三种深蹲动作模式肌电特征的研究

目的：对3种不同深蹲模式进行肌电测试,以期探讨不同模式下动作的合理性,为教学、训练提供一定的理论依据。方法：本文运用文献资料法、实验法和数理统计法对不同模式的肌电测试进行对比分析研究。结果：动作模式1与动作模式2相比,股内侧肌、股直肌、股外侧肌、臀大肌有非常显著性差异（P〈0.01）,股二头肌有显著性差异（P〈0.05）。动作模式1与动作模式3相比,股内侧肌、股直肌、股外侧肌、臀大肌有非常显著性差异（P〈0.01）,股二头肌有显著性差异（P〈0.05）。动作模式2与动作模式3相比,股内侧肌、臀大肌有非常显著性差异（P〈0.01）,股直肌、股外侧肌有显著性差异（P〈0.05）,股二头肌没有显著性差异（P〉0.05）。结论：3种不同模式深蹲动作的股外侧肌、股直肌、股内侧肌、股二头肌、臀大肌的积分肌电数值表现出显著性差异,动作模式3优于其它两种动作模式。在深蹲训练中强调臀部肌肉的主动收缩,才能更好的提高下肢力量的作用。     

上海优秀男子青少年中跑运动员髋、膝关节等速肌力测试分析

通过对男子青少年中跑运动员进行髋、膝关节等速肌力测试,发现男子青少年中跑运动员髋、膝关节肌力特点及薄弱肌群。方法：对16名上海优秀男子青少年中跑运动员进行髋、膝关节单侧等速向心60°／s×6和240°／s×6测试记录测试峰力矩、最大功率、屈伸肌峰力矩比值。结果：髋关节屈肌峰力矩和相对峰力矩在两个速度存在显著差异（P〈0．05）,伸肌峰力矩和相对峰力矩两个速度存在高度显著差异（P〈0．01）,屈伸肌峰力矩比值存在显著差异（P〈0．05）,膝关节屈肌峰力矩及相对峰力矩无差异,而伸肌峰力矩和相对峰力矩在两个速度存在显著差异（P〈0．05）,屈伸肌峰力矩比值无差异。研究对象髋关节屈肌最大功率和相对最大功率在两个速度存在高度显著差异（P〈0．01）,伸肌最大功率和相对最大功率存在显著差异（P〈0．05）,膝关节屈伸肌最大功率和相对最大功率在两个速度存在高度显著差异（P〈0．01）。结论：髋关节随测试速度增加最大力矩呈现下降趋势,高速测试时峰力矩屈／伸值下降,髋关节屈肌力量需加强;膝关节伸肌峰力矩随测试速度增加减小,屈肌及峰力矩屈／伸值变化不明显。     

自由式滑雪空中技巧国家队运动员膝关节屈伸肌群肌肉力量特征

目的：为了观察我国自由式滑雪空中技巧队男女运动员下肢膝关节屈伸肌群力量特点,发现目前下肢力量训练中存在的问题,以便为力量训练提供参考依据。方法：使用美国BIODEX公司生产的biodex system4等动测试系统对自由式滑雪空中技巧队男女运动员（男5名,女6名）的下肢膝关节屈伸肌群进行向心收缩的等动测试,测试速度分别为60°/s和180°/s。结果：男女运动员伸肌群的相对峰值力矩和相对平均功率都要显著高于屈肌群（P<0.01）。相对峰值力矩随着测试速度的增加而显著减小（P<0.01）,相对平均功率随测试速度的增加而显著增加（P<0.01）。男女运动员下肢屈伸肌比平均在50%～65%之间,并且随着测试速度的增加屈伸肌比显著增加（P<0.05）。在同一速度下,男女运动员伸肌峰值力矩出现的角度要显著大于屈肌（P<0.01）,但是在不同速度下,男女运动员伸肌峰值力矩出现的角度表现出不同的变化。随着测试速度的增加,屈伸肌群峰值力矩出现的时间显著变短（P<0.01）,并且同一速度下,屈肌群峰值力矩出现的时间要短于伸肌群（P<0.05）。左右腿膝关节屈伸肌群相对峰值力矩、相对平均功率、屈伸肌比等指标没有差异（P>0.05）。结论：了解到目前我国自由式滑雪空中技巧队男女运动员下肢肌肉的力量特点,其中男女运动员下肢膝关节屈伸肌比（H/Q）较低,应该注重发展股后肌群的力量,以提升屈伸肌比值。左右腿肌肉力量发展比较均衡。     

