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1.
Developed from traditional Chinese martial arts, Tai Chi exercise includes different forms and interactive Push Hands but biomechanical analyses have focused on the former only. To analyse the techniques of Push Hands, an experienced master was asked to defend pushing by four opponents. Movements were videotaped and digitized using a motion analysis system. Surface electrodes were used to record the electromyographic activity of ten muscle groups. Two force plates were used to measure the ground reaction force on each foot. Inexperienced individuals performed the same procedure to serve as the control group. The results indicate that the master adopted a postural adjustment to maintain balance. A clear shift of body weight from the front to the rear foot and mediolateral displacement of the centre of gravity was observed. Low electromyographic activity was observed in the upper body muscle groups, while high electromyographic activity was observed in the right rectus femoris and very high activity in the left rectus femoris during the defence. All inexperienced participants lost their balance in resisting pushing. It is concluded that the Tai Chi defensive technique includes a subtle postural adjustment that slightly changes the pushing force direction, and allows the rear leg to resist the incoming force.  相似文献   

2.
Abstract

Push Hand is an advanced training technique for the Yang-style old frame 108 forms Tai Chi Chuan. It is performed by two practitioners. To clarify how people use forces during Push Hand training, it is important to review the ground reaction force (GRF). Here, we quantify the characteristics of the GRF during Push Hand training. Kinematic data and GRF data from 10 Tai Chi Chuan practitioners (29.9 ± 7.87 years) were synchronously recorded using a three-dimensional motion analysis system (200 frames · s?1) and three-dimensional force plates (1000 Hz). The resultant GRF for both feet for the 0%, 50% and 100% phases of attack and defence were compared to body weight using a paired-samples t-test. The differences in the resultant GRF between the 0%, 50% and 100% phases of attack and defence were tested by one-way repeated-measures ANOVA. The significance level was set to 0.05. The total resultant GRF was almost equal to the participant’s body weight in push hand. This result was consistent throughout the entire push hand process. Our results revealed that the GRF was comparable to the body weight, implying that practitioners do not push or resist their opponents during the push hand process.  相似文献   

3.
Background:During an experiment,a ski racer equipped with various measurement devices suffered an anterior cruciate ligament(ACL)rupture in his right knee.The aim of this study was to describe the underlying injury mechanism from a functional perspective.Methods:Eight giant slalom turns(i.e.,4 left turns),followed by 1 left turn at which the ACL injury occurred,were recorded by 2 video cameras,electromyography of 4 relevant muscle groups,inertial measurement units to measure knee and hip angles,and pressure insoles to determine ground reaction forces.Results:Due to a loss of balance,the ski racer began to slide sideways at the apex of a left turn.During sliding,his right(outside)leg was actively abducted upward without touching the ground.The ski racer then attempted to stand up again by dropping his leg back towards the snow surface.The end of this dropping was accompanied by a decrease in electromyographic activity in the knee stabilizing muscles.Once the inside edge of the outer ski caught the snow surface,a rapidly increasing peak force,knee flexion,and an aggressive sudden activation of the vastus medialis muscle were observed,while biceps femoris and rectus femoris further decreased their activation levels.This likely resulted in excessive anterior translation of the tibia relative to the femur,causing damage to the ACL.Conclusion:Our example emphasizes that ski racers should not get up until they stop sliding.Remember:“When you’re down,stay down.”  相似文献   

4.

In this study, we analyzed the relationship between running economy (RE) and biomechanical parameters in a group running at the same relative intensity and same absolute velocity. Sixteen homogeneous male long-distance runners performed a test to determine RE at 4.4 m.s-1, corresponding to 11.1% below velocity at the ventilatory threshold. We found significant correlations between RE and biomechanical variables (vertical oscillation of the center of mass, stride frequency, stride length, balance time, relative stride length, range of elbow motion, internal knee, ankle angles at foot strike, and electromyographic activity of the semitendinosus and rectus femoris muscles). In conclusion, changes in running technique can influence RE and lead to improved running performance.  相似文献   

5.
PurposeThe purpose of the present study was to examine the effects of a 24-week Tai Chi exercise intervention on balance and other physical changes such as flexibility and reaction time (RT) among healthy older males.MethodsThirty-eight male subjects aged 55–65 years without prior Tai Chi experience were recruited from a local community in Shanghai, China. A 60-min Tai Chi exercise session was performed three times a week for 24 weeks. Changes in RT, sit-and-reach flexibility and balance (static balance with eyes open and closed respectively) were measured before and after the Tai Chi intervention.ResultsAfter the 24-week Tai Chi intervention, the choice RT (p < 0.05) decreased, and sit-and-reach flexibility improved (p < 0.01) over the pre-test (7.8±6.2 vs. 7.1±3.0cm). Sway length, area, X-axis deviation amplitude and Y-axis deviation amplitude performance decreased significantly after the intervention with a double-foot stance with eyes open (p < 0.05). Sway length, area and average sway speed showed a statistically significant decrease after the intervention with the double-foot stance with eyes closed. In the single-foot stance with eyes open condition, sway length and average sway speed showed a statistically significant decrease (p < 0.05).ConclusionThe 24-week Tai Chi exercise intervention had a positive influence on balance control in older males.  相似文献   

