Hamstrings‐to‐quadriceps strength and size ratios of male professional soccer players with muscle imbalance

The aim of this study was to determine the correlation between the concentric hamstrings/quadriceps muscle strength (H_con:Q_con) and cross‐sectional area ratios (H_csa:Q_csa) in professional soccer players with H_con:Q_con imbalance. Nine male professional soccer players (25·3 ± 4·1 years) performed five maximal concentric contractions of the knee extensors (KE) and flexors (KF) at 60 s^?1 to assess H_con:Q_con. The test was performed using the dominant (preferred kicking), and non‐dominant limb with a 5‐min recovery period was allowed between them. Only players with H_con:Q_con < 0·60 (range: 0·45–0·59) in both limbs were included in this study. The muscle cross‐sectional area (CSA) of KE and KF was determined by magnetic resonance imaging. The correlations between H_con:Q_con and H_csa:Q_csa in the dominant leg (r = ?0·33), non‐dominant leg (r = 0·19) and in the both legs combined (r = 0·28) were not statistically significant (P>0·05). Thus, the H_con:Q_con seems not to be determined by H_csa:Q_csa in professional soccer players with H_con:Q_con imbalance.     

Influence of age and physical activity on isokinetic characteristics of hamstring and quadriceps muscles of young gymnasts and soccer players]

OBJECTIVE: The aim of this work is the assessment of age and sport influences on the isokinetic knee muscle characteristics. SUBJECTS AND METHOD: Subjects performed a bilateral knee flexion/extension test on an isokinetic device at 60 and 180 degrees.s(-1) speed in concentric mode. The three parameters studied in this work were the Peak Torque, Average Power and hamstring/quadriceps ratio. Thirty-eight soccer players (16,6 +/- 1.4 years old) and 22 gymnasts (18 +/- 2.8 years old) were tested. The population was separated into three groups : 15 years old, 17 years old, 20 years old. RESULTS: The isokinetic values of soccer players were significantly higher (p < 0.0001) than those of the the gymnasts. The isokinetic values of the oldest soccer players were significantly higher (0.005 < p < 0.05) for hamstrings than those of the younger soccer players. The isokinetic values of the oldest gymnasts were significantly higher (0.005 < p < 0.05) for the quadriceps than those of the younger gymnasts. There were no significant differences between dominant and non dominant limbs in soccer players. CONCLUSION: In the present study, the muscular maturation improves the absolute strength of the older sportsmen in comparison to the younger. Soccer favor most the absolute strength of the inferior member in comparison to the gymnastics.     

Kinesiotape on quadriceps and gluteus in counter movement jump and sprint in soccer players

BackgroundKinesiotape (KT) is a technique commonly used in sports practice. It may be beneficial in enhancing muscle function by additional cutaneous afferent stimulation. The objective of this study was to analyse the effect of KT on countermovement jump (CMJ) and 20-m sprints (sp) immediately and 24 h after its application on the quadriceps and gluteus maximus.Methods37 male soccer players (19.7 ± 0.9 years old) were randomly assigned to one of 3 groups: experimental group: KT activation (KTact), placebo group: sham tape (KTst), and control group (CG). Participants performed a 30-min preliminary warm-up, after which they conducted CMJ and 20-m sp tests. These tests were repeated later (with KT application or not) and after 24 h.ResultsIntergroup results found no significant differences either post-test (CMJ, p = 0.115; sp, p = 0.307) or after 24 h (p = 0.053). Intragroup results showed no significant results for CMJ, although 20-m sp seemed to display significant differences in the (KTst) (p = 0.002, post-hoc: 0.015 in pre_sp vs post_sp) and the (KTact) (0.021, in post-hoc: 0.007 in pre_sp vs post_sp), with a moderate effect in pre_sp vs post_sp (0.66) in the (KTact) after KT was applied.ConclusionKT application on the gluteus maximus and quadriceps in young soccer players increases the sprint execution time immediately and 24 h after application, even that the sprint execution time had not been grater that one tenth of the second (0.08 s). It also has no effect on CMJ.     

