Functional hamstrings: quadriceps ratios in elite women's soccer players     

Nathaniel D.M. Jenkins  Matthew J. Hawkey  Pablo B. Costa  Ryan E. Fiddler  Brennan J. Thompson  Eric D. Ryan 《Journal of sports sciences》2013,31(6):612-617

Abstract

We compared starters and non-starters for various isokinetic strength variables in elite women’s soccer players. A convenience sample of 10 starters (mean ± s; age = 20 ± 2 years; height = 170 ± 4 cm; body mass = 65 ± 5 kg) and 7 non-starters (age = 20 ± 1 years; height = 164 ± 3 cm; body mass = 63 ± 4 kg) performed maximal voluntary muscle actions of the leg extensors (concentric) and flexors (eccentric) on an isokinetic dynamometer in order to measure concentric peak torque for the leg extensors, eccentric peak torque for the leg flexors, and the functional hamstrings:quadriceps (H:Q) ratio at 1.047 rad · s^-1 and 4.189 rad · s^-1 concentric peak torque for the leg extensors was not different between starters and non-starters. However, it was greater at 1.047 rad · s^-1 than at 4.189 rad · s^-1 in both groups. Eccentric peak torque for the leg flexors was greater for the starters versus non-starters at 4.189 rad · s^-1. Eccentric strength of the leg flexors at fast movement velocities may be used as an effective physiological profile and may discriminate between playing status in elite women’s soccer players.  相似文献   

The effects of eccentric exercise-induced muscle damage on running kinematics at different speeds     

Themistoklis Tsatalas  Giannis Spyropoulos  Vasileios Sideris  Savvas Lazaridis  Christos Kotzamanidis 《Journal of sports sciences》2013,31(3):288-298

Abstract

This study investigated the effects of knee localised muscle damage on running kinematics at varying speeds. Nineteen young women (23.2 ± 2.8 years; 164 ± 8 cm; 53.6 ± 5.4 kg), performed a maximal eccentric muscle damage protocol (5 × 15) of the knee extensors and flexors of both legs at 60 rad · s^-1. Lower body kinematics was assessed during level running on a treadmill at three speeds pre- and 48 h after. Evaluated muscle damage indices included isometric torque, muscle soreness and serum creatine kinase activity. The results revealed that all indices changed significantly after exercise, indicating muscle injury. Step length decreased and stride frequency significantly increased 48 h post-exercise only at the fastest running speed (3 m · s^-1). Support time and knee flexion at toe-off increased only at the preferred transition speed and 2.5 m · s^-1. Knee flexion at foot contact, pelvic tilt and obliquity significantly increased, whereas hip extension during stance-phase, knee flexion during swing-phase, as well as knee and ankle joints range of motion significantly decreased 48 h post-exercise at all speeds. In conclusion, the effects of eccentric exercise of both knee extensors and flexors on particular tempo-spatial parameters and knee kinematics of running are speed-dependent. However, several pelvic and lower joint kinematics present similar behaviour at the three running speeds examined. These findings provide new insights into how running kinematics at different speeds are adapted to compensate for the impaired function of the knee musculature following muscle damage.  相似文献   

Acute effects of static and dynamic stretching on hamstrings’ response times     

Francisco Ayala  Mark De Ste Croix  Pilar Sainz de Baranda  Fernando Santonja 《Journal of sports sciences》2013,31(9):817-825

Abstract

The main purposes of this study were to (a) investigate acute effects of static and dynamic lower limb stretching routines on total response time, pre-motor time and motor time of the medial and lateral hamstrings during maximal eccentric isokinetic knee flexion; and (b) determine whether static and dynamic routines elicit similar responses. A total of 38 active adults completed the following intervention protocols in a randomised order on separate days: (a) non-stretching (control condition), (b) static stretching and (c) dynamic stretching. After the stretching or control intervention, total response time, pre-motor time and motor time of the medial and lateral hamstrings were assessed during eccentric knee flexion movements with participants prone. Measures were compared via a mixed-design factorial ANOVA. There were no main effects for total response time, pre-motor time and motor time. The results suggest that dynamic and static stretching has no influence on hamstrings response times (total response time, pre-motor time and motor time) and hence neither form of stretching reduces this primary risk factor for anterior cruciate ligament injury.  相似文献   