耐力训练时脂肪甘油三酯脂肪酶与工作肌糖代谢和线粒体密度——基于ATGL基因敲除小鼠的研究

目的：（1）观察ATGL基因敲除小鼠耐力训练时胰岛素抵抗、工作肌糖转运蛋白及线粒体密度的变化;（2）测定Akt、PKC、PPAR-α蛋白激活及含量,探究其与胰岛素抵抗、工作肌糖转运蛋白及线粒体密度的变化之间的关系。方法：ATGL^-/-、ATGL^+/-和C57BL/6J小鼠跑台耐力训练训练7天,测定小鼠体重、肌糖原、血糖、血胰岛素和胰岛素抵抗,蛋白印记法测定腓肠肌和比目鱼肌GLUT-4（内外膜）、p-Akt、Akt、p-PKC、PKC含量和PPAR-α水平。结果：（1）运动训练后,腓肠肌和比目鱼肌糖原含量、HOMA-IR指数存在基因类型、运动训练的差异（P<0.05）。运动训练引起血糖和血胰岛素在基因类型的差异（P<0.05）。（2）运动训练后,腓肠肌和比目鱼肌Akt、PKC、磷酸化水平、腓肠肌总Akt、PPAR-α蛋白表达存在基因类型、运动训练的差异（P<0.05）。比目鱼肌总Akt表达、腓肠肌和比目鱼肌总PKC、PPAR-α蛋白运动训练的差异不具有显著性意义（P>0.05）。结论：耐力训练时,ATGL通过上调Akt和PKC促进胰岛素敏感性和改善胰岛素抵抗;ATGL上调PPAR-α起到促进线粒体含量。     

自行车把手类型和坡度对上肢肌群平均肌电活动的影响

目的：探讨不同把手类型自行车在不同坡度路面骑行时上肢肌群的用力变化特征,为自行车专业选手和骑行爱好者针对性专项训练或比赛, 以及动感单车制造商标注器材使用方法和锻炼效果提供科学理论参考。方法：8名健康男性大学体育专业志愿者,骑行不同把手类型（下弯型、平直 型和上翘型）的自行车,分别在模拟下坡4°和上坡4°地面上以60 rpm的转速行驶,阻力设定为功率120 W,检测骑行者上肢相关肌群（身体右侧的腕 伸肌、腕屈肌、肱二头肌、肱三头肌、三角肌、斜方肌、背阔肌）表面肌电平均振幅。结果：双因素方差分析显示,把手类型对骑行者腕屈肌、肱二头肌、 肱三头肌、三角肌和背阔肌AEMG有显著影响（P<0.05）;坡度对骑行者腕伸肌、肱二头肌、三角肌和背阔肌AEMG有显著影响（P<0.05）;把手类型和 坡度除了三角肌AEMG存在显著交互作用外（P<0.007）,其余各被检上肢肌群AEMG均无显著交互作用。结论：平直型把手可以显著提高腕屈肌肌 肉激活;上翘型把手在上坡4°条件下可以显著提高肱二头肌和背阔肌的肌肉激活;下弯型把手可以显著提高肱三头肌和三角肌的肌肉激活,但要视 坡度情形而定;坡度增加可以显著提高骑行者腕伸肌、肱二头肌和背阔肌的肌肉激活。     