膝骨关节炎患者股四头肌功能水平及髋关节步态运动学特征分析

目的:观察中老年膝骨关节炎(KOA)患者股四头肌功能水平及步行过程中髋关节的运动学特征。方法:选取18例KOA患者为KOA组,8例无KOA者为对照组,2组的年龄、身高、体重和身体质量指数(BMI值)相匹配。2组受试者均进行等速肌力测试、无线表面肌电测试及步态测试,测试及比较2组股四头肌峰力矩(PT值)、股内侧肌(VM)、股外侧肌(VL)和股直肌(RF)的积分肌电值(iEMG)、均方根值(RMS)、平均功率频率(MPF)及峰值髋内收、外展角度等和步行中髋关节的运动学特征,将股四头肌肌力与髋关节运动学特征进行相关性分析。结果:KOA组股四头肌等长和等速运动时PT值较对照组显著下降(P<0.01),VL在60°/s等速收缩时表面肌电信号RMS值显著高于对照组(P<0.05),RF在180°/s等速收缩时表面肌电信号RMS值显著高于对照组(P<0.01),步行时峰值髋关节内收及外展角度显著低于对照组(P<0.05),股四头肌肌力与髋关节运动学特征无相关。结论:KOA组较对照组股四头肌肌力显著降低,活动时神经支配效率显著下降,且步行过程中峰值髋内收、外展角度显著减少,股四...     

The influence of athletic status on maximal and rapid isometric torque characteristics and postural balance performance in Division I female soccer athletes and non‐athlete controls

The purpose of this study was to examine the effectiveness of maximal and rapid isometric torque characteristics of the hip extensor muscles and postural balance performance to discriminate between female collegiate soccer athletes and non‐athlete controls. Ten athletes (mean ± SE: age = 19·20 ± 0·36 year; mass = 62·23 ± 3·12 kg; height = 162·43 ± 1·70 cm) and 10 non‐athletes (age = 20·30 ± 0·40 year; mass = 69·64 ± 3·20 kg; height = 163·22 ± 2·10 cm) performed two isometric maximal voluntary contractions (MVCs) of the hip extensor muscles. Peak torque (PT) and absolute and relative rate of torque development (RTD) at early (0–50 ms) and late (100–200 ms) phases of muscle contraction were examined during each MVC. Postural balance was assessed using a commercially designed balance testing device, which provides a measurement of static stability based on sway index (SI). Results indicated that absolute and relative RTD at 0–50 ms (RTD50 and RTD50norm) were greater (P = 0·007 and 0·026), and postural SI was lower (P = 0·022) in the athletes compared with the non‐athletes. However, no differences (P = 0·375–0·709) were observed for PT nor absolute and relative RTD at 100–200 ms (RTD100–200 and RTD100–200norm). Significant relationships were also observed between RTD50 and RTD50norm and SI (r = ?0·559 and ?0·521; P = 0·010 and 0·019). These findings suggest that early rapid torque characteristics of the hip extensor muscles and postural balance performance may be sensitive and effective measures for discriminating between college‐aged athletes and non‐athletes. Coaches and practitioners may use these findings as performance evaluation tools to help in identifying athletes with both superior early rapid torque and balance performance abilities, which may possibly be an indicator of overall athletic potential.     

上肢圆周运动中综合力向量与等速肌力的相关性研究

目的:分析正常人采用“XOS”仪进行上肢圆周运动产生的综合力向量指标与等速肌力检测指标之间的关系和意义,探讨该仪器在肌力检测中的价值。方法:选择30例健康自愿者,年龄21±1岁,接受“XOS”仪的综合力向量测定,同时测定肢体主要肌群的等速肌力和躯干肌力,比较这些肌群不同角速度峰力矩与各区综合力向量值之间的相关性。结果:一区综合力向量值与屈伸膝肌、屈肘肌峰力矩,三区综合力向量值与屈肘肌峰力矩和腰背肌支撑时间,四区与屈膝肌峰力矩之间的相关系数为0.6—0.7。结论:上肢圆周运动中综合力向量值与肢体主要肌群等速峰力矩和躯干肌力之间具有不同程度的相关,综合力向量值变化可以作为反映相应肌群肌力变化的客观指标。     

膝关节骨性关节炎患者髋外展肌等速肌力的研究

摘要 目的：观察膝关节骨性关节炎（KOA）患者髋外展肌等速肌力变化。 方法：采用Biodex system 4对23例双侧KOA患者及14例正常对照者进行角速度为30°/s及60°/s的髋外展肌等速肌力测试,分别采用配对样本t检验及独立样本t检验比较KOA患者主患侧与对侧、KOA组主患侧与正常对照组髋外展肌等速肌力。 结果：KOA组30°/s峰力矩主患侧显著小于对侧（1.15 vs 1.22Nm/kg, P=0.039）,峰力矩均值、单次最佳做功主患侧亦显著小于对侧（P＜0.05）,总功、平均功率无显著性差异（P＞0.05）;60°/s峰力矩主患侧显著小于对侧（1.03 vs 1.13Nm/kg, P=0.006）,峰力矩均值、单次最佳做功、总功、平均功率主患侧亦显著小于对侧（P＜0.05）。髋外展肌30°/s峰力矩均值、平均功率、单次最佳做功及总功KOA组主患侧显著小于正常对照组（P≤0.05）;60°/s时峰力矩KOA组显著小于正常对照组（1.03 vs 1.25Nm/Kg, P=0.032）,余观察指标两组无显著性差异（P＞0.05）。 结论：膝骨关节炎患者主患侧髋外展肌等速肌力峰力矩、做功能力、运动效率较对侧减弱。膝骨关节炎患者髋外展肌等速肌力峰力矩、做功能力、运动效率较正常对照组减弱。     

