Showing 7 results for Kinematics
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Volume 0, Issue 0 (11-2019)
Abstract
Introduction and Objective: One of the strategies that athletes can use to temporarily increase strength and muscle power is post-activation potentiation (PAP) during warm-up. However, the effect of this phenomenon on kinematics of special movement has not been determined. Therefore, the aim of this study is to investigate the acute effect of PAP during warm-up on lower extremity kinematic characteristics during heading in soccer players.
Methodology: The study sample consisted of 24 semi-professional youth soccer players with an average age of 18.67±1.11 years, height 182.32±7.12 cm, mass 74.17±7.46 kg. who performed four different warm-up methods, including PAP-take-off, PAP-landing, combined-PAP, and general warm-up, derived from the stages of soccer heading. Knee and hip angular velocities during the take-off phase, maximum knee flexion angle, and duration of knee joint pause during the landing phase were recorded using a three-dimensional motion analysis device (vicon peak ltd, oxford, vicon UK) with four T20 cameras with a frequency of 1000 Hz. Finally, analysis of variance with repeated measurements and post hoc Bonferroni test were used at a significance level of P<0.05.
Results: There was a significant increase in knee and hip angular velocities following combined-PAP and then PAP-take-off compared to other warm-up programs. Moreover, there was a significant increase in knee flexion angle after PAP-landing compared to other warm-up programs. Additionally, there was a significant increase in the duration of knee joint pause after general warm-up compared to other warm-up programs.
Discussion and Conclusion: PAP-take-off improves jumping performance, while PAP-landing improves landing performance. The combination of these two methods, i.e., combined-PAP, will yield better results overall.
Sasan Naderi, Dr Fariborz Mohammadi Pour, Dr Mohammad Reza Amir Seifo Dini,
Volume 13, Issue 9 (4-2015)
Abstract
The purpose of current study was to investigate the spatio-temporal gait parameters and knee varus angle
during walking at different speeds in young with knee varus. 18 subjects with varus deformity classified at
grade 3 of bowleg and 17 healthy subjects, volunteered to participate in this study. The following variables
include stance, swing, double support and cycle time, cadence, stride length, angle of varus at the heel
contact, midstance and toe off when walking on the treadmill at speeds of 80, 100 and 120 percent of
preferred walking speed, were measured from using the three-dimensional motion analysis system with six
optoelectronic cameras. The results of between-group tests showed that spatio-temporal gait parameters
in the varus group is similar to the normal group. Also varus angular variables in varus group, was indicate
higher values in comparison to the healthy group, but there were no significant differences. The results of
inter-group tests also showed the knee varus angle generally increases with increasing speed, that none of
the differences were not significant. According to the results, the increase in walking speed will caused to
increase knee varus angle. Therefore, walking with speed less than the normal walking speed, probably is
a suitable solution to reduce the loads exerted on the knee joint and prevention of premature osteoarthritis
in young with knee varus.
Mr Saeid Eimani Zadeh, Dr Mansoor Sahebzamani, Dr Mohamad Taghi Amiri Khorasani,
Volume 13, Issue 10 (10-2015)
Abstract
The purpose of this study was to investigate the effect of soccer specific functional fatigue on hip and knee
joints angles during landing in professional players.15 soccer players with at least 2 years experience in
Kerman soccer clubs were selected randomly. To evaluate the lower extremity kinematics following
jumping and soccer specific- heading, three cameras (with50Hz) were used. To cause fatigue in subjects,
specific functional protocol similar to specific bangsbo soccer was used and Quantic sport v21 soft ware
was administrated for kinematic analysis of the recorded films. To statistical analyzing of data, descriptive
statistical methods, and paired-t test were administrated at α=0.05.Finding revealed that hip and knee
angles in sagittal and frontal plane in landing is influenced by functional fatigue. This results has been
reducing knee and hip flexion angles and increased varus in knee joint. Results demonstrated a more
erect landing posture due to a decrease in hip and knee flexion angles in the post fatigue condition.
However, functional fatigue significantly decrease lower extremity control ability in male soccer player
during landing.
