wrist Finger Baseball Kinematics
a b s t r a c t Previous research on baseball pitchers’ wrists, elbows, and should joints contributes to our understanding of pitchers’ control over delicate joint motion and ball release. However, limited research on forearm, wrist, and hand joints prevents full comprehension of the throwing mechanism. The present descriptive laboratory study quantifies angular performances of hand and wrist joints while pitching breaking balls, including fastballs, curveballs and sliders, among pitchers with different skill levels. Nineteen baseball pitchers performed required pitching tasks (10 from university and 9 from high school). A three-dimensional motion analysis system collected pitching motion data. The range of joint motion in the wrist and proximal interphalangeal (PIP) and metacarpophalangeal (MP) joints of the index and middle fingers were compared among fastballs, curveballs and sliders. Thirteen reflective markers were placed on selected anatomic landmarks of the wrist, middle and index fingers of the hand. Wrist flexion angle in the pitching acceleration phase was larger in fastballs (20.58 ± 4.07°) and sliders (22.48 ± 5.45°) than in curveballs (9.08 ± 3.03°) (p = .001). The flexion angle of the PIP joint was significantly larger in curveballs (38.5 ± 3.8°) than in fastballs (30.3 ± 4.8°) and sliders (30.2 ± 4.5°)
⇑ Corresponding author. Tel.: +886 6 2757575x31631; fax: +886 6 2095626. E-mail addresses: [email protected] (L.-H. Wang), [email protected] (L.-C. Kuo), [email protected] (S.-W. Shih), [email protected] (K.-C. Lo), [email protected] (F.-C. Su). 1 Tel.: +886 6 2353535x5908. 2 Tel.: +886 6 2727175x230; fax: +886 6 2095626. 3 Tel.: +886 6 2757575x63422; fax: +886 6 2343270. 0167-9457/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.humov.2013.01.003
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(p = .004) of the middle finger. Abduction angle of MP joint on the middle finger was significantly larger in curveballs (15.4 ± 3.6°) than in fastballs (8.9 ± 1.2°) and sliders (6.9 ± 2.9°) (p = .001) of the middle finger, and the abduction angle of index finger was significantly larger in sliders (13.5 ± 15.0°) than in fastballs (7.2 ± 2.8°) (p = .007). Hand and wrist motion and grip types affect the relative position between fingers and ball, which produces different types of baseball pitches. A larger extension angle of the wrist joint and the coordination of middle and index fingers are crucial when pitching a fastball. Abduction and flexion movement on the MP joint of the middle finger are important for a curveball. MP joint abduction and flexion movement of the index finger produce sliders. Understanding the control mechanism in a throwing hand can help improve training protocols in either injury prevention or performance improvement for baseball pitchers. Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction Upper-limb extremities play an important role in pitching breaking balls, improving strike zone control, and enhancing ball rotation. Ball spin may affect pitching quality and ball traction sharpness in the strike zone. Ball spin is generated from friction between the fingers and ball surface and seams. Control of the wrist and fingers determines ball spin quality, accuracy, and sharpness (Hore, Watts, & Martin, 1996). Breaking ball control is mainly produced by the distal segment of upper extremities (Barrentine, Matsuo, Escamilla, Fleisig, & Andrews, 1998). Unfortunately, literature that addresses the kinematics of the distal part of the upper limb is scant, and only some reports indicate kinematic differences of the wrist joint among different pitch types (Floyd & Thompson, 2004). Deviation of pitching quality might relate not only to the wrist, but also to grasping and controlling patterns of the fingers in different types of breaking ball throws. Previous studies of baseball pitchers’ wrist, elbow and shoulder joints contribute to our understanding of pitchers’ control over delicate joint motion and ball release (BR). However, limited research on forearm, wrist, and hand joint motion precludes thorough comprehension of the throwing mechanism. Observing eight collegiate pitchers throw the fastball, curveball, and changeup, Barrentine et al. (1998) found that the wrist joint mainly extended in either the arm-cocking or acceleration phase. They observed slight flexion of about 3 ± 11° at the wrist joint in the release phase. Previous studies indicated that the wrist joint maintains the neutral posture with little flexion during a fastball throw. Nissen et al. (2007) analyzed