6.
The effects of long-term Tai Chi exercise on body stability of the elderly during stair ascent under high and low illumination were investigated. Forty-five healthy elderly women were divided into three groups, namely, Tai Chi exercise group, brisk walking group and no-exercise control group. All the participants ascended a staircase, during which force platforms and a motion capture system collected the data. Under the high illumination, Tai Chi exercise participants exhibited higher loading rate and anteroposterior centre of pressure (COPap) displacement as well as a lower braking impulse than no-exercise group. Under the low illumination, Tai Chi exercise participants demonstrated higher COPap and mediolateral centre of pressure (COPml) displacements as well as lower braking and lateral impulses compared with no-exercise participants. The centre of mass (COM)ml sway in Tai Chi and no exercise participants were higher, the loading rates in Tai Chi and walking participants were higher, and the lateral impulse in no exercise participants was higher under low illumination than under high illumination. Thus, low illumination increases the risk of falling. Tai Chi participants increased their foot clearance, head inclination angle and COPap displacement under low illumination to increase their stability during stair ascent.  相似文献   

7.
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.  相似文献   

8.
太极(Tai Chi)拳动作多为直立姿势,类似于舞蹈动作.广泛流传在中国,作为军事训练或锻炼的一种形式.通过Tai Chi练习获得的身体上益处包括平衡能力和肌肉力量,心理上的益处包括注意力、睡眠和焦急.进行Tai Chi练习心血管系统功能改善,包括心率和血压下降、增加迷走神经的活性,降低胆固醇.Tai Chi练习能够对疼痛综合症产生良性的影响,包括纤维组织肌痛、骨关节炎和风湿性关节炎.最近,研究发现通过Tai Chi练习,自身免疫和免疫功能也会发生良性改变,包括骨质疏松症、糖尿病和HIV.Tai Chi是一项中等强度的有氧运动,可促进不同性别,不同年龄的机体获得良性的效果.  相似文献   

9.
研究目的:研究长期练习太极拳、交谊舞、慢走对老年女性平衡能力的影响。研究方法:采用秒表和芬兰Good Balance平衡训练测试系统对太极拳组(15名)、交谊舞组(15名)和慢走组(14名)老年女性进行平衡能力的测试。实验结果:在闭眼单足站立中,太极拳组与慢走组具有显著性差异。在静态平衡能力测试中,太极拳组与慢走组在双脚睁眼、双脚闭眼、单腿睁眼中出现显著性差异。交谊舞组与慢走组在半脚测试中出现显著性差异。在动态平衡能力测试中,时间T与人体重心COP移动的总距离D,太极拳组与慢走组有显著性差异。COP在X轴上的移动距离MLD,太极拳组与慢走组,交谊舞组与慢走组之间都具有显著性差异。结论:太极拳和交谊舞在改善老年人平衡能力方面效果都优于慢走;太极拳和交谊舞具有良好的防止老年人跌倒的功效。  相似文献   

10.
The purposes of this study were to examine: 1) the potential muscle-specific differences in voluntary electromechanical delay (EMD) and relaxation electromechanical delay (R-EMD), and 2) the effects of intensity on EMD and R-EMD during step incremental isometric muscle actions from 10 to 100% maximal voluntary isometric contraction (MVIC). EMD and R-EMD measures were calculated from the simultaneous assessments of electromyography, mechanomyography, and force production from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) during step isometric muscle actions. There were no differences between the VL, VM, and RF for the voluntary EMDE-M (onsets of the electromyographic to mechanomyographic signals), EMDM-F (onsets the mechanomyographic to force production), or EMDE-F (onsets of the electromyographic signal to force production) as well as R-EMDE-M (cessation of electromyographic to mechanomyographic signal), R-EMDM-F (cessation of mechanomyographic signal to force cessation), or R-EMDE-F (cessation of electromyorgraphic signal to force cessation) at any intensity. There were decreases in all EMD and R-EMD measures with increases in intensity. The relative contributions from EMDE-M and EMDM-F to EMDE-F as well as R-EMDE-M and R-EMDM-F to R-EMDE-F remained similar across all intensities. The superficial muscles of the quadriceps femoris shared similar EMD and R-EMD measurements.  相似文献   

