排序方式： 共有61条查询结果，搜索用时 15 毫秒
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Stanley P. Sady Mark P. Savage Wade H. Thomson Marlene M. Petratis 《Research quarterly for exercise and sport》2013,84(3):302-304
Abstract When subjects make simultaneous aiming movements of the upper limbs over different distances, assimilation effects are shown; the shorter distance limb overshoots when paired with a longer distance limb. However, it is not known whether assimilation effects are due to variations in distance per se or to variations in target location. To separate the possible influences of distance and location, 60 subjects made rapid bimanual aiming movements in one of four conditions. The two different-distance groups made a 20° movement in the left hand and a 60° movement in the right hand to either the same or different target locations. The comparison groups moved 20° in each limb. Somewhat surprisingly, spatial assimilations were greater when moving different distances to the same, rather than different, target locations, which suggests interlimb differences in distance mediate assimilation effects rather than target location. Temporal assimilations were greater when distance and location were varied, but the assimilations were not related to interlimb differences in velocity, as predicted by Marteniuk and MacKenzie (1980). 相似文献
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S. W. Farrell H. W. Kohl T. Rogers G. F. Knadler 《Research quarterly for exercise and sport》2013,84(2):99-102
Abstract The current study examines maximal heart rate and maximal treadmill time differences among three ethnic groups. In 1985, 1,047 city employees (572 male, 475 female) participated in a comprehensive health promotion program. Data were collected from a self-administered health and lifestyle questionnaire, maximal treadmill exercise stress test, and other clinical measures. The participants were divided into white male (n = 368), black male (n = 159), Mexican-American male (n = 45), white female (n = 256), black female (n = 189), and Mexican-American female (n = 30) subgroups based on self-reported ethnic identity. Univariate analyses revealed no significant differences in age-adjusted maximal heart rate or maximal treadmill time for males. Mean age-adjusted treadmill time for black females (478.0 ± 228.2 s) was significantly lower than for white (652.5 ± 227.7 s) and Mexican-American (594.5 ± 226.7 s) females (p <. 05). Mean age-adjusted maximal heart rate for black females (174.4 ± 12.4 beats/min) was significantly lower than for white (179.3 ± 13.4 beats/min) and Mexican-American (182.0 ± 13.5 beats/min) females (p < .05). Following adjustment for cardiovascular fitness level, that is, treadmill time, as well as age, these differences were no longer apparent. We concluded that the comparatively low maximal heart rate of black females may be partially explained by a significantly lower cardiovascular fitness level relative to white and Mexican-American females. 相似文献
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目的:确定跑步疲劳进程中下肢生物力学模式的变化,包括垂直和前后地面反作用力(ground reaction force,GRF)、垂直地面反作用力(vertical ground reaction force,vGRF)负载率、关节力学和刚度。方法:14名男性受试,采用Vicon红外摄像头和Bertec三维测力跑台,每隔2 min采集受试疲劳干预中的15 s GRF数据以及标记点轨迹。受试需穿着统一的跑鞋在测力跑台以恒速3.33 m/s跑至疲劳。满足以下标准时,干预结束:1)最大心率大于当下年龄的90%;2)受试不能继续跑步。对比受试跑至疲劳进程中4个时刻(疲劳前、33%、67%和100%)的着地冲击和下肢三关节触地角度、最大角度、关节活动度、角度变化量、关节蹬伸力矩和刚度等特征,采集并分析受试安静状态、疲劳后即刻、疲劳后4 min、疲劳后9 min的血乳酸浓度。结果:与疲劳前相比,1)血乳酸浓度在疲劳后即刻、疲劳后4 min和疲劳后9 min均显著增加;2)垂直/前后矢状轴GRF和vGRF负载率等参数在疲劳干预过程中均未观察到显著性变化;3)髋关节活动度在疲劳过程的33%、67%和100%时刻显著增加,膝关节活动度在67%时刻显著增加;4)踝关节运动学及踝、膝和髋关节的蹬伸力矩峰值均无变化;5)垂直刚度在67%和100%时刻显著降低。结论:疲劳干预过程中,GRF特征参数均没有明显变化,但是观察到下肢运动学和动力学模式的非线性改变。特别是从疲劳干预中期开始,人体下肢通过增加髋、膝关节活动度并减小垂直刚度实现“软着陆”策略,维持相似的冲击力特征,以减小长时间跑步可能带来损伤的风险。 相似文献
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目的:以去卵巢小鼠模拟妇女绝经后骨质疏松症状,对比研究上、下坡跑台运动对去卵巢小鼠破骨细胞分化及相关调节因子的影响.方法:64只8周龄C57 BL/6雌性小鼠随机分为4组:假手术安静组(SHAM),去卵巢安静组(OVX),去卵巢上坡跑组(OVX +UP),去卵巢下坡跑组(OVX +DOWN).结果:与SHAM组相比,OVX组小鼠干细胞向巨噬细胞分化的能力、巨噬细胞向破骨细胞分化的能力均显著增强;骨组织RANKL、M-CSF和RANK的基因表达显著增加,而OPG的基因表达显著降低.与OVX组相比,两运动组小鼠破骨细胞的分化得到了较好的抑制.结论:跑台运动可有效抑制小鼠去卵巢后破骨细胞的大量分化,从而有利于预防骨质疏松症的发生,且下坡跑运动比上坡跑运动更有效. 相似文献
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中长跑运动员跑台跑与场地跑下肢肌肉工作情况的比较分析 总被引：1，自引：0，他引：1
