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1.
To this day, how shoulder muscles react to a strong fatigue stimulus during dynamic shoulder rotations remains unknown. The aims of this study were to assess the effect of repeated maximal internal-external isokinetic shoulder rotations on shoulder strength and muscle activity. Twenty-four individuals completed a 50-repetition fatiguing isokinetic protocol while electromyography was recorded on eleven muscles of the shoulder girdle. Time-frequency transformation and an ANOVA model using statistical parametric mapping methods were used to analyze shifts in instantaneous median frequency (MDF) between each 10-repetition Blocks. Peak torques decreased in both internal and external rotation (P < 0.01) by 24.8% on average which indicated the presence of fatigue. Significant decrease in MDF (P < 0.01) was observed for pectoralis, middle deltoid, upper, middle and lower trapezius, infraspinatus and subscapularis muscles. The observed fatigue to the periscapular and rotator cuff muscles suggests that shoulder stability could be compromised during repeated shoulder rotations, which could underlie the increased risk of scapular dyskinesis and shoulder impingement during fatiguing tasks. The present study provides a deeper understanding on the manifestations of fatigue within muscles of the shoulder girdle and the results could be applied toward improvements in athlete shoulder injury prevention and rehabilitation programs.  相似文献   

2.
Abstract

The aim of the present study was to investigate the patterns of shoulder muscle activation and joint torques during maximal effort eccentric contractions with shoulder extension, abduction, and diagonal movements on the isokinetic device. Participants in this investigation were nine men and four women with no history of shoulder injury or disorders. They all participated in overhead sports at least three days a week, and volunteered to participate in this study for shoulder isokinetic muscle strength testing. They performed eccentric muscle action with shoulder flexion, abduction, and diagonal movements at velocities of 60 rad·s?1 and 180 rad· s?1, which was followed alternately by passive shoulder flexion, abduction and diagonal movement at a velocity of 30 rad· s?1, and total range of motion was standardised to 90°. Electromyography (EMG) and torque values were calculated to every 10°, except for the start and end 5° during each task. During each test, the isokinetic force output and muscle activation were synchronised. EMG data were normalised by percentage of maximum voluntary isometric contraction (%MVIC). EMG signals were recorded by surface EMG from the anterior deltoid (AD), middle deltoid (MD), posterior deltoid (PD), upper trapezius (UT), middle trapezius (MT), and biceps brachii (BB) muscles during this test. All of the muscle patterns were significantly decreased at the last compared with the initial part during eccentric shoulder flexion movement, except for the BB muscle (P < 0.05). AD and BB muscles played a similar role when peak torque was generated under load during eccentric muscle action with varying shoulder movements. PD and UT muscle activities were significantly lower than the other muscle activities during eccentric contraction with shoulder flexion and abduction movements, and the PD and UT muscles played a significant role in conjunction with MD and MT muscles in varying degrees during eccentric contraction with shoulder diagonal movements at 180 rad·s?1 (P < 0.05). Our study demonstrated that MT muscle activity was greatly influenced when torque values showed a peak moment under load during maximum effort, eccentric contraction with shoulder abduction and diagonal movements. However, the MD, PD, UT, and MT muscle activities had no great influence when peak torque was generated under load during eccentric muscle action with shoulder diagonal movement at high velocity. The present study suggested that varying eccentric muscle activity patterns may be needed to investigate proper training and functional contributions of upper extremity muscles to stabilisation of the shoulder joint when peak torque was generated under load.  相似文献   

3.
The abbreviated tennis serve is a relatively novel modification of the traditional serve that has been reported to provide performance advantages over the traditional technique. However, there are limited objective data regarding the benefits and biomechanics of the abbreviated serve; no data exist that describe shoulder muscle activations during the abbreviated serve. The purpose of this study was to compare muscle activations between the traditional and abbreviated serves. Electromyographic data were collected for the anterior and posterior deltoid, infraspinatus, middle trapezius, latissimus dorsi, serratus anterior, and pectoralis major. When muscle activations were compared during each serve phase, no significant differences were observed between the traditional and abbreviated tennis serve techniques, indicating that the traditional and abbreviated serves are similar regarding shoulder muscle activations. These results could have implications for performance of and injury related to the abbreviated versus traditional serve technique. Although the abbreviated serve has anecdotally been described as advantageous, the present data do not indicate any significant advantages or disadvantages in performing the abbreviated serve technique versus the traditional serve.  相似文献   