11.
The proximal-to-distal segmental sequence has been identified in many sports activities, including baseball pitching and ball kicking. However, proximal-to-distal sequential muscle activity has not been identified. The aims of this study were to establish whether sequential muscle activity does occur and, if it does, to determine its functional role. We recorded surface electromyograms (EMGs) for 17 muscles from the upper extremity and abdomen during overarm throwing and detected the onset and peak times as indices of muscle activity. The following electromyographic properties were commonly identified in the participants. First, sequential muscle activity was observed from the scapular protractors to the shoulder horizontal flexors and from the shoulder horizontal flexors to the elbow extensor, but not from the elbow extensor to the wrist flexor or forearm pronator. Secondly, the external oblique contralateral to the throwing arm became activated before the ipsilateral external oblique. This sequence is considered to be very effective for the generation of high force and energy in the trunk. Thirdly, the ipsilateral external oblique began its activity almost at foot strike. Finally, the main activity of the rectus abdominis appeared just before the point of release.  相似文献   

12.
Abstract

This study aimed to investigate the effect of whole body vibration (WBV) training on the knee kinematics and neuromuscular control after single-legged drop landings. Surface electromyographic (EMG) activity of the rectus femoris and hamstring muscles and knee and ankle accelerometry signals were acquired from 42 healthy volunteers. Participants performed three pre-test landings and after a recovery period of three minutes, they completed one set of six bouts of WBV each of one minute duration (30 Hz – 4 mm), followed by a single-leg drop landing. After the WBV intervention no significant changes were observed in the kinematic outcomes measured, although the time to stabilise the lower-limb was significantly lower after the vibration training (F(8,41) = 6.55; P < 0.01). EMG analysis showed no significant differences in the amplitude of rectus femoris or hamstring muscles after WBV training, however, significant differences in EMG frequency of the rectus femoris were found before (F(8,41) = 7.595; P < 0.01) and after toe-down (F(8,41) = 4.440; P < 0.001). Finally, no significant changes were observed in knee or ankle acceleration after WBV. Results suggest that WBV can help to acutely enhance knee neuromuscular control, which may have clinical significance and help in the design of rehabilitation programmes.  相似文献   

13.
The proximal-to-distal segmental sequence has been identified in many sports activities, including baseball pitching and ball kicking. However, proximal-to-distal sequential muscle activity has not been identified. The aims of this study were to establish whether sequential muscle activity does occur and, if it does, to determine its functional role. We recorded surface electromyograms (EMGs) for 17 muscles from the upper extremity and abdomen during overarm throwing and detected the onset and peak times as indices of muscle activity. The following electromyographic properties were commonly identified in the participants. First, sequential muscle activity was observed from the scapular protractors to the shoulder horizontal flexors and from the shoulder horizontal flexors to the elbow extensor, but not from the elbow extensor to the wrist flexor or forearm pronator. Secondly, the external oblique contralateral to the throwing arm became activated before the ipsilateral external oblique. This sequence is considered to be very effective for the generation of high force and energy in the trunk. Thirdly, the ipsilateral external oblique began its activity almost at foot strike. Finally, the main activity of the rectus abdominis appeared just before the point of release.  相似文献   

14.
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.  相似文献   

15.
目的：验证6个月的新型太极拳康复方案干预是否可以改善老年女性膝关节炎患者的下肢肌力和动态平衡能力。方法：招募46名老年女性膝骨关节炎患者，随机分为太极组和对照组，进行为期6个月的实验干预。实验前后，通过等速肌力测试仪和动态平衡测试指标，测量所有受试者下肢肌力和动态平衡能力。结果：6个月前后，太极组下肢肌力无显著性差异（P>0.05），但动态稳定性显著性提高（P<0.05）。结论：新型太极拳康复干预可促进女性膝骨关节炎患者动态平衡稳定性，简易有效，易于推广。  相似文献   

16.
The purpose of this study was to evaluate the effects of cold-water immersion on the electromyographic (EMG) response of the lower limb and balance during unipodal jump landing. The evaluation comprised 40 individuals (20 basketball players and 20 non-athletes). The EMG response in the lateral gastrocnemius, tibialis anterior, fibular longus, rectus femoris, hamstring and gluteus medius; amplitude and mean speed of the centre of pressure, flight time and ground reaction force (GRF) were analysed. All volunteers remained for 20 min with their ankle immersed in cold-water, and were re-evaluated immediately post and after 10, 20 and 30 min of reheating. The Shapiro–Wilk test, Friedman test and Dunn’s post test (P < 0.05) were used. The EMG response values decreased for the lateral gastrocnemius, tibialis anterior, fibular longus and rectus femoris of both athletes and non-athletes (P < 0.05). The comparison between the groups showed that the EMG response was lower for the athletes. Lower jump flight time and GRF, greater amplitude and mean speed of centre of pressure were predominant in the athletes. Cold-water immersion decreased the EMG activity of the lower limb, flight time and GRF and increased the amplitude and mean speed of centre of pressure.  相似文献   

17.