the fastball pitches of 24 adolescent pitchers with the kinematic and kinetic parameters of their wrist joints, finding elbow moments relatively larger than those for the wrist. The maximum wrist extension moment was 2.4 ± 1.9 N m after BR and rapid wrist supination exposed the elbow to high valgus moments. When inexperienced pitchers with incorrect techniques perform frequent pitches, the risk for injury increases. The fingers can flex and extend at the metacarpophalangeal joints, where the intrinsic hand muscles also control abduction and adduction (Chikenji et al., 2010; Langer, Fadale, & Hulstyn, 2006; Loftice, Fleisig, Zheng, & Andrews, 2004; Nassab & Schickendantz, 2006; Sakurai, Ikegami, Okamoto, Yabe, & Toyoshima, 1993). Disability of complicated hand functions occurs when coordination of these muscles is lacking (Chikenji et al., 2010). Investigating how precisely the central nervous system (CNS) dominated finger muscle contraction during skill movements, Hore, Watts, Martin, and Miller (1995) found that time differences in ball release did not change with variations in target distance. Hore et al. (1996) used the magnetic-field search-coil technique to measure pitching fingers’ movement and the timing of ball release and finger initiation. Finger flexion occurred only after the ball was off the fingers.
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Using force transducers, researchers analyzed finger kinematics to see whether reaction forces, caused by balls of different weights to fingers, would result in finger kinematics variation. The study found that different ball weights had little to do with finger extension, and finger flexors exerted larger torques to compensate for the larger reaction forces during finger extension (Hore, Watts, & Tweed, 1999). The central nervous system anticipates the different reaction forces from different ball weights, adjusting finger flexor torques in accordance to ball weights. Hore, Watts, Leschuk, and MacDougall (2001), however, claimed that the ball’s reaction forces on the finger increased throughout an over-arm throw, while grip force progressively increased in opposing correspondence. These forces balance accurately for fairly constant finger-opening amplitude between each pitch during ball release. Finger-joint opening is faster when ball velocity increases, and proximal interphalangeal (PIP) joint extension range remains unchanged at different ball velocities during pitching (Hore & Watts, 2005). Previous studies indicated that proprioceptive feedback of pitching precision control did not come from the elbow joint. Throw speed, not timing scheme, dominated finger-opening velocity (Hore & Watts, 2005). During fast arm movements, finger control over ball release and finger flexion or extension before ball release is composed of small, speedy movements. Even pitchers themselves cannot describe the process in detail (Bahill & Baldwin, 2007). Finger and wrist motion in different baseball pitching types remains unexplored. This study quantifies the kinematics of wrist, index and middle fingers motion during the acceleration phase of pitching, comparing the difference between fastballs, sliders, and curveballs. Kinematic parameters may allow pitching learners to find tips of control in the wrist and fingers and to better understand the pitching mechanism’s effect on distal segments of upper extremities among these types of pitching. This study hypothesizes that there are differences of kinematic performances in the wrist joint, index and middle fingers during acceleration phase among the fastball, slider and curveball. In other words, the movement characteristics of the wrist joint, index and middle fingers among the three pitching patterns are statistically different.
2. Methods 2.1. Subjects Nineteen baseball pitchers recruited in this study were voluntary practitioners (10 from university and 9 from high school). All of these participants had at least five years of baseball practice experience. The university players played in Taiwan’s first-division college league, and the high-school players were in the senior baseball league. Before testing, all participants were informed of the detailed procedures and signed an informed consent form describing the possible risks and benefits of participation. Potential participants were excluded from the study if they were judged to have inferior pitching technique – that is, if they could not perform at least two pitching types – presented upper extremity injuries or had undergone an upper extremity surgery within the last three months.
