kinematic

The purpose of the present study is to evaluating the role of kinematic factors in predicting the motor performance of gymnastic children aged 10-12 years by examining the effect of choking under pressure. The statistical sample of the research consisted of 40 skilled female gymnasts with an age range of 10-12 years, who were selected as available and their motor performance (execution of a chain of gymnastic floor movements) after evaluating some kinematic factors (motion range and sense joint position) was measured and evaluated in low-pressure and high-pressure conditions by two referees and a gymnastics coach. Data analysis was done using descriptive statistics (mean and standard deviation) and inferential (linear regression) methods in SPSS software. The results of the research showed that kinematic factors in conditions of high pressure can predict the motor performance of gymnasts. Therefore, it can be concluded that kinematic factors may play a significant role in predicting the motor performance of gymnasts under psychological pressure and change it.

The Prone Hip Extension test (PHE) is used to evaluate the quality of motor control in the lumbopelvic region. Because of the similarity of this test to the walking and running pattern, it seems that muscle interaction in this test is important in hamstring injury. Therefore, this study aimed to investigate the effect of changing the activation patterns of muscles in prone hip extension on kinematical variables affecting hamstring injury. 28 male soccer players participated in this study. The prone hip extension test was used to evaluate and classify subjects, and based on the activation pattern, they were divided into two groups: normal pattern (N=14) and altered pattern (N=14). We used the Myon electromyography device to evaluate the prone hip extension test muscles activation pattern. Also, the kinematic evaluation of running was done on a treadmill at a speed of 20 km/h. Two-dimensional and three-dimensional video analyses were used to extract kinematic data (pelvic tilt, trunk lateral flexion, and trunk flexion). The range of motion in a running cycle and the amount of each variable at the moment of initial foot contact were used. An Independent t-test was used to analyze the data. The results of this research showed that there is a significant difference in the amount of trunk lateral flexion (p= 0/002), and trunk flexion (p= 0/024) at the moment of the initial foot contact and the range of motion of trunk lateral flexion (p=0/019), and trunk flexion (p=0/035) and pelvic tilt (p=0/008) in a running cycle between the changed pattern group and the normal group. The results of this research showed that changing the pattern of muscle activation in the prone hip extension test can increase the risk of a hamstring injury.

90-degree marching is a kind of military marching that can be analyzed as a special type of gait. The purpose of this research was kinematic evaluation of lower body in 90-degree marching based on one- segment model of the leg.

Subjects of this study were 13 Imam Hossein University Students performing 90-degree military march at self-selected speeds recorded by a high speed camera at 300 fps from the sagittal plane. Two passive markers were placed on hip and ankle of the participants and the direct distance between these two markers was defined as leg. Kinematic of the leg, hip and ankle movement in a complete cycle of marching was analyzed using the motion analysis software.

The profiles of displacement, velocity and acceleration to angular movement of the leg and curvilinear movement of the ankle were presented and analyzed. Average propulsion velocity was 0.60±0.14m/s. The leg angular acceleration curve had three peaks and the profiles of vertical, horizontal and resultant acceleration of the ankle showed three, five and one important peaks relatively. 90-degree marching was described based on these peaks which were the movement characteristics.

90-degree military marching at self-selected speed is consisted of stance and swing phases. In support phase, the leg rotates on the ankle as an inverted pendulum. In swing phase, following an initial acceleration, the leg goes up and come down during a pendulum movement around the hip. The moment of impact with the ground is the critical instant which may impose big accelerations to leg.

This study aimed to determine the role of strength, expulsive power and range of motion of lower limb muscle on the fencing performance of elite florists. In this study, eight elite fencers’ participated. Kinetic variables measured using force plate and kinematic variable measured using motion analysis system. The squat jump test used to measure the compulsive power of the lower extremity muscles of the fencers. The Drop-jump test used to measure the lower strength of the muscles of the lower extremity muscles. Descriptive statistics (mean and standard deviation) used to describe the data and Pearson correlation coefficient used for determine the relationship between data (P≤0.05). The results of this study showed there is a significant relationship between squat jump power and mechanical energy and drop jump height with lunge speed and also between ankle range of motion with peak force and impulse in the anterior direction (P<0.05). Given the results of this study, coaches should have a special attention on the strength and explosive power of plantar flexor muscles.