4.
The abbreviated tennis serve is a relatively novel modification of the traditional serve that has been reported to provide performance advantages over the traditional technique. However, there are limited objective data regarding the benefits and biomechanics of the abbreviated serve; no data exist that describe shoulder muscle activations during the abbreviated serve. The purpose of this study was to compare muscle activations between the traditional and abbreviated serves. Electromyographic data were collected for the anterior and posterior deltoid, infraspinatus, middle trapezius, latissimus dorsi, serratus anterior, and pectoralis major. When muscle activations were compared during each serve phase, no significant differences were observed between the traditional and abbreviated tennis serve techniques, indicating that the traditional and abbreviated serves are similar regarding shoulder muscle activations. These results could have implications for performance of and injury related to the abbreviated versus traditional serve technique. Although the abbreviated serve has anecdotally been described as advantageous, the present data do not indicate any significant advantages or disadvantages in performing the abbreviated serve technique versus the traditional serve.  相似文献   

5.
Shoulders of elite field hockey players are loaded continuously during play. However, shoulder girdle muscle performance in this population has never been examined yet. This study aimed to compare isokinetic shoulder girdle performance in elite male field hockey players to matched controls, with respect to strength, endurance and muscle balance. The complete male national field hockey team of Belgium (n = 25) was included and matched to a gender- and age-matched control group of healthy participants (n = 25). A Biodex system-4 dynamometer was used to measure glenohumeral and scapular muscle strength at 2 velocities in a concentric/concentric mode. With the main outcome measures being isokinetic strength values, peak force (protraction-retraction), peak torque (rotations), fatigue index and agonist/antagonist ratio’s. Measurement results showed that elite male field hockey players were stronger than their matched controls, for both the rotational and the protraction-retraction movement. Concerning rotational strength, symmetrical findings were established, contrary to scapular strength, where side differences were noted. At low velocity, retraction peak force was higher on the dominant side. Protraction peak force was higher on the non-dominant side when measured at high velocity. In conclusion, elite field hockey players have a symmetrical rotational strength profile, in contrast to their scapular strength profile.  相似文献   

6.
Abstract

This article presents an investigation, by means of electromyography, of the functions of the biceps brachii, the deltoideus, the latissimus dorsi, the pectoralis major, the serratus anterior, the cleido mastoideus, the teres major, the trapezius, and the triceps brachii (long head) in movements of the upper arm and the shoulder girdle at scapulo-humeral, acromioclavicular, and sternoclavicular joints. The procedure for collecting the data was established on the basis of records taken on twelve subjects; and the findings that are reported were based on 20 complete sets taken on five subjects.  相似文献   

7.
The aim of the study was to quantify the activation of arm and shoulder muscles during a static therapeutic climbing exercise and to investigate the possibility of altering the muscle activation through arm position (Jug, Undercling, Sidepull internal rotated, Sidepull external rotated), hand support (one-handed, double-handed) and wall inclination (0°, 12°). Electromyographic (EMG) activity of 14 healthy, climbing unexperienced males for the right m. biceps brachii (BB), m. serratus anterior (SA), m. upper, middle and lower trapezius (UT, MT, LT) showed mainly low to moderate EMG activation levels (BB: 4.1–40.1% maximum voluntary isometric contraction (MVIC), SA: 4.5–24.5% MVIC, UT: 1.3–28.0% MVIC, MT: 8.6–47.1% MVIC, LT: 3.8–47.3% MVIC). Significant differences occurred between the four arm positions for the UT and LT. The one-handed support revealed significant higher muscle activation than the double-handed support in every condition except for SA in Undercling arm position at 12° wall inclination. Increasing the wall inclination (from 0° to 12° overhang) led to a significant increase in muscle activation in nearly every exercise variation and muscle. These findings suggest that arm position, hand support and wall inclination are appropriate possibilities of altering muscle activation patterns in therapeutic climbing.  相似文献   