2.2. Instruments For kinematic analysis, thirteen reflective landmarks were attached to the index finger (fingertip of index finger, distal interphalangeal joint, proximal interphalangeal joint, metacarpophalangeal joint, midpoint of metacarpal bone), middle finger (fingertip of index finger, distal interphalangeal joint, proximal interphalangeal joint, metacarpophalangeal joint, midpoint of metacarpal bone) and the wrist (ulna styloid processes, radial styloid processes, dorsal wrist) (Fig. 1). A three-dimensional eight-camera motion-analysis system (Motion Analysis Corp., Santa Rosa, CA, USA) collected the throwing motion data of the hand and wrist joints with a sampling frequency of 500 Hz. At least two cameras monitored each reflective marker. The retro-reflective markers were spherical balls with 9.0 mm diameter covered by 3 M reflective tape. A digital video camcorder captured the throwing motions and quantified the total successful numbers. A foot switch (MA-136, Motion Lab Systems, Inc., USA) defined the pitching phase, functioning synchronously with motion analysis systems to Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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Fig. 1. Placement of reflective markers on the dorsum of wrist, index and middle finger. Index finger – G (fingertip of index finger); H (distal interphalangeal joint, DIP); I (proximal interphalangeal joint PIP); J (metacarpophalangeal joint, MP); K (midpoint of metacarpal bone). Middle finger – L (fingertip); M (distal interphalangeal joint, DIP); N (proximal interphalangeal joint, PIP); O (metacarpophalangeal joint, MP); P (midpoint of metacarpal bone); wrist – Q (radial styloid processes); R (dorsal wrist); S (ulna styloid processes).
determine maximum shoulder external rotation at leading foot contact (Fleisig et al., 2006). A Radar gun (Decatur Electronics Inc., Decatur, IL, USA) was used to measure the ball speed in each pitch trial.
2.3. Procedures An L-shaped frame established a global coordinate system in the testing space. Before motion data collection, the participants warmed-up and practiced pitching in the testing environment. Participants were first asked to stand still in an anatomically neutral position to collect reference frame data. All participants used the dominant hand (right hand) for pitching and wore a fielding glove on the opposite hand. The mound and cleats were unavailable for pitching motion data collection in our laboratory environment. Three static data and five pitching trials of each style were collected for three seconds (Fig. 2). The visual focus was on the center of the standing target, which was necessary to compute arm translation. Successful pitches must land within a specified 30-by-30 square-centimeter area (3 m away from participants and at eye level for each participant) locating at the front of a net. Pitchers threw the types of pitches that they routinely used during competition (Fig. 3). The initial pitch was determined according to the ball’s trajectory and then a specific pitch sequence was assigned. Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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Fig. 2. Pitching motion data collection from acceleration phase to ball release.
Fig. 3. The wrist, index finger (blue line), and middle finger (red line) specifically produce the fastball (left), slider (center) and curveball (right) before ball release. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
2.4. Data processing Kinematic parameters include the major action of MP joint (abduction/adduction, flexion/extension) at the middle and index fingers, PIP joints (flexion/extension), and wrist joints (flexion/extension, ulnar/radial deviation) during the pitching motion. Previous studies defined abduction angle at the MP joint from static data (neutral and closed fingers), relating the vectors between fingertip and MP joint for middle and index fingers to dynamic motion during pitching (Fig. 4). They calculated flexion angle of the PIP and MP joint from two vectors by dot product (since there was only one degree of freedom on a hinge joint) (Fig. 5). For the wrist joint, previous studies used the Euler angle to describe the orientation of a distal segment coordinate system relative to a proximal segment coordinate system (Elliott, Grove, Gibson, & Thurston, 1986). The joint subsequently rotated in the order X-Z0 -Y00 . 2.5. Data analysis Acquiring parameters from kinematic data of the body segments during experiments requires further analysis. Three-dimensional marker trajectory data were collected at 500 Hz and filtered using a low-pass fourth-order Butterworth’s filter with the cutoff frequency set at 6 Hz. EVaRT 4.2 software Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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Fig. 4. (1) MP joint diagram for abduction angle at middle and index finger. (2) Static position of middle and index finger.