Inspiratory muscle training improves performance of a repeated sprints ability test in professional soccer players

BackgroundInspiratory muscle training (IMT) is an important method of attenuating both respiratory and peripheral effort perceptions, consequently improving neuromuscular performance and resulting in greater improvements in exercise capacity than exercise training alone.ObjectiveThe aim of this study was to investigate the effects of IMT on exercise tolerance, repeated sprint ability (RSA) performance, maximal inspiratory pressure (MIP), and peak inspiratory flow (PIF) in a cohort of professional male soccer players.MethodsTwenty-two healthy male professional soccer players (18.3 ± 1.4 years; 174.5 ± 6.1 cm; 70.5 kg ± 4.6 kg; body fat 10.1 ± 4.2%) from a club in the Brazilian first division soccer league participated in this study. IMT consisted of 15 and 30 self-paced inspiratory breaths (each to 50% maximal static inspiratory pressure [P₀]) in the 1-and 2-week intervention period, respectively. IMT was performed prior to soccer training (1 sets.d⁻¹; 6 d.wk⁻¹) with repeated sprint ability (RSA) assessed pre- and post- the 2-week period of IMT.ResultsStatistical analyses identified a significant (p < 0.001) decrease in sprint time post-IMT. Additionally, RSA_best, RSA_mean, total sprint time and percentage of RSA performance decrement (RSA _{% dec}) also showed significant decreases (p < 0.0001) post-IMT. Additional measures including MIP and PIF were also significantly elevated (p < 0.0002) following the 2-week period of IMT.ConclusionIn conclusion, our results raise two important issues. Firstly, IMT demonstrated enhanced inspiratory muscle strength in professional soccer players. Secondly, this increase in inspiratory muscle efficiency led to a decrease in sprint time and improved exercise tolerance. We recommend that a standard training protocol be developed and tested in an experimental and control group with a large representative sample.     

等速技术在膝关节损伤后功能评价和康复训练中的应用

等速技术是一项新的肌肉功能评价和训练技术 ,其在肌肉功能评价方面具有较好的准确性和可重复性 ;等速肌力训练时 ,运动速度预先在等速仪器上设定 ,运动中阻力与肌肉实际力量相匹配 ,是一种顺应性阻力 ,这使肌肉在整个活动范围内始终承受最大阻力 ,产生最大肌力 ,因此 ,等速肌力训练在膝关节损伤后的康复治疗中即有效又安全。     

Strength and size ratios between reciprocal muscle groups in the thigh and lower leg of male collegiate soccer players

This study investigated the strength and size ratios between reciprocal muscle groups in the thigh and lower leg of soccer players. In 11 male collegiate soccer players and 21 male non‐soccer players, the joint torques developed during isometric maximal voluntary contractions of the knee extensors (TQ_KE) and flexors (TQ_KF), plantar flexors (TQ_PF) and dorsiflexors (TQ_DF) were determined using a dynamometer. The muscle volumes of the same muscles (i.e. MV_KE, MV_KF, MV_PF and MV_DF) were determined by magnetic resonance imaging. There were no significant differences in any of the joint torques or muscle volumes between soccer and non‐soccer players. TQ_KE/TQ_KF was significantly lower for soccer players than for non‐soccer players. On the other hand, no significant difference in TQ_PF/TQ_DF was found between soccer and non‐soccer players. MV_KE/MV_KF and MV_PF/MV_DF for soccer players were not significantly different from those for non‐soccer players. Additionally, there were no significant correlations between MV_KE/MV_KF and TQ_KE/TQ_KF and between MV_PF/MV_DF and TQ_PF/TQ_DF of soccer players. Thus, the strength ratios appear not to be affected by the size ratios between the knee extensors and flexors and between the plantar flexors and dorsiflexors in soccer players.     

