, , ,
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.
, , , ,
Volume 0, Issue 0 (11-2019)
Abstract
Since identifying the best way of performing the Judan Mai-Mawashi-Geri technique is one of the concerns of coaches and karatekas, the aim of this study was to compare the selected kinematic variables of four methods of implementing the Judan Mai-Mawashi-Geri technique by elite male karatekas. Eighteen elite male kumite practitioners voluntarily and purposefully participated in this study. Five markers were attached to the anatomical points of the hitting foot. The four methods of implementing the Judan Mai-Mawashi-Geri technique were filmed by three Hero3 cameras at an imaging speed of 240 Hz. Using SkillSpector software (version: 1.3.2), the resultant of the peak velocity of the lower limb joints, total distance, total velocity, and total acceleration was directly obtained. The one-way analysis of variance and the Bonferroni post-hoc test (p≤0.05) were used with SPSS software (version: 22) for statistical analysis due to the normality of data distribution. The results showed a significant difference in the four methods of performing the Judan Mai-Mawashi-Geri technique in the peak velocity of the pelvic, knee, and ankle joints as well as total distance, total velocity, and total acceleration. According to the research results, the first method of implementation can be recommended as a more efficient technique to kumite practitioners due to its high speed and the possibility of scoring in the shortest time interval and because it closes the opponent’s attack route, compared with Dai and Deashi tactics.
Mr. Amirali Jafarnezhadgero, Ms. Arezoo Madahi, Mr. Milad Piran Hamlabadi,
Volume 0, Issue 0 (11-2019)
Abstract
Background and Aims: The surface quality and type are an important factor that may influence the risk of sustaining injuries during running. The aim of the present study was to compare forces excreted on the foot while running on the ground and artificial turf in people with pronated and supinated feet.
Materials and Methods: The statistical population of the present study consisted of healthy men with pronated and supinated feet in Ardabil province. A statistical sample of 30 people aged 20-25 years was selected by available sampling and participated in the present study. Statistical samples were divided into three groups. There were 10 patients in the pronated foot group, 10 people in the supinated foot group and the third group of 10 people as the control group. The navicular drop test was used to measure foot type. A Bertec force plate was used to record ground reaction forces while running on ground and artificial turf at constant speed (about 3.2 m/s). The ground reaction forces in the vertical (Fz), anterior-posterior (Fy) and medio-lateral (Fx) directions were recorded during running.
Results: The results revealed greater medio-lateral ground reaction force at the heel contact in males with pronated feet while running on the ground than that artificial grass. In addition, the time to reach the peak of the vertical component at heel contact during running on grass was greater compared to the ground.
Conclusion: The results showed that the use of artificial turf can improve the risk factors for injury in people with pronated and supinated feet.
Mr Saeed Mollahoseini Paghale, Mr Milad Fallahzade, Dr Mohammadreza Amirseyfadini,
Volume 0, Issue 0 (11-2019)
Abstract
Introduction and objectives: In the past decades, the control of hand tremors in neurological disorders such as Parkinson's has attracted a lot of attention. The theories of closed-loop deep brain stimulation method are increasing significantly. The purpose of this article is to provide an automatic closed-loop method for the rehabilitation of Parkinson's patients with hand tremor symptoms using machine learning.
Materials and methods: In this article, a mathematical model including muscle model, basal ganglia, cerebral cortex and supplementary motor area is used to simulate tremor. Also, to control hand tremors, a non-integer proportional-derivative-integral controller (non-integer PID) has been used, as well as using the smart Proximal Policy Optimization (PPO) algorithm as a subset of reinforcement learning to adjust the coefficients.
Findings: In addition to reducing hand tremors and automatic learning for use in different levels of the disease, which has given acceptable results compared to other control methods, among the advantages of the Prihadi method is the practical implementation of this method in the real world due to the simplicity of the controller. And also the easy implementation of the intelligent algorithm is due to the automatic adjustment of the coefficients of artificial intelligence networks.
Conclusion: In addition to optimizing output symptoms such as hand tremors compared to other controllers, the proposed intelligent system can also be used for all levels of the disease due to its adaptability, causing a significant reduction in the side effects caused by continuous brain stimulation in the brain stimulation method. It opens in the form of a ring.