跑台运动对小鼠骨性关节炎的影响机制

研究运动对软骨细胞基质降解酶MMP13、Adamts4、Adamts5及软骨标记蛋白 Col2、Col10、Runx2、Sox9的影响,为骨性关节炎运动医学角度提供科学依据。方法：对36只8周雄性小鼠,随机分成不手术对照组（C）,手术自由活动组（F）和手术跑台组, 手术为DMM关节炎手术,对照组不手术自由喂养,手术自由组进行DMM手术后自由喂养,手术跑台组进行DMM手术后5天后进行跑台,每天进行20m跑台训练,6周后处死取样。对3组小鼠膝关节进行石蜡包埋切片,通过fast green-Safranin O染色对关节炎进行评级,然后在通过Q-PCR和Western Blotting 检测相关基因mRNA和蛋白水平的表达。结果：1）与C组比较,F组和R组关节均有不同级别损伤,而R关节受损程度更加严重。2）与C组和F组相比,R组MMP13mRNA表达均有非常显著性升高（P<0.01）,F组与C组无显著性差异;与C组和F组相比,R组Adamts4 mRNA表达有均有非常显著性升高（P<0.01）,与C组相比,F 组Adamts4 mRNA也有显著性升高（P<0.05）;与C组和F组相比,R组Adamts5 mRNA表达均有非常显著性升高（P<0.01）,F组与C组相比也有非常显著性升高（P<0.01）;与C组和F组相比,R组Col2 mRNA表达有均有非常显著性降低（P<0.01）,F组与C组相比有非常显著性降低（P<0.01）。3）与C组和F组相比,R组col2蛋白表达量均有非常显著性下降（P<0.01）,F组比C组的Col2蛋白表达量也有非常显著性下降（P<0.01）;与C组和F组相比,R组Sox9蛋白表达均有非常显著性下降（P<0.01）,F组比C组Sox9蛋白表达量也有非常显著性下降（P<0.01）;与C组和F组相比,R组Col10蛋白表达都有非常显著性增加（P<0.01）, F组比C组Col10蛋白表达量也有非常显著性增加（P<0.01）;与C组和F组相比,R组Runx2蛋白表达都有非常显著性增加（P<0.01）, F组比C组Runx2蛋白表达量也有非常显著性增加（P<0.01）。结论：跑台运动加快骨性关节炎小鼠关节软骨的降解和钙化,加重了关节软骨损伤。     

非特异性腰痛患者腰骶结构特征及其影响因素

研究非特异性腰痛（non-specific low back pain,NLBP）患者的腰骶结构特征及其影响因素。方法：招募筛选NLBP患者71例（NLBP组）及29例无腰痛的健康人群（Con组）。填写问卷评估疼痛程度和腰功能障碍,并分别拍摄矢状面及额状面的X光片,测定腰椎前凸程度和骨盆侧倾程度的相关指标。研究发现：①NLBP组腰椎前凸程度与Con组相比无显著性差异（P>0.05）;②NLBP组与Con组相比骨盆发生明显侧倾（P<0.05）;③性别对NLBP患者腰骶结构没有影响;④不同年龄的NLBP患者腰椎结构有发生不同的改变,青年患者与中老年患者相比,腰骶出现了显著的腰曲变直（P<0.05）及骨盆侧倾（P<0.01）;⑤症状也会影响NLBP患者的腰椎前凸程度（P<0.05）。研究结论：①骨盆侧倾是NLBP患者的共性,可将该指标用于临床诊断和疗效评估;②不同年龄、性别和症状的NLBP患者进行康复时应有针对性。     

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。     

我国花样滑冰优秀运动员膝关节力量研究

通过测试我国优秀花样滑冰运动员等速状态下膝关节屈肌群与伸肌群力量,对我国优秀花样滑冰运动员膝关节力量状况进行研究,结果：在60°/s等速测试中,我国优秀花样滑冰运动员相对最大峰力矩均值左侧膝关节屈肌为1.51 N·m/kg,伸肌为2.44 N·m/kg,右侧为1.54 N·m/kg和2.70N·m/kg;左侧膝关节屈肌群与伸肌群力矩比为62.02%,右侧为57.49%;膝关节左侧屈肌群与右侧屈肌群比值的均值为99.60%;左侧伸肌群与右侧伸肌群比值的均值为91.77%;差异均未出现显著性（P〉0.5）。结论：1）总体上说我国优秀花样滑冰运动员双膝力量未存在显著性差异;2）就单个运动员而言,我国优秀花样滑冰运动员双膝力量存在一定差异;3）我国优秀花样滑冰运动员膝关节屈肌群力量有待增强。     

