جستجوی مقالات مرتبط با کلیدواژه « کینماتیک » در نشریات گروه « تربیت بدنی »

Deficient movement patterns can alter the kinematics of lower limb during landing jump tasks, potentially leading to non-contact anterior cruciate ligament injuries. The aim of this study is to investigate the impact of an eight-week kinematic feedback training program on male athletes exhibiting selected movement control issues during jumping tasks.

This study is a randomized clinical trial conducted before and after the intervention. Thirty-four male recreational athletes with movement control deficiencies were chosen based on predetermined criteria and randomly assigned to either a control or feedback group in a 1:1 ratio. Kinematic variables were recorded in the sagittal and frontal planes while participants performed jumping and landing tasks before and after a two-month jump training program, with feedback provided to the feedback group and not to the control group. Data analysis utilized two-way analysis of variance and Bonferroni tests for each movement task, with significance set at P < 0.05.

Results from the statistical analysis revealed that the eight-week feedback training program significantly influenced hip, knee, and ankle kinematics in athletes with motor control deficiencies during jump-landing tasks. Additionally, feedback was effective in reducing knee valgus.

 The findings demonstrate that feedback effectively impacts kinematic parameters in both sagittal and frontal planes, suggesting its potential utility in correcting incomplete movement patterns during jump-landing tasks.

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.

Injuries caused by overuse in the upper limbs of softball players are very common. Regarding the importance of core muscles and the adverse effect of fatigue on these muscles on the kinetic chain, the purpose of this study was to investigate the effect of core muscle fatigue on upper limb kinematic factors in overhead throwing and to identify risk factors for common injuries in softball players.

12 female softball players of the national league between the ages of 20 and 30 and a BMI of 18 to 25 were selected and performed the core stabilization muscle fatigue protocol between pre-test and post-test as one group. Upper limb kinematic data were collected from the foot contact to ball release using eight cameras with a sampling rate of 550 frames per second and the Qualis movement recording system. Data were analyzed using paired t-tests and Willcoxon tests.

The fatigue of core muscles results in significant increases in horizontal abduction angle at foot contact (P=0.01), and maximal external rotation angle of the shoulder (P=0.04), but there was no significant effect on shoulder abduction angle at foot contact and front face (P>0.05).

The present study showed that core muscle fatigue affects the kinematic risk factors of shoulder injuries and causes a change in the motion pattern of throwing in softball players.

Running is known as one of the most popular sports for which there is no time and space limit. Recently, due to lifestyle changes, the use of treadmills for walking and running has increased. However, the biomechanical differences in coordination between running on a treadmill at different speeds have not been sufficiently addressed. The aim of this study was to investigate the effect of increasing running speed on three-dimensional changes of lower extremity joint angles in the open motor chain and swing phase.

28 elite runners participated in this study. Subjects ran on an equipped treadmill while kinematic running data was recorded for 30 seconds through a three-dimensional 12-camera motion recording system at speeds of 2.5, 3.5 and 4.5 m / s. Data were normalized based on the subjects' body mass as well as 101 time points in the running cycle. The normality and homogeneity of variance of the dependent variable were tested using Bartlett and Leven’s tests. Repeated measurement test was performed to measure the angles of the pelvis, knee and ankle between the dominant and non-dominant lower limb joints in the running swing phase.

In the range of motion of hip, knee and ankle joint, there were significant differences among all the three speed rates of 2.5, 3.5 and 4.5 on all planes.

Changes in the angle and range of motion of the hip, knee and ankle joints are significantly greater in the swing phase as the running speed increases. Due to the fact that in high-speed running, the stability of the body decreases, the central nervous system commands to increase the range of motion of the angle of the mentioned joints to regulate the structure of the body and reduce the instability in response to the applied disorders. The results also show that the ankle joint, as the closest joint in contact with the ground, helps to run faster and more efficiently by increasing changes in the angle and range of motion of the ankle joint during running, and by reducing the time of foot contact with the ground at each step. It can be concluded that this point is effective in increasing speed.