Fig. 5. (1) Dot product for calculating the flexion angle of PIP and MP joints. (2) Vectors diagram for calculating angle of PIP and MP joints at middle and index finger.
(Motion Analysis Corporation, Santa Rosa, USA) traced and identified motion-trajectory images. Finally, the self-designed MATLAB program calculated angular-movement and range-of-motion data for each joint. Descriptive statistics indicated the height, weight, pitch type, handedness, and ball speed of participants. For this analysis, the analyzed parameters were the range of motion (ROM, maximum–minimum displacement), the dependent variables were MP joints (abduction/adduction, flexion/ extension) at the middle and index fingers, PIP joints (flexion/extension), and wrist joints (flexion/ extension, ulnar/radial deviation) during the pitching motion. One-way ANOVA was used to compare the kinematic variables of each pitch types from the acceleration phase to ball release (from maximum shoulder external rotation angle to ball release) during pitching. Values of p < .05 were considered to be statistically significant for all the statistical analyses, which were performed with SPSS 14 (the Scientific Package for Social Sciences, version 14, Chicago, IL, USA). Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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3. Results The mean age of the 19 participants was 18.7 ± 2.7 years. Average height was 1.75 ± 0.05 m. Mean body weight was 73.3 ± 14.5 kg. 3.1. Ball speed Pitchers threw the types of pitches that they routinely used during competition. The 19 participants threw one fastball each. Only 14 of the subjects could throw sliders and only 10 of them could throw a curveball; therefore data on only 14 sliders and on only 10 curveballs were collected. Fastball speed (27.16 ± 3.42 m/s) was significantly higher than that of sliders (23.81 ± 2.91 m/s) (p < .05) and curveballs (22.43 ± 2.56 m/s) (p < .05). There was no significant difference between sliders and curveballs. 3.2. Wrist joint During the fastball pitch, the wrist extended approximately 10° before the acceleration phase, reaching a maximum extension angle of roughly 37.82° with an ulnar deviation of approximately 7.32° during acceleration. At ball release, the wrist flexion and ulnar deviation were roughly 0.63° and 8.4°, respectively. The mean extension angle was significantly larger in fastballs (20.58 ± 4.07°) and sliders (22.48 ± 5.45°) than in curveballs (9.08 ± 3.03°). Curveball pitches did not display larger ulnar or radial deviation angles compared with fastballs or curveballs, and the ROM in the flexion and extension angles was significantly smaller than others (p < .05) (Table 1). 3.3. Proximal interphalangeal joint The maximum and minimum flexion angle of the PIP joint at middle and index finger occurred in the acceleration phase of pitch motion. During the fastball pitch, the release timing of the middle and index fingers was almost simultaneous, thus displaying similar angle variation for these two fingers. At the beginning of the acceleration phase, they extended and then flexed rapidly until ball release for both fastballs and sliders (Fig. 6(1) and (2)). For curveballs, the PIP flexion angle at the middle finger (38.5 ± 3.8°) was significantly larger than for sliders (30.2 ± 4.5°) and fastballs (30.3 ± 4.8°) (p < .004); the ROM in sliders and fastballs was significantly less than in curveballs (p = .003) (Table 2). 3.4. Metacarpophalangeal joint The MP joint maintained its extension angle during the late cocking phase, with larger angle variation in the late acceleration phase (Fig. 3 and 4). The mean flexion angle of MP joint at middle and index fingers was larger in curveballs (middle: 42.9 ± 5.4°, index: 25.6 ± 15.5°) and sliders (middle:
Table 1 Comparison the mean value of wrist joint angle and ROM during acceleration phase in three types of pitch. Movement
Angle (°) Flexion()/Extension(+)
Pitch types
Comparison
Fastball (n = 19)
Slider (n = 14)
Curveball (n = 11)
p
20.58 ± 4.07
22.48 ± 5.45
9.08 ± 3.03
.001
Ulnar(+)/Radial() deviation
5.33 ± 5.89
4.18 ± 13.57
4.02 ± 3.79
.970
ROM Flexion()/Extension(+) Ulnar(+)/Radial() deviation
34.12 ± 7.46 32.1 ± 21.86
14.7 ± 19.76 10.0 ± 13.52
9.3 ± 11.0 8.5 ± 10.4
.068 .653
FA > CU SL > CU
Mean ± SD; p < .05.
