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21.
The aim of this study was to analyse gait variability and symmetry in race walkers. Eighteen senior and 17 junior athletes race walked on an instrumented treadmill (for 10 km and 5 km, respectively) at speeds equivalent to 103% of season’s best time for 20 km and 10 km, respectively. Spatio-temporal and ground reaction force (GRF) data were recorded at 2.5 km, and at 4.5, 6.5 and 8.5 km for a subsection of athletes. Gait variability was measured using median absolute deviation (MAD) whereas inter-leg symmetry was measured using the symmetry angle. Both groups showed low variability for step length (<0.9%), step frequency (<1.1%), contact time (≤1.2%) and vertical peak force values (<5%), and neither variability nor symmetry changed with distance walked. Junior athletes were more variable for both step length (P = 0.004) and loading force (P = 0.003); no differences for gait symmetry were found. Whereas there was little mean asymmetry overall, individual analyses identified asymmetry in several athletes (symmetry angle ≥ 1.2%). Importantly, asymmetrical step lengths were found in 12 athletes and could result from underlying imbalances. Coaches are advised to observe athletes on an individual basis to monitor for both variability and asymmetry. 相似文献
22.
The aim of this study was to analyse lower limb work patterns in world-class race walkers. Seventeen male and female athletes race walked at competitive pace. Ground reaction forces (1000 Hz) and high-speed videos (100 Hz) were recorded and normalised joint moments, work and power, stride length, stride frequency and speed estimated. The hip flexors and extensors were the main generators of energy (24.5 J (±6.9) and 40.3 J (±8.3), respectively), with the ankle plantarflexors (16.3 J (±4.3)) contributing to the energy generated during late stance. The knee generated little energy but performed considerable negative work during swing (?49.1 J (±8.7)); the energy absorbed by the knee extensors was associated with smaller changes in velocity during stance (r = .783, P < .001), as was the energy generated by the hip flexors (r = ?.689, P = .002). The knee flexors did most negative work (?38.6 J (±5.8)) and the frequent injuries to the hamstrings are probably due to this considerable negative work. Coaches should note the important contributions of the hip and ankle muscles to energy generation and the need to develop knee flexor strength in reducing the risk of injury. 相似文献
23.
JONATHAN SINCLAIR JIM RICHARDS PAUL J. TAYLOR CHRISTOPHER J. EDMUNDSON DARRELL BROOKS SARAH J. HOBBS 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):272-282
The treadmill is an attractive device for the investigation of human locomotion, yet the extent to which lower limb kinematics differ from overground running remains a controversial topic. This study aimed to provide an extensive three-dimensional kinematic comparison of the lower extremities during overground and treadmill running. Twelve participants ran at 4.0 m/s ( ± 5%) in both treadmill and overground conditions. Angular kinematic parameters of the lower extremities during the stance phase were collected at 250 Hz using an eight-camera motion analysis system. Hip, knee, and ankle joint kinematics were quantified in the sagittal, coronal, and transverse planes, and contrasted using paired t-tests. Of the analysed parameters hip flexion at footstrike and ankle excursion to peak angle were found to be significantly reduced during treadmill running by 12° (p = 0.001) and 6.6° (p = 0.010), respectively. Treadmill running was found to be associated with significantly greater peak ankle eversion (by 6.3°, p = 0.006). It was concluded that the mechanics of treadmill running cannot be generalized to overground running. 相似文献
24.
Brian Hanley Athanassios Bissas Andrew Drake 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(2):110-124
The aim of this study was to analyse the important kinematic variables in elite men's and women's 20 km race walking. Thirty men and 30 women were analysed from video data recorded during the World Race Walking Cup. Video data were also recorded at four points during the European Cup Race Walking and 12 men and 12 women analysed from these data. Two camcorders operating at 50 Hz recorded at each race for 3D analysis. The two main performance determinants of speed were step length and cadence. Men were faster than women because of their greater step lengths but there was no difference in cadence. A reduction in step length was the initial cause of slowing down with later decreases in speed caused by reductions in cadence. Shorter contact times were important in optimising both step length and cadence, and faster athletes tended to have longer flight times than slower athletes. It was less clear which other kinematic variables were critical for successful walking, particularly with regard to joint angles. Different associations were found for some key variables in men and women, suggesting that their techniques may differ due to differences in height and mass. 相似文献
25.
