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1.
Joint angles of the throwing limb were examined from the acceleration phase up until release for the sidearm throwing motion when using a flying disc. 17 individuals (ten skilled, seven unskilled) threw a disc as far as possible ten times. Throwing motions were recorded using three-dimensional high-speed videography. The initial condition of disc release and joint angle kinematics of the upper limb during the throwing motion were obtained. Mean ( ± standard deviation) throwing distance and disc spin rate were significantly greater for skilled throwers (51.4 ± 6.6 m, 12.9 ± 1.3 rps) than for unskilled throwers (29.5 ± 7.6 m, 9.4 ± 1.3 rps), although there was no significant difference in initial velocity of the disc between the two groups (skilled: 21.7 ± 1.7 m/s; unskilled: 20.7 ± 2.5 m/s). A marked difference in motion of supination/pronation of the forearm before disc release was identified, with the forearm supinated in the final acceleration phase leading up to disc release for the unskilled participants, while the forearm was pronated in the same phase for the skilled participants. These differences in joint kinematics could be related to differences in disc spin rate, and thus led to the substantial differences in throwing distance.  相似文献   

2.
We aimed to assess the relationship between throwing distance and kinematic release parameters of the flying disc in unskilled throwers, and to assess the relationship between kinetic variables acting on flying discs and the change in spin velocity during long forehand throws by skilled and unskilled throwers. Ten skilled and eleven unskilled throwers performed throws at maximum effort. Reflective marker positions on the disc and body were recorded with a 3D motion capture system during the throws to derive kinematic variables of a disc and kinetic variables acting on the disc. The analysis interval was from maximum external shoulder rotation to disc release. Significant correlations were observed between the throwing distance and spin velocity in skilled (r = 0.722, P < 0.05) and unskilled throwers (r = 0.794, P < 0.01), between the change in spin velocity and the angular impulse of moments of force, in unskilled throwers (r = 0.703, P < 0.05), and between the change in spin velocity and the angular impulse of torque among skilled throwers (r = 0.680, P < 0.01). Therefore, a strategy for increasing spin velocity in unskilled throwers could be used to generate a larger torque, similar to that observed in skilled throwers.  相似文献   

3.
We tested the hypothesis that variability in the timing of ball release in overarm throws affects ball speed. Nine unskilled and six skilled throwers made 30 throws fast and accurately from a sitting and standing position. Angular positions of finger and arm segments were recorded with search-coils at 1000 Hz; ball speed was measured with a radar gun. The time of ball release from the fingertips was measured with respect to seven arm kinematic reference points. Mean timing windows for ball release were 28?ms for unskilled throwers and 7?ms for skilled throwers. Mixed-model analyses of variance showed that a there was a statistically significant relationship between ball speed and the timing of ball release in unskilled throwers, but not in skilled throwers. This was presumably due to the difference in variability of the timing of ball release between the two groups. In contrast, skilled throwers showed a relationship between ball speed and peak forearm angular velocity (one measure of arm speed). We conclude that although variability in the timing of ball release can affect ball speed, this is only a major factor in unskilled throwers. When skilled throwers throw fast, variability in ball speed is due to variability in arm speed.  相似文献   

4.
We tested the hypothesis that variability in the timing of ball release in overarm throws affects ball speed. Nine unskilled and six skilled throwers made 30 throws fast and accurately from a sitting and standing position. Angular positions of finger and arm segments were recorded with search-coils at 1000 Hz; ball speed was measured with a radar gun. The time of ball release from the fingertips was measured with respect to seven arm kinematic reference points. Mean timing windows for ball release were 28 ms for unskilled throwers and 7 ms for skilled throwers. Mixed-model analyses of variance showed that a there was a statistically significant relationship between ball speed and the timing of ball release in unskilled throwers, but not in skilled throwers. This was presumably due to the difference in variability of the timing of ball release between the two groups. In contrast, skilled throwers showed a relationship between ball speed and peak forearm angular velocity (one measure of arm speed). We conclude that although variability in the timing of ball release can affect ball speed, this is only a major factor in unskilled throwers. When skilled throwers throw fast, variability in ball speed is due to variability in arm speed.  相似文献   

