Functional torque ratios and torque curve analysis of shoulder rotations in overhead athletes with and without impingement symptoms

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.     

Functional shoulder ratios with high velocities of shoulder internal rotation are most sensitive to determine shoulder rotation torque imbalance: a cross-sectional study with elite handball players and controls

The aim of the present study was to determine which approach to calculating shoulder ratios is the most sensitive for determining shoulder torque imbalance in handball players. Twenty-six participants (handball athletes, n = 13; healthy controls, n = 13) performed isokinetic concentric and eccentric shoulder internal rotation (IR) and external rotation (ER) assessment at 60, 180 and 300°/s. We used eight approaches to calculating shoulder ratios: four concentric (i.e. concentric ER torque divided by concentric IR torque), and four functional (i.e. eccentric ER torque divided by concentric IR torque) at the velocities of 60, 180 and 300°/s for both IR and ER, and combining 60°/s of ER and 300°/s of IR. A three factorial ANOVA (factors: shoulder ratios, upper limb sides, and groups) along with Tukey’s post-hoc analysis, and effect sizes were calculated. The findings suggested the functional shoulder ratio combining 60°/s of ER and 300°/s of IR is the most sensitive to detect differences between upper limbs for handball players, and between players and controls for the dominant side. The functional shoulder ratio combining 60°/s of ER with 300°/s of IR seems to present advantages over the other approaches for identifying upper limb asymmetries and differences in shoulder torque balance related to throwing.     

Scapular motion adaptations in junior overhead athletes: a three-dimensional kinematic analysis in tennis players and non-overhead athletes

Adult overhead athletes without a history of shoulder injury show scapular adaptations. There is a lack of detailed assessment of scapular kinematics in junior overhead athletes. This study aims to investigate three-dimensional scapular kinematics in junior overhead athletes. We recruited a total of 20 junior tennis players and 20 healthy children without participation in any overhead sports in this study. Bilateral scapular kinematic data were recorded using an electromagnetic tracking device for scapular plane glenohumeral elevation. The data were further analysed at 30°, 45°, 60°, 90° and 120° during glenohumeral elevation and lowering. Statistical comparisons of the data between groups (junior overhead athletes and non-overhead athletes) and sides (serve dominant and non-dominant shoulders of the overhead athletes) were analysed with the ANOVA. Comparisons showed that, in general, the scapula was more upwardly rotated and anteriorly tilted in overhead athletes when compared to non-overhead athletes, however there was no side-to-side differences when serve dominant and non-dominant shoulders compared in junior overhead athletes. The serve dominant arm of junior overhead athletes had alternations in scapular kinematics when compared with the non-overhead athletes. These findings provide clinical evaluation implications and the need for clinicians to assess for potential adaptations in junior overhead athletes.     

Vertical jumping height and horizontal overhead throwing velocity in young male athletes

Abstract

The purpose of this study was to examine the effects of calendar and skeletal age, anthropometric dimensions, training history and their interactions on vertical jumping height and horizontal overhead throwing velocity in a cross‐section of 318 young male athletes (age range 9–16 years) participating in cross‐country skiing (n = 70), basketball (n = 40), apparatus gymnastics (n = 19), ice hockey (n = 50), track and field (n = 89) and wrestling (n = 50). Vertical jumping height was measured with four different loads held on the shoulders and then interpolated for loads representing 0 and 40% body mass. Horizontal overhead throwing velocity using both hands was determined for seven balls of different weights and then interpolated for weights representing 1 and 5% body mass.

Both vertical jumping height and overhead throwing velocity were found to increase (P< 0.01) from the skeletally youngest to the oldest cohort when the effects of body height and mass were controlled. The inter‐event comparisons did not reveal statistically significant differences in respect of vertical jumping height. Also in the overhead throwing tests, the inter‐event differences were small, although the analysis of variance revealed statistically significant (P< 0.001) differences for the skeletal age cohorts of 13 and 14 years. While the quantity of training had no effect on vertical jumping height, it explained the results in the overhead throwing test.

