Analysis of ankle protection in Association football

Football ankle protectors were evaluated against a kick from a studded boot. An anatomically correct test rig was used to evaluate materials and designs. Sensors were used to determine peak pressures on the bony protuberances, and load spreading. Finite element analysis (FEA), varying the material parameters and component dimensions, were used to explore pressure distributions and shell buckling. Current designs, with thin ethylene vinyl acetate (EVA) foam and low-density polyethylene (LDPE) shells, cannot prevent some football kicks causing bruising of the ankle. The protection level could be improved by using thicker foams of higher modulus, and domed shells of higher stiffness.     

我国优秀蹦床运动员踝关节撞击综合症康复治疗效果探究

通过对中国优秀蹦床运动员的康复个案,探讨康复训练对踝关节撞击综合症的干预效果。在为期16周的第一期康复治疗结束后,队员的力量、稳定性、核心稳定性和FMS测试均呈现良好的状态,运动员可以进行正常的训练和比赛;在为期16周的第二期康复训练结束后,运动员的各项身体能力都有所提高,有效的保障了正常的比赛和训练,取得了良好的效果。     

女子手球运动员踝关节屈伸肌群等速测试与分析

目的：探讨女子手球运动员的踝关节等速测试力量特征。方法：运用CON-TREX对受测试运动员的踝关节进行等速向心测试。结果：受试队员两关节伸肌的相对峰力矩值均显著大于屈肌;女手队员的比值范围在32%～40%之间;踝关节伸肌的平均功率值显著大于屈肌;踝关节伸屈肌的总功值随测试速度的增大而减小。结论：1）女手队员踝关节屈肌最大力量强于伸肌;2）女手队员踝关节屈伸肌力量比例合理;3）女手队员踝关节屈肌的快速力量强于伸肌;4）女手队员踝关节伸屈肌的总工作能力比较弱。     

A comparison of the reverse and power punches in oriental martial arts

Abstract

In this study, we compared mechanical factors in the reverse and three-inch power punches. Twelve expert male martial artists stood on a force plate, and executed reverse and power punches against a padded target fixed to a wall-mounted force plate. The force plates measured horizontal forces, and subsequently impulses and body centre of mass velocity changes. The motions of four markers attached to the arm were also collected, and were used to compute the horizontal velocities of the knuckle and of the arm centre of mass. The power punch produced smaller velocities immediately before impact than the reverse punch for the whole-body centre of mass (0.14 vs. 0.31 m · s^?1), for the arm centre of mass (2.86 vs. 4.68 m · s^?1), and for the knuckle (4.09 vs. 6.43 m · s^?1). The peak force exerted by the fist was much smaller in the power punch than in the reverse punch (790 vs. 1450 N). However, the linear impulse exerted by the fist during the first 0.20 s of contact was slightly larger in the power punch than in the reverse punch (43.2 vs. 37.7 N · s). The results indicate that the power punch is less potent than the reverse punch, but slightly more effective for throwing the opponent off balance.     

Do ankle braces provide similar effects on ankle biomechanical variables in subjects with and without chronic ankle instability during landing?

PurposeThe purpose of this study was to examine effects of a sport version of a semi-rigid ankle brace (Element?) and a soft ankle brace (ASO) on ankle biomechanics and ground reaction forces (GRFs) during a drop landing activity in subjects with chronic ankle instability (CAI) compared to healthy subjects with no history of CAI.MethodsTen healthy subjects and 10 subjects who had multiple ankle sprains participated in the study as the control and unstable subjects, respectively. The CAI subjects were age, body mass index and gender matched with the control subjects. The arch index and ankle functions of the subjects were measured in a subject screening session. During the biomechanical test session, participants performed five trials of drop landing from 0.6 m, wearing no brace (NB), Element? brace and ASO brace. Simultaneous recording of three-dimensional kinematic (240 Hz) and GRF (1200 Hz) data were performed.ResultsThe CAI subjects had lower ankle functional survey scores. The arch index and deformity results showed greater arch deformity of Element? against a static load than in NB and ASO due to greater initial arch position held by the brace. CAI participants had greater eversion velocity than healthy controls. The ASO brace reduced the first peak vertical GRF whereas Element? increased 2nd peak vertical GRF. Element? brace reduced eversion range of motion (ROM) and peak eversion velocity compared to NB and ASO. In addition, Element? reduced dorsiflexion ROM and increased peak plantarflexion moment compared to NB and ASO.ConclusionResults of static arch measurements and dynamic ankle motion suggest that the restrictions offered by both braces are in part due to more dorsiflexed ankle positions at contact, and higher initial arch position and stiffer ankle for Element?.     