5.
In this study we compared the kinematic features of the throwing motion between young baseball players of different age groups. Forty-four Japanese baseball players aged 6.1 to 12.3 years who regularly played baseball, including pitchers and position players, had their throwing actions analyzed three-dimensionally using high speed videography. Of this sample, 26 players aged above 9 years of age were categorized as the senior group, while the remaining 18 were categorized as the junior group. Senior group throwers had greater height and body mass, and produced a greater ball speed than junior group throwers. The throwing arm movement of senior group throwers was similar to that of adult skilled players. However, in the junior group throwers, the shoulder horizontal adduction angle was larger during the arm acceleration phase, and the maximum angular velocities of elbow extension and shoulder internal rotation occurred later than in senior group throwers. These results indicate that players aged above 9 years can acquire a mature throwing arm movement, while players younger than that will use an immature motion. A possible reason why these differences were shown is that the official baseball is relatively heavy for junior group throwers; they would be better advised to use a lighter ball in throwing practice.  相似文献   

6.
We examined mechanisms of coordination that enable skilled recreational baseball players to make fast overarm throws with their skilled arm and which are absent or rudimentary in their unskilled arm. Arm segment angular kinematics in three dimensions at 1000 Hz were recorded with the search-coil technique from the arms of eight individuals who on one occasion threw with their skilled right arm and on another with their unskilled left arm. Compared with their unskilled arm, the skilled arm had: a larger angular deceleration of the upper arm in space in the forward horizontal direction; a larger shoulder internal rotation velocity at ball release (unskilled arms had a negative velocity); a period of elbow extension deceleration before ball release; and an increase in wrist velocity with an increase in ball speed. It is suggested that some of these differences in arm kinematics occur because of differences between the skilled and unskilled arms in their ability to control interaction torques (the passive torque at one joint due to motion at adjacent joints). It is proposed that one reason unskilled individuals cannot throw fast is that, unlike their skilled counterparts, they have not developed the coordination mechanisms to effectively exploit interaction torques.  相似文献   

7.
Abstract

In this study we compared the kinematic features of the throwing motion between young baseball players of different age groups. Forty‐four Japanese baseball players aged 6.1 to 12.3 years who regularly played baseball, including pitchers and position players, had their throwing actions analyzed three‐dimensionally using high speed videography. Of this sample, 26 players aged above 9 years of age were categorized as the senior group, while the remaining 18 were categorized as the junior group. Senior group throwers had greater height and body mass, and produced a greater ball speed than junior group throwers. The throwing arm movement of senior group throwers was similar to that of adult skilled players. However, in the junior group throwers, the shoulder horizontal adduction angle was larger during the arm acceleration phase, and the maximum angular velocities of elbow extension and shoulder internal rotation occurred later than in senior group throwers. These results indicate that players aged above 9 years can acquire a mature throwing arm movement, while players younger than that will use an immature motion. A possible reason why these differences were shown is that the official baseball is relatively heavy for junior group throwers; they would be better advised to use a lighter ball in throwing practice.  相似文献   

8.
Abstract

We examined mechanisms of coordination that enable skilled recreational baseball players to make fast overarm throws with their skilled arm and which are absent or rudimentary in their unskilled arm. Arm segment angular kinematics in three dimensions at 1000 Hz were recorded with the search-coil technique from the arms of eight individuals who on one occasion threw with their skilled right arm and on another with their unskilled left arm. Compared with their unskilled arm, the skilled arm had: a larger angular deceleration of the upper arm in space in the forward horizontal direction; a larger shoulder internal rotation velocity at ball release (unskilled arms had a negative velocity); a period of elbow extension deceleration before ball release; and an increase in wrist velocity with an increase in ball speed. It is suggested that some of these differences in arm kinematics occur because of differences between the skilled and unskilled arms in their ability to control interaction torques (the passive torque at one joint due to motion at adjacent joints). It is proposed that one reason unskilled individuals cannot throw fast is that, unlike their skilled counterparts, they have not developed the coordination mechanisms to effectively exploit interaction torques.  相似文献   

9.
The purpose of this study was to determine the critical values at which throwing patterns change when scaling up on the control parameter of velocity. Thirty-six participants (ages: 6-12 years) were categorized into four throwing levels according to patterns represented by temporal joint lag. Each participant was required to complete 5 overhand throws at each of 10 relative velocities for a total of 50 trials per participant. The lowest velocity was 10% of maximum, with increases in increments of 10% up to a maximum effort. Quantitative and qualitative analyses indicated that critical values varied according to throwing category and joint. Generally, lower skilled throwers (Levels 1 and 2) had less stable joint lag and changed patterns at lower velocities than higher skilled (Levels 3 and 4) throwers.  相似文献   