The effects of training on vertical jumping and horizontal overhead throwing among adolescent athletes were considered to be small, while maturational processes and anthropometric development followed by increase in calendar age were deemed to be of greater importance.     

Vertical jumping height and horizontal overhead throwing velocity in young male athletes.

The purpose of this study was to examine the effects of calendar and skeletal age, anthropometric dimensions, training history and their interactions on vertical jumping height and horizontal overhead throwing velocity in a cross-section of 318 young male athletes (age range 9-16 years) participating in cross-country skiing (n = 70), basketball (n = 40), apparatus gymnastics (n = 19), ice hockey (n = 50), track and field (n = 89) and wrestling (n = 50). Vertical jumping height was measured with four different loads held on the shoulders and then interpolated for loads representing 0 and 40% body mass. Horizontal overhead throwing velocity using both hands was determined for seven balls of different weights and then interpolated for weights representing 1 and 5% body mass. Both vertical jumping height and overhead throwing velocity were found to increase (P < 0.01) from the skeletally youngest to the oldest cohort when the effects of body height and mass were controlled. The inter-event comparisons did not reveal statistically significant differences in respect of vertical jumping height. Also in the overhead throwing tests, the inter-event differences were small, although the analysis of variance revealed statistically significant (P < 0.001) differences for the skeletal age cohorts of 13 and 14 years. While the quantity of training had no effect on vertical jumping height, it explained the results in the overhead throwing test. The effects of training on vertical jumping and horizontal overhead throwing among adolescent athletes were considered to be small, while maturational processes and anthropometric development followed by increase in calendar age were deemed to be of greater importance.     

Cognitive-motor dual-task ability of athletes with and without intellectual impairment

Cognition is important in many sports, for example, making split-second-decisions under pressure, or memorising complex movement sequences. The dual-task (DT) paradigm is an ecologically valid approach for the assessment of cognitive function in conjunction with motor demands. This study aimed to determine the impact of impaired intelligence on DT performance. The motor task required balancing on one leg on a beam, and the cognitive task was a multiple-object-tracking (MOT) task assessing dynamic visual-search capacity. The sample included 206 well-trained athletes with and without intellectual impairment (II), matched for sport, age and training volume (140 males, 66 females, M age = 23.2 ± 4.1 years, M training experience = 12.3 ± 5.7 years). In the single-task condition, II-athletes showed reduced balance control (F = 55.9, P < .001, η² = .23) and reduced MOT (F = 86.3, P < .001, η² = .32) compared to the control group. A mixed-model ANCOVA revealed significant differences in DT performance for the balance and the MOT task between both groups. The DT costs were significantly larger for the II-athletes (?8.28% versus ?1.34% for MOT and ?33.13% versus ?12.89% for balance). The assessment of MOT in a DT paradigm provided insight in how impaired intelligence constrains the ability of II-athletes to successfully perform at the highest levels in the complex and dynamical sport-environment.     

Evolution of muscular fatigue in periscapular and rotator cuff muscles during isokinetic shoulder rotations

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.     

乒乓球运动员肩关节损伤原因及预防对策

肩关节损伤在乒乓球运动损伤中最为常见,损伤不仅影响运动员运动成绩的提高、运动寿命的减短,甚至给运动员的生理、心理造成严重的影响。本文分析了乒乓球运动员肩关节损伤的原因,并相应提出有效的预防措施,旨在为保证训练的正常进行及提高运动员的运动寿命提供参考。     

Global and regional cardiac function in lifelong endurance athletes with and without myocardial fibrosis

