青少年男子短跑运动员膝关节等速肌力特征研究

目的：通过对36名二级青少年男子短跑运动员双侧膝关节进行等速测试，探析青少年短跑运动员膝关节向心屈伸肌群的生物力学特性．为运动训练、科学选材及临床康复等提供理论依据。方法：利用Kinitech等速康复肌力测试系统对青少年男子短跑运动员膝关节屈伸肌群进行等速测试。结果：青少年男子短跑运动员双侧膝关节屈伸峰力矩随测试速度的增加呈递减趋势，且膝伸肌大于膝屈肌（P〈0．05），峰力矩屈伸比（V／E）随给定测试速度的增加呈递增趋势；最大功率随测试速度的增大而增加，同一测试速度下屈、伸肌群最大功率无明显差异，左、右侧相比也无显著性差异（600／s伸肌除外）；屈伸肌群达峰力矩的角度（APT）表现为伸肌角度明显低于屈肌角度，随速度增加左右两侧膝关节达峰力矩的角度无显著差异：双侧膝关节屈伸肌群达峰力矩的时间（TPT）随测试速度的增加而减小，同一测试速度下伸肌达峰力矩的时间大于屈肌；右侧膝关节屈肌相对峰力矩（PT／BM）与下肢形态学指标表现出不同程度的正相关。结论：青少年男子短跑运动员膝关节峰力矩变化规律与成年人相一致，但左右侧膝关节屈伸肌群做功能力发展不平衡，屈伸肌群运动达峰力矩角度、达峰力矩的时间存在显著差异。     

Kinematics and kinetics of youth baseball pitching with standard and lightweight balls

Because youth athletes are smaller and weaker than their adult counterparts, smaller equipment and fields are often used in youth sports. Previous research has shown that youth baseball pitchers use similar motions to older pitchers, but generate lower kinetics and angular velocities at the shoulder and elbow. The purpose of this study was to determine potential biomechanical benefits for youth pitchers to use lighter baseballs. Thirty-four youth (11.1 ± 0.7 years) pitchers pitched both standard [5 ounce (142 g)] and lightweight [4 ounce(113 g)] baseballs in a laboratory setting. Kinematic and kinetic parameters were measured with a six-camera high-speed motion analysis system. Three repeated measures MANOVAs were used to compare (p > 0.05) position, velocity, and kinetic parameters between the standard and lightweight baseballs. Subjective data were also collected. Pitching the lightweight ball produced no difference in arm position, but greater shoulder, elbow, and ball velocities. With the lightweight ball, pitchers produced decreased kinetics.Post-hoc analysis of the kinetic data revealed significant decreases in elbow varus torque and shoulder internal rotation torque. The data suggest that playing with lightweight baseballs may reduce the risk of overuse injury in the youth pitcher and also help develop arm speed. However, before introducing lightweight baseballs into the youth game, the effect of lighter, faster pitched balls for the batters and fielders should also be considered.     

Gender Differences in Strength

The purpose of this study was to examine gender differences in upper and lower body strength as a function of lean body weight and the distribution of muscle and subcutaneous fat in the upper and lower limbs. The subjects were 103 physically active men (n = 48) and women (n = 55). The peak torques produced during shoulder flexion (SF) and knee extension (KE) were used as measures of upper body and lower body strength, respectively. Flexed arm girth, thigh girth, triceps skinfold, and thigh skinfold were used to estimate the distribution of muscle and subcutaneous fat in the limbs. Results of the MANOVA revealed that the overall strength of men was significantly greater than that of women. Results of MANCOVA indicated that the SF and KE strength of women and men did not differ significantly when differences in lean body weight, arm girth, thigh girth, triceps skinfold and thigh skinfold were statistically controlled. High levels of SF and KE strength were associated with a high lean body weight and a large arm girth. Results of the multiple regression analysis indicated that for men a substantial portion of the variance in both SF and KE strength was explained by lean body weight alone; whereas strength variations in women were explained more adequately by including limb variables along with lean body weight. Within the limitations of this study, it was concluded that gender differences in upper and lower body strength are a function of differences in lean body weight and the distribution of muscle and subcutaneous fat in the body segments. Upper body strength is relatively more important than lower body strength in characterizing the gender difference in strength.     

Body Composition and Anthropometric Correlates of Isokinetic Leg Extension Strength of Young Adult Males

Abstract

The present study examined the relative importance of body size and composition as determinants of individual differences in isokinetic leg extensor strength in young adult males performing at slow, moderate, and fast speeds. The subjects were 31 males between the ages of 19 and 29 years, who were not participating in weight training programs. Low to moderate correlations were found between isokinetic strength and body size or body composition measurements. At each speed, similar proportions of the variance in peak torque values were accounted for by lean body weight (23-30%) and thigh volume (20-37%). However, body weight, often suggested as the best reference standard for equalizing strength scores, also accounted for only 13-24% of the variance in peak torque values at each of the speeds tested. The moderate correlations reported in this study do not support the use of body size and composition measurements as a means of adjusting strength values.     