The aim of this study was to investigate the kinematic characteristics of the two skills of Judan and Chudan Giakozuki Karate, professional and semi-professional male men.

10 Professional and 10 semi -professional amateur male Karate athlethes participated in this study and performed the techniques. The ground reaction force during the impact, which was an indirect parameter to calculate the impact power, was measured using a force plate with a frequency of 250 Hz. The ADXL320 accelerometer was also used to calculate the hand transfer acceleration. The motion data were recorded using Phase Space real time optical tracking system with 8 high speed cameras at 480 fps. Then the kinematic parameters associated with each fist were modeled and quantified by a three-dimensional imaging system.Paired t-test and independent t-test were used to analyze the research data.The test results in the parameters of wrist, elbow, shoulder movement in Judan and Chuadan Gyakozuki skills, ground reaction force, peak speed of elbow and shoulder in Chuan Gyakozuki skill, peak wrist velocity in Judan Gyakozuki skill in semi-professional karate and professional showed a significant difference. Fainaly, the results showed that the type of impact and the level of experience of karatekas were the main factors in determining the size of the displacement parameters and peak velocity, which are considered an important factor in success in competitions and lead to better scores in competitions.

The aim of this study was to investigate the effect of lumbopelvic control (LPC) weakness on the symmetry of foot pressure distribution, vertical ground reaction force (GRF) and postural sways of athletes with frequent landings. In this case-control study, 34 professional players participated. LPC was assessed by Knee Lift Abdominal, Bent Knee Fall Out, Active Straight Leg Raising, and PRONE tests by Pressure Biofeedback Unit. Based on the results, participants were divided into two groups: appropriate LPC (n=17) and poor LPC (n=17). Foot pressure data were collected using PT-scan. The results showed that there was a significant difference between the mean scores of the foot pressure distribution symmetry, depth force, second peak force, area of sways, anterior-posterior and medial-lateral sways. Thus, poor LPC affects the symmetry of the foot pressure, GRF, and the postural sways of athletes with frequent landings, so can be a risk factor for lower limb injuries.

Having high correlation with the explosive power of the lower body, the muscular strength of the athletes and production of high power levels in the shortest time (power) and high level of agility, is essential to achieve optimal performance in Parkour. It seems that using polymetric trainings can make it possible to achieve the highest performance. Therefore, the aim of the present study was to investigate the effect of eight weeks of plyometric training on kinematical parameters, BMI, agility and liner jump strength in parkour athletes aged 19 to 26 years.

In this semi experimental study, with pre-test and post-test design, 20 Parkour elite athletes were selected in the age group of 19 to 26 years and were randomly divided into two groups of 10 persons, including: 1- Experimental group 2- Control group. The experimental groupchr('39')s training program Carried out for eight weeks, three sessions a week, for one hour. Before and after eight weeks of exercises, measurements of kinematical parameters of knee, the Illinois tests, and the liner jump strength and body Mass index (BMI) analysis were done of subjects. The research data were analyzed using t-test at a significant level (p≤0/05).

The results of statistical analysis of each group showed that performing plyometric trainings for eight weeks had a significant relationship with kinematical parameters of the knee (p=0/003). Also the strength of linear jump, agility and body fat percentage of parkour athletes improved (p≤0/05).

The findings of this study showed that there is a significant relationship between plyometric trainings and kinematical parameters of the knee and may increase the strength of jumping and agility and decrease body fat percentage in parkour athletes but since the basis of parkour sport is very similar to plyometric trainings more research is needed.

90-degree marching is a kind of military marching that can be analyzed as a special type of gait. The purpose of this research was kinematic evaluation of lower body in 90-degree marching based on one- segment model of the leg.

Subjects of this study were 13 Imam Hossein University Students performing 90-degree military march at self-selected speeds recorded by a high speed camera at 300 fps from the sagittal plane. Two passive markers were placed on hip and ankle of the participants and the direct distance between these two markers was defined as leg. Kinematic of the leg, hip and ankle movement in a complete cycle of marching was analyzed using the motion analysis software.

The profiles of displacement, velocity and acceleration to angular movement of the leg and curvilinear movement of the ankle were presented and analyzed. Average propulsion velocity was 0.60±0.14m/s. The leg angular acceleration curve had three peaks and the profiles of vertical, horizontal and resultant acceleration of the ankle showed three, five and one important peaks relatively. 90-degree marching was described based on these peaks which were the movement characteristics.

