مطالب مرتبط با کلیدواژه

Biomechanics


۱.

Does Really Lower Limbs Behave Asymmetric in Gait of People Without Impairments(مقاله علمی وزارت علوم)

نویسنده:

کلیدواژه‌ها: Biomechanics Gait Symmetry

حوزه های تخصصی:
تعداد بازدید : ۱۱۷۵ تعداد دانلود : ۵۴۰
Using two consecutive gait cycles، simultaneous and bilateral kinetic gait data، the main objectives of this study were a) to identify the main functional roles of ankle، knee and hip extensors/flexors، and b) to determine whether the action taken by these muscle groups appears to be symmetric or not. Gait of our able-bodied subjects appears to be asymmetric with significant differences noted between each two corresponding peak muscle moment values. Using Principal Component Analysis (PCA) as a curve structure detection method، task discrepancies were recognized when comparisons were made between each two corresponding representative moment curves at each joint (local asymmetry). Muscle moment behaved symmetrically when the right limb representative curve was compared to its corresponding principal component (PC) at the contralateral limb. Gait of able-bodied subjects appears to be symmetric، while control and propulsion were recognized as two major roles of the extensors and flexors (global gait asymmetry). Symmetrical behavior of the lower limbs should be considered a consequence of local asymmetry which indicates different levels of within and between muscle activities developed at each joint during gait cycles
۲.

Comparing Biomechanical Risk Factors of Anterior Cruciate Ligament Injury of Elite Female Soccer Players During the Shearing Maneuver and Header on the Natural Grass and Artificial Turf(مقاله علمی وزارت علوم)

کلیدواژه‌ها: anterior cruciate ligament Artificial Turf Biomechanics cutting maneuver Heading

حوزه های تخصصی:
تعداد بازدید : ۲۶۹ تعداد دانلود : ۳۷۳
Introduction: Nowadays, the use of artificial turf fields has become widespread. Given the high prevalence of noncontact injuries among female soccer players and high contribution of the Anterior Cruciate Ligament (ACL) injury, this research was conducted to compare biomechanical risk factors in the incidence of ACL injury for elite female soccer players during shearing maneuver and header on the natural grass and artificial turf fields. Methods: Sixteen players were selected from U-14 women’s national team by the convenience sampling method and started to perform the skills. Knee joint information was calculated by a 3D imaging system and a force plate. Statistical differences were reported using the dependent t-test at a significant level of 0.05. Results: The findings showed that the biomechanical behavior of the lower extremity while performing soccer skills on the natural grass was affected differently from that on the artificial turf. Results also demonstrated that the torque applied to the knee joint on the natural grass was higher than that on the artificial turf (P=0.039). Angular velocity on the artificial turf was also higher than that on the natural grass (P=0.006). Conclusion: The higher knee joint torque and the lower angular velocity on natural grass may result in a higher risk of ACL injury on the natural grass than on the artificial turf. Therefore, the use of prevention programs for ACL injury is crucial to minimize the incidence of lower extremity injuries.
۳.

Comparison of Kinematics and kinetics Symmetry of Lower Limbs during running(مقاله علمی وزارت علوم)

کلیدواژه‌ها: Running Symmetry moment angle Biomechanics

حوزه های تخصصی:
تعداد بازدید : ۱۳۸ تعداد دانلود : ۹۵
Aim and background: The aim of this study was to investigate Kinematics and kinetics Symmetry of Lower Limbs during running at a constant speed. Methods: 28 Elite runner (age: 34.75±6.63years) participated in this study. Running at constant speed was conducted by each subject at 2/5 m.s-1 on treadmill while kinematic and kinetic data were captured at 150 Hz and 300 Hz, respectively. The peak of joint moments and flexion angles in sagittal plane were calculated. The normality and homogeneity of variances assumptions of the dependent variables was tested using Bartlett and Leven’s test. Independent t tests were conducted to examine the symmetry of hip, knee and ankle moments between dominant and non-dominant joints during stance phase of running (p<0.05). Results: results of the present study showed no significant difference exists between dominant and non-dominant lower joints regarding the peak moments of Hip, Knee and ankle in sagittal plane during stance phase (p>0.05) as well as between peak flexion angles during running. Conclusion: Symmetry exists in lower joints sagittal moments and flexion angle during running at the constant speed. According to the results dominant and non- dominant lower joints play propulsive and absorbent roles cooperatively.
۴.

The effect of neuromuscular training on kinetic variables in male athletes with trunk control defects(مقاله علمی وزارت علوم)

کلیدواژه‌ها: Biomechanics neuromuscular training sport injuries

حوزه های تخصصی:
تعداد بازدید : ۱۲۷ تعداد دانلود : ۱۰۴
Background: Trunk control defect is one of the neuromuscular defects that can cause sports-related injuries in athletes. Aim: This research investigated whether neuromuscular training affects several kinetic parameters in male athletes who had trouble controlling their trunks during a change-of-direction movement. Materials and Methods: The present study used a pre-test-post-test design and was conducted semi-experimentally. Purposefully chosen male athletes (n= 29) with trunk control defects were randomly divided into two groups: control (n= 14) and experiment (n= 15). A Kistler force plate was used to quantify kinetic variables. The exercises were performed for 6 weeks, 3 sessions per week (30 min each session). To analyze the data, dependent t-test and analysis of covariance and SPSS software version 21 were used at the significance level of P <0.05. Results: The findings indicated a significant decrease in the time to peak anterior-posterior force ( P =0.010), time to peak mediolateral force ( P =0.001), time to peak vertical force ( P =0.003), and rate of loading ( P =0.001) of the experimental group. The differences in all control group variables were insignificant, P >0.05. Conclusion: Performing neuromuscular training is likely to improve the direction change mechanism and prevent injury in athletes with trunk control defects.