Showing 8 results for Kinetic
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Volume 11, Issue 6 (10-2013)
Abstract
Balance and strength are important abilities that athletes should have them. This study was designed to investigate the relationship between maximum leg press (non-weight bearing closed kinetic chain) and squat (weight bearing closed kinetic chain) strength with statistic and dynamic balance. Thirty (15 men and 15 women) physically active participants (age, 22.13 ± 1.54 years; height, 171.26 ± 6.92 cm; weight, 66.02 ± 8.27 kg) completed the study. The Biodex Balance System was used to evaluate balance performance. Subjects completed two, 40 seconds trials attempting to maintain their statistic and dynamic balance and Overall Stability Index, Anterior/Posterior Index and Medial/Lateral Index were obtained. Maximum strength also was measured with a 1RM squat and leg press. Significant correlations were found between the measurements of 1RM squat with static anterior-posterior indices (r, 0.019; P=-0.541) and dynamic medial-lateral indices (r, 0.021, P=-0.532) in men and with static anterior-posterior indices (r, 0.016, P=-0.552) and dynamic anterior-posterior indices (r, 0.032; P=-0.491) in women. No significant correlations were found between the measures of 1RM leg press and balance indices in both groups. The results of this study indicate that maximum squat strength has more relation with some indices of static and dynamic balance than maximum leg press.
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Volume 12, Issue 7 (4-2014)
Abstract
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.
Dr Abbas Saremi, Dr Masood Golpayegani, Mrs Zeinab Moradi,
Volume 13, Issue 10 (10-2015)
Abstract
Introdiction and Aim: Nowadays, due to the epidemic of sports supplements, the effects of these
supplements on athletic performance require analysis and evaluation.The aim of the present study was to
investigate the effect of arginine supplementation for one week on oxygen uptake kinetics and time to
exhaustion in female taekwondo athletes.
Method: In this semi-experimental study with pretest – posttest design, eighty female taekwondo athletes
(age: 19.88±2.33 y, height: 167.53±6.04 cm, weight: 60.98±2.4 kg) were randomly assigned to argenine
supplementation (n=9) or placebo (n=9) groups. Subjects performed the incremental test (initially, the work
load 50 watts and 30 watts increase in workload every minutes, as long as subjects will be able to maintain
the highest pedal rate and the failure to reach). To simulate a taekwondo match day test session consisted
of three maximal incremental test intervals (1 to 2 hours). The experimental group was supplemented with
6g arginine powder and placebo group received 6g microcrystalline cellulose each day for one week.
Seven days after, post test accordingly pretest was used by all subjects. Pulmonary gas exchange was
measured by gas analyzer to breath-by breath method. Oxygen uptake kinetics variables (oxygen deficit,
time constant 1, time constant 2) were evaluated by gas analyzer with breath-by breath method. Data was
analyzed using two ways ANOVA.
Results: The time to exhaustion was extended following consumption of arginine (p<0.05). Also the
findings showed that arginine supplementation resulted in a speeding of the oxygen uptake kinetic (oxygen
deficit, time constant 1, time constant 2) (p<0.05).
Conclusion: It seems that arginine supplementation improves oxygen kinetics factors and time to
exhaustion in female taekwondo athletes.
Mohamad Hadi Ghasemi, Mohamad Fashi,
Volume 16, Issue 15 (9-2018)
Abstract
The aim of present study was comparison of advanced physical fitness profile between Olympic soccer team members of Iran according to playing position. 29 Invited soccer players to the 17th national Olympic soccer team of Iran dispatched to 17th Asian Olympics Games, Incheon 2014 )mean age of 20.39± 2.01 yrs(, divided into five group of goalkeepers, defenders, midfield players, wingers and attackers according to playing position participated in the study. Body composition parameters (including body mass index, body fat percentage), isokinetic force (peak torque, agonist/antagonist ratio, work fatigue, total work of extension and flexion), aerobic power by analysis of respiratory gases and anaerobic power and fatigue index by Wingate test were packaged for data collection. Descriptive statistics (i.e., mean ± standard deviation) and inferential statistics (i.e., one way ANOVA with Hopkins post hoc after subtracting data of pre- post) used for analysis data. While it was unbelievable the findings did not show any significant difference between five groups of present study. It seems that Olympic soccer team players of Iran has not prepared in a conditioning principle and based on playing position for participate in 17th Asian games. Moreover it supposed that national players spent most of the preparation periods & specific based conditioning workouts on their clubs, hence due to the short time of conditioning in the national camps trainings, players have not dispatched to the games with favorable preparation.
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.
Ms Sepideh Samavati Sharif, Phd Abbas Ferjad Pezeshk, Phd Mohammad Yousefi,
Volume 19, Issue 22 (12-2021)
Abstract
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.
Dr Amir Ghiamirad, Mr Farhad Esmkhani, Mr Salar Hariri,
Volume 19, Issue 22 (12-2021)
Abstract
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. Methods: 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.
Alireza Hosseini, Dr Mostafa Zareei, Fariborz Hovanloo,
Volume 19, Issue 22 (12-2021)
Abstract
Wrestling is a high contact sport with a significant risk of injuries. Identifying risk factors can help preventing wrestler’s injuries. little is known about the contribution of balance and proprioception to sport injuries. The purpose of this study was to find out the relationship between dynamic balance and knee proprioception and the injuries in young wrestler.72 young wrestlers from Tehran primer league participated in this study. Before the start of season, proprioception was measured at 30°, 60° and 90° knee flexion using the Biodex Isokinetic pro 4 system. Dynamic balance was measured by Biodex balance system. Injuries were recorded by the team's medical staff. Logistic regression modeling indicated that there is no significant relation between Dynamic balance and proprioception of knee at 30 and 60 and at 90 degree and musculoskeletal injuries. Balance and proprioception testing, as performed in the present study, cannot be recommended as a screening test to predict injuries in young male wrestler.