Isokinetic imbalance of hip muscles in soccer players with osteitis pubis     

Walaa Sayed Mohammad  Osama Ragaa Abdelraouf  Salam Mohamed Elhafez  Nagui Sobhi Nassif 《Journal of sports sciences》2013,31(10):934-939

Abstract

In this study, we compared the isokinetic torques of hip flexors/extensors and abductors/adductors in soccer players suffering from osteitis pubis (OP), with normal soccer players. Twenty soccer male athletes with OP and 20 normal soccer athletes were included in this study. Peak torque/body weight (PT/BW) was recorded from hip flexor/extensor and abductor/adductor muscles during isokinetic concentric contraction modes at angular velocity of 2.1 rad · s^?1, for both groups. The results showed a significant difference between the normal and OP groups for hip flexors (P < 0.05). The normal group had significant, lower PT/BW value than the OP group for their hip flexors (P < 0.05). The hip flexor/extensor PT ratio of OP affected and non-affected limbs was significantly different from that of normal dominant and non-dominant limbs. There were no significant differences between the normal and OP groups for hip extensor, adductor and abductor muscles (P > 0.05). Regarding the hip adductor/abductor PT ratio, there was no significant difference between the normal and OP groups of athletes (P > 0.05). The OP group displayed increase in hip flexor strength that disturbed the hip flexor/extensor torque ratio of OP. Therefore, increasing the hip extensor strength should be part of rehabilitation programmes of patients with OP.  相似文献   

Effects of Training on the Estimation of Muscular Moment in Submaximal Exercise     

Celine Leverrier  Antoine Gauthier  Arnaud Nicolas  Corinne Molinaro 《Research quarterly for exercise and sport》2013,84(3):458-465

Abstract

The purpose of this study was to observe the effects of a submaximal isometric training program on estimation capacity at 25, 50, and 75% of maximal contraction in isometric action and at two angular velocities. The second purpose was to study the variability of isometric action. To achieve these purposes, participants carried out an isokinetic extension movement of the dominant lower limb during six test sessions and nine training sessions. Following the training program, estimation capacity in the different actions did not improve. However, an improvement in performance was observed with a reduction in the variability of submaximal isometric actions. The proprioceptors activated in isometric action seemed to adapt to the training program itself, which would promote better adaptation by a greater solicitation of internal feedback.  相似文献   

Analysis of elbow muscle strength parameters in Brazilian jiu-jitsu practitioners     

Bruno Follmer  Rodolfo André Dellagrana  Luis Antonio Pereira de Lima  Walter Herzog 《Journal of sports sciences》2017,35(23):2373-2379

Upper-body dynamic and isometric maximum strength are essential components for success in Brazilian jiu-jitsu (BJJ). This study was aimed at analysing strength parameters in the elbow flexor and extensor muscles of BJJ practitioners. Participants (n = 28) performed maximum isometric contractions of elbow flexors and extensors to determine peak torque (PT), rate of force development (RFD), and the torque–angle (T–A) relationship at elbow angles of 45°, 60°, 75°, 90°, 105°, and 120°. Additionally, concentric and eccentric PTs were measured at 1.04 rad·s^-1. Student t-test and ANOVA were performed using α = 0.05. Elbow flexors were stronger isometrically (P < 0.001, ES = 1.23) but weaker concentrically (P < 0.05, ES = 0.54) than extensor muscles, possibly because of the extensive grip disputes and pushing of opponents in BJJ. The T–A relationship had an inverted “U”-shape. Torque differences across elbow angles were moderate (ES = 0.62) for the extensor and large (ES = 0.92) for the flexor muscles. Isometric torque was greatest for elbow angles of 105° and 75° and smallest for 45° and 120° for extensor and flexor muscles, respectively. Elbow flexors had a greater RFD than extensors, regardless of elbow angle. The present study provides comprehensive results for elbow muscle strength in BJJ practitioners.  相似文献   

