Effect of defence response time during lunge in foil fencing

The aim of this study was to analyse the effect of stimulus change timing on reaction response time parameters, horizontal velocity of the centre of mass (CM) and precision during offensive actions in fencing. Twelve fencers from the Spanish National Foil Team were included in the study. Two 500 Hz force plates were used to register the horizontal component of the reaction force while a 3D video camera set at 250 Hz recorded the spatial position of 11 body markers and a projector connected to a programmed stopwatch projected a moving target (stimulus) on a screen. When the circle (target) appeared in the centre of the plastron, fencers had to execute a step-forward-lunge as fast as possible, trying to touch the circle with the tip of the foil. During the lunge, the position of the target could randomly shift or not to three different positions. The stimulus change was performed randomly at four different times with a progressive delay. The results show that target changes did not have any effect when they occurred at the beginning of the movement sequence. However, when the target change was delayed, reaction and movement times increased and the technical execution of the lunge changed, leading to more errors.     

Biomechanical insights into the determinants of speed in the fencing lunge

For fencing, speed of the lunge is considered critical to success. The aim of this study is to investigate determinants of lunge speed based on biomechanics. Ground reaction force (GRF) and three-dimensional kinematic data were collected from 7 elite fencers and 12 intermediate-level fencers performing maximum-effort lunges. The results showed that elite fencers acquired a higher horizontal peak velocity of the centre of gravity (HPV) and concomitantly a higher horizontal peak GRF exerted by rear leg (PGRF) than intermediate-level fencers (P?P?P?P?≤?.05). Our findings suggest that training aimed at enhancing strength and power of rear knee extensors is important for fencers to improve speed of the lunge. Also, increasing the extension of rear knee during the lunge, at the same time decreasing the flexion of the forward knee before extension are positive for lunge performance.     

Kinetic changes during a six-week minimal footwear and gait-retraining intervention in runners

An evaluation of a six-week Combined minimal footwear transition and gait-retraining combination vs. gait retraining only on impact characteristics and leg stiffness. Twenty-four trained male runners were randomly assigned to either (1) Minimalist footwear transition Combined with gait-retraining over a six-week period (“Combined” group; n = 12) examined in both footwear, or (2) a gait-retraining group only with no minimalist footwear exposure (“Control”; n = 12). Participants were assessed for loading rate, impact peak, vertical, knee and ankle stiffness, and foot-strike using 3D and kinetic analysis. Loading rate was significantly higher in the Combined group in minimal shoes in pre-tests compared to a Control (P ≤ 0.001), reduced significantly in the Combined group over time (P ≤ 0.001), and was not different to the Control group in post-tests (P = 0.16). The impact peak (P = 0.056) and ankle stiffness reduced in both groups (P = 0.006). Loading rate and vertical stiffness was higher in minimalist footwear than conventional running shoes both pre (P ≤ 0.001) and post (P = 0.046) the intervention. There has a higher tendency to non-rearfoot strike in both interventions, but more acute changes in the minimalist footwear. A Combined intervention can potentially reduce impact variables. However, higher loading rate initially in minimalist footwear may increase the risk of injury in this condition.     

Gender differences in foot shape: a study of Chinese young adults

One important extrinsic factor that causes foot deformity and pain in women is footwear. Women's sports shoes are designed as smaller versions of men's shoes. Based on this, the current study aims to identify foot shape in 1,236 Chinese young adult men and 1,085 Chinese young adult women. Three-dimensional foot shape data were collected through video filming. Nineteen foot shape variables were measured, including girth (4 variables), length (4 variables), width (3 variables), height (7 variables), and angle (1 variable). A comparison of foot measures within the range of the common foot length (FL) categories indicates that women showed significantly smaller values of foot measures in width, height, and girth than men. Three foot types were classified, and distributions of different foot shapes within the same FL were found between women and men. Foot width, medial ball length, ball angle, and instep height showed significant differences among foot types in the same FL for both genders. There were differences in the foot shape between Chinese young women and men, which should be considered in the design of Chinese young adults’ sports shoes.     