锻炼与针刺组合对退行性膝关节炎微循环血流灌注量的影响

目的：锻炼与针刺组合对退行性膝关节炎微循环血流灌注量的影响。方法：研究对象40例随机分为2组，分别是针刺组（单纯针刺）和锻炼组（站桩与针刺组合），对其实验前后疼痛程度（VAS）、微循环血流灌注量（MBPU）及皮肤温度的变化进行检测分析。结果：两组实验后，VAS评分明显降低（P<0.01），锻炼组优于针刺组（P<0.05）；MBPU降低（P<0.01），锻炼组优于针刺组（P<0.05）；局部温度明显提高（P<0.05）。结论：锻炼与针刺组合可以明显缓解退行性膝关节炎的疼痛症状，降低局部微循环血流灌注量，提高皮肤温度；优于单纯针刺疗法。     

Functional differences in the activity of the hamstring muscles with increasing running speed

Abstract

In this study, we examined hamstring muscle activation at different running speeds to help better understand the functional characteristics of each hamstring muscle. Eight healthy male track and field athletes (20.1 ± 1.1 years) performed treadmill running at 50%, 75%, 85%, and 95% of their maximum velocity. Lower extremity kinematics of the hip and knee joint were calculated. The surface electromyographic activities of the biceps femoris and semitendinosus muscles were also recorded. Increasing the running speed from 85% to 95% significantly increased the activation of the hamstring muscles during the late swing phase, while lower extremity kinematics did not change significantly. During the middle swing phase, the activity of the semitendinosus muscle was significantly greater than that of the biceps femoris muscle at 75%, 85%, and 95% of running speed. Statistically significant differences in peak activation time were observed between the biceps femoris and semitendinosus during 95%max running (P < 0.05 for stance phase, P < 0.01 for late swing phase). Significant differences in the activation patterns between the biceps femoris and semitendinosus muscles were observed as running speed was increased, indicating that complex neuromuscular coordination patterns occurred during the running cycle at near maximum sprinting speeds.     

Peak muscle activation, joint kinematics, and kinetics during elliptical and stepping movement pattern on a Precor Adaptive Motion Trainer

Kinematic, kinetic, and electromyography data were collected from the biceps femoris, rectus femoris (RF), gluteus maximus, and erector spinae (ES) during a step and elliptical exercise at a standardized workload with no hand use. Findings depicted 95% greater ankle plantar flexion (p = .01), 29% more knee extension (p = .003), 101% higher peak knee flexor moments (p < .001) 54% greater hip extensor moments (p < .001), 268% greater anterior joint reaction force (p = .009), 37% more RF activation (p < .001), and 200 % more ES activation (p <. 001) for the elliptical motion. Sixteen percent more hip flexion (p < .001), 42% higher knee extensor moments (p < .001), and 54% greater hip flexor moments (p = .041) occurred during the step motion. Biomechanical differences between motions should be considered when planning an exercise regimen.     

Saddle height effects on pedal forces,joint mechanical work and kinematics of cyclists and triathletes