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(1)
MER
BR
45
flexion(-)/extension(+) adduction(-)/abduction(+)
40
Joint angle(degree)
35 30 25 20 15 10
BR
MER
50
MF PIP flexion(+)/extension(-) MF DIP flexion(+)/extension(-)
40
Joint angle(degree)
(3)
30 20 10 0 -10
5 0
-20 0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
Cycle%
50
60
70
80
90
100
Cycle%
(2)
BR
MER
(4)
45
MER
BR
50
MF PIP flexion(+)/extension(-) MF DIP flexion(+)/extension(-)
40
flexion(-)/extension(+) adduction(-)/abduction(+)
40
Joint angle(degree)
Joint angle(degree)
35 30 25 20 15 10
30 20 10 0 -10
5
-20
0 0
10
20
30
40
50
60
70
80
90
0
100
10
20
30
40
50
60
70
80
90
100
Cycle%
Cycle%
Fig. 6. (1) Comparison PIP joint at middle and index finger of fastball during acceleration phase (BR: ball release; MER: maximum shoulder external rotation). (2) Comparison PIP joint at middle and index finger of slider during acceleration phase (BR: ball release; MER: maximum shoulder external rotation). (3) Comparison MP joint at middle and index finger of fastball during acceleration (BR: ball release; MER: maximum shoulder external rotation). (4) Comparison MP joint at middle and index finger of slider during acceleration phase (BR: ball release; MER: maximum shoulder external rotation). Table 2 Comparison the mean value of MP joint, PIP joint angle and ROM at middle finger and index finger during acceleration phase in three types of pitch. Abbreviations: FA, Fastball; SL, Slider; CU, Curveball; NS, No Significance. Angle (°)
Slider
Curveball
p
Comparison
0.4 ± 15.5
21.0 ± 14.9
25.6 ± 15.5
.004
Index Finger_Abduction/adduction Middle Finger_Flexion/extension
7.2 ± 2.8 7.5 ± 17.3
13.5 ± 15.0 30.9 ± 10.9
8.1 ± 4.1 42.9 ± 5.4
.007 .002
Middle Finger_Abduction/adduction
8.9 ± 1.2
6.9 ± 2.9
15.4 ± 3.6
.001
CU > FA SL > FA SL > FA SL > FA CU > FA CU > FA, SL
ROM at MP joint Index Finger_Flexion/extension Index Finger_Abduction/adduction Middle Finger_Flexion/extension Middle Finger_Abduction/adduction
22.7 ± 3.7 20.4 ± 4.7 27.6 ± 7.2 25.4 ± 10.3
13.7 ± 5.2 19.0 ± 8.0 17.2 ± 10.1 23.9 ± 8.8
27.6 ± 8.1 19.0 ± 3.7 14.8 ± 4.3 15.4 ± 7.3
.005 .89 .24 .19
CU > SL NS NS NS
PIP joint Index Finger_Flexion/extension Middle Finger_Flexion/extension
30.3 ± 6.7 30.3 ± 4.8
33.1 ± 8.8 30.2 ± 4.5
22.6 ± 14.1 38.5 ± 3.8
.16 .004
NS CU > SL, FA
ROM at PIP joint Index Finger_Flexion/extension Middle Finger_Flexion/extension
30.2 ± 29.5 19.2 ± 9.7
12.7 ± 12.9 14.6 ± 7.8
56.7 ± 43.0 26.8 ± 13.0
.014 .003
FA > SL CU > FA
MP joint Index Finger_Flexion/extension
Fastball
Mean ± SD; p < .05.