Attention can be paid to the biomechanical characteristics of running since the speed of running varies. The aim of the present study was to investigate the effects of increasing running speed on the three-dimensional kinematics of the lower limb joints in the stance phase.

The research was quasi-experimental. 27 volunteer subjects ran on a treadmill and the kinematic and kinetics data were collected through a three-dimensional system at three speed levels (2.5, 3.5, and 4.5) m/s. kinematics and kinetics data were recorded by 12 cameras (120 Hz) and force platform (150 Hz), respectively.   The stance phase was derived according to the ground reaction Force value of the force platform. Hip, knee and ankle kinematics including peak of the absolute angles in three dimensions and three speeds were calculated for further analysis. Repeated measurement with Bonferroni post Hoc tests were employed to investigate the differences between the variables in three dimensions using SPSS software (P <0.05).

The results showed that during increasing speed, significant differences were observed in frontal (2.5 & 3.5, 2.5 & 4.5 m/s) and sagittal (2.5 & 3.5. 2.5 & 4.5, 3.5 & 4.5 m/s) planes in hip as well as only in transverse (2.5 &4.5, 3.5 & 4.5 m/s) plane for knee. No significant differences were obvious in peak of ankle joints during increasing speed in all three planes.

The results of the present study showed that hip and knee joints are more susceptible to changes of kinematics behavior during running progressively. Ankle joint seems to be more stable during the progressive running situation. Coaches and athletes may also enhance their performance using the results of the present study.

  However, due to the long-term recovery process in anterior cruciate ligament injury and the occurrence of secondary problems after surgery, as well as the lack of adherence to postoperative rehabilitation programs, however, there is a risk of re-rupture of this ligament. Therefore, the aim of the present study was to compare the kinematic parameters of the trunk and lower limbs during shear maneuvers in healthy and reconstructed athletes of the anterior cruciate ligament.

The subjects of this study included 34 male athletes who were randomly divided into experimental (reconstructed cruciate ligament) and control (healthy) groups. Kinematic and Kinetic data were recorded using a camera motion capture system (Vicon, Oxford Metrics Ltd) sampling at 200 Hz, synchronously with ground reaction forces from force platform at 1000 Hz (Kistler AG, Winterthur, Switzerland). The calculation of kinematic variables from initial foot contact to toe-off with force plate was performed by Visual3D (C-Motion Inc) software.

The results of independent t-test concerning trunk flexion, hip and ankle flexion did not show a significant difference between the healthy and ACLR groups (P>0.05), but decrease in knee joint flexion in the ACLR group,was significant (P=0.008) compared to the healthy group Also in the ACLR group, an increase in knee joint valgus was significant (P=0.05). ACLR group's tibia rotation with respect to femur was also significant (P=0.038) compared to that of the healthy group.

Due to the change in the kinematics of ACLR group compared to that of the healthy individuals and the increased risk of re-rupture in ACLR individuals, it is suggested that in designing exercises and postoperative rehabilitation courses, proper training of techniques and movements be performed to reduce the likelihood of re-injury by achieving the desired kinematics in the joints and limbs as well as the athletes' awareness.

Hip abductors muscles play a role in providing stability and movement to the lower limbs. The purpose of this study was to examine the effects of hip abductors muscles fatigue on kinematics gait parameters in the Elderly men.

The participants of this study included sixteen healthy elderly men without a history of falling with a mean age (65.62±5.77 years(, mass (75.25±1.37 kg(, height (169±6.07 cm(. In the pre-test, gait kinematics evaluation was performed using a motion analysis device. Then the subjects participated in the hip abductor muscles fatigue program and immediately after the fatigue, gait kinematics evaluation was performed like a pre-test. Data collected through the Cortex software was analyzed and extracted in Excel file format. A paired sample t-test was used to compare the results before and after fatigue.