Neuromuscular control during stepping down in continuous gait in individuals with and without ankle instability

Abstract

Ankle sprains are a common injury and those affected are at a risk of developing chronic ankle instability (CAI). Complications of an acute sprain include increased risk of re-injury and persistent disability; however, the exact link between ankle sprains and chronic instability has yet to be elucidated. The purpose of this study was to investigate neuromuscular control (including kinematics, kinetics and EMG) during stepping down from a curb, a common yet challenging daily activity, in persons with ankle instability (n = 11), those with a history of ankle sprain without persistent instability, called ankle sprain “copers” (CPRs) (n = 9) and uninjured controls (CTLs) (n = 13). A significant group difference was noted as the CPR group demonstrated increased tibialis anterior activity in both the preparatory (pre-touchdown) and reactive (post-touchdown) phases when compared to healthy and unstable groups (P < 0.05). It follows that the CPR group also demonstrated a significantly less plantar-flexed position at touchdown than the other two groups (P < 0.05). This is a more stable position to load the ankle and this strategy differed from that used by participants with CAI and uninjured CTLs. These findings provide insight into the neuromuscular control strategies of CPRs, which may allow them to more appropriately control ankle stability following sprains.     

地表面倾斜度与踝关节护具对垂直着地运动中地面反作用力、踝关节运动学和动力学的效应

研究背景：现有研究文献尚无有关在着地过程中不同表面倾斜度和踝关节护具效应的运动学、动力学和地面反作用力的综合数据。通过对比25°斜面和平面的着地以及使用和不使用踝关节护具情况下来检测踝关节的生物力学特性。研究方法： 11名健康受试者[年龄：（24.6±3.5）岁,身高：（24.6±0.10）m,质量：（65.6±14.9）kg）参与本次研究。受试者在4个动态运动条件下各进行5五次实验：从0.45米高处垂直下落至25°的斜面（IS）或平面（FS）上,使用或不使用半刚性踝关节护具,同时采集三维运动学和测力台地面反作用力数据。利用2×2(表面X踝关节护具)的重复测量方差分析来评估选定的变量。研究结果：与平面着地相比,斜面着地造成较小的垂直和内侧地面反作用力峰值。研究还发现踝关节背曲运动范围、着地角度和背曲速度、最大外翻与跖曲角速度提高,但产生了更大内翻角度和运动范围、着地内翻速度和最大跖曲力矩。踝关节护具在斜面着地时减少了达到地面反作用力第二垂直峰值的时间、着地角度、背曲速度、最大外翻和跖曲速度,但增加了跖曲力矩的最大值。研究结论：斜面增加踝关节额状面的运动范围和踝关节负荷。但是,就斜面着地而言,踝关节护具对踝关节额状面的运动范围和踝关节负荷的影响是相当有限的。     

Durability of running shoes with ethylene vinyl acetate or polyurethane midsoles

Abstract

Ethylene vinyl acetate and polyurethane are widely used materials for shoe midsoles. The present study investigated the durability of running shoes made from ethylene vinyl acetate and one type of polyurethane (polyurethane-1), which have similar hardness and density, and another type of polyurethane (polyurethane-2), which has high hardness/density. All shoes differed from one another only in terms of the midsole material used. Eight male runners participated in the present study and used the shoes to run 500 km (10 × 50 km). The cushioning and energy return characteristics of each shoe were measured using an impact tester before and after each 50-km run. The results showed that as the running distance increased, the peak force of midsole materials changed with different patterns. Ethylene vinyl acetate and polyurethane-1 showed greater cushioning than polyurethane-2 over 500 km (ethylene vinyl acetate, 918.2–968.0 N; polyurethane-1, 909.6–972.9 N; polyurethane-2, 983.0–1105.6 N). Polyurethane-1 showed greater cushioning from 200 km to 300 km compared with 0 km (0 km, 972.9 ± 66.3 N; 200 km, 909.6 ± 61.2 N; 250 km, 921.9 ± 51.2 N; 300 km, 924.6 ± 51.9 N). The cushioning of ethylene vinyl acetate shoes was diminished after 500 km compared with that at 0 km (968.0 ± 25.9 N vs. 921.1 ± 20.1 N). Ethylene vinyl acetate resulted in greater energy returns than polyurethane. Both foam category and hardness/density affected the critical biomechanical properties of running shoes.