Dr. Amir Fatollahi, Dr. Amirali Jafarnezhadgero, Dr. Hamidreza Maghami,
Volume 0, Issue 0 (11-2019)
Abstract
Abstract
Biomechanics is the knowledge that shows what forces enter the motion system of the human body and how it causes human movement. Therefore, the aim of this Meta-Analysis study was to review the studies conducted in the field of the effects of training on sand surface on biomechanics and physical fitness factors of human body during translational motions. The current study was a library and systematic review, the search for articles in Persian and Latin was from the beginning of 2000 to the end of 2023, which was done in the specialized databases of PubMed, WOS, Scopus, ISC and Google Scholar search engine. 568 related articles were selected based on inclusion and exclusion criteria. Standardized mean differences (SMDs) were calculated using random-effects models. The findings of eight articles indicated the improvement of mucle activity during training on sand. Examining the findings of one article indicated positive effects of kinematic variabls during training on sand. A number of two articles also reported that the reduction of the ground reaction forces and impact shock. In addition, five articles reported the improvement of sports performance in athletes, the increase of physical fitness factors. In general, training on sand surface can have significant positive effects on people's daily and sport life. Further study is warranted.
Saeed Arsham,
Volume 0, Issue 0 (11-2019)
Abstract
Introduction and purpose: The ability to control different positions of the body in space results from the complex interaction of nervous, sensory, and skeletal-muscular systems, which is generally defined as posture control. Therefore, it is important to study how new interactions occur through sensory inputs and create different motor responses to restore balance disturbances. The purpose of this study was to investigate the underlying mechanisms of age-related differences in postural control of 7-18-year-old girls by determining the differences between different age groups and adults in their sensory preferences for compensatory responses. Methodology: 118 non-athlete girls aged 7 to 18 years were selected using the available sampling method from schools in the 3rd district of Tehran and divided into four age groups: 7-9 (n=31), 10-12 (n=32), 13-15 (n=28) and 16-18 (n=27) were divided. Also, a reference group of adults (n=28 with an average age of 27.9 years) were investigated for comparison (total = 146). A sensory organization test (SOT) with Computerized Dynamic Posturography was used to manipulate different sensory inputs. Findings: The results of the one-way analysis of variance with a post hoc test showed that there is a significant difference between all age groups in 6 conditions of the test (P<0.05). The use of bodily and vestibular sensory inputs to maintain balance was almost the same in different age groups, but significant differences were observed in the use of visual inputs. Discussion and conclusion: From the age of 13, the postural control performance of girls becomes similar to that of adults, which can be due to the delayed development of the visual system. In general, it seems that for optimum control, the maturation of the somatosensory system occurs before the maturation of the vestibular and visual systems. After that, vestibular and visual systems are matured respectively.
Mr. Milad Piran Hamlabadi, Dr. Amirali Jafarnezhadgero, Hamed Naghizadeh,
Volume 0, Issue 0 (11-2019)
Abstract
Background and Aims: Running is one of the most important activities for soldiers, and boots play an effective role in this activity. The aim of the present study was to investigate the effects of three types of military boots mileage on ground reaction force variables during running.
Materials and Methods: The current research was a clinical trial. 15 healthy male students (20-25 years old) used three different types of used and new boots. Using Bartec force plate with dimensions (60 x 40 cm2), ground reaction forces were measured in vertical (Fz), anterior-posterior (Fy) and medio-lateral (Fx) directions while running at constant speed. Two-way ANOVA was used for statistical analysis at a significance level of 0.05.
Results: Results demonstrated significant main effects of "Time" for FXHC (P=0.001, d=0.407), FXPO (P=0.001, d=0.674), TTPFXPO (P=0.001, d=0.394) and TTPFYPO (P=0.031, d=0.226). Findings showed significant main effect of group for FZHC (P=0.027, d=0.163) and TTPFYHC (p=0.035, d=0.150). Furthermore, significant group-by-time interactions was found for FZHC (P=0.001, d=0.404) and FXPO (P=0.014, d=0.272).
Conclusion: The results of this research showed that using military boots, the vertical ground reaction force, the medio-lateral force at heel contact and the peak medio-lateral force were increased. The increase of this value can be related to fracture injuries caused by pressure and patella femoral pain. The results of this study showed that the type of boots can be effective in preventing lower limb injuries. Therefore, using new operational boots is suggested for the military application.