目的:通过EMG记录分析跑台跑和场地跑肌肉用力情况特征,比较这两种状态跑时肌肉用力方式的各自特点。方法:11名中长跑运动员,每名运动员分两天测试,随机让其以10 km/h、12 km/h、14 km/h、16 km/h、18 km/h的速度在场地和跑台(0%、5%、10%坡度)运动6min,每种速度跑之间间歇10min。使用便携式Megawin ME-6000肌电仪记录其下肢肌群(臀大肌、股外侧肌、股二头肌、腓肠肌内侧头、胫骨前肌)EMG变化情况。结果表明:在肌肉用力方面,5%坡度的跑台跑可以模拟场地跑,而10%坡度的跑台跑则可以给予下肢肌群更强的刺激,以满足训练的需要;跑台跑时,胫骨前肌需要比在场地跑时动员更多的运动单位参与工作,而跑台的坡度和速度增加对动员更多的运动单位影响不大。 相似文献
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探讨运动对大鼠大脑皮层SOD、MDA、NO及NOS活性变化情况的结果表明,中等和大强度训练后大鼠安静时大脑皮层的NO含量以及NOS、SOD活性较未训练对照组显著上升,MDA无明显变化;训练运动后即刻组的NO含量以及NOS、SOD活性较训练对照组有所增加,但无显著性意义;一次性力竭运动组运动后即刻大脑皮层的SOD活性有所下降,MDA、NOS稍有升高,无显著性意义,NO含量显著下降.研究结果提示:训练可以提高大鼠大脑皮层NO的基础含量以及NOS、SOD活性;一次性力竭运动大鼠大脑皮层NOS活性升高而NO含量下降. 相似文献
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旨在通过对不同速度和不同坡度的控制,比较受试者在步态跑台上步态参数的异同。为使步态跑台更好地应用于健身、训练及康复提供参考和建议。采集并比较14名健康大学生以三种不同速度、三种不同坡度走时的时空和动力学参数。结果发现:步幅、步长与速度正相关,双支撑时长、单脚支撑时长、每步时长、步态周期与速度呈负相关。支撑力、触地受力时长、推动力随着速度增加而减小。在不同坡度的条件下行走,步长随着坡度的上升而增加,步态周期则相反。随着坡度的增加,触底受力时长、推动力、支撑力均变小。X轴方向平均力值与速度和坡度均呈正相关。 相似文献
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Laura Simoni Guido Pasquini Silvia Pancani Federica Vannetti Claudio Macchi Silvia Pogliaghi 《Journal of sports sciences》2020,38(20):2321-2328
ABSTRACT Studies on running biomechanics and energetics are usually conducted on a treadmill. To ensure that locomotion on a treadmill is comparable to locomotion overground, participants need to be expert in the use of the device. This study aimed to identify the number and duration of sessions needed to obtain stable measurements for spatiotemporal and metabolic parameters in unexperienced treadmill runners. Fourteen male recreational runners performed three 15-min treadmill running trials in different days at a submaximal speed. Spatiotemporal and metabolic parameters were registered at minutes: 5, 10, 15 and their within-trial and between-trial changes were analysed using a two-way repeated measures ANOVA and Bonferroni post-hoc test. Within-trial differences were found in step frequency (decreased over time), Step Length and Contact Time (increased), reaching stability at different time points. Ventilator parameters increased, reaching stability after 5–10 min, while heart rate increased progressively over time. The only between-trial differences were an increase in step length and a decrease in step frequency at min 1, between trials 1 and 3. In conclusion, at least three running trials of 15 min are required to familiarize with the device. The last 5 min of the third trial can be regarded as stable measurements. 相似文献
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Effect of speed on local dynamic stability of locomotion under different task constraints in running
《European Journal of Sport Science》2013,13(8):791-798
AbstractA number of studies have investigated effects of speed on local dynamic stability of walking, although this relationship has been rarely investigated under changing task constraints, such as during forward and backward running. To rectify this gap in the literature, the aim of this study was to investigate the effect of running speed on local dynamic stability of forward and backward running on a treadmill. Fifteen healthy male participants took part in this study. Participants ran in forward and backward directions at speeds of 80%, 100% and 120% of their preferred running speed. The three-dimensional motion of a C7 marker was recorded using a motion capture system. Local dynamic stability of the marker was quantified using short- and long-term largest finite-time Lyapunov exponents (LyE). Results showed that short-term largest finite-time LyE values increased with participant speed meaning that local dynamic stability decreased with increasing speed. Long-term largest finite-time LyEs, however, remained unaffected as speed increased. Results of this study indicated that, as in walking, slow running is more stable than fast running. These findings improve understanding of how stability is regulated when constraints on the speed of movements is altered. Implications for the design of rehabilitation or sport practice programmes suggest how task constraints could be manipulated to facilitate adaptations in locomotion stability during athletic training. 相似文献