膝关节等速测试峰力矩与总功及平均功率的相关分析

利用４０例正常男性ＢＩＯＤＥＸ多关节等带测试和康复系统测试的膝关节等速向心收缩资料,分析峰力矩与总功及平均功率的相关性。结果：无 团中开链、屈曲或伸展运动、慢或快收缩,等速向心收缩的峰力矩与总功及平均功率的相关系数在０．５３２－０．９９１。     

Biochemical assessments of oxidative stress, erythrocyte membrane fluidity and antioxidant status in professional soccer players and sedentary controls

BACKGROUND: Physical exercise is characterized by an increase in oxygen consumption by the whole body. This leads to a decrease in antioxidant levels that could promote both an increase in the markers of lipoprotein peroxidation and damage to the erythrocyte membrane with consequent modification of membrane fluidity. MATERIALS AND METHODS: Different markers of oxidative stress, erythrocyte membrane fluidity and antioxidant status were determined in 20 professional soccer players and 20 sedentary controls. Plasma lipoperoxides and kinetics of Cu-stimulated plasma peroxidation were measured together with hydrosoluble (albumin, uric acid and vitamin C), liposoluble (vitamin E and bilirubin) and enzymatic (superoxide dismutase and glutathione peroxidase) serum antioxidants. Erythrocyte membrane rigidity was determined by measuring fluorescence anisotropy (rs) of the fluorescent probe 1, 3, 5 diphenylexatriene. RESULTS: The sportsmen showed higher levels of the following plasmatic antioxidants: ascorbic acid (P<0.0001), uric acid (P<0.0001), alpha-tocopherol (P=0.03) and superoxide dismutase activity (P=0.0001). According to this evidence, the lipoperoxide levels (P=0.0158), the duration of the latency phase of plasma peroxidation (P=0.0123) and erythrocytes membrane fluidity (P=0.0152) were found to be significantly higher in the soccer players. DISCUSSION: Athletes undergoing regular and adequate training show improved antioxidant status together with a more fluid membrane status, which could contribute to improving both peripheral resistance to insulin and all the functional metabolic interchanges in the cellular membrane.     

膝关节骨性关节炎经关节镜手术后的等速肌力评价

目的评价单侧膝关节骨性关节炎患者经关节镜手术前后膝屈伸肌群的肌肉功能。方法用LKSS量表及CYBEX-6000型等速肌力测试系统对24例单侧膝关节骨性关节炎患者膝关节镜手术的疗效及肌肉功能进行测试。结果膝关节镜术后1年关节疼痛及关节活动度有明显改善,患膝股四头肌峰力矩、总作功量和爆发力有明显提高,而月国绳肌与股四头肌峰力矩的比值较术前有所降低。结论膝关节镜手术术后应加强屈膝肌力的训练以改善膝关节的稳定性。     

Efficacy of kinesio taping on isokinetic quadriceps torque in knee osteoarthritis: a double blinded randomized controlled study

Abstract

Study design: Double blind pre-test post-test control group design. Objectives: To compare the isokinetic quadriceps torque, standardized stair-climbing task (SSCT) and pain during SSCT between subjects diagnosed with knee osteoarthritis pre and post kinesio tape (KT) application with and without tension. Background: Strength of the quadriceps and torque producing capability is frequently found to be compromised in knee osteoarthritis. The efficacy of KT in improving isokinetic quadriceps torque in knee osteoarthritis is unknown, forming the basis for this study. Methods and measures: Forty subjects were randomly allocated to either the experimental (therapeutic KT with tension) or control group (sham KT without tension) with the allocation being concealed. Pre and post test measurements of isokinetic quadriceps torque, SSCT and pain during SSCT were carried out by a blinded assessor. Results: A large effect size with significant improvements in the peak quadriceps torque (concentric and eccentric at angular velocities of 90° per second and 120° per second), SSCT and pain were obtained in the experimental group when compared to the control group. Conclusion: Application of therapeutic KT is effective in improving isokinetic quadriceps torque, SSCT and reducing pain in knee osteoarthritis.     

偏瘫患者膝关节伸屈肌等速肌力测试研究

目的了解偏瘫病人恢复独立行走后患肢和健肢的肌力、屈伸肌力比,探讨膝关节不稳定的原因.方法采用CybexNORM系统对10例脑卒中偏瘫病人进行膝伸、屈肌等速肌力测试.结果3种角速度60、120、180(°/8)向心和60°/s离心伸屈肌峰力矩平均值健侧均高于患侧,伸肌120°、180°/8和屈肌60°、180°/s健侧峰力矩显著高于患侧(P值均＜0.05),离心伸肌60°/s时(P＜0.05);离心收缩大于向心收缩,峰值比(H/Q)均在40%～70%范围.60°/s膝10°位向心和离心伸肌力矩健侧显著高于患侧(P均＜0.05).结论偏瘫病人伸、屈肌肌力不足是造成行走时患膝不稳(膝过伸)的重要原因.     