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30.9 ± 10.9°, index: 21.0 ± 14.9°) than in fastballs (p = .004). ROM at the index finger was larger in curveballs than in sliders (p = .005). The abduction angle of the middle finger was significantly larger in curveballs (15.4 ± 3.6°) than in fastballs (8.9 ± 1.2°) and sliders (6.9 ± 2.9°) (p = .001) and the abduction angle of index finger was significantly larger in sliders (13.5 ± 15.0°) than in fastballs (7.2 ± 2.8°) (p = .007). There were no significant differences between these pitch types in the mean range-of-motion value (Table 2).
4. Discussion The main achievement of the current study was the kinematic model: results from the wrist, hand and fingers quantitatively distinguished joint performance among different baseball pitching types. Although the focus of an increasing proportion of baseball pitching studies is shifting from the shoulder and elbow to the forearm and wrist (Barrentine et al., 1998), few studies focus on hand and finger control during pitching. This study analyzes the fastest movement of distal segments (index finger and middle finger). Because of the limited quantitative research on the pitching hand, it is difficult to provide a precise interpretation of the results. Ball speed results in this study are similar to previous reports indicating that the fastball is fastest among different pitch types (Barrentine et al., 1998; Elliott et al., 1986). Compared with previous reports, lower ball speed was anticipated by the authors of this study, as the indoor environment limits pitching performance. Nissen et al. (2009) found significantly higher ROM on wrist ulnar deviation in curveballs (17 ± 7°) than in fastballs (14 ± 5°). Barrentine et al. (1998) also reported higher ulnar deviation at the instant of ball release in curveballs (24 ± 16°) than in fastballs (19 ± 15°). In Barrrentine’s and our own separate studies, with adult participants, there were no significant differences in curveballs and fastballs on mean ulnar deviation angle during the acceleration phase, while studies with adolescent subjects by Nissen did. This could be attributed to the different age of participants in the different studies. In addition, the most obvious differences of kinematic results might result from the different marker setups among these three studies. These different marker placements lead to different establishment of segmental coordinate systems and influence the measurement in the ranges of joint motion and angular representation. The difference might be due to the larger standard deviation among this study’s participants. The larger wrist extension angle during the acceleration phase of fastballs and sliders is related to pitch type and ball speed. Similar motion between these two types of pitching highlights a sagittal plane of motion for the wrist and hand. The trajectory of a pitched ball is determined by rotation velocity, rotation axis and angle of release (Jinji & Sakurai, 2006). Jinji reported the trajectory of pitched fastballs and curveballs, finding that the fastball was back-spun and raised, while the curveball was top-spun and described a parabola (due to the Magnus effect) before dropping into the catcher’s glove (Hore & Watts, 2005). Friction between fingers and ball derives from the hand grip and finger motion. When curveballs were pitched, forearm supination and wrist ulnar deviation at the instant of ball release made the hand and fingers more horizontal compared with the ball surface (Barrentine et al., 1998). To produce the top-spin, therefore, pitchers need to increase the abduction and flexion angles in the MP joint and flexion angle in the PIP joint at the instant of ball release. The angle increases with the decrease of attached surface on the ball. Ball-release sequence follows the pattern of thumb, index, and then middle finger. The last ball-releasing finger has the greatest effect on ball spin and propulsion. Thus, the motion was larger on the MP and PIP joints in the middle finger for curveballs than fastballs. Relative positions between fingers and ball show more differences between fastballs and sliders than in curveballs. The pitcher grips the ball on its back surface by the middle and index fingers and releases them at the same time to pitch a fastball. All participants pitched four-seam fastballs. These two fingers cross the seams and produce friction on the ball; the ball then rotates with a back-spin because it is progressively released from the ventral finger surfaces, finger pads, then finger tips. That limits flexion angle on the MP and PIP joints due to the reactive force of the ball; this plane of motion requires less abduction and adduction. The grip type for a slider is similar to that of a curveball, but the wrist motion resembles that of a fastball. The rotation axis of a slider