The aim of the present study was to compare cardiac structure as well as global and regional cardiac function in athletes with and without myocardial fibrosis (MF). Cardiac magnetic resonance imaging with late gadolinium enhancement was used to detect MF and global cardiac structure in nine lifelong veteran endurance athletes (58?±?5 years, 43?±?5 years of training). Transthoracic echocardiography using tissue-Doppler and myocardial strain imaging assessed global and regional (18 segments) longitudinal left ventricular function. MF was present in four athletes (range 1–8?g) and not present in five athletes. MF was located near the insertion points of the right ventricular free wall on the left ventricle in three athletes and in the epicardial lateral wall in one athlete. Athletes with MF demonstrated a larger end diastolic volume (205?±?24 vs 173?±?18?ml) and posterior wall thickness (11?±?1 vs 9?±?1?mm) compared to those without MF. The presence of MF did not mediate global tissue velocities or global longitudinal strain and strain rate; however, regional analysis of longitudinal strain demonstrated reduced function in some fibrotic regions. Furthermore, base to apex gradient was affected in three out of four athletes with MF. Lifelong veteran endurance athletes with MF demonstrate larger cardiac dimensions and normal global cardiac function. Fibrotic areas may demonstrate some co-localised regional cardiac dysfunction, evidenced by an affected cardiac strain and base to apex gradient. These data emphasize the heterogeneous phenotype of MF in athletes.     

Insights into the epidemiology,aetiology and associations of infraspinatus atrophy in overhead athletes: a systematic review

Infraspinatus atrophy (IA) is much more prevalent in overhead sports compared with the general population. Its exact aetiology in this group of athletes remains unclear and definitive associations with pathology and performance have not yet been reached. The aim of this systematic review is to present the evidence on IA in overhead athletes focussing on the proposed mechanisms of suprascapular neuropathy and its associations with shoulder pathology and performance. A thorough literature search via Medline, EMBASE and Scopus was performed. From the nine articles identified, the majority of authors propose suprascapular nerve (SN) injury at the spinoglenoid notch; however, the suprascapular notch has also been suggested as a potential site of injury. With regard to the exact mechanism of suprascapular neuropathy, the majority of authors propose repeated traction of the nerve during extreme shoulder abduction and horizontal adduction and/or eccentric contractions of the infraspinatus. In the limited relevant literature, convincing links between IA and performance or shoulder pathology have not been identified. IA in overhead sports is most likely of multi-factorial aetiology. Important questions about IA and its significance in overhead sports remain unanswered and more biomechanical and prospective studies are warranted to provide further insights into this athletic injury.     

我国优秀划艇运动员肩、肘关节肌力特征的比较研究

运用等速测试系统对备战伦敦奥运会的国家划艇运动员的肩关节、肘关节肌力进行测试与分析。结果表明:1)从力矩角度来看,优秀运动员与一般运动员在肩、肘关节肌力特征中存在显著性差异(P<0.05),且屈肌和伸肌的力矩角度分别呈现不同的特征;2)从峰力矩比值来看,在不同速度运动下,国家队优秀运动员和一般运动员均存在屈伸比的失衡问题,即最大力量上存在屈伸肌群发展的不合理化现象(<50%),随着测试速度的增加,屈伸比呈递减趋势;3)在肘关节两侧同名肌群的比较中同样存在不均衡现象,尤其是伸肌的两侧差值较大;4)肩关节的肌力特征也存在类似的现象,但屈肌明显不如伸肌力量。结论:应逐步加强划艇运动员肩、肘关节同侧屈伸肌群和异侧同名肌群的力量均衡性训练,并提高肩关节的屈肌力量能力。     

Implicit and explicit attitudes towards sport among young elite athletes with high versus low burnout symptoms

The development of cynical attitudes towards elite sport is a core symptom of athlete burnout and has been associated with dropout from elite sport. To date, this phenomenon has mainly been studied by investigating explicit attitudes towards sport, whereas athletes’ automatic evaluations (i.e. implicit attitudes) that have been shown to influence behavior as well were not considered. This study aimed to compare explicit and implicit attitudes towards sport of young elite athletes with high (N = 24) versus low (N = 26) burnout symptoms. Using self-reported measures, general and athlete burnout symptoms were assessed. Additionally, a single-target implicit association test was administered to examine participants’ automatic evaluation of sport. Statistical analysis revealed greater emotional/physical exhaustion and sport devaluation in athletes reporting high compared to low burnout symptoms. Implicit attitudes towards sport did not significantly differ between the groups. Furthermore, no significant correlations were observed between different athlete burnout symptoms and implicit attitudes. Athletes with high burnout symptoms show a tendency to explicitly detach themselves from sport, thus fostering sport devaluation as a core symptom of athlete burnout. However, this process does not seem to be reflected in their implicit attitudes towards sport.     

