Compensatory adjustments in lower extremity kinematics in response to a reduced cushioning of the impact interface in heel–toe running

The response of heel-toe runners to changes in cushioning of the impact interface was investigated. Ground reaction force and sagittal plane kinematic data were collected for six heel-toe runners performing barefoot running trials on a conventional asphalt surface and an asphalt surface with additional cushioning. Statistical analysis indicated that similar peak impact force values were maintained when running on the two surfaces (p < 0.1). When running on the less cushioned surface, significant reductions were detected in ankle dorsi-flexion angle immediately prior to ground impact and peak ankle plantar-flexion velocity immediately following impact (p > 0.1). In addition, individual subjects demonstrated reductions in heel velocity and increases in knee flexion immediately prior to ground contact. The observed reduction in ankle dorsiflexion at impact, resulting in a flatter foot at ground contact, supports previous suggestions that this is a strategy to reduce local plantar pressure loads. The additional use of adjustments in heel velocity and initial knee flexion highlights the ability of some subjects to adopt compensatory measures to reduce peak impact loading. However, some subjects appear unable to make these adjustments, resulting in higher impact loading on the less cushioned surface for these subjects. This study provides experimental evidence to support the theoretical potential of heel impact velocity and initial knee flexion to influence impact loading in running.     

英语宝典

铅球 一般特征 当奥布莱恩·帕里发明了背向滑步推铅球技术之后,成绩才有了较大的提高。从此以后,许多运动员都改进了推铅球技术,即便是那些身高、体壮的运动员也提高了其动作速度和身体的灵活性,推铅球的成绩也有了很大的提高。     

Acute changes in kinematic and muscle activity patterns in habitually shod rearfoot strikers while running barefoot

The aim of this study was to observe changes in the kinematics and muscle activities when barefoot running was initially adopted by six habitually shod, recreational rearfoot striking runners. Participants ran on a treadmill shod for 5 min, completed 3 × 10-min intervals of barefoot running and then completed a final minute of shod running at a self-selected pace. Dependent variables (speed, joint angles at foot-contact, joint range of motion (ROM), mean and peak electromyography (EMG) activity) were compared across conditions using repeated measures ANOVAs. Anterior pelvic tilt and hip flexion significantly decreased during barefoot conditions at foot contact. The ROM for the trunk, pelvis, knee and ankle angles decreased during the barefoot conditions. Mean EMG activity was reduced for biceps femoris, gastrocnemius lateralis and tibialis anterior during barefoot running. The peak activity across the running cycle decreased in biceps femoris, vastus medialis, gastrocnemius medialis and tibialis anterior during barefoot running. During barefoot running, tibialis anterior activity significantly decreased during the pre-activation and initial contact phases; gastrocnemius lateralis and medialis activity significantly decreased during the push-off phase. Barefoot running caused immediate biomechanical and neuromuscular adaptations at the hip and pelvis, which persisted when the runners donned their shoes, indicating that some learning had occurred during an initial short bout of barefoot running.     

Foot strike pattern in preschool children during running: sex and shod–unshod differences

Purpose: This study aims to determine the foot strike patterns (FSPs) and neutral support (no inversion [INV]/eversion [EVE] and no foot rotation) in preschool children, as well as to determine the influence of shod/unshod conditions and sex. Methods: A total of 1356 children aged 3–6 years (673 boys and 683 girls) participated in this study. A sagittal and frontal-plane video (240?Hz) was recorded using a high-speed camcorder to record the following variables: rearfoot strike (RFS), midfoot strike (MFS), forefoot strike (FFS), inversion/ eversion (INV/EVE) and foot rotation on initial contact. Results: There were no between-sex significant differences in both shod and unshod conditions in RFS. In the unshod condition, there was a significant reduction (p?Conclusion: In preschool children, no between-sex differences were found in relation to prevalence of RFS and neutral support (no INV/EVE). Shod running alters FSP of running barefoot, producing a significant increase of RFS prevalence.     

裸足与着鞋下跑步生物力学及损伤特征的研究现状

研究已证实跑步有很多益处,包括增强心血管机能,促进身体和心理健康。但是,有太多的损伤与跑步相关,在当今裸足跑或者是穿"裸足"鞋跑步的流行趋势下,总结了大量高水平研究论文,其目的是通过运动学测量,能量消耗和生物力学来比较穿鞋和裸足跑步者的相似处和差异性,深入探究跑步步态学,并为因跑步导致肌肉骨骼损伤的病人了解跑步生物力学原理并制定合理训练计划。     

青少年赤足与穿鞋运动的生物力学分析

采用德国Novel公司的Pedar鞋垫式(in-sole)足底压力测量系统,对40名中学生赤足与穿着慢跑鞋在1.5m·s-1、3.0m·s8-1和5.0m·s-13个速度下的步态周期、最大地面反作用力、最大足底压强、平均足底压强和力量-时间积分值进行分析,探讨赤足运动与穿鞋运动的生物力学特性,以及引起赤足和穿鞋运动之间差异的原因,为指导青少年健康运动提供科学、可靠的参考依据.研究结果证实,赤足运动与穿鞋运动在步态、用力方式、压力分布上都存在显著差异,穿着慢跑鞋运动可有效降低运动损伤出现的几率,为青少年的健康运动提供基础保障.     