Effects of turf and cleat footwear on plantar load distributions in adolescent American football players during resisted pushing

Metatarsal and midfoot injuries are common in American football. Footwear design may influence injury rates by altering plantar foot loading patterns in these regions. The purpose of this study was to determine the effect of cleat design on in-shoe plantar foot loading during a football-specific, resisted pushing task. Twenty competitive football players (age 14.7 ± 1.8 years, height 1.72 ± 0.10 m, and mass 71.8 ± 26.9 kg) completed three trials of pushing a weighted sled at maximal effort in a standard shoe (CLEAT) and artificial turf-specific shoe (TURF), with flexible in-shoe force measuring insoles. Repeated measures ANOVAs identified mean differences in maximum force and relative load under all regions of the foot. Results showed higher forces in the CLEAT under the medial (p < 0.001) and lateral (p = 0.004) midfoot, central (p = 0.007) and lateral (p < 0.001) forefoot, and lesser toes (p = 0.01), but lower forces in the hallux (p = 0.02) compared to the TURF shoe. Additionally, relative loading was higher in the CLEAT under the medial (p < 0.001) and lateral (p = 0.002) midfoot and lateral (p < 0.001) forefoot, but lower in the medial forefoot (p = 0.006) and hallux (p < 0.001) compared to the TURF shoe. The two shoes elicited distinct plantar loading profiles and may influence shoe selection decisions during injury prevention or rehabilitation practices.     

Systematic reduction of leg muscle activity throughout a standard assessment of running footwear

Purpose:This study aimed to investigate whether there is a systematic change of leg muscle activity,as quantified by surface electromyography(EMG),throughout a standard running footwear assessment protocol at a predetermined running speed.Methods:Thirty-one physically active adults(15 females and 16 males) completed 5 testing rounds consisting of overground running trials at a speed of 3.5 m/s.The level of muscle activity from 6 major leg muscles was recorded using surface EMG.The variables asse...     

Effects of two football stud configurations on biomechanical characteristics of single-leg landing and cutting movements on infilled synthetic turf

Multiple playing surfaces and footwear used in American football warrant a better understanding of relationship between different combinations of turf and footwear. The purpose of this study was to examine effects of shoe and stud types on ground reaction force (GRF) and ankle and knee kinematics of a 180° cut and a single-leg 90° land-cut on synthetic turf. Fourteen recreational football players performed five trials of the 180° cut and 90° land-cut in three shoe conditions: non-studded running shoe, and football shoe with natural and synthetic turf studs. Variables were analyzed with a 3 × 2 (shoe × movement) repeated measures analysis of variance (p < 0.05). Peak vertical GRF (p < 0.001) and loading rate (p < 0.001) were greater during 90° land-cut than 180° cut. For 180° cut, natural turf studs produced smaller peak medial GRFs compared to synthetic turf studs and non-studded shoe (p = 0.012). For land-cut, peak eversion velocity was reduced in running shoes compared to natural (p = 0.016) and synthetic (p = 0.002) turf studs. The 90° land-cut movement resulted in greater peak vertical GRF and loading rate compared to the 180° cut. Overall, increased GRFs in the 90° land-cut movement may increase the chance of injury.     

Influence of footwear designed to boost energy return on running economy in comparison to a conventional running shoe

Running economy is a reflection of the amount of inspired oxygen required to maintain a given velocity and is considered a determining factor for running performance. Athletic footwear has been advocated as a mechanism by which running economy can be enhanced. New commercially available footwear has been developed in order to increase energy return, although their efficacy has not been investigated. This study aimed to examine the effects of energy return footwear on running economy in relation to conventional running shoes. Twelve male runners completed 6-min steady-state runs in conventional and energy return footwear. Overall, oxygen consumption (VO₂), heart rate, respiratory exchange ratio, shoe comfort and rating of perceived exertion were assessed. Moreover, participants subjectively indicated which shoe condition they preferred for running. Differences in shoe comfort and physiological parameters were examined using Wilcoxon signed-rank tests, whilst shoe preferences were tested using a chi-square analysis. The results showed that VO₂ and respiratory exchange ratio were significantly lower, and shoe comfort was significantly greater, in the energy return footwear. Given the relationship between running economy and running performance, these observations indicate that the energy return footwear may be associated with enhanced running performance in comparison to conventional shoes.     

The effect of minimal shoes on arch structure and intrinsic foot muscle strength

BackgroundThis prospective study explored the effects of endurance running (ER) in minimal versus standard running shoes on the foot's superficial layer intrinsic muscles and the function of the longitudinal arch. Our hypothesis was that running in minimal shoes would cause hypertrophy in these muscles and lead to higher, stronger, stiffer arches.MethodsThe hypothesis was tested using a sample of 33 healthy runners randomized into two groups, a control group shod in traditional running footwear and an experimental group shod in minimal support footwear, whose feet were scanned in an MRI before and after a 12-week training regime. Running kinematics as well as arch stiffness and height were also assessed before and after the treatment period.ResultsAnalysis of anatomical cross-sectional areas and muscle volumes indicate that the flexor digitorum brevis muscle became larger in both groups by 11% and 21%, respectively, but only the minimally shod runners had significant areal and volumetric increases of the abductor digiti minimi of 18% and 22%, respectively, and significantly increased longitudinal arch stiffness (60%).ConclusionThese results suggest that endurance running in minimal support footwear with 4 mm offset or less makes greater use of the spring-like function of the longitudinal arch, thus leading to greater demands on the intrinsic muscles that support the arch, thereby strengthening the foot.     