Purpose: This study compared the relative peak torque and normalized electromyographic (EMG) mean frequency (MNF) responses during fatiguing isokinetic muscle actions for men versus women. Method: Twenty men (M age ± SD = 22 ± 2 years) and 20 women (M age ± SD = 22 ± 1 years) performed 50 maximal concentric isokinetic muscle actions of the leg extensors at a velocity of 180°/s while surface EMG signals were detected from the vastus lateralis, rectus femoris, and vastus medialis. The dependent variables were initial, final, and average peak torque; percent decline; the estimated percentage of fast-twitch fibers for the vastus lateralis; and the linear slope coefficients and y-intercepts for normalized EMG MNF versus repetition number. The data were analyzed with independent-samples t tests and 2-way mixed-factorial analyses of variance. Results: The mean initial, final, and average peak torque values for men were greater than those for women. There were no mean differences for percent decline and the estimated percentage of fast-twitch fibers for the vastus lateralis. There were also no sex differences for the linear slope coefficients, but there were differences among the muscles (vastus medialis>vastus lateralis>rectus femoris). The mean y-intercept for the vastus lateralis for men was greater than that for women. Conclusions: Men demonstrated greater peak torque values than those for women, but the declines in peak torque and normalized EMG MNF were similar between the sexes. The vastus medialis was more fatigue-resistant than both the vastus lateralis and rectus femoris.  相似文献   

18.
太极推手是太极拳文化重要的组成部分。对太极拳的研究不能遗忘对太极推手的研究。也因此,对太极推手的文化技术研究显得弥足珍贵。通过文献资料的查阅,在研读太极拳古籍文本的基础上,运用哲学思辩的理论和方法,对太极推手技术理论进行归纳分析。研究认为,太极推手技理的哲学意义表现为：沾粘连随求得机得势;引化拿发达以柔克刚;刚柔并济显以巧斗力;舍己从人示和谐向善。文章最后指出,在太极推手技法体系中,各个环节是一个统一的有机体,沾粘连随是基础,引化拿发是表现,刚柔并济是手段,舍己从人是目标。  相似文献   

19.
目的:探索太极拳练习和快走练习对老年人平衡能力的影响效果。方法:31名老年女性被随机分成太极拳组(TC)和快走组(BW)。两组受试者分别接受16周的太极拳练习和快走练习,每周5次,每次1h,随后停止练习跟踪8周。受试者每4周测试一次平衡能力,共测试7次。测试指标包括睁眼(SLO)和闭眼(SLC)状态下的单腿站立时间(TIME)、足底压力中心在左右方向的最大位移量(DX)、足底压力中心在前后方向的最大位移量(DY)。结果:太极拳组(TC)TIME-SLO/SLC从第4周显著性增加,而快走组(BW)从第8周显著性增加;太极拳组DX-SLO/SLC、DY-SLO/SLC从第8周显著性减少,而快走组从第12周显著减少。停练阶段,太极组的平衡能力指标未有显著性变化,但快走组指标中除了DY,其他指标均有明显变化的趋势。结论:太极拳和快走练习均可以提高老年人的平衡能力,太极拳提高的更快(太极vs.快走:8周vs.12周);8周的停练阶段,两种练习方式对平衡能力均有较好的维持作用,但太极拳的维持效果更好。因此,相比于快走练习,老年人可以考虑将太极拳作为首选的练习方式。  相似文献   

20.
运用摄影测量法和Novel Pedar-X足底压力测试系统采集了16名太极拳练习者在太极拳运动和正常步行中足底压力和运动影像信息,并对两种运动方式的单脚支撑姿势持续时间指标进行对比分析。研究表明:与正常步行相比,在太极拳运动中单脚支撑姿势总的持续时间所占比例(标准化值)较少(P<0.05);单次单脚支撑姿势平均持续时间较长(P<0.01);认为太极拳运动可以提高人体单脚平衡能力。另外还发现太极拳运动和正常步行中地面反作用力都在不断变化;太极拳运动中地面反作用力小于其正常步行值。  相似文献   

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