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21.
Nili Steinberg Roger Adams Gordon Waddington Janet Karin Oren Tirosh 《Journal of motor behavior》2017,49(2):163-171
Aimed to investigate whether young male and female dancers have different patterns of association between static and dynamic postural balance (PB), 60 dancers from the Australian Ballet School (14–19 years old) were tested for static and dynamic PB with head and lumbar accelerometers. Monotonic relationships between static and dynamic PB were found in head movements among young female dancers in all three directions, but were found for young male dancers in the mediolateral (ML) and anteroposterior (AP) directions only. In lumbar movements, monotonic relationships were found for young female dancers in the AP direction only. Comparing head with lumbar movements in static PB, young male dancers demonstrated monotonic relationships between head and lumbar movements in all 3 directions; however, young female dancers demonstrated monotonic relationships in the AP direction only. In the dynamic measurements, both male and female dancers demonstrated monotonic relationships between head and lumbar movements for all parameters measured in the ML and vertical directions (p < .05). In conclusions, among female dancers static PB ability is correlated with their dynamic ability, whereas among male dancers, no relationship between the static and dynamic PB in the AP direction exists. Male dancers showed head and lumbar coordination in the static PB movement, but both genders manifested no head and lumbar coordination in the AP direction measured for dynamic PB. 相似文献
22.
The authors aimed to characterize age-related changes in the performance of maximum reach and identify kinematic parameters that explain the age-related discrepancy between perceived and actual maximum reach distance. Maximum reach was evaluated in 22 younger women (21.3 years old) and 20 older women (81.2 years old). Both the perceived and actual maximum forward reach and forward excursion of the center of pressure was shorter in older women. Older women also overestimated their maximum reach distance to a greater extent. Decline of movement at the hip joint specifically correlated with both the maximum distance and the overestimation. Based on these results, decline of hip control may be a primary factor for the age-related retardation of perceived and actual maximum reach. 相似文献
23.
Unilateral Fatigue Affects the Unipedal Postural Balance in Individuals With Intellectual Disability
Rihab Borji Haithem Rebai Rym Baccouch Rabeb Laatar Sonia Sahli 《Journal of motor behavior》2017,49(4):407-413
This study aimed to explore the effect of local muscle fatigue on the unipedal stance in men with intellectual disability (ID). The Centre of pressure (CoP) excursions and the isometric maximal voluntary contraction (MVC) were measured before and after a fatiguing exercise. Higher baseline values of CoP excursions and lower MVC values were recorded in the ID group. After the fatiguing exercise, this group showed higher MVC decrease and higher percentage of increase of the mean CoP velocity. In conclusion, men with ID are more vulnerable to the disturbing effects of fatigue during the unipedal stance compared to men without ID. 相似文献
24.
神经肌肉下意识前馈与反馈控制的知觉线索效应 总被引:1,自引:0,他引:1
为研究视觉和时间知觉线索对突发外部姿势干扰下中枢神经系统对动作肌肉和姿势肌肉预期姿势调节(APAs)和补偿姿势调节(CPAs)的影响, 本研究被试分别在视觉和时间线索引导下完成经典落球试验, 同步采集右侧动作肌肉肱二头肌和姿势肌肉腰部竖脊肌和腰部多裂肌的sEMG信号, 计算被检肌肉APAs发生率、预激活时间和CPAs反应强度。结果发现, 视觉线索可以引发动作肌肉和姿势肌肉APAs发生率明显增加, 预激活时间明显提前, 以及动作肌肉CPAs反应强度明显减小; 而时间线索主要引发动作肌肉预激活提前, 对姿势肌肉APAs和CPAs无明显影响。该结果表明, 视觉和时间引导线索对突发外部姿势干扰条件下人体姿势肌肉和动作肌肉的中枢运动控制具有不同的作用。视觉引导线索能够明显增加姿势肌肉和动作肌肉预激活发生率和提早预激活时间, 表现出明显的“视觉线索预激活优势现象”; 而时间引导线索主要引发动作肌肉预激活提前, 对姿势肌肉APAs和CPAs无明显影响。 相似文献
25.
Altered Arm-Body Coordination with Triggered Pointing Responses as Influenced by Task Predictability
AbstractReaching movements generate reaction forces that affect postural stability, requiring sophisticated coordination between body and arm movement to maintain balance. In voluntary movement, this coordination involves feedforward shifts of posture, and such anticipatory postural muscle activity also accompanies the rapid modulation of an ongoing point to suddenly a shifting target (double-step). However, it is unknown if this early postural activity depends on target-shift predictability and whether arm and body motion are similar coordinated to voluntary movement. Body and arm motion coordination during double-step pointing movements from standing were done under differing conditions of target-shift predictability. In a proportion of trials, the pointing target was displaced, with the predictability of target-shift direction varied between two peripheral targets (target-shift direction known) and two central targets (target-shift direction uncertain). The target jump evoked an adjustment in the arm then body response, opposite to the pointing responses to the initial target. The triggered arm-then-body ordering was consistent across target-shift predictability, although known target-shift direction resulted in closer timing of arm and body onsets. The altered coordination in triggered corrections suggests that the body component in triggered reactions depend on response predictability, showing an altered control of arm and body motion. 相似文献
26.