10.
This study investigated the contribution of flexor muscles to the forearm through fatigue; therefore, the differences in forearm mechanisms on the pitching motion in fastball were analysed. Fifteen baseball pitchers were included in this study. Ultrasonographical examination of participants’ ulnar nerve in the cubital tunnel with the elbow extended and at 45°, 90° and 120° of flexion was carried. A three-dimensional motion analysis system with 14 reflective markers attached on participants was used for motion data collection. The electromyography system was applied over the flexor carpi ulnaris, flexor carpi radialis and extensor carpi radialis muscles of the dominant arm. Flexor carpi ulnaris muscle activity showed a significant difference during the acceleration phase, with a peak value during fastball post-fatigue (P = 0.02). Significant differences in the distance between ulnar nerve and medial condyle on throwing arm and non-throwing arm were observed as the distance increased with the elbow movement from 0° to 120° of flexion (P = 0.01). The significant increase of the flexor carpi ulnaris muscle activity might be responsible for maintaining the stability of the wrist joint. The increased diameter might compress the ulnar nerve and cause several pathological changes. Therefore, fatigue in baseball pitchers still poses a threat to the ulnar nerve because the flexor carpi ulnaris and flexor carpi radialis all originate from the medial side of the elbow, and the swelling tendons after fatigue might be a key point.  相似文献   

11.
The aim of this study was to investigate the throwing velocity and kinematics of overarm throwing in team handball of elite female and male handball players. Kinematics and ball velocity of a 7 metre-throw in eleven elite male (age 23.6 ± 5.2 yr, body mass 87.0 ± 6.8 kg, height 1.85 ± 0.05 m) and eleven elite female (age 20.3 ± 1.8 yr, body mass 69.9 ± 5.5 kg, height 1.75 ± 0.05 m) team handball players were recorded. The analysis consisted of maximal joint angles, angles at ball release, maximal angular velocities of the joint movements, and maximal linear velocities of the distal endpoints of segments and their timing during the throw. The ball release velocity of the male handball players was significantly higher than the females (21.1 vs. 19.2 m · s(-1); p < 0.05). No major differences in kinematics were found, except for the maximal endpoint velocities of the hand and wrist segment, indicating that male and female handball players throw with the same technique. It was concluded that differences in throwing velocity in elite male and female handball players are generally not the result of changes in kinematics in the joint movements.  相似文献   

12.
Training a non-dominant limb may increase a competitor's ability to perform with either side of his or her body and confer an advantage over competitors that use one side of the body exclusively. The aim of this study was to determine the kinematic differences between dominant and non-dominant arm throwing techniques for speed and accuracy in Under-17 and Under-19 high-performance cricketers. Seven participants performed ten throws for each arm (dominant/non-dominant) and condition (speed/accuracy) at a target positioned 10 m in front of them. Three-dimensional kinematic variables were measured using a Vicon motion analysis system. Digital footage was used to calculate stride data, ball speed, and record target accuracy. Data were analysed using repeated-measures analysis of variance and chi-squared tests. The non-dominant arm throws had significantly lower maximum lead knee lift, did not extend the lead knee in the arm acceleration phase, had significantly less elbow flexion before extension, had significantly less shoulder external rotation at the start of the arm acceleration phase, did not have a delay between the initiation of pelvic and upper torso internal rotation, and displayed a less than optimal coordination pattern. A speed-accuracy trade-off existed for the dominant arm throws. No trade-off was identified for the non-dominant arm throws. Through an enhanced understanding of how throwing technique varies between dominant and non-dominant arms, an opportunity exists for a performance-enhancing programme to be implemented so that ambidexterity of the throwing skill can be improved.  相似文献   