Differences in distal lower extremity tissue masses and mass ratios exist in athletes of sports involving repetitive impacts

Abstract

The purpose of this study was to compare changes in aerobic condition, strength, and muscular endurance following 8 weeks of endurance rowing alone or in combination with weight-training. Twenty-two elite rowers were assigned to (1) rowing (n = 10, 250–270 km · week^?1) or (2) rowing (n = 12, 190–210 km · week^?1) plus four weight-training sessions each week. Pre and post mean and standardized effect-size (ES) differences in aerobic condition (watts at 4 mmol · L^?1) and strength (isometric pull, N), prone bench-pull (6-repetition maximum, 6-RM), 5- and 30-repetition leg-press and 60-repetition seated-arm-pull (J, performed on a dynamometer) normalized by body mass and log-transformed were analysed, after adjusting for gender. The standardized differences between groups were trivial for aerobic condition (ES [±90% CI] = 0.15; ±0.28, P = 0.37) and prone bench-pull (ES = 0.27; ±0.33, P = 0.18), although a moderate positive benefit in favour of rowing only was observed for the seated-arm-pull (ES = 0.42; ±0.4, P = 0.08). Only the weight-training group improved isometric pull (12.4 ± 8.9%, P < 0.01), 5-repetition (4.0 ± 5.7%, P < 0.01) and 30-repetition (2.4 ± 5.4%, P < 0.01) leg-press. In conclusion, while gains in aerobic condition and upper-body strength were comparable to extensive endurance rowing, weight-training led to moderately greater lower-body muscular-endurance and strength gains.     

我国奥运项目一、二线等级运动员发展比较分析及人数预测研究

我国一、二线等级运动员比例从1984年的1：0．6增长到2001年的1：6。1991年后，一线运动队运动健将与二级运动员人数呈逆向发展的趋势。预测到2008年，我国奥运项目一线运动员人数将会达到17006-21652人，二线运动员为51525人，三线运动员为407710人，一、二、三线运动队人数的比例关系将达到1：3．0：23．8，二三线后备队伍将会获得更好的生存环境，奥运项目金字塔结构将获得一个更加雄厚的基础。     

Tissue mass ratios and the reporting of distal lower extremity injuries in varsity athletes at a Canadian University

Abstract

The purpose of this preliminary investigation was to determine the relative role of the distal lower extremity tissue masses of varsity athletes in predicting distal lower extremity injury sustained during a competitive season. One hundred male and female varsity athletes (basketball, volleyball, soccer, cross country) completed a questionnaire on general health, physiological, and psychosocial variables, during each sport's respective training camp. A series of anthropometric measurements were used as inputs to distal lower extremity tissue mass prediction equations to calculate lean mass, fat mass, bone mineral content and wobbling mass (lean mass + fat mass) and tissue mass ratios. Athletes were monitored throughout their respective seasons and were instructed to report any distal lower extremity injuries to a certified athletic therapist who was responsible for assessing and confirming the reports. Logistic regression analyses were performed to determine which variables significantly predicted distal lower extremity injury. Mean leg fat mass:bone mass (OR = 1.6, CI = 1.0 – 2.5), and competition surface (rubber OR = 8.5, CI = 1.5 – 47.7; artificial turf OR = 4.0, CI = 0.77 – 22.9) were identified as significant predictors of injury. Overall, tibia bone injuries were significantly associated with the ratio of fat mass:bone mineral content and the surface on which the athletes compete.     