Morteza Hoseini, Dr Heydar Sadeghi, Dr Razieh Yousefian Molla,
Volume 0, Issue 0 (11-2019)
Abstract
Background and purpose: Determining specific abilities and skills in volleyball players depends on the amount of anthropometric, physiological, biomechanics and psychological characteristics of the players in this field and is vital for improving the performance of sports skills in them. Since by comparing these important factors in the group of teenagers and young adults, it is possible to guide teenagers towards success factors in youth and adulthood, the purpose of this research was to compare the main characteristics of elite teenage and young male volleyball players.
Methods: 30 male members of the national youth volleyball team of the Islamic Republic of Iran (15 youths and 15 teenagers) were examined in terms of their main anthropometric, biomechanics, physiological and psychological characteristics with the aim of evaluating and determining the main components and comparing them. In order to determine he main components of the evaluated indicators, first the PCA statistical method and then the independent t statistical method were used to compare the two groups(0.05≥p).
Results: Among the main indices of anthropometric, biomechanical, physiological and psychological characteristics, only the physiological index of maximum heart rate showed a significant difference between the two groups (0.05≥p).
Conclusion: It seems that the main differences of volleyball players in these two age groups are more related to experience in the game and mastery in the implementation of various skills and techniques, and all these main features can be found in the talent search process of this group of young people.
Dr Nohamadjavad Razi, Hasan Modares, Zahra Shakeri Hosinabad,
Volume 0, Issue 0 (11-2019)
Abstract
The aim of this study was to investigate the effect of virtual education conditions and increasing sitting time on musculoskeletal status and physical activity of students during the corona pandemic. In the present study, standard Nordic musculoskeletal status and Beck physical activity questionnaires were used. The statistical population of the present study included male and female students of Farhangian University of Yazd Campus, of which 450 people participated in the present study as a sample. McNemar's, Mann–Whitney U and Spearman correlation tests were used at the significance level of P≤0.05. There was a significant difference between the prevalence of musculoskeletal disorders in the neck, shoulders, back, and waist before and during the coronavirus pandemic (P≤ 0.05). There was a significant relationship between physical activity and musculoskeletal disorders (p <0.05). There was a significant relationship between Internet Time usage and musculoskeletal disorders (p <0.05). Musculoskeletal disorders in students who did not follow the sitting pattern, in the neck (p <0.0001), shoulder (p = 0.006), wrist (p = 0.002), waist (p = 0.001) pelvis (P = 0.01) and knee (p = 0.001) were significant. The corona epidemic and the quarantine conditions may have adverse effects on the musculoskeletal condition of students, and prolonged sitting and non-observance of the principles of sitting aggravates these factors.
Mrs Masume Fadaei, Dr Mehrdad Anbarian,
Volume 0, Issue 0 (11-2019)
Abstract
The purpose of this study was to evaluate the effect of quadriceps muscle fatigue on electromyographic activity of selected lower limb muscles during lifting loads using different techniques. Surface electromyography activity of the rectus femoris, vastus latralis, vastus medialis, biceps femoris, semitendinous, gastrocnemius medialis and tibialis anterior muscles of 20 able-bodied women were recorded before and after the quadriceps muscle fatigue using leg-press movement, squat, stoop and strudel techniques with 20% of body weight. Analysis of Variance with repeated measures was used for data analyses (p<0.05). After fatigue when lifting the load, the activity of the rectus femoris, vastus medialis, biceps femoris and gastrocnemius medialis in squat and stoop techniques was significantly different compared to before fatigue condition. But no significant difference was observed between the activity of any of the muscles before and after fatigue in the straddle method. According to the results, it seems that when quadriceps muscle fatigue, the use of straddle technique to lift the load is more appropriate.
Mr Ehsan Ebrahimipour, Ms Fereshteh Sabet, Mr Shayan Hajebrahimi, Dr Mohammadreza Seyfaddini,
Volume 0, Issue 0 (11-2019)
Abstract
Circadian rhythms play a crucial role in regulating various physiological functions of the human body and can impact the ability to perform motor tasks. In this study, we aimed to investigate the effect of time of day on static and dynamic balance using a cognitive task approach. We recruited 24 elderly men aged between 60-70 years who performed both static (standing on the foot scanner) and dynamic (timed up and go) balance tests with and without cognitive dual tasks. Our statistical analysis, using a significance level of 0.05, revealed significant differences in the parameters of the 95% confidence ellipse (fluctuation range), length of path, and average velocity of the center of pressure when performing the dual task compared to normal walking. However, these variables did not significantly differ at different times of the day. Interestingly, our results showed that the center of pressure fluctuations in closed eyes and different times of the day did not have a significant difference. Overall, our findings suggest that healthy elderly individuals are at similar risk of falling or tripping during different hours of the day. Nonetheless, the simultaneous execution of dual cognitive tasks leads to balance disruption in both eyes-arm closed positions.