Results:

 The findings showed that after applying the fatigue protocol, the angular displacement of the lower limbs during gait was significantly decreased (p <0.05). In addition, the step length of gait after fatigue decreased significantly before fatigue (p< 0.05).

Conclusion :

The results of this study showed that the step length and kinematic of the hip, knee, and ankle joints during of walking are the effects of fatigue the hip abductor muscles. Therefore, the hip abductor muscles weakness can be a risk factor for falling and injuring during walking in the elderly population.

Recently the reactive neuromuscular training (RNT) has received increasing attention due to its function in decreasing the sport injuries. These exercises help athletes to quickly correct their faulty movement patterns. The aim of this study was to investigate the effect of eight weeks of reactive neuromuscular training on landing kinematics in Female Basketball Players. Thirty three players from the three teams of the Tehran Female's Basketball Premier League participated in this study. The teams were randomly divided into three groups: experimental 1 (n=11), experimental 2 (n=11) and control group (n=11). Experimental group 1 performed prevent injury and enhance performance (PEP) exercises for eight weeks and experimental group 2 performed PEP exercises with RNT instead of regular warming up. The control group performed their usual exercises. The kinematics of the trunk and lower extremity joints during landing were evaluated by pre-test and post-test. Three-dimensional lower-extremity kinematics was measured during drop jump with a single leg landing. Data were analyzed by 2-way repeated measures analysis of variance. The results showed that eight weeks of reactive neuromuscular training had a significant effect on hip flexion angle at landing (F(2,27)=3.40, P=0.04, ηp2=0.20). But there was no significant effect on knee valgus, knee flexion, ankle dorsiflexion, and trunk flexion at the moment of landing following RNT training. The presented results indicated that the injury prevention program using reactive neuromuscular exercises could well modify the athletes' movement patterns toward a lower risk of anterior cruciate ligament injury.

The aim of this study was the effect of educational intervention on gait kinematic characteristics in motor in children 3-5 years old. Twenty-four children aged 3-5 years old were randomly divided into two groups (intervention group: 12 per, and control group: 12 per). The intervention group practiced for six weeks and two sessions a week. The range of motion of the hip, knee and ankle joints was measured on the sagittal plane at the moment the heel contact the ground and the moment the toe off from the ground, before and after the intervention. Paired t-test showed that educational intervention had a significant effect on the change of lower extremity kinematic variables at the level of α = 0.05 (In the intervention group: at the moment of heel contact with the ground, the amount of dorsiflexion of the ankle increased by 35.5% after the intervention, knee flexion decreased by 20.62% and hip flexion decreased by 20%. Also, at the moment of toe off from the ground, the amount of plantar flexion of the ankle increased by 37.73% after the intervention, knee flexion decreased by 16.74% and hip extension increased by 37.61%). Based on the results of ANOVA analysis, there was a significant difference between the exercise and control groups in the kinematic variables of walking. The results showed that a linear pedagogy course is suitable for changing the kinematic pattern of walking in children 3-5 years old.

The purpose of this study was to investigate the effect of focus of attention in mental imagery on kinematics of basketball free throw. Twenty female students (21 ±1.2 years old, without experience in basketball) were randomly selected from the students of Shahid Beheshti University and randomly divided into two distant focusing imagery groups. The task was 20 free basketball shoots, which were performed in two conditions of imagery: the imagery of far external attention (attention to the ring) and the imagery of near external attention (attention to the ball’s path). The wrist kinematic data was also recorded by six motion analyzer cameras (OSPREY manufacturing USA motion Analysis Company and data analyses with cortex 2.6 version software).The results of analysis of variance revealed that there was no difference between the two groups of far and near external attention imagery in the kinematic variables of displacement range of the wrist joint (P =0/386). However, the displacement range of the wrist joint in the posttest between two groups was significantly higher than the pretest condition (P =0/072). The results of this study are based on Wulf’s constrained action hypothesis, which states that attention to external signs associated with motion can be useful for performance. The effect of the optimal distance in the focus of attention and the degrees of freedom theory of Bernstein, support the idea that the release of degrees of freedom for beginners may help to perform the exercise more efficiently.