Effect of target change during the simple attack in fencing

Abstract

The aim of this study was to test the effect that changing targets during a simple long lunge attack in fencing exerts on the temporal parameters of the reaction response, the execution speed, and the precision and the coordination of the movement pattern. Thirty fencers with more than 10 years of experience participated in this study. Two force platforms were used to record the horizontal components of the reaction forces and thereby to determine the beginning of the movement. A three-dimensional (3D) system recorded the spatial positions of the 9 markers situated on the fencer plus the epee, while a moving target was projected on a screen, enabling the control of the target change. The results indicated that when a target change is provoked the reaction time (RT), movement time (MT), and the time used in the acceleration phase of the centre of mass (CM) increases significantly with respect to the attack executed with a straight thrust. The speed and horizontal distance reached by the CM at the end of the acceleration phase (V_X(CM) and S_X(CM), respectively) significantly decreased, while the errors increased. However, the temporal sequence of the movement pattern did not appreciably change.     

The influence of shoe drop on the kinematics and kinetics of children tennis players

This study investigated the immediate effects of reducing the shoe drop (i.e. the difference between the heel and the forefoot height) on the kinematics and kinetics of the lower extremities of children tennis players performing a tennis-specific movement. Thirteen children tennis players performed a series of simulated open stance forehands wearing 3 pairs of shoes differing only in the drop: 0 (D0), 6 (D6) and the control condition of 12?mm (D12). Two embedded forceplates and a motion capture system were used to analyse the ground reaction forces and ankle and knee joint angles and moments of the leading lower limb. In D6 compared with D12, the peak impact force was reduced by 24% (p?=?.004) and the ankle was less dorsiflexed at foot strike (p?=?.037). In D0 compared with D12, the peak impact force was reduced by 17% (p?=?.049), the ankle was less dorsiflexed at foot strike (p?=?.045) and the knee was more flexed at foot strike (p?=?.007). In addition, 4 out of 13 participants (31%) presented a forefoot strike pattern for some of the trials in D0. No difference was observed across shoe conditions for the peak knee extensor moment (p?=?.658) or the peak ankle plantarflexor moment (p?=?.071). The results provide preliminary data supporting the hypothesis that for children tennis players, using a 6-mm lower shoe drop might reduce heel impact forces and thus limit potentially impact-related injuries.     

The influence of different footwear on 3-D kinematics and muscle activation during the barbell back squat in males

Abstract

The barbell back squat is commonly used by athletes participating in resistance training. The barbell squat is typically performed using standard athletic shoes, or specially designed weightlifting footwear, although there are now a large number of athletes who prefer to squat barefoot or in barefoot-inspired footwear. This study aimed to determine how these footwear influence 3-D kinematics and muscle activation potentials during the barbell back squat. Fourteen experienced male participants completed squats at 70% 1 rep max in each footwear condition. 3-D kinematics from the torso, hip, knee and ankle were measured using an eight-camera motion analysis system. In addition, electromyographical (EMG) measurements were obtained from the rectus femoris, tibialis anterior, gastrocnemius, erector spinae and biceps femoris muscles. EMG parameters and joint kinematics were compared between footwear using repeated-measures analyses of variance. Participants were also asked to subjectively rate which footwear they preferred when performing their squat lifts; this was examined a chi-squared test. The kinematic analysis indicated that, in comparison to barefoot the running shoe was associated with increased squat depth, knee flexion and rectus femoris activation. The chi-squared test was significant and showed that participants preferred to squat barefoot. This study supports anecdotal evidence of athletes who prefer to train barefoot or in barefoot-inspired footwear although no biomechanical evidence was found to support this notion.     

中华剑术文化与当今剑术套路演练之研究

中华剑术文化的兴起与发展，有如下特征：即剑术的兴起与剑器的发生、发展关系密切，围绕剑器可形成的技击方法是剑术发展和演变过程的主要内涵。从此点出发，论述了当今剑术套路演练中剑术技法训练的主要内容及其功力训练等相关问题。     

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.     