Mr Mohammad Ali Naseri Rouhani, Dr Mohammad Taghi Amiri Khorasani, Dr Mohammad Reza Amir Seifaldini,
Volume 14, Issue 11 (4-2016)
Abstract
Objective: The aim of this study was to investigate the effect of non- stability surface of support leg on the instep kicking kinematics in soccer players. Materials and Methods: 30 male soccer players participated in this study. After the measurement of static and dynamic balance tests by the Biodex System, 20 players were selected who were at a desired level of the balance. Data were recorded using the three- dimensional motion analysis system with 6 optoelectronic cameras (200 HZ). The kinematic parameters in three critical moments of kicking (Forward swing of hip, Contact to ball, Follow through) were compared by using repeated measures of variance and independent t- test (0/05). Results: The results showed that the values of maximum angular velocity and displacement of hip and velocity of ball at the kicking over stability surface was significantly higher from the kicking over non- stability surface. Conclusion: These results indicate that the kicking over non- stability surface causes the lower of kinematic parameters in the more of the kicking skill phases and the movement prime velocity of ball
N Jamali, Kh Khayambashi, Sh Lenjannejadian, H Esmaeili,
Volume 18, Issue 19 (7-2020)
Abstract
Although hip muscle strengthening has been reported as an effective way to decrease PFPS symptoms, however its effect on lower extremity kinematics is less clear. The current study was done with the aim of investigating the effect of hip abductor and external rotator muscles strengthening exercises on lower extremity kinematics in static and dynamic states. In a randomized controlled trial, 33 patients with patellofemoral pain (PFP) were randomly assigned into exercise (8 female, 30±6.8 y/o, 23.8±2.6 BMI and 8 male, 31.2±7 y/o, 25.6±1.5 BMI) and control (9 female, 29.9±7.3 y/o, 23.2±3.2 BMI and 8 male, 32±6 y/o, 25.5±1.9 BMI) groups. In exercise group they received hip abductor and external rotator strengthening exercises by thera-band 3 times per week for 12 weeks under supervision by a physiotherapist. The control group did not receive any training intervention. Hip muscles strength and kinematics in static and dynamic states, were assessed at baseline and post-intervention. Repeated measures ANOVA by using SPSS were applied to assess the effects of the exercise on measured variables (α=0/05). After 12 weeks of strengthening program, by an increase in abductor muscle strength in women from 19.6 to 26.4 %BW (P=0.000) and in men from 29.9 to 38.1 %BW (P=0.003), and in hip external rotator muscles in women from 13.2 to 16.9 %BW (P=0.024) and in men from 26.3 to 34.9 %BW (P=0.000), dynamic knee valgus angle during single-legged squat improved in women from 170 to 174.6 degrees (P=0.018) and in men from 171.8 to 176.8 degrees (P=0.017) and contralateral pelvic drop angle during stair descending improved only in women from 7.9 to 6 degrees (P=0.04) in the exercise group. No significant difference was observed at quadriceps angle (P≥0.05). The findings suggest that hip muscles strengthening can alter the lower extremity kinematics, in dynamic state, at the frontal plane, and it might be said that due to these changes following hip abductor and external rotator muscles strengthening exercises by thera-band, the symptoms of PFP improve more consistent.
Azadeh Doroodgar, Khalil Khayambashi, Shahram Lenjannejadian, Ghasem Yadegarfar,
Volume 19, Issue 21 (9-2021)
Abstract
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.
Ali Abbasi, Heydar Sadeghi, Mehdi Zamanian , Anoshirvan Kazemnejad,
Volume 20, Issue 23 (9-2022)
Abstract
The purpose of present study was to examine the effects of short time static and dynamic stretching of muscles on kinematics variability of lower extremity in healthy active males during cycling. 15 physical education and sport sciences male students from Kharazmi University voluntarily participated in this study. Subjects referred to the laboratory during two days, with 48 hours intervals between each sessions, and lower extremity kinematics data were collected from 30 pedaling cycle on the stationary cycle in 70 RPM in situation of without stretching, after 2, 5, and 10 minutes post stretching by means of motion analysis camera in 50 Hz frequency. Hip, knee and ankle joints angular displacement and velocity were extracted for constructing time series and variability calculation. Results of repeated measure ANOVA did not show any significant differences in angular displacement and velocity variability in hip, knee and ankle joints after 2, 5, and 10 minutes post stretching (P>0.05). Regarding results, probably it can be use static and dynamic stretching in warm up programs before cycling or rehabilitation on stationary cycle.