8.
Surface electromyographic (EMG) signals were recorded from the hamstring muscles during six sets of submaximal isokinetic (2.6 rad x s(-1)) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions. The EMG per unit torque increased during eccentric (P < 0.01) but not during concentric exercise. Similarly, the median frequency increased during eccentric (P < 0.01) but not during concentric exercise. The EMG per unit torque was lower for submaximal eccentric than maximum isometric contractions (P < 0.001), and lower for submaximal concentric than maximum isometric contractions (P < 0.01). The EMG per unit torque was lower for eccentric than concentric contractions (P < 0.05). The median frequency was higher for submaximal eccentric than maximum isometric contractions (P < 0.001); it was similar, however, between submaximal concentric and maximum isometric contractions (P = 0.07). Eccentric exercise resulted in significant isometric strength loss (P < 0.01), pain (P < 0.01) and muscle tenderness (P < 0.05). The greatest strength loss was seen 1 day after eccentric exercise, while the most severe pain and muscle tenderness occurred 2 days after eccentric exercise. A lower EMG per unit torque is consistent with the selective recruitment of a small number of motor units during eccentric exercise. A higher median frequency during eccentric contractions may be explained by selective recruitment of fast-twitch motor units. The present results are consistent with the theory that muscle damage results from excessive stress on a small number of active fibres during eccentric contractions.  相似文献   

9.
采用文献资料法、专家访谈法、测试法、数理统计法,探讨和研究了舞龙运动员等速运动状态下肩关节屈伸肌群的力学特征以及肌力的相互关系。结果表明:舞龙运动员肩关节屈伸肌的峰值力矩和相对峰力矩随着测试角速度的增加而下降;且左侧肩关节屈伸肌的峰值力矩和相对峰力矩均大于另一侧;肩关节屈伸肌峰力矩和相对峰力矩值均表现为伸肌群明显大于屈肌群;肩关节伸肌的峰力矩均大于屈肌的峰力矩;伸肌群的平均功率也明显大于屈肌群的平均功率。  相似文献   

10.
目的：探讨振动杆训练对射箭运动员固势-撒放阶段稳定性的影响。方法：以26名射箭运动员为研究对象,随机分为实验组（振动杆）和对照组,每组13名。对照组只进行常规射箭力量训练,实验组在常规射箭力量训练的基础上再进行振动杆训练（每次训练30 min,每周3次,共8周）,所有运动员在训练前及训练8周后分别测试积分肌电值（iEMG）、12支箭固势-撒放时间、黄心命中率等指标,并进行比较。结果：训练8周后,仅实验组射箭运动员双侧肩关节的前锯肌、上斜方肌、中斜方肌、下斜方肌、菱形肌和肩胛下肌的iEMG、固势-撒放时间、黄心命中率,较训练前有显著性差异（P＜0.05）。组间比较时,实验组双侧肩关节的前锯肌、上斜方肌、中斜方肌、下斜方肌、菱形肌和肩胛下肌的iEMG和肌肉活性、固势-撒放时间、黄心命中率,与对照组比较均具有显著性差异（P＜0.05）。结论：振动杆练习能显著提高肩胛骨主要稳定肌的激活水平,缩短固势-撒放时间以及提高黄心命中率,可作为射箭运动员体能训练的一种有效辅助手段。  相似文献   

11.
In this study, we evaluated the peak torque, functional torque ratios, and torque curve profile of the shoulder rotators in overhead athletes with impingement symptoms so as to examine possible alterations in response to sports training and shoulder pain. Twenty-one overhead athletes with impingement symptoms were compared with 25 overhead athletes and 21 non-athletes, none of whom were symptomatic for impingement. The participants performed five maximal isokinetic concentric and eccentric contractions of medial and lateral shoulder rotations at 1.57 rad · s(-1) and 3.14 rad · s(-1). Isokinetic peak torque was used to calculate the eccentric lateral rotation-to-concentric medial rotation and the eccentric medial rotation-to-concentric lateral rotation ratios. An analysis of the torque curve profiles was also carried out. The eccentric lateral rotation-to-concentric medial rotation torque ratio of asymptomatic athletes was lower than that of non-athletes at both test velocities. The concentric medial rotation isokinetic peak torque of the asymptomatic athletes, at 3.14 rad · s(-1), was greater than that of the non-athletes, and the peak appeared to occur earlier in the movement for athletes than non-athletes. These findings suggest that there may be adaptations to shoulder function in response to throwing practice. The eccentric medial rotation-to-concentric lateral rotation torque ratio was altered neither by the practice of university-level overhead sports nor impingement symptoms.  相似文献   