Effects of prior hamstring strain injury on strength,flexibility, and running mechanics

Background

Previous studies have shown evidence of residual scar tissue at the musculotendon junction following a hamstring strain injury, which could influence re-injury risk. The purpose of this study was to investigate whether bilateral differences in strength, neuromuscular patterns, and musculotendon kinematics during sprinting are present in individuals with a history of unilateral hamstring injury, and whether such differences are linked to the presence of scar tissue.

Methods

Eighteen subjects with a previous hamstring injury (> 5 months prior) participated in a magnetic resonance (MR) imaging exam, isokinetic strength testing, and a biomechanical assessment of treadmill sprinting. Bilateral comparisons were made for peak knee flexion torque, angle of peak torque, and the hamstrings:quadriceps strength ratio, as well as muscle activations and peak hamstring stretch during sprinting. MR images were used to measure the volumes of the proximal tendon/aponeurois of the biceps femoris, with asymmetries considered indicative of scar tissue.

Findings

A significantly enlarged proximal biceps femoris tendon volume was measured on the side of prior injury. However, no significant differences between the previously injured and uninjured limbs were found in strength measures, peak hamstring stretch, or muscle activation patterns. Further, the degree of asymmetry in tendon volume was not correlated to any of the functional measures.

Interpretation

Injury-induced changes in morphology do not seem discernable from strength measures, running kinematics, or muscle activation patterns. Further research is warranted to ascertain whether residual scarring alters localized musculotendon mechanics in a way that may contribute to the high rates of muscle re-injury that are observed clinically.     

偏瘫膝关节肌力的力学分析

目的强调肌力训练在偏瘫康复中的重要性,分析当前治疗误区,寻求最佳运动治疗对策。方法选择14例进行步态训练的偏瘫患者接受等速肌力标准化测试,在角速度分别为60、120、180rad/s下的双膝关节屈伸肌群的峰力矩(PT)与总作功(TW)。结果患侧伸膝肌群在3种角速度峰力矩分别为59.43、41.86、32.14N·m,总作功分别为61.14、46.93、36.57J,与健侧比较差异明显（P<0.01）。患侧屈膝肌群在3种角速度峰力矩分别为24.86、21.00、31.00N·m,总作功分别为26.07、18.86、13.43J。除120rad/s峰力矩双侧比较无显著意义外,其余P值均<0.01。结论传统康复治疗中神经促进技术等运动疗法训练后存在严重的肌力不足,应如何解决值得深思。     

Running velocities and heart rates at fixed blood lactate concentrations in elite soccer players

This study was undertaken to examine the endurance performance of elite soccer players, according to age and playing position. A total of 197 male soccer players participated in this study. Each player performed exercise tests on the treadmill that included 3-minute runs and 30-second blood sampling intervals. During these tests, running speeds at the first and second stages were 10 km/hr^-1 and 12 km/hr^-1, respectively. When these tests were completed, running speed was increased by 1 km/hr every 3 minutes until the runner reached exhaustion. Blood samples were analyzed immediately by means of an automated lactate analyzer. Heart rate was monitored continuously at 5-second intervals. Running velocities and heart rates at 2-mmol/L^-1, 2.5-mmol/L^-1, 3-mmol/L^-1, and 4-mmol/L^-1 blood lactate concentrations were calculated with use of the spline function. Analysis of variance was used to analyze data to determine the differences between playing positions (goalkeepers, defenders, midfielders, and forwards) and age groups (older than 30 years of age, between 25 and 29 years old, between 20 and 24 years old, and 19 years old and younger). Statistical significance was set at P > .01. No significant differences were revealed between defenders, midfielders, and forwards regarding running velocities and heart rates and their correlation with specified lactate concentrations. Goalkeepers demonstrated lower endurance performance than players in the other playing positions (P > .001). Running velocities corresponding to all lactate concentrations showed no significant differences in all age groups, but heart rates in soccer players older than 30 years of age were significantly lower than those of players in other age groups (P > .01). Results of this study suggest that the endurance performance level of professional players is similar for players in all positions, except for goalkeepers, and that endurance performance is not adversely affected when a person\rss age increases beyond 30 years of age.