Effect of bag holding on the center of foot pressure and the lower leg muscle activities

Abstract

This study examined the influence of holding a bag with one hand on the center of foot pressure (COP) and the electromyographic responses in lower leg muscles. Thirteen healthy male adults participated in this study to keep an upright posture while holding a load with the dominant hand with four bag weight conditions (0%, 15%, 30%, and 45% of maximal voluntary contraction (MVC) of the jerk strength). Integrated Electromyography (iEMG) and mean power frequency (MPF) of EMG were calculated to estimate the degree of muscle activity and fatigue in the tibialis anterior and soleus that are involved in ankle joint control. Body sway was evaluated by the mean position of left-right (X) and front-back (Y) axis sway and the following 4 body sway factors; unit time sway factor (F1), front-back sway factor (F2), left-right sway factor (F3), high frequency band power spectrum factor (F4). When holding a bag at 45% MVC or more of the jerk strength with a single hand for one minute, muscle activity in the lower leg on the side of the bag increased markedly, and muscle fatigue was induced in the antigravity muscles of both legs. As a result, anteroposterior sway increased to a short, quick sway.     

Stresses in the plantar region for long- and short-range throws in women basketball players

Abstract

This study aimed to assess plantar pressure pattern modifications caused by short- and long-distance shots in women basketball players. To this end, 24 experienced national- and regional-level basketball players performed 3 trials of 4 technical gestures (free throw, jump stop shot, three-point shot and lay-up) barefoot on a pressure platform placed in fixed positions on the court. Raw data were processed to calculate location and magnitude of pressure peaks in three sub-regions (forefoot, midfoot and rearfoot), and the increase ratio was calculated relative to plantar pressure measured during a static bipedal and unipedal upright stance. The results showed significant increases (p<0.001) in plantar pressure peaks in forefoot (but not midfoot and rearfoot) for all the gestures that involved the use of both legs. Particularly large increases were detected for the three-point shot. All three sub-regions underwent significant changes of the pressure peak in the case of lay-up (forefoot and rearfoot: p<0.001, midfoot: p=0.002). The high levels of contact stress detected for routinely performed technical gestures suggest that a detailed knowledge of changes in the physiological patterns of plantar stresses that take place during play is crucial in reducing the risk of foot injuries and establishing proper training and rehabilitation protocols.     

Comparison of plantar loads among runners with different strike patterns

ABSTRACT

This study aimed to explore the plantar loading variables between habitual rearfoot strike (RFS) and non-rearfoot strike (NRFS) during running. 78 healthy males participated in this study (41 RFS, 37 NRFS). In-shoe pressure sensors were used to measure plantar loading while the participants were running on a 15 m indoor runway with their preferred foot strike pattern (FSP) at 12.0 ± 5% km/h. Results indicate that force and pressure parameters were much higher in the rearfoot and midfoot regions during RFS running and relatively greater in forefoot region during NRFS running. However, compared with NRFS running, the contact area, maximum force and force-time-integrals during RFS running on total foot were 21.44% (P < 0.001, ES = 2.29), 13.99% (P = 0.006, ES = 0.64) and 21.27% (P < 0.001, ES = 0.85) higher, respectively. Total foot peak pressure and pressure-time-integral between two FSPs were similar. Higher loads in the rearfoot region may transmit to the knee joint and result in patellofemoral joint injuries. NRFS runners’ higher loads in forefoot seem to be ralated to metatarsal stress fractures and compensatory damage to the Achilles tendon. Therefore, runners should choose proper FSPs according to their unique physical conditions.     