Abstract The aims of this study were to examine ground contact characteristics, their relationship with race performance, and the time course of any changes in ground contact time during competitive 800 m and 1500 m races. Twenty-two seeded, single-sex middle-distance races totalling 181 runners were filmed at a competitive athletics meeting. Races were filmed at 100 Hz. Ground contact time was recorded one step for each athlete, on each lap of their race. Forefoot and midfoot strikers had significantly shorter ground contact times than heel strikers. Forefoot and midfoot strikers had significantly faster average race speed than heel strikers. There were strong large correlations between ground contact time and average race speed for the women's events and men’s 1500 m (r = ?0.521 to ?0.623; P < 0.05), whereas the men's 800 m displayed only a moderate relationship (r = ?0.361; P = 0.002). For each event, ground contact time for the first lap was significantly shorter than for the last lap, which might reflect runners becoming fatigued. 相似文献
26.
为了探讨形态学参数(身高、体重、罗勒指数、克托莱指数、BMI)对运动员100 m比赛成绩的影响,根据平均成绩(10.87 s),将女子100 m历史上突破11秒的71名运动员分为2组:FG(Faster Group)和SG(SlowerGroup),分析其形态学参数对比赛成绩的影响.结果表明,女子100 m运动员的身高、体重、罗勒指数、克托莱指数、BMI与比赛成绩不存在显著性相关(P>0.05);FG与SG在形态学参数上不存在显著性差异(P>0.05);形态学参数对100 m比赛成绩的影响不存在性别差异,步态参数对100 m比赛成绩的影响存在性别差异. 相似文献
27.
目的:探讨快速步行时,脑卒中患者与健康被试下肢肌肉在活动持续时间百分比、AEMG、MPF、复杂度等指标上的差异。方法:男性脑卒中患者10名及健康对照组被试10名,按照步长40cm步频60次/min的不同步速在平地上直线行走8步,采集患者偏瘫侧及健康被试对照侧胫骨前肌、内侧腓肠肌、股直肌、股二头肌的肌电信号,并利用足底步态开关记录行走过程中的步态周期。结果:①患者胫骨前肌在摆动期、内侧腓肠肌在摆动期及第一次双侧支撑期的活动持续时间均显著长于健康被试;②患者胫骨前肌及股二头肌的平均肌电值增加,股直肌的平均功率频率下降率变小。 相似文献
28.
Gait recognition is the key question of functional electrical stimulation (FES) system control for paraplegic walking. A new risk-tendency-graph (RTG) method was proposed to recognize the stability information in FES-assisted walking gait. The main instrument was a specialized walker dynamometer system based on a multi-channel strain-gauge bridge network fixed on the walker frame. During walking process, this system collected the reaction forces between patient's upper extremities and walker and converted them into RTG morphologic curves of dynamic gait stability in temporal and spatial domains. To demonstrate the potential usefulness of RTG, preliminary clinical trials were done with paraplegic patients. The gait stability levels of two walking cases with 4- and 12-week FES training from one subject were quantified (0.43 and 0.19) from the results of temporal and spatial RTG. Relevant instable phases in gait cycle and dangerous inclinations of patient's body during walking process were also brought forward. In conclusion, the new RTG method is practical for distinguishing more useful gait stability information for FES system control. 相似文献
29.
lintroductionAtpresent,thefirst-stepsurfaceadhesionofmostwallclimbingrobotsdependsonsomeoutsideforce,whichisprovidedeitherbyhumanoperatorsorbysuchaspecialpurposemechanicaldeviceasamanipulator.ThisnotonlyrestrictsInanyspecialapplicationsofwall-climbingrobo… 相似文献
30.
青少年女性穿不同鞋行走时步态的动力学研究 总被引：8，自引：1，他引：7
通过SIMI-MOTION录像解析系统对青少年女性穿不同鞋行走时的步态进行运动学分析.结果表明:青少年女性裸足或穿球鞋行走时,步态特征表现为:步长长,步速快,步态周期短,重心起伏幅度小,单支撑时相占支撑时相比例高,踝关节、膝关节和髋关节灵活性好;青少年女性穿高跟鞋或松糕鞋行走时的步态特征表现为:步长短,步速慢,步态周期长,重心起伏幅度大,单支撑时相占支撑时相比例低,说明青少年女性穿高跟鞋和松糕鞋行走使下肢肌肉机能减弱.提示青少年女性穿高跟鞋或松糕鞋行走对青少年女性的生长发育有重大不利影响,建议青少年女性日常生活少穿或者不穿鞋跟较高的鞋. 相似文献