竞技舞龙运动员肩关节屈伸肌群等速肌力特征研究     

莫兰  ;雷军蓉 《辽宁体育科技》2014,(3):26-28

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   

Lower extremity injury in female basketball players is related to a large difference in peak eversion torque between barefoot and shod conditions     

《运动与健康科学(英文)》2014,3(3):227-232

BackgroundThe majority of injuries reported in female basketball players are ankle sprains and mechanisms leading to injury have been debated. Investigations into muscular imbalances in barefoot versus shod conditions and their relationship with injury severity have not been performed. The purpose of this study was to investigate the effects of wearing athletic shoes on muscular strength and its relationship to lower extremity injuries, specifically female basketball players due to the high incidence of ankle injuries in this population.MethodsDuring pre-season, 11 female collegiate basketball players underwent inversion and eversion muscle strength testing using an isokinetic dynamometer in both a barefoot and shod conditions. The difference between conditions was calculated for inversion and eversion peak torque, time to peak torque as well as eversion-to-inversion peak torque percent strength ratio for both conditions. Lower extremity injuries were documented and ranked in severity. The ranked difference between barefoot and shod conditions for peak torque and time to peak torque as well as percent strength ratio was correlated with injury ranking using a Spearman rho correlation (ρ) with an α level of 0.05.ResultsThe ranked differences in barefoot and shod for peak eversion and inversion torque at 120°/s were correlated with their injury ranking. Ranking of the athletes based on the severity of injuries that were sustained during the season was found to have a strong, positive relationship with the difference in peak eversion torque between barefoot and shod (ρ = 0.78; p = 0.02).ConclusionIt is possible that a large discrepancy between strength in barefoot and shod conditions can predispose an athlete to injury. Narrowing the difference in peak eversion torque between barefoot and shod could decrease propensity to injury. Future work should investigate the effect of restoration of muscular strength during barefoot and shod exercise on injury rates.  相似文献   

优秀男子游泳运动员肩关节等速肌力特征分析     

卢澎涛 《成都体育学院学报》2014,(12)

目的：：探讨优秀男子游泳运动员肩关节肌群力量的特点。方法：采用德国产IsoMed 2000等速肌力测试系统,对46名优秀男子游泳运动员,进行双侧肩关节屈、伸,内收、外展和内旋、外旋(慢速、60。/S,快速、240。/S)定量测试。结果：(1)60。/S测试,双侧内收和内旋相对峰力矩值差异显著(P<0.05)。240。/S测试,双侧外旋相对峰力矩值差异非常显著(P<0.001);(2)肩关节(60。/S和240。/S)内收/外展峰力矩比,左、右侧差异显著(P<0.05)。60。/S测试中左、右侧内旋/外旋峰力矩比差异显著(P<0.05);(3)肩关节屈/伸肌群峰力矩比为0.50-0.60,内收/外展肌群峰力矩比为0.80-0.99,内旋/外旋肌群峰力矩比为1.60-1.78。结论：多名受试者左肩的内收、内旋的绝对力量,外旋爆发力,双肩外旋肌群的耐力有待加强,建议在平时的力量训练中注意肩关节各个自由度的强度练习,需均衡发展,减少伤病发生的可能性。  相似文献   

底盘测功机车辆油耗试验计算机系统的开发及研究     

莫舒玥 《南宁职业技术学院学报》2014,(4):93-96

相对于目前在规定道路下进行一定条件限制的等速油耗试验,采用底盘测功机进行汽车燃油经济性试验更科学。由于采用计算机模拟道路、气候、风速、湿度等客观试验条件,确保试验的过程更接近真实车辆使用情况,获得的油耗也更接近实际。对底盘测功机台架试验中模拟各种实际行车路况和环境的计算机系统进行开发,并进行车辆在底盘测功机上的燃油经济性试验,利用计算机系统模拟一般道路状况下车辆的等速行驶,并对油耗进行统计。试验结果表明,这种方法具有很强的可操作性,可作为一般企业或检测机构进行油耗试验的首选方法。  相似文献