Measurement of intrinsic foot stiffness in minimally and traditionally shod runners using ultrasound elastography: A pilot study

ABSTRACT

Running is an activity with a consistently high injury rate. Running footwear design that mimics barefoot running has been proposed to reduce injury rate by increasing the strength of foot structures. However, there is little evidence to support this. The purpose of the current study is to use shear wave ultrasound elastography to examine material properties (shear modulus) of intrinsic foot structures in experienced minimally and traditionally shod runners. It is hypothesized that minimalist runners will exhibit increased stiffness compared to controls demonstrating the strengthening of these structures. Eighteen healthy runners (8 minimalist and 10 traditionalist), running a minimum of 10 mi · wk^?1, participated. Elastography scans were performed on the left foot of each participant. There is no apparent stiffening of foot structures associated with wearing minimalist shoes. Only the FHB tendon is different between shoe types and, contrary to the hypothesis, was stiffer in traditionalist compared to minimalist runners (257.26 ± 51.64 kPa vs 160.88 ± 27.79 kPa, respectively). A moderate positive (r = 0.7) relationship between training load and tendon stiffness suggests strengthening of tendon when running in traditional shoes. If running in minimalist shoes increases loading on these structures without resulting in stronger tissues, it is possible that minimalist footwear may increase injury risk.     

The acute effects of vibration stimulus following FIFA 11+ on agility and reactive strength in collegiate soccer players

PurposeThe aim of this study was to assess the effects of combining the FIFA 11+ and acute vibration training on reactive strength index (RSI) and 505 agility.MethodsSeventy-four male collegiate soccer players took part in the study and were randomly assigned to FIFA 11+ with acute vibration group (FIFA + WBV), FIFA 11+ with isometric squat group (FIFA + IS) or a control group consisting of the FIFA 11+ alone (Con). The warm-up consisted of the FIFA 11+ and was administered to all participants. The participants in the acute vibration group were exposed to 30 s whole body vibration in squat position immediately post warm-up. The isometric group completed an isometric squat for 30 s immediately post warm-up.ResultsRSI significantly improved pre- to post-intervention amongst FIFA + WBV (p < 0.001) due to a decrease in contact time (p < 0.001) in comparison to FIFA + IS and Con, but 505 agility was not affected.ConclusionThe results of this study suggest the inclusion of an acute bout of WBV post FIFA 11+ warm-up produces a neuromuscular response leading to an improvement in RSI. Future research is required to examine the exact mechanisms behind these improvements amongst other populations and over time course of the performance.     

武术运动员操作思维敏捷性研究初探

以山东省运动技术学院武术队、山东体育学院武术专选学生、济南市业余体校武术队各随机抽１２名被试,进行操作思维水平试验,对实验结果作方差分析和ｑ值检验。结果显示不同组别运动员操作思维水平不同,操作思维同运动成绩密切相关,成绩越好操作思维的步数减少,时间越短：操作思维有随年龄增长而步数减少、时间缩短的趋势。应把操作思维敏捷性作为武术运动员的选材指标之一。     

Do stiffness and asymmetries predict change of direction performance?

Change of direction speed (CODS) underpins performance in a wide range of sports but little is known about how stiffness and asymmetries affect CODS. Eighteen healthy males performed unilateral drop jumps to determine vertical, ankle, knee and hip stiffness, and a CODS test to evaluate left and right leg cutting performance during which ground reaction force data were sampled. A step-wise regression analysis was performed to ascertain the determinants of CODS time. A two-variable regression model explained 63% (R² = 0.63; P = 0.001) of CODS performance. The model included the mean vertical stiffness and jump height asymmetry determined during the drop jump. Faster athletes (n = 9) exhibited greater vertical stiffness (F = 12.40; P = 0.001) and less asymmetry in drop jump height (F = 6.02; P = 0.026) than slower athletes (n = 9); effect sizes were both “large” in magnitude. Results suggest that overall vertical stiffness and drop jump height asymmetry are the strongest predictors of CODS in a healthy, non-athletic population.     

儿童单纯性肥胖的运动干预原理与方法研究

儿童肥胖率持续上升已经成为一个全球性问题,引起了社会各界的高度关注。为能够让更多人了解运动的减肥原理,正确应用运动减肥的方法,有效预防、干预儿童单纯性肥胖,依据儿童身心发展的特征和规律,对儿童单纯性肥胖的危害、诊断方法、表现特征、诱发原因,以及运动干预的原理和方法,做了详细的分析和阐释。