12.
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 welltrained 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   

13.
Surface electromyographic (EMG) signals were recorded from the hamstring muscles during six sets of submaximal isokinetic (2.6 rad s -1 ) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions. The EMG per unit torque increased during eccentric (P < 0.01) but not during concentric exercise. Similarly, the median frequency increased during eccentric (P < 0.01) but not during concentric exercise. The EMG per unit torque was lower for submaximal eccentric than maximum isometric contractions (P < 0.001), and lower for submaximal concentric than maximum isometric contractions (P < 0.01). The EMG per unit torque was lower for eccentric than concentric contractions (P < 0.05). The median frequency was higher for submaximal eccentric than maximum isometric contractions (P < 0.001); it was similar, however, between submaximal concentric and maximum isometric contractions (P = 0.07). Eccentric exercise resulted in significant isometric strength loss (P < 0.01), pain (P < 0.01) and muscle tenderness (P < 0.05). The greatest strength loss was seen 1 day after eccentric exercise, while the most severe pain and muscle tenderness occurred 2 days after eccentric exercise. A lower EMG per unit torque is consistent with the selective recruitment of a small number of motor units during eccentric exercise. A higher median frequency during eccentric contractions may be explained by selective recruitment of fast-twitch motor units. The present results are consistent with the theory that muscle damage results from excessive stress on a small number of active fibres during eccentric contractions.  相似文献   

14.
The proximal-to-distal segmental sequence has been identified in many sports activities, including baseball pitching and ball kicking. However, proximal-to-distal sequential muscle activity has not been identified. The aims of this study were to establish whether sequential muscle activity does occur and, if it does, to determine its functional role. We recorded surface electromyograms (EMGs) for 17 muscles from the upper extremity and abdomen during overarm throwing and detected the onset and peak times as indices of muscle activity. The following electromyographic properties were commonly identified in the participants. First, sequential muscle activity was observed from the scapular protractors to the shoulder horizontal flexors and from the shoulder horizontal flexors to the elbow extensor, but not from the elbow extensor to the wrist flexor or forearm pronator. Secondly, the external oblique contralateral to the throwing arm became activated before the ipsilateral external oblique. This sequence is considered to be very effective for the generation of high force and energy in the trunk. Thirdly, the ipsilateral external oblique began its activity almost at foot strike. Finally, the main activity of the rectus abdominis appeared just before the point of release.  相似文献   

15.
The proximal-to-distal segmental sequence has been identified in many sports activities, including baseball pitching and ball kicking. However, proximal-to-distal sequential muscle activity has not been identified. The aims of this study were to establish whether sequential muscle activity does occur and, if it does, to determine its functional role. We recorded surface electromyograms (EMGs) for 17 muscles from the upper extremity and abdomen during overarm throwing and detected the onset and peak times as indices of muscle activity. The following electromyographic properties were commonly identified in the participants. First, sequential muscle activity was observed from the scapular protractors to the shoulder horizontal flexors and from the shoulder horizontal flexors to the elbow extensor, but not from the elbow extensor to the wrist flexor or forearm pronator. Secondly, the external oblique contralateral to the throwing arm became activated before the ipsilateral external oblique. This sequence is considered to be very effective for the generation of high force and energy in the trunk. Thirdly, the ipsilateral external oblique began its activity almost at foot strike. Finally, the main activity of the rectus abdominis appeared just before the point of release.  相似文献   