points up and to the left for the right-handed pitcher (Bahill & Baldwin, 2007). Thus, the middle and index finPlease cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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gers, pressing the side and exerting downward force on the ball, produce a bullet-like rotation. The lateral and downward movement creates a large finger-flexion angle. This study found larger flexion and abduction angles of the index finger and larger flexion angle of the middle finger at the MP joint for sliders than for fastballs. The index finger might perform the latest release sequence at the instant of ball release. This study presented hand and finger pitching characteristics through kinematic analysis of the pitching movement. Some studies focused on physics of the ball rotation and deflection through imaging or a wind tunnel (Alaways, Mish, & Hubbard, 2001; Bahill & Baldwin, 2007; Bahill, Baldwin, & Venkateswaran, 2005; Hore & Watts, 2005). Ball performance depends on movement of body segments, forearm control, and wrist and finger control of ball spin. Quantification of ball release was still limited in this study. Future studies should quantify the release sequence from data of the hand and fingers, finger attachment positions on the ball and release angle at the instant of ball release from the fingers. Limitations of this study include the non-standard pitching distance and the lack of a practical pitching environment, like a pitching mound and catcher. Neither did the study take hand anthropometric data into consideration. This may affect hand grip patterns and finger action. The complicated but delicate manipulative and prehensile functions of the hand are possible because of well-coordinated neuromuscular controls on the numbers of extrinsic and intrinsic muscles of the hand. Unlike the rigorous emphasis on shoulder muscular strengthening, pitchers’ training protocols rarely advocate routine exercises on the distal part of the upper limb, especially for the tiny intrinsic muscles inside the hand. This study quantitatively reveals the motion demands of the wrist and hand joints in different pitching types. The flexion and extension of the MP and PIP joints allow speculation on the roles of the flexor and extensor digitorums and the lumbrical muscles while throwing. The interossei muscles of the hand contribute to the abduction and adduction of the fingers that help pitchers control their curve and slider balls. Unfortunately, even professional athletes seldom focus considerably on strengthening and endurance of these muscles so that muscle fatigue might appear after a number of throws. Unlike the rigorous emphasis on shoulder muscular strengthening, pitchers’ training protocols rarely advocate routine exercises of the distal part of the upper limb, and in particular the tiny intrinsic muscles of the hand. EMG data provide direct and detailed information of the involved muscles in a specific task. Unfortunately, the surface electrodes suitable for detecting the hand muscles, especially the intrinsic muscles, are still unavailable for the modern EMG system. This unavailability is due to the fact that the bulkiness of the surface electrode system precludes precise measurement of a delicate ball gripping movement. With the limitation of measurement instruments, the information retrieved from EMG still needs improvement in terms of accuracy and possible extension in the topic’s research ability. 5. Conclusion This study provides a significant new direction in investigating the effect of finger and wrist-joint biomechanics on precision pitching tasks and related ball performance. Hand and wrist motion and grip types affect the relative position between fingers and ball, which produces different types of baseball pitches. Larger extension angle of the wrist joint and coordination of middle and index fingers are crucial when a fastball is pitched. Abduction and flexion movement on the MP joint of the middle finger are important characteristics for a curveball. MP joint abduction and flexion movement of the index finger produce slider pitching. These results may be useful for those wanting to pitch a breaking ball. Understanding the mechanism of the throwing hand could be useful in clinical training to improve muscle strength and motor control among baseball pitchers. Acknowledgments This study is supported by National Science Council grants NSC 98-2410-H-006-107-MY2, TAIWAN, ROC. The author thanks Yen-Sung Liao for technical support. Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003
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Please cite this article in press as: Wang, L.-H., et al. Comparison of dominant hand range of motion among throwing types in baseball pitchers. Human Movement Science (2013), http://dx.doi.org/10.1016/j.humov.2013.01.003