Abstract

The effects of saddle height on pedal forces and joint kinetics (e.g. mechanical work) are unclear. Therefore, we assessed the effects of saddle height on pedal forces, joint mechanical work and kinematics in 12 cyclists and 12 triathletes. Four sub-maximal 2-min cycling trials (3.4 W/kg and 90 rpm) were conducted using preferred, low and high saddle heights (±10° knee flexion at 6 o'clock crank position from the individual preferred height) and an advocated optimal saddle height (25° knee flexion at 6 o'clock crank position). Right pedal forces and lower limb kinematics were compared using effect sizes (ES). Increases in saddle height (5% of preferred height, ES=4.6) resulted in large increases in index of effectiveness (7%, ES=1.2) at the optimal compared to the preferred saddle height for cyclists. Greater knee (11–15%, ES=1.6) and smaller hip (6–8%, ES=1.7) angles were observed at the low (cyclists and triathletes) and preferred (triathletes only) saddle heights compared to high and optimal saddle heights. Smaller hip angle (5%, ES=1.0) and greater hip range of motion (9%, ES=1.0) were observed at the preferred saddle height for triathletes compared to cyclists. Changes in saddle height up to 5% of preferred saddle height for cyclists and 7% for triathletes affected hip and knee angles but not joint mechanical work. Cyclists and triathletes would opt for saddle heights <5 and <7%, respectively, within a range of their existing saddle height.     

Study of mechanical characteristics of the knee extensor and flexor musculature of volleyball players

Abstract

The aim of the present study was to analyse differences in muscle response and mechanical characteristics of the vastus medialis, rectus femoris, vastus lateralis, and biceps femoris in elite volleyball players of both sexes using tensiomyography. To this end, 47 players of nine nationalities playing for teams in the men's and women's Spanish Superleagues were assessed. The sample comprised 22 women (age 24.6±4.3 years; weight 72.14±10.06 kg; height 178.40±8.50 cm) and 25 men (age 25.0±4.3 years; weight 88.76±9.07 kg; height 194.71±7.84 cm). Tensiomyography was used to assess muscular response and muscular mechanical characteristics. For this purpose, the following variables were analysed: maximum radial displacement of muscle belly and normalized response speed. The findings show, both in men and women, a higher normalized response speed score in the vastus lateralis and vastus medialis compared with the rectus femoris and biceps femoris. A marked lateral symmetry of maximum radial displacement of the muscle belly was also observed in the musculature of the lower limbs, with no statistically significant differences being detected in either men or women. There were, however, clear differences in terms of normalized response speed between male and female volleyball players: women displayed a more pronounced difference in the normalized response speed of the musculature responsible for extension (vastus medialis, rectus femoris, and vastus lateralis) and flexion (biceps femoris) of the knee joint than men. Moreover, tensiomyography proved to be a highly sensitive tool for detecting such changes.     

Mechanics of the muscles crossing the hip joint during sprint running

Abstract

We aimed to demonstrate the changes over time in the lengths and forces of the muscles crossing the hip joint during overground sprinting and investigate the relationships between muscle lengths and muscle–tendon unit forces – particularly peak biceps femoris force. We obtained three-dimensional kinematics during 1 running cycle from 8 healthy sprinters sprinting at maximum speed. Muscle lengths and muscle–tendon unit forces were calculated for the iliacus, rectus femoris, gluteus maximus, and biceps femoris muscles of the target leg as well as the contralateral iliacus and rectus femoris. Our results showed that during sprinting, the muscles crossing the hip joint demonstrate a stretch-shortening cycle and 1 or 2 peak forces. The timing of peak biceps femoris force, expressed as a percentage of the running cycle (mean [SD], 80.5 [2.9]%), was synchronous with those of the maximum biceps femoris length (82.8 [1.9]%) and peak forces of the gluteus maximus (83.8 [9.1]%), iliacus (81.1 [5.2]%), and contralateral iliacus (78.5 [5.8]%) and also that of the peak pelvic anterior tilt. The force of the biceps femoris appeared to be influenced by the actions of the muscles crossing the hip joint as well as by the pelvic anterior tilt.     