Mr Amin Mardazad, Dr Amirali Jafarnezhadgero, Mr Sajad Avazzadeh,
Volume 0, Issue 0 (11-2019)
Abstract
Warm up method can be considered as a strategy for improving athlete’s performance. The purpose of this study was to provide a useful data as warm up to improve the performance of athletes, including volleyball players by increasing their jump height. In the present review study by using the following keywords included Post-Activation Potentiation, Squat Jump, Warm-up, Volleyball, Jump Height, Force Plate, and electromyography the search process was done in Google scholar, the Pubmed databases and Scientific Information database and Google scholar. In the identification stage, 387 English and 15 Persian articles related to the mentioned keywords were found. Finally, the number of English articles reached 42 and the number of Persian articles reached 6. The results of this review-descriptive study showed in the final stages of Post-Activation Potentiation warm-up, performing high intensity squats by creating acute changes in neuromuscular system can increase in jump height of athletes including volleyball players in match and practice.
Mr Hamidreza Zanguie, Dr Mohammad Yousefi, Dr Abbas Farjadpezeshk, Khorshid Bijari,
Volume 0, Issue 0 (11-2019)
Abstract
Understanding the correct biomechanics of the knee joint during single-leg landing and correcting Incorrect movement patterns can be one of the ways to prevent the recurrence of anterior cruciate ligament injury. Therefore, the purpose of this study is to review the researches that investigated the biomechanics of the coronal plane of the lower limb during multidirectional single leg landing. The relevant articles from valid databases with the keywords Single Leg Landing, Landing, Kinematic, Biomechanics, Return to Sport, Performance Test, Functional Test, Hop Test, Kinetic thematic search methods from 1995 to 2023 were examined. A total of 1022 articles were identified then duplicate studies were eliminated in the next stage, the titles and abstracts of the studies were reviewed and 439 studies were excluded due to inconsistency with the research question. Finally, only 19 articles that met the inclusion criteria were examined. This review showed that only SLL in the forward direction has been investigated in most of the literature using a 3D motion analysis system. There is also no evidence on the biomechanics of other directions of SLL and on the use of 2D motion analysis to evaluate the biomechanics of multidirectional SLL.
Mohammadreza Rahimi, Neda Boroushak,
Volume 0, Issue 0 (11-2019)
Abstract
The main goal of this research was to design and evaluate the features of a "home-based weightless fitness device with digital adjustment" for performing muscular exercises in a home environment. To achieve this goal, a combined quantitative and qualitative approach was employed, and a detailed assessment of the device's performance was conducted. In the initial stage, existing fitness equipment, resistance training methods, and technological advancements were investigated. This review provided fundamental information for the initial design of the device. Subsequently, using design software such as Rhino Cross 6 and AutoCAD 2018, precise three-dimensional models and initial prototypes were created. To validate the device's resistance, a digital force gauge was utilized, measuring the displayed force in eight different settings with the resistance adjusted on the device, allowing for the calculation of device deviation from standard and error margin. Furthermore, to assess the device's reliability three seated movements—leg press extension, seated chest press, and seated front raise bicep curl—, each performed with eight consecutive repetitions using a 10-kilogram weight. The results of Pearson's correlation coefficient (0.9) showed that the instrument has high reliability. Also, the results of intra-correlation reliability coefficient (0.8) showed that the device has good reliability and high accuracy in the produced resistance in different movements and repetitions. Ultimately, this research introduces an effective tool for muscular exercises in a home setting. With its precise resistance adjustment capability and versatility in exercise options, the device empowers athletes to perform exercises with greater precision. Overall, this study yields practical and implementable results, potentially playing a crucial role in enhancing the health and fitness of athletes and the general community.