90-degree military marching at self-selected speed is consisted of stance and swing phases. In support phase, the leg rotates on the ankle as an inverted pendulum. In swing phase, following an initial acceleration, the leg goes up and come down during a pendulum movement around the hip. The moment of impact with the ground is the critical instant which may impose big accelerations to leg.

 The aim of this study is investigate the core muscles dysfunctions and their consequences in patients with chronic ankle instability.

 In this review study, search was conducted in three online databases of PubMed, Scopus, and Google scholar based on Patient, Intervention, Comparison, Outcome (PICO) strategy, and using keywords related to the role and function of core muscles, their electromyography, kinematic patterns of proximal segments, and postural stability in individuals with chronic ankle instability.

 Seven studies were finally selected for the review based on the inclusion and exclusion criteria. The results indicated that individuals with chronic ankle instability in comparison with healthy peers have different electromyography and kinematic patterns of proximal segments (trunk, abdomen and pelvis).

 Muscle activity and kinematic patterns of proximal segments in individuals with chronic ankle instability are different to those of healthy ones. These differences are compensatory strategies for postural stability. These strategies may not provide the body’s need to maintain and control the poster in new environments or during complex activities. Further studies are needed to investigate effects of the correction of core muscle function on the postural control in individuals with chronic ankle instability.

The aim of this study was to investigate the effect of the height of placement (lower and middle) of two types of backpacks (conventional backpack and modified backpack) with 10% of body weight on the kinetic (including 1st and 2nd peak, minimum force, and loading rate) and kinematic (including cadence, step length, step width, swing and double support phases) parameters of gait in schoolchildren. 28 school boys participated in the study after their inclusion and exclusion criteria were considered. They were evaluated by Gaitway treadmill in four conditions including backpack-low, backpack-middle, modified backpack-low, and modified backpack-middle. ANOVA test with repeated measures showed that the mean of the first and second peaks of the backpack-middle was higher than other conditions and had a significant difference with the backpack-low (P<0.05). Among the backpacks, the minimum vertical force in the backpack-low was more than both modified backpack conditions (P<0.05). Given the increase in the first and second peaks of the backpack-middle compared with the backpack-low, it seems better to place the backpack in the lumbar region in terms of forces applied to the body, but this difference was not observed for the modified backpack.

Over recent years, due to scientific advances in various aspects of sport, rapid development and improvement has taken place in sport performance standards as well as athlete's performance. In the swimming tournament starting on time and correctly, one of the factors that plays an important role in the success of swimmers, especially speed swimmers. The aim of this study was Comparison of selected kinematic variables frontand rear- weighted track start of elite male swimmers.
Fourteen male elite male swimmers with an average age of 17.86±1.92 years were targeted and available among those who had better starters and had the right foot (dominant legs) place in this study. The following kinematic parameters were analysed: take off angle, take off velocity, entry angle, entry velocity and flight distance. Used a top speed of 100 fps video camera to detect body position and biomechanical parameters during the performance two start techniques.the statistical methods were Kolmogorov-smirnov test to chek for normal distribution of data and T-test for comparison between two types of kinematic quantities start with 0.05 alpha levels.
Findings indicated that flight distance were significant difference between two start techniques (P Because of the difference in flight distance and Time off the platform in two types of startes, coaches and swimmers can use either of the two startes depending on the type of competition (Speed and endurance of swimming).

The present study was done to evaluate the effectiveness of some kinetic and kinematic features of healthy athletes during increased heel strike pattern. This case-control study was carried out on 13 professional healthy male athletes in two positions of normal and increased heel strike gait patterns. Range of motion, knee and ankle joint torque and vertical ground reaction force measured by the Kistler and Vicon motion analysis system. Results showed that increased heel strike compare to normal level walking caused significantly reduced knee flexion angle at the moment of heel contact and stance phase, mean values ​​of external rotational and adductor knee moments. In addition, increased ankle dorsiflexion during midstance was significantly high in increase heel strike pattern compare to usual pattern. It seems that increased heel strike pattern decreases knee mechanical loading and more importantly, increasing elasticity of gastrocnemius-soleus muscles provided by heel strike pattern.