AbstractSelf-initiated postural adjustments commonly occur in daily life. To accessibly measure this type of dynamic balance, we developed a simple computer program to induce virtual perturbations and combined it with a commercially available balance board and portable EMG system to measure resulting self-initiated postural adjustments. When performing perturbed balance tests, safety harness with body weight support (BWS) is often used. However, influences of these harnesses on postural reactions are not well known. This study investigated the sensitivity of our assessment tool under different BWS conditions and muscle responses during postural adjustments following perturbation at different directions. Fifteen neurologically intact participants performed self-initiated postural adjustments under conditions with: (1) no harness; (2) harness with no BWS; and (3) harness with 10% BWS. Postural adjustment time and muscle activities of the lower leg were measured. We observed significant increases in postural adjustment time in the harness with no BWS condition and differneces in lower leg muscles response to virtual perturbation. Our findings suggest that the combination of our customized program with EMG is a sensitive and convenient tool to measure postural adjustments that approximate real-world scenarios. This method can be used with light body weight support to ensure safety without influencing muscle synergies. 相似文献
27.
《Journal of motor behavior》2012,44(1):79-88
AbstractIn the present study we investigated how attention contributes to the interaction between reach planning and execution, and postural control. Reaching movements were generated while standing and were performed either in isolation or in conjunction with a secondary reaction time (RT) task. In addition, to better understand how online movement control is affected by this interaction, the reaching movements could be unexpectedly perturbed medial-laterally. Postural kinetic, arm kinematic and RT, and secondary RT measures were used to characterize the responses. Results indicate task performance worsened when both the reaching and secondary tasks were completed simultaneously. Our results imply the generation of reaching movements while standing requires attentional resources to properly coordinate the interaction between the reaching task and postural control. 相似文献
28.
J.J. Wang S. Bhattacharyya Q. Li T.W. Heo X.Q. Ma Long-Qing Chen 《Philosophical Magazine Letters》2013,93(7):327-335
An efficient numerical algorithm is proposed to accurately compute the elastic fields in two-dimensional (2D) or three-dimensional (3D) microstructures with arbitrary elastic inhomogeneity and anisotropy. It combines the equivalent inclusion method of Eshelby, the microelasticity theory of Khachaturyan, and the spectral iterative perturbation method of Hu and Chen. Its efficiency is compared with those of existing approaches in the literature. The method can be conveniently implemented in phase-field modeling of stress-dependent microstructure evolution and/or of mass/electrical transport. 相似文献
29.
Localized muscle fatigue and postural perturbation have separately been shown to alter whole-body movement but little is known about how humans respond when subjected to both factors combined. Here we sought to quantify the kinematics of postural control and repetitive upper limb movement during standing surface perturbations and in the presence of fatigue. Subjects stood on a motion-based platform and repetitively reached between two shoulder-height targets until noticeably fatigued (rating of perceived exertion = 8/10). Every minute, subjects experienced a posterior and an anterior platform translation while reaching to the distal target. Outcomes were compared prior to and with fatigue (first vs. final minute data). When fatigued, regardless of the perturbation condition, subjects decreased their shoulder abduction and increased contralateral trunk flexion, a strategy that may relieve the load on the fatiguing upper limb musculature. During perturbations, kinematic adaptations emerged across the trunk and arm to preserve task performance. In contrast to our expectation, the kinematic response to the perturbations did not alter in the presence of fatigue. Kinematic adaptations in response to the perturbation predominantly occurred in the direction of the reach whereas fatigue adaptations occurred orthogonal to the reach. These findings suggest that during repetitive reaching, fatigue and postural perturbation compensations organize so as to minimize interaction with each other and preserve the global task characteristics of endpoint motion. 相似文献
30.
Rainer Beurskens Thomas Muehlbauer Lena Grabow Reinhold Kliegl Urs Granacher 《Journal of motor behavior》2013,45(6):500-508
Primary school children perform parts of their everyday activities while carrying school supplies and being involved in attention-demanding situations. Twenty-eight children (8–10 years old) performed a 1-legged stance and a 10 m walking test under single- and dual-task situations in unloaded (i.e., no backpack) and loaded conditions (i.e., backpack with 20% of body mass). Results showed that load carriage did not significantly influence children's standing and walking performance (all p > .05), while divided attention affected all proxies of walking (all p < .001). Last, no significant load by attention interactions was detected. The single application of attentional but not load demand negatively affects children's walking performance. A combined application of both did not further deteriorate their gait behavior. 相似文献