13.
Training a non-dominant limb may increase a competitor's ability to perform with either side of his or her body and confer an advantage over competitors that use one side of the body exclusively. The aim of this study was to determine the kinematic differences between dominant and non-dominant arm throwing techniques for speed and accuracy in Under-17 and Under-19 high-performance cricketers. Seven participants performed ten throws for each arm (dominant/non-dominant) and condition (speed/accuracy) at a target positioned 10 m in front of them. Three-dimensional kinematic variables were measured using a Vicon motion analysis system. Digital footage was used to calculate stride data, ball speed, and record target accuracy. Data were analysed using repeated-measures analysis of variance and chi-squared tests. The non-dominant arm throws had significantly lower maximum lead knee lift, did not extend the lead knee in the arm acceleration phase, had significantly less elbow flexion before extension, had significantly less shoulder external rotation at the start of the arm acceleration phase, did not have a delay between the initiation of pelvic and upper torso internal rotation, and displayed a less than optimal coordination pattern. A speed–accuracy trade-off existed for the dominant arm throws. No trade-off was identified for the non-dominant arm throws. Through an enhanced understanding of how throwing technique varies between dominant and non-dominant arms, an opportunity exists for a performance-enhancing programme to be implemented so that ambidexterity of the throwing skill can be improved.  相似文献   

14.
The purpose of this study was to investigate joint kinetics of the throwing arms and role of trunk motion in skilled elementary school boys during an overarm distance throw. Throwing motions of 42 boys from second, fourth, and sixth grade were videotaped with three high-speed cameras operating at 300 fps. Seven skilled boys from each grade were selected on the basis of throwing distance for three-dimensional kinetic analysis. Joint forces, torques, and torque powers of the throwing arm joints were calculated from reconstructed three-dimensional coordinate data smoothed at cut-off frequencies of 10.5–15 Hz and by the inverse dynamics method. Throwing distance and ball velocity significantly increased with school grade. The angular velocity of elbow extension before ball release increased with school grade, although no significant increase between the grades was observed in peak extension torque of elbow joint. The joint torque power of shoulder internal/external rotation tended to increase with school grade. When teaching the overarm throw, elementary school teachers should observe large backward twisting of trunk during the striding phase and should keep in mind that young children, such as second graders (age 8 years), will be unable to effectively utilise shoulder external/internal rotation during the throwing phase.  相似文献   

15.
This study was conducted to determine whether a supination phase of the forearm exists around ball release (BRL), and, if present, to determine whether this supination is explained by a reaction force or by the body configuration required for this task. A 16-camera motion analysis system with a sampling frequency of 1,000 Hz recorded 20 healthy male semi-professional pitchers pitching from an indoor pitching mound. A short supination phase around BRL was confirmed for all participants in the current study. Correlation analyses revealed that the supination angle at BRL had significant relationships with several measurements of shoulder movement kinematics. Mechanical work analysis of the forearm’s longitudinal axis revealed several variations in joint power curve and various patterns of mechanical work among the participants, suggesting that a reaction force originating from accelerating a ball might not be the main cause of supination. The raw data also were down-sampled to a sampling frequency of 250 Hz, to match previous studies and to investigate the discrepancy among previous studies concerning the existence of the supination phase. The experience of participants and methodological differences, such as the definition of BRL and the time-normalisation technique, influenced whether the supination phase was observed.  相似文献   

16.
The purpose of this study was to determine the effects of sequences of the trunk and arm angular motions on the performance of javelin throwing. In this study, 32 male and 30 female elite javelin throwers participated and were separated into a short official distance group or a long official distance group in each gender. Three-dimensional coordinates of 21 body landmarks and 3 marks on the javelin in the best trial were collected for each subject. Joint center linear velocities and selected trunk and arm segment and joint angles and angular velocities were calculated. The times of the initiations of the selected segment and joint angular motions and maximum angular velocities were determined. The sequences of the initiations of the selected segment and joint angular motions and maximum angular velocities were compared between short and long official distance groups and between genders. The results demonstrated that short and long official distance groups employed similar sequences of the trunk and arm motions. Male and female javelin throwers employed different sequences of the trunk and arm motions. The sequences of the trunk and arm motions were different from those of the maximal joint center linear velocities.  相似文献   