Ground reaction forces and knee mechanics in the weight acceptance phase of a dance leap take-off and landing

Aesthetic constraints allow dancers fewer technique modifications than other athletes to negotiate the demands of leaping. We examined vertical ground reaction force and knee mechanics during a saut de chat performed by healthy dancers. It was hypothesized that vertical ground reaction force during landing would exceed that of take-off, resulting in greater knee extensor moments and greater knee angular stiffness. Twelve dancers (six males, six females; age 18.9 ± 1.2 years, mass 59.2 ± 9.5 kg, height 1.68 ± 0.08 m, dance training 8.9 ± 5.1 years) with no history of low back pain or lower extremity pathology participated in the study. Saut de chat data were captured using an eight-camera Vicon system and AMTI force platforms. Peak ground reaction force was 26% greater during the landing phase, but did not result in increased peak knee extensor moments. Taking into account the 67% greater knee angular displacement during landing, this resulted in less knee angular stiffness during landing. In conclusion, landing was accomplished with less knee angular stiffness despite the greater peak ground reaction force. A link between decreased joint angular stiffness and increased soft tissue injury risk has been proposed elsewhere; therefore, landing from a saut de chat may be more injurious to the knee soft tissue than take-off.     

Kinematic and EMG activities during front and back squat variations in maximum loads

The aim of this study was to compare the musculature activity and kinematics of knee and hip joints during front and back squat with maximal loading. Two-dimensional kinematical data were collected and electromyographic activities of vastus lateralis, vastus medialis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus and erector spinae were measured while participants (n = 12, 21.2 ± 1.9 years old) were completing front and back squat exercises with maximum loading. Paired sample t-test was used for comparisons between two techniques. Results showed that the electromyographic activity of vastus medialis was found to be greater in the front squat compared to the back squat during the ascending phase (P < 0.05, d = 0.62; 95% CI, ?15.0/?4.17) and the whole manoeuvre (P < 0.05, d = 0.41; 95% CI, ?12.8/?0.43), while semitendinosus (P < 0.05, d = ?0.79; 95% CI, 0.62/20.59) electromyographic activity was greater in the back squat during the ascending phase. Compared to the front squat version, back squat exhibited significantly greater trunk lean, with no differences occurring in the knee joint kinematics throughout the movement. Results may suggest that the front squat may be preferred to the back squat for knee extensor development and for preventing possible lumbar injuries during maximum loading.     

Effects of muscle-tendon length on joint moment and power during sprint starts

The aim of this study was to examine the effects of muscle-tendon length on joint moment and power during maximal sprint starts. Nine male sprinters performed maximal sprint starts from the blocks that were adjusted either to 40 degrees or 65 degrees to the horizontal. Ground reaction forces were recorded at 833 Hz using a force platform and kinematic data were recorded at 200 Hz with a film camera. Joint moments and powers were analysed using kinematic and kinetic data. Muscle - tendon lengths of the medial gastrocnemius, soleus, vastus medialis, rectus femoris and biceps femoris were calculated from the set position to the end of the first single leg contact. The results indicated that block velocity (the horizontal velocity of centre of mass at the end of the block phase) was greater (P < 0.01) in the 40 degrees than in the 65 degrees block angle condition (3.39 +/- 0.23 vs. 3.30 +/- 0.21 m . s(-1)). Similarly, the initial lengths of the gastrocnemius and soleus of the front leg in the block at the beginning of force production until half way through the block phase were longer (P < 0.001) in the 40 degrees than in the 65 degrees block angle condition. The initial length and the length in the middle of the block phase were also longer in the 40 degrees than in the 65 degrees block angle condition both for both the gastrocnemius (P < 0.01) and soleus (P < 0.01-0.05) of the rear leg. In contrast, the initial lengths of the rectus femoris and vastus medialis of the front leg were longer (P < 0.05) in the 65 degrees than in the 40 degrees block angle condition. All differences gradually disappeared during the later block phase. The peak ankle joint moment (P < 0.01) and power (P < 0.05) during the block phase were greater in the 40 degrees than in the 65 degrees block angle condition for the rear leg. The peak ankle joint moment during the block phase was greater (P < 0.05) in the 40 degrees block angle for the front leg, whereas the peak knee joint moment of the rear leg was greater (P < 0.01) in the 65 degrees block angle condition. The results suggest that the longer initial muscle-tendon lengths of the gastrocnemius and soleus in the block phase at the beginning of force production contribute to the greater peak ankle joint moment and power and consequently the greater block velocity during the sprint start.