16.
Abstract

In this study, we evaluated the peak torque, functional torque ratios, and torque curve profile of the shoulder rotators in overhead athletes with impingement symptoms so as to examine possible alterations in response to sports training and shoulder pain. Twenty-one overhead athletes with impingement symptoms were compared with 25 overhead athletes and 21 non-athletes, none of whom were symptomatic for impingement. The participants performed five maximal isokinetic concentric and eccentric contractions of medial and lateral shoulder rotations at 1.57 rad · s?1 and 3.14 rad · s?1. Isokinetic peak torque was used to calculate the eccentric lateral rotation-to-concentric medial rotation and the eccentric medial rotation-to-concentric lateral rotation ratios. An analysis of the torque curve profiles was also carried out. The eccentric lateral rotation-to-concentric medial rotation torque ratio of asymptomatic athletes was lower than that of non-athletes at both test velocities. The concentric medial rotation isokinetic peak torque of the asymptomatic athletes, at 3.14 rad · s?1, was greater than that of the non-athletes, and the peak appeared to occur earlier in the movement for athletes than non-athletes. These findings suggest that there may be adaptations to shoulder function in response to throwing practice. The eccentric medial rotation-to-concentric lateral rotation torque ratio was altered neither by the practice of university-level overhead sports nor impingement symptoms.  相似文献   

17.
The purpose of this study was to evaluate the effects of whole-body vibration (WBV) on the muscle recruitment of selected upper and lower body muscles during the baseball swing. Participants were recreationally trained males (n = 16, 22 +/- 2 years, 181.4 +/- 7.4 cm, 84.7 +/- 9.0 kg), with previous baseball experience. Subjects participated in three randomized sessions on separate days, consisting of three sets of five swings offa hitting tee. Exercises (upper and lower body dynamic and static movements) with or without WBVexposure were performed between swing sets. During each swing, the gastrocnemius, biceps femoris, gluteus maximus, pectoralis major, latissimus dorsi, and triceps brachii were evaluated for electromyographic (EMG) activity. EMG values were normalized to EMG measured during maximal voluntary isometric contraction. Statistical analysis revealed no significant differences in EMG activity across the three treatments. In addition, the results displayed a specific muscle recruitment order during the swing, starting with the lower body followed by the upper body muscles. This study was the first to report the recruitment order during the baseball swing. Although acute exposure to WBV did not significantly alter the muscle recruitment, these results may prove useful for practitioners looking to enhance baseball swing performance.  相似文献   

18.
Isokinetic dynamometry is used in the assessment and rehabilitation of shoulder function in tennis players. The aim of this study was to validate a newly installed Biodex III Isokinetic Dynamometer for internal and external shoulder rotation. A non-injured male performed this movement which replicates an integral section of the tennis service action (Cohen et al., 1994). Three maximal trials were performed at six randomly assigned angular velocities (0.52, 1.05, 1.57, 2.09, 2.62 and 3.14 rad x s(-1)) with 90 s rest between each set. Trials were recorded using an on-line motion analysis system and kinematic data were obtained. Kinematic angular displacement of the lever arm was slightly greater (> or = 0.01 rad x s(-1)) than for the isokinetic dynamometer at all test angular velocities. Mean angular velocities from the kinematic data were almost identical to those from the isokinetic dynamometer but less than the target values, and this difference (e.g. 2.55 rad x s(-1) at 3.14 rad x s(-1)) was greater at higher angular velocities owing to the greater acceleration phases required. Peak angular velocity was similar on the isokinetic dynamometer to the target values, but substantially less than those from the kinematic data (e.g. 0.68 rad x s(-1) at 0.52 rad x s(-1)). This suggests that the isokinetic data are over-smoothed and may mask important information. In summary, criterion validity of this isokinetic dynamometer is supported for displacement and mean angular velocity, but not for peak angular velocity. Shoulder rotations in tennis are often at angular velocities greater than the Biodex can reproduce, but for the purpose of monitoring the shoulder strength and range of motion of tennis players and providing safe functional rehabilitation, the use of slower angular velocities is acceptable.  相似文献   

19.
运用等速测试方法分析青年女子柔道运动员的肌力特征,为针对性力量训练和伤病预防提供依据。研究发现:躯干相对峰力矩偏低,屈肌1.7,伸肌2.46。肩关节内外旋拮抗比0.7-0.9,左侧显著高于右侧。膝关节屈伸肌群拮抗比0.5-0.6,内外旋拮抗比0.6-0.8,双侧差异显著。踝关节屈伸肌群拮抗比0.4-0.5,内外旋拮抗比0.5-0.8,双侧差异显著。结果表明:青年女子柔道运动员的肩、膝、踝关节双侧差异和拮抗肌群肌力比率均为高损伤风险指征,提示青少年阶段就应当开始加强薄弱肌群的训练,提前降低受伤风险。  相似文献   

20.
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   

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