mouseout="msoCommentHide('_com_1')" on
mouseover="msoCommentShow('_anchor_1','_com_1')"> [R1]مجددا بازبینی و ترجمه شد متن
Dr Shirin Yazdani, Prof Nader Farahpour,
Volume 19, Issue 21 (9-2021)
Abstract
Background and Objective: although it is documented that the spine and hip alignments alter in scoliosis subjects, but the effect of these changes on the lower extremities’ biomechanics have not been well understood yet. So, the aim of this study was to compare hip, knee and ankle joint’s power generation and absorption during gait in patients with adolescent idiopathic scoliosis (AIS) and healthy controls. Methods: Using motion analysis system with 4 Vicon-460 cameras and two Kistler force plates, the kinematics and kinetics of gait was assessed in twenty girls with AIS and 20 matched healthy controls, then the power of the right and left hip, knee and ankle joints in sagittal plane was calculated. Data was analyzed using ANOVA statistical method with significance level of α<0.05. Results: Results showed that in scoliosis group, the peak power absorption of the right knee was significantly 12.5% smaller than that in control group (p=0.01). But, peak power generation and absorption of the hip and ankle joints in both right and left limbs were not statistically differed between the two groups (p>0.05). Conclusion: scoliosis is associated with the smaller power absorption of the knee joint at convex side. This might be linked with unilateral alterations of the joints' moment, joint forces, and the related muscle activity which might impose asymmetrical force to the hip and cause curve progression.
Golnaz Mousavi, Mehdi Varsei , Abosaeed Rashidi, Reza Ghazisaeidi,
Volume 19, Issue 21 (9-2021)
Abstract
The purpose of this article is to biomechanically simulate athlete's leg and compression garment to measure the pressure on a young athlete's leg in order to apply more optimal and uniform pressure distribution while providing a greater sense of comfort when wearing.
The body condition and body shape of the athlete are measured by anthropometric method. Although Using a CT scan of the athlete's body (athlete's limb) and the mechanical properties of the pressure garment (leggings) that made of elastane spacer fabric was simulated by finite element technique. The results of measuring the real pressure on the young athlete's foot were measured and compared by a kikuhime device. The values of pressure applied by the leg in the real state and simulation indicate a maximum error of 14/44 percent (Cross section below the knee and the point behind the leg), a minimum error of 8 percent (Cross section of the ankle and the front point of the leg). Despite the assumptions and sources of error in this simulation, the results show that measured pressure values in the simulation mode with the real mode with incredible accuracy
Leila Nazari, Saba Rahmati,
Volume 19, Issue 22 (12-2021)
Abstract
One of the most important issues in community is health and progress people. Because of durability of a community depends on health each person. In this regard, the present study aims to compare anthropometric, biomechanical and psychological factors between university student and student girls done. Subjects of the study were 86 girls 15-17 years old and 113 university student 18-24 years old, took part randomly in this study. Measure anthropometric, biomechanical characteristic also psychological characteristics including general health (GHQ-28) and personality (NEO-FFI) were measured. The result of independent t-test showed that between percent fat and lean body mass, static balance and muscular endurance and all of the general health factors, there are significant differences between the two groups. In generally the subjects are in the border abdominal obesity and high risks associated health them. Doing prevention programs are essential. One of the most important proceedings for this group doing of physical activity and fitness and have a regular exercise program.
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.
Dr Heydar Sadeghi, Mohsen Ali Darchini, Hossein Nabavi Nik,
Volume 19, Issue 22 (12-2021)
Abstract
Core stability (CS) is a popular term that has evolved into a fundamental concept the much rehabilitation, performance training and preventative programs. The purpose of this study is considering the relationship between CS power and endurance with performance of adolescence athletes. 12 male swimmers participated in the study. McGill Protocol, the core stability power, MBESTT and 30/60 sit-up test were used to measure the CS endurance and power, respectively. Participants' performance was measured as the specific (stroke-index, 100m crawl stroke) and general performance (standing-broad-jump (SBJ), vertical Jump, 9.1 m sprint, shuttle-run, flexibility and seated medicine-ball toss tests). The Pearson correlation coefficient was used to determine the relationship between the CS power and endurance with general and specific athletes' performance. The results showed only significance relationship between trunk flexion with SBJ and seated medicine-ball toss, and flexibility and total CS power score with flexibility. Also, negative significance relationship found between left lateral flexion with shuttle-run test and trunk flexion with stroke-index. The findings of this study showed a weak correlation between CS with specific and general athletes' performance. Based on our findings, there is no necessity for focusing on swimming training programs.
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.