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 the current research was to compare minigolf shots in beginner and expert players and analyze its kinematics. The present research was applied and semi-experimental and the research design was of causal-comparative research. The statistical population of this research was all the beginner and expert mini-golf players in Mashhad city. According to the limitations in the field of data processing,This is the moment when the putter is at its farthest point in the x direction. This process was done using Matlab software. Then the shoulder, elbow, hip and knee angle variables were calculated as an average and at the moment of impact. Also, the variables of putter speed, displacement and duration of swing of the putter from the moment of preparation to the time of impact were calculated. data collection, the obtained data were analyzed by independent t-test and Excel, Spss software. The results of the present research showed that there was a significant difference between the knee angle and the maximum linear speed of the putter in both beginner and expert groups (p≥0.05) and there was no significant difference in other variables between the two groups (p≤0.05). . Therefore, there was a difference between skilled and beginner players only in limited variables, but when referring to the average value, a significant difference was observed. It seems that the shape of the pattern should be close to that of skilled players in order to achieve a suitable pattern for beginner players and to train and train skilled players.

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 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.

Hamstrings (Hams) to Quadriceps (Quadr) strength ratio is known as a risk factor for Anterior Cruciate Ligament (ACL) injury and affects by knee and hip flexion angles. Gluteus Maximus (Gmax) muscle acts as a synergist for Hams in hip extension in a closed kinetic chain. The aim of this study was to investigate the effect of Gmax strengthening exercises on the kinetic and kinematic risk factors of ACL injury when single-leg landing from a jump. 25 volunteer women aged 18-30 years were assigned into control (n =13) and experimental (n =12) groups. Maximum isometric strength of Gmax, hip and knee joint angles and ground reaction force (GRF) was measured at landing, by dynamometer, 2D imaging and foot scan respectively,. After 8 weeks of 3 sessions of Gmax resistance training, Following the significant within-subject difference for GRF (F=5.245, P=0.032) by using Two-way mixed model ANOVA, Pre and post-test Differences were significant with 16.63% decrease (P= 0.038, t=2.354). Differences between pre and post-test peak force, time to peak, mean joint angles, impact and load rate were not significant (α = 0.05). According to a 4.55% and 3.47% increase in Gmax strength and time to peak force, and considering the fact that at the beginning of landing, the mechanical advantage of Hams is lower than that of Gmax, the risk of ACL injury could be reduced by reducing GRF following an increase in the Gmax strength.

The proper implementation of Dachi in karate as a basic technique has a direct impact on the implementation of other techniques. Therefore, the aim of the present study was to compare the maximal angular velocity of hip, knee and ankle joints in differen  Zenkotsu dachi techniques in karate.

12 male karate athletes (Height 175 ± 5, mass 75 ± 5, Age 25 ± 5, Background 8 ± 2) participated in this test .A three-dimensional analyzer(motion analyzer),with six matched infrared cameras at a speed of 200 frames per second was used. And  records were analyzed by cortex2.5.0 software. The normality of the data distribution was confirmed by Shapirovilk test. To test the hypotheses of the research, the data were analyzed by repeated measures ANOVA and Bonferroni post hoc test at the significant level of 0.05 using statistical software (SPSS 25).

In this research, we performed Zenkotsu dachi forward movement in six different ways, and the results show that there is a significant difference only between the third and fourth methods and also between the fourth and fifth methods in the hip joint If there is no significant difference in knee joint and ankle joint in any of the methods. Because each of these methods changes the position and range of motion of the hip and pelvic floor muscles.

By sitting more forward and lower back flexing, the individual optimizes the involved limbs and muscles and creates greater angular velocity in the hip joint.