Isokinetic imbalance of adductor–abductor hip muscles in professional soccer players with chronic adductor-related groin pain

This study aims to compare the isokinetic profile of hip abductor and adductor muscle groups between soccer players suffering from chronic adductor-related groin pain (ARGP), soccer players without ARGP and healthy volunteers from general population. Study included 36 male professional soccer players, who were randomly selected and followed-up over two years. Of the 21 soccer players eligible to participate in the study, 9 players went on to develop chronic ARGP and 12 players did not. Ten healthy male volunteers were randomly selected from the general population as a control group. Comparison between the abductor and adductor muscle peak torques for players with and without chronic ARGP found a statistically significant difference on the dominant and non-dominant sides (p?p?p?=?.008). The adductor muscle strength was also significantly decreased on the affected side. This imbalance appears to be a risk factor for adductor-related groin injury. Therefore, restoring the correct relationship between these two agonist and antagonist hip muscles may be an important preventative measure that should be a primary concern of training and rehabilitation programmes.     

The Relationships Among Isokinetic Endurance,Initial Strength Level,and Fiber Type

Abstract

Knee extension isokinetic peak torque was assessed at angular velocities of 0, 30, 180, and 240[ddot]/sec, and isokinetic endurance was assessed by 50 consecutive contractions at 180[ddot]/sec in eight college age men. Also, muscle fiber type of the vastus lateralis was determined and related to isokinetic strength and fatigability. To determine the influence of initial strength on isokinetic endurance the 50 serial isokinetic contractions were assessed after subjects performed two bicycle exercise regimens designed to affect initial strength levels. Neither isokinetic peak torques (made relative to MVC or per Kg of body weight) nor the amount of strength loss over the 50 contractions correlated with fiber type. The peak torques at 180[ddot]/sec at the start of the 50 contractions differed over the three conditions (unfatigued and after the two bicycle exercise regimens), however, the amount of of strength loss over the 50 trials was similar for the three conditions. Also, the patterns of the three isokinetic fatigue curves were remarkably similar. Thus, the initial strength level across the treatments did not affect the rate of fatigue. However, when the treatment conditions were examined separately, the amount of strength loss over the 50 trials correlated significantly with initial strength. Thus, factors other than, or in addition to, fiber type and initial strength level must influence the rate of isokinetic fatigue.     

优秀女子自行车运动员踝关节肌群等动向心测试研究

利用等动测力系统(Cybex-6000)对10名优秀女子自行车运动员进行踝关节肌力的等动向心测试。研究的结果表明:1)踝关节肌群等动向心收缩时峰力矩及相对峰力矩随运动速度的增加而减少,总功及相对总功随测试速度的增加而减小,而平均功率及相对值随测试速度的增加而增大;2)踝关节前后侧肌力矩相差很大,而且显示出速度的差异性。自行车运动员踝关节肌群的肌力特征,反映了踝关节的肌肉配布与踝关节肌群的训练特征,体现了其合肌肉规律,合肌群特色,合运动实际的规律。     

髌骨软化症患者股内肌机能状况与髌骨位置对髌骨疼痛的影响──兼论点揉血海穴对缓解髌骨疼痛的作用

通过观察髌骨软化症患者屈膝疼痛时股内肌和股外肌的肌电活动、膝关节Ｘ光轴位片以及伸膝等动力量测定，拟在探讨髌骨软化症患者髌骨疼痛、髌骨位置及股内肌机能状况的相互关系。结果表明：髌骨软化症患者股内肌张力相对较高，导致髌骨向内偏移、屈膝时疼痛。而点揉血海穴后股内肌张力下降，髌骨位置外移并恢复正常，屈膝疼痛缓解。因此认为髌骨软化患者屈膝疼痛与骸骨向内偏移有关。建议在运动训练中注意掌握正确的动作结构，屈膝旋转时应保持大小腿和足在同一平面的同步活动，使髌骨保持正常的活动位置     

陕西省优秀跆拳道运动员髋关节屈伸肌群等速测试与研究

采用ISOMED2000获得陕西省优秀跆拳道运动员髋关节等速收缩的生物力学特征。右髋关节屈肌群等速离心收缩峰值力矩出现时的关节角度在133．7°-140．20之间,伸肌群等速离心收缩峰值力矩出现时的关节角度在121．2°-106．30之间;髋关节屈伸肌群向心收缩、离心收缩速度在240°／s时相对力矩梯度达到最大。     

青年女子柔道运动员等速肌力特征研究

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。