Components of attack response inhibition in fencing: Components of attack response inhibition in fencing

Applying the Go/No-Go paradigm to fencing, we investigated the relationship between the moment at which the No-Go signal appeared after a movement had been initiated and the time required by fencers to suppress the motor execution of a step-lunge. Secondarily, we determined a time threshold from which movement inhibition results in an error. The No-Go stimulus was represented by a real attack movement. 18 elite fencers and a fencing master were included in the study. Four force plates measured the horizontal components of the fencer's and master's reaction forces, which were used to calculate the time components of the attack and the response inhibition process. Also, the velocity and displacement of the master's and fencer's respective centres of mass were estimated using inverse dynamics. In all cases, cognitive inhibition processes were completed after the onset of movement. Movement time was calculated using four time components (muscle activation, muscle deactivation, transition and braking time). The results obtained revealed that cognitive processes were not significantly affected by the timing of the appearance of the No-Go signal. In contrast, movement time and its time components tended to decrease when the time delay between the No-Go stimulus and the onset of the fencer's movement increased. In conclusion, any attempt to withhold an attack movement when it has already started leads to an error that increases the risk of being hit by the opponent, especially when attack is inhibited within 150?ms after the movement has started.     

Effects of replica running shoes upon external forces and muscle activity during running

Abstract

Twelve participants ran (9 km · h^?1) to test two types of running shoes: replica and original shoes. Ground reaction force, plantar pressure and electromyographic activity were recorded. The shoes were tested randomly and on different days. Comparisons between the two experimental conditions were made by analysis of variance (ANOVA) test (P ≤ 0.05). The time to first peak, loading rate of the first peak and impulse of the first 75 ms of stance were significantly different between the shoes (P ≤ 0.05), revealing an increase of impact forces for the replica shoes. The peak plantar pressure values were significantly higher (P ≤ 0.05) when wearing replica shoes. During running, the contact area was significantly smaller (P ≤ 0.05) for the replica shoe. The electromyographic activity of the analysed muscles did not show changes between the two shoes in running. These findings suggest that the use of replica running shoes can increase the external load applied to the human body, but may not change the muscle activity pattern during locomotion. This new mechanical situation may increase the risk of injuries in these movements.     

Differential effects of speed on two-dimensional foot strike pattern during barefoot and shod running in recreationally active men

ABSTRACT

The majority of barefoot running studies have not considered speed as an influential factor on foot strike pattern. The aim of this study was to investigate differences in foot strike pattern and spatiotemporal characteristics between barefoot and shod overground running at varying speeds. We first determined maximal running speed (Vm) over 50 m in 15 recreationally active men who self-reported as habitual rearfoot strikers. Participants then completed shod and barefoot running trials at different speeds equivalent to approximately 90%, 80%, 70% and 60% of Vm. Sagittal plane two-dimensional (2D) foot-ground contact angle, ankle plantar-dorsi flexion angle, contact time, flight time, step length and step rate variables for each trial were recorded. A significant interaction effect of running speed and footwear condition (p < 0.05) on foot-ground contact angle, ankle plantar-dorsi flexion angle and contact time was observed. There was a main effect of running speed (p < 0.01) on flight time, step length and step rate. There was a main effect of footwear condition on step length (p < 0.01). Participants were more inclined to plantarflex the ankle and contact the ground with the forefoot at higher percentages of Vm, especially when running barefoot.     

两种习惯性着地方式对跑步支撑期下肢动力学特征的影响

目的：探究习惯后足着地者和习惯前足着地者在跑步支撑期下肢动力学的不同。方法：采用 Kistler三维测力台（采集力学指标,1 000 Hz）采集受试者跑步支撑期（测试足从足着地到足离地）的动力学数据。结果：习惯后足着地组（RFS）在支撑时间上比习惯前足着地组（FFS）的时间微长,但二者不具有显著差异（P>0.05）;RFS组在支撑期内外方向的最小值和最大值均小于FFS组,且呈显著差异（P＜0.05）;RFS组在支撑期前后方向的最小值（即制动力峰值）和最大值（即加速力峰值）均要高于FFS组,且呈显著差异（P＜0.05）;FFS组在支撑期垂直方向的最大峰值力和第一载荷率均高于RFS组,但不具有显著差异,且出现峰值时间无显著差异（P＞0.05）。结论：跑步时不同的着地方式影响了下肢的生物力学特征,习惯后足着地者跑步支撑期下肢动力学特征与习惯前足着地者主要在内外方向和前后方向上具有一定的差异。