Muscle recruitment patterns of the subscapularis,serratus anterior and other shoulder girdle muscles during isokinetic internal and external rotations

The aims of this study were to investigate the differences in peak muscle activity and recruitment patterns during high- and low-velocity, concentric and eccentric, internal and external isokinetic shoulder rotations. Electromyographic activity of the rotator cuff and eight superficial muscles of the shoulder girdle was recorded on 25 healthy adults during isokinetic internal and external shoulder rotation at 60°/s and 240°/s. Peak muscle activity, electromyographic envelopes and peak isokinetic moments were analyzed using three-factor ANOVA and statistical parametric mapping. The subscapularis and serratus anterior showed moderate to high peak activity levels during each conditions, while the middle and posterior deltoids, upper, middle and lower trapezius, infraspinatus and supraspinatus showed higher peak activity levels during external rotations (+36.5% of maximum voluntary activation (MVA)). The pectoralis major and latissimus dorsi were more active during internal rotations (+40% of MVA). Only middle trapezius and pectoralis major electromyographic activity decreased with increasing velocity. Peak muscle activity was similar or lower during eccentric contractions, although the peak isokinetic moment increased by 35% on average. The subscapularis and serratus anterior appear to be important stabilizers of the glenohumeral joint and scapula. Isokinetic eccentric training at high velocities may allow for faster recruitment of the shoulder girdle muscles, which could improve joint stability during shoulder internal and external rotations.     

竞技舞龙运动员肩关节屈伸肌群等速肌力特征研究

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。     

23例运动员膝关节损伤的MRI影像分析

目的探讨与总结磁共振成像在臻关节损伤的影像应用中的价值.方法分析运动员膝关节创伤的病例原因及特点.结果 23例膝关节创伤引起的软骨、软骨下骨、韧带、肌肉及关节囊损伤在MRI中的影像学信号改变.结论 MRI对于膝关节损伤具有高度敏感性,尤其是各种序列的应用对发现细微的病变及增加检出率很有帮助.     

从国外运动员的投掷特征看我国优秀女子链球选手的投掷技术

对我国5名优秀女子链球运动员使用近景动态三维录像分析系统分析运动员的投掷技术,结果表明,第四圈双支撑阶段加速能力较强,但在第四圈单支撑阶段速度损失过大;链球旋转速度增量与各圈轨迹中双支撑与单支撑的比值有关,增大链球各圈轨迹中双支撑与单支撑的比值有助于链球旋转速度增量的提高;加大投掷动作的动作幅度,增大各圈旋转中运动员的各运动环节的最大值与最小值的差值对链球旋转速度增量的提高具有十分重要意义。     

Eating psychopathology as a risk factor for depressive symptoms in a sample of British athletes

Abstract

Within the clinical literature it is accepted that there is a strong connection between eating disorders and depression; however the nature of the casual relationship is somewhat unclear. Therefore the aim of the present study was to determine the prospective relationship between eating psychopathology and depressive symptoms among competitive British athletes. A total of 122 athletes completed the Eating Disorder Examination Questionnaire and the depression subscale of the Symptom Checklist-90R over a 6-month period. Partial correlations revealed that when controlling for baseline eating psychopathology, athletes’ baseline depressive symptoms was not related to their eating psychopathology 6 months later. However, when controlling for baseline depressive symptoms, athletes’ initial eating psychopathology was positively and significantly related to depressive symptoms 6 months later. Subsequent hierarchical multiple regression analyses revealed athletes’ initial levels of eating psychopathology significantly predicted depressive symptoms 6 months later. The current findings support the assertion that elevated eating psychopathology serves as a potential risk factor for the development of depression in athletes. Thus, National Governing Bodies, athletic clubs, sport organisations and universities need to recognise and be aware that exposure to the factors that increase the risk of eating disorders inadvertently serves to increase athletes’ vulnerability for depression.