Increased toe-flexor muscle strength does not alter metatarsophalangeal and ankle joint mechanics or running economy

ABSTRACT

The intrinsic foot musculature (IFM) supports the arches of the foot and controls metatarsophalangeal joint (MTPJ) motion. Stronger IFM can increase the effective foot length, potentially altering lower-extremity gearing similar to that of using carbon-fibre-plated footwear. The purpose of this study was to investigate if strengthening of the IFM can alter gait mechanics and improve running economy. Eleven participants were randomly assigned into an experimental group and nine into a control group. The experimental group performed IFM strengthening exercises for ten weeks. Toe-flexor strength, gait mechanics, and running economy were assessed at baseline, five weeks, and ten weeks; using a custom strength testing apparatus, motion capture and force-instrumented treadmill, and indirect calorimetry. Toe-flexor strength increased in the experimental group (p = .006); however, MTPJ and ankle mechanics and running economy did not change. The dearth of changes in mechanics may be due to a lack of mechanical advantage of the IFM, runners staying within their preferred movement path, a need for MTPJ dorsiflexion to facilitate the windlass mechanism, or the primary function of the IFM being to support the longitudinal arch of the foot as opposed to modulating MTPJ mechanics.     

论陵川郝经雁足传书与清代杂剧《雁帛书》

雁足传书并非汉代苏武事,而是发生在元代山西陵川郝经出使南宋时一件真实的历史事件,《元史·都经传》及元明清三代各种文献资料,都有明确记载清代许云峤因慕郝经忠贞,遂作《雁帛书》杂剧,敷演郝经出使南宋被南宋拘禁,因雁足传书而归的千古传奇,体现了郝经不辱使命,忠贞不二,成武不屈的民族气节与人格情操太行深处小小陵川县,养育了郝经这样一位忠贞传奇人物,这是陵川的骄傲与荣耀。     

正骨手法治疗足踝部软组织损伤

本文采用拔牵、摇挤、顺按、牵正等四步正骨推拿手法并配以中药薰洗治疗62例尺踝部软组织损伤收到良好效果。笔者认为此种以手法为主,药物理疗为辅的综合疗法对踝部损伤具有疗效高、恢复快、简便易行等优点,值得同道试用。     

足部反射区按摩治疗41例腰肌劳损临床报告

腰肌劳损是运动训练和比赛中常见的运动性创伤。本文阐述了其产生的原因、症状及其诊断治疗方法。     

Effects of forefoot bending stiffness of badminton shoes on agility,comfort perception and lower leg kinematics during typical badminton movements

This study investigated whether an increase in the forefoot bending stiffness of a badminton shoe would positively affect agility, comfort and biomechanical variables during badminton-specific movements. Three shoe conditions with identical shoe upper and sole designs with different bending stiffness (Flexible, Regular and Stiff) were used. Elite male badminton players completed an agility test on a standard badminton court involving consecutive lunges in six directions, a comfort test performed by a pair of participants conducting a game-like practice trial and a biomechanics test involving a random assignment of consecutive right forward lunges. No significant differences were found in agility time and biomechanical variables among the three shoes. The players wearing the shoe with a flexible forefoot outsole demonstrated a decreased perception of comfort in the forefoot cushion compared to regular and stiffer conditions during the comfort test (p < 0.05). The results suggested that the modification of forefoot bending stiffness would influence individual perception of comfort but would not influence performance and lower extremity kinematics during the tested badminton-specific tasks. It was concluded that an optimisation of forefoot structure and materials in badminton shoes should consider the individual’s perception to maximise footwear comfort in performance.     

1759-1949年天山北麓中部聚落空间演变及其影响因素

研究干旱区聚落的空间演变过程对探究历史时期干旱区的土地利用变化和人地关系具有重要意义.本文结合历史文献、现代地方志、遥感影像等数据,运用核密度分析、标准差椭圆等方法研究1759-1949年新疆天山北麓中部木垒—奇台—吉木萨尔地区聚落的演变规律及其影响因素.结果 表明:①1759-1949年聚落主要分布在坡度10°以下,...     

以体育"学分制"为基础的末尾淘汰制

以体育“学分制”为基础的末尾淘汰制是在传统的体育管理模式上创新的一种学生体育成绩评分管理细则；是丢弃传统理念对体育教学管理进行改革的大胆构想和尝试；是新世纪大学生成才的阶梯。它不仅强调学生自主性、兴趣性、锻炼的实用性，培养学生终身体育锻炼的意识，同时体现高校体育教学的公平性、自由性、竞争性，为加快现代体育教学管理的发展进程提供了宝贵的实践经验和重要的帮助。