Motion analysis systems are useful and effective equipment in biomechanics research. Unfortunately these systems are available for few researchers because these are expensive equipment. The aim of this study was to design and validation of a practical and inexpensive software, to determine the exact markers position in space and compute the kinematic of movement. In designing the software, the exact image processing algorithms and Direct Liner Transformation (DLT) method were used to calculate markers position in space. To validate the software, the markers position in static, dynamic, linear, angular, 2D and 3D conditions were calculateted by other standard tools and compared with software outputs using Mann-Whitney U test and no significant difference were observed. The validity and reliability of the software was assessed using Pearson Correlation Coefficient and Intraclass Correlations Coefficient and during all test conditions, very high levels of these coefficients were found (≥0.97). In a nutshell, present software, with features such as automatic tracking markers, inexpensive price, the possibility to outdoor use and image processing in 2D and 3D conditions, is valid and reliable software for kinematics analysis.

The purpose of the present study was to investigate the effect of near external and far external focus of attention on performance and kinematic of horizontal jump in skilled athletes. Participants were 15 males’ students’ member of volleyball and basketball team with an average age (23±4) that purposefully selected. The task was the horizontal jumping test which was executed under three condition (3 trials in per conditions; CON, EXN and EXF). Participants in the control condition did not receive any instruction, in EXF condition, participants were instructed to focus on a cone 5m far from the jumping lines, in EXN condition, participants were instructed to focus on the jumping lines on the floor. Kinematic data of knee joint was recorded by 3 markers in knee joint and 8 camera motion analysis. The results indicated that participant in EXN and EXF condition had significantly higher performance and also less maximum knee flexion than CON condition (P≤0.05). However, there was no significant difference between EXF and EXN condition (P>0.05). The result of the present study support “constrained action hypothesis” and show that focusing on the movement effect on the environment improve motor performance like jumping.

The aim of this study was comparing the ground reaction forces, center of pressure and body center of mass changes in voluntary, semi-voluntary and involuntary gait termination in healthy young men.
In this study, 12 young men performed termination of gait in three different patterns. The variable of peak antero-posterior and vertical forces in two directions at both limbs, the time to reach peak and average forces in every limb in both directions, the center of pressure displacement of medio-lateral and antero-posterior direction for each limb and the net center of pressure and the displacement of the center of mass motion in all three motion plates were recorded using motion analysis system and force plate.The repeated measurements test was used to compare three patterns of gait termination at significance level of p&le0.5.
The results showed a significant difference in variables of peak antero-posterior force, the time to reach peak antero-posterior force and mean antero-posterior forces of the leading limb, the peak antero-posterior force of the trialing limbs, the depth force of leading limbs, medio-lateral cop of leading limbs displacement and vertical displacement of the center of mass, among different patterns of gait termination.
While walking, the probability of a fall or collision damage, when a sudden or unexpected stop is required, increases. Therefore, more coordination between neuromuscular systems is required.

The main purpose of the present study was to investigate the kinematics and kinetics of successful versus unsuccessful basketball free throw shots. Six professional basketball players (age= 23±2.09 years members of Iranian premier basketball league participat in test. Kinematics of arm motion during basketball free throws were recorded by two Casio zr200 camera in frequency of 240 Hz. Wilcoxon test was used for significant differences between successful versus unsuccessful free throws (p ≤ 0/05). Angular velocity of the wrist was found to be significantly higher in successful versus unsuccessful shots at the time of ball release (p ≤ 0/028). Wrist (p ≤ 0/008) and shoulder (p ≤ 0/023) joints were found to have significantly more flexion in successful versus unsuccessful shots while elbow (p ≤ 0/002) remained significantly less flexed in successful shots. Angular displacement of wrist (p ≤ 0/034) and elbow (p ≤ 0/004) was shown to be significantly greater in successful versus unsuccessful shots. Integrated EMG of Anterior Deltoid (AD), Triceps Brachii (TB) and Flexor Carpi Radialis (FCR) muscles was more in successful free throw versus unsuccessful free throw, but the only significant difference was observed in the Integrated EMG of the Triceps Brachii muscle (p ≤ 0/034). In summery, increasing the wrist angular velocity and activity of triceps brachii muscle affected successful free throws.