17.
The aims of this study were to establish the temporal-spatial relationship between muscle activity and the smash stroke of skilled badminton players and to assess performance accuracy using the ellipse of constant distance. We recorded the surface electromyographic (EMG) activity of selected superficial muscles of the stroking arm and shoulder--flexor carpi ulnalis, extensor carpi radialis, triceps brachii (lateral head), biceps brachii and trapezius (upper)--during the badminton smash. In the first part of the study, we examined the characteristics of muscle function and performance accuracy of skilled and unskilled individuals during the badminton smash. Five well-trained badminton players and five students with no experience of badminton were asked to smash a shuttle as hard as they could towards a vertical square target 4 m away, repeating the stroke 30 times. In general, the skilled players showed a more constant time from peak electromyographic amplitude to impact. Immediately after impact, the electromyographic activity of the triceps brachii and flexor carpi radialis of the skilled players decreased; in the unskilled participants, however, it continued until well after impact. The area of the ellipse of constant distance and the off-target distance, which were used as indices of performance accuracy, were smaller for the skilled than for the unskilled participants. In the second part of the study, one skilled and one unskilled participant performed 100 trials a day for 6 days. The time from peak electromyographic amplitude to impact in the extensor carpi radialis and flexor carpi ulnalis was more variable in the unskilled than in the skilled participant even after 6 days of practice, but the proximal muscles of the unskilled participant had a similar pattern of activity to that of the skilled player. Thus, controlling the distal muscles appears to be important for achieving accurate performance of the smash in badminton.  相似文献   

18.
We investigated the differences in mechanical power flow in early and late practice stages during a cyclic movement consisting of upper arm circumduction to clarify the change in mechanical energy use with skill acquisition. Seven participants practiced the task every other day until their joint angular movements conformed to those of an expert. During the practice sessions, participants' motions were digitally recorded once a week using four high-speed infrared cameras, and the joint kinematics and joint powers of the right arm were calculated. With practice, the inflow power derived from the net joint force increased at the hand, forearm, and upper arm segments by 143.1 +/- 17.2%, 57.1 +/- 7.3%, and 198.1 +/- 35.4%, respectively. In contrast, the power caused by the muscle joint moments was not significantly increased. These results suggested that participants acquired a motor pattern promoting transfer of the joint reaction forces. Results may provide some support for Bernstein's (1967) ideas that skill acquisition involves improving movement efficiency by greater use of nonmuscular forces.  相似文献   

19.
The muscular patterning of three skilled throwers who were less skilled servers, three skilled servers who were less skilled throwers, and three individuals skilled in both sport skills, was studied by means of electromyography and tri-plane cinematography during performances of the throw and serve. Surface electrodes were used to record electrical activity from two trunk, four shoulder girdle, and four shoulder joint muscles. Regardless of skill level, the nine female subjects used common joint and segment movements and employed, with minor exceptions, the same number of muscles during late preparatory and force production phases in the two skills. However, for the two skills, there were differences in the duration during which the muscles were active. The serve took longer to perform and involved a different sequential coordination of muscular activity than did the throw. Differences in muscle patterning between the two skills were greater during the force production phase in individuals judged to be skilled in both sport skills. The temporal differences between the two overarm skills suggested that, if performers can perceive time differences between 200 to 800 mseconds, then reference to or practice in the throw may not be a good method to gain expertise in the serve.  相似文献   

20.
The aims of this study were to examine the acute effects of static stretching on peak torque, work, the joint angle at peak torque, acceleration time, isokinetic range of motion, mechanomyographic amplitude, and electromyographic amplitude of the rectus femoris during maximal concentric isokinetic leg extensions at 1.04 and 5.23 rad x s(-1) in men and women. Ten women (mean +/- s: age 23.0 +/- 2.9 years, stature 1.61 +/- 0.12 m, mass 63.3 +/- 9.9 kg) and eight men (age 21.4 +/- 3.0 years, stature 1.83 +/- 0.11 m, mass 83.1 +/- 15.2 kg) performed maximal voluntary concentric isokinetic leg extensions at 1.04 and 5.23 rad x s(-1). Following the initial isokinetic tests, the dominant leg extensors were stretched using four static stretching exercises. After the stretching, the isokinetic tests were repeated. Peak torque, acceleration time, and electromyographic amplitude decreased (P< or = 0.05) from pre- to post-stretching at 1.04 and 5.23 rad . s(-1); there were no changes (P > 0.05) in work, joint angle at peak torque, isokinetic range of motion, or mechanomyographic amplitude. These findings indicate no stretching-related changes in the area under the angle - torque curve (work), but a significant decrease in peak torque, which suggests that static stretching may cause a "flattening" of the angle - torque curve that reduces peak strength but allows for greater force production at other joint angles. These findings, in conjunction with the increased limb acceleration rates (decreased acceleration time) observed in the present study, provide tentative support for the hypothesis that static stretching alters the angle - torque relationship and/or sarcomere shortening velocity.  相似文献   

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