Research in Sport Medicine and Technology

The aim of the study was to compare the electrical activity pattern of major muscles involved in handball
triple shooting in two groups of adolescents and adults. Ten adolescent elite handball players playing in
national club league (16.4 ± 0.69) and 10 adult handball players (23.55± 2.69) participated in this research.
They performed triple shooting و assuming in a match situation and electrical activity of the Biceps brachii,
Triceps brachii, pectorialis major muscles and three anterior, middle and posterior parts of deltoid was
recorded using surface electromyography. Parameters related to the muscular activity pattern, including
time, peak, action amplitude and contraction sequences were obtained. The results of t-student statistical
test for two independent groups (p≤ 0.05) shown that there were no significant difference between time,
peak and electrical activity amplitude variables between groups. It seems the factors such as experience in
adolescent athletes, better utilization of muscle and being close to the end of puberty makes no difference
between adolescents and adults.

Take-off is the critical phase of the long jump event. The aim of this study was to explore the relationships
between different variables and success in take-off. 37 trials performed by 8 long jumper, participants in
fourth indoor Asian senior athletics championships held in Tehran, with personal best average of 7.68±0.28
meter were recorded at 300 Hz. Five speed-related, five technical and four strength-related variables as well
as an anthropometric variable were measured using motion analysis software. More gain in vertical velocity
and less loss of horizontal velocity are considered as two criteria of take-off success and their relationships
with other variables were determined through correlation and regression analysis. Significant level of 0.05
was set. Some variables of all four groups were significantly correlated with success criteria. These variables
along with some others were entered in regression equations. The results emphasized on dominant role of
the technique and approach velocity and represented the effect of anthropometric characteristics on success
in takeoff. Furthermore eccentric strength of knee extensors was shown as the main strength factor in this
performance.

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.

The purpose of this study was the effect of eight weeks of circuit training on the Irisin levels and
the Insulin Resistance Index (HOMA-IR) in overweight women. Materials and Methods: In this study 22
overweight women voluntarily were chosen (Age 26.04±4.43 yrs, BMI 29.35±2.53 kg/m2) and were divided
to two groups of control (n=11) and experimental (n=11). In the experimental group, subjects performed
circuit training for eight weeks and four times per week. Blood sample was taken before and 48 hours after
the last training session. Statistical analysis at the level of P<0.05 was done. Findings: After eight weeks of
training, the level of Irisin in experimental group significantly increased while the HOMA-IR had a
significant reduction (p<0.05). Also Pearson correlation co-efficiency test shows that there is a reverse
relationship between irisin and HOMA-IR (P≤0.05). Conclusion: It appears that circuit training improves
body composition and metabolic disorders such as insulin resistance through Irisin induction in overweight
women.

The incidence of lower extremity injuries in young soccer players is high, but the risk factors for injuries are unknown. Thus, the aim of this study was to investigate relationship between static lower extremity alignment and injuries in adolescent soccer players. Four teams (78 players) playing at Tehran Asia vision adolescence primer league (14-16 years old) participated in this study. Before entering the season Navicular drop, quadriceps angle, knee hyperextension, genu varum and body mass index was measured. Players were monitored for musculoskeletal injuries through a season (7-month period). overall injury rate was 8.7 injuries/1000 player-hours (95% CI=7.01-10.10). Logistic regression modeling indicated that Navicular drop in preferred foot (OR=4.5; p=0.001), Q angel in preferred leg (OR=2.77; p=0.048), and genu varum (OR=4.06; p=0.021) were all associated with injuries but no association was found in other parameters. Players had an approximately 4.5 times greater chance of suffering a lower extremity injury if they have Navicular drop greater than 1.5 centimeter and approximately 2.77 times greater chance of suffering injury if they have Q angel greater than 15.5 degrees. These findings show that multiple anatomic measures such as Navicular drop, genu varum and Q angle can predict soccer players’ injuries. Results of this study are valuable for coaches and players for injury prevention.

Introduction and Objectives. The trajectory of center of pressure (COP) during the stance phase of gait is considered as an important parameter in assessing of dynamic balance, foot and ankle function and effectiveness of shoe and orthotics. The aim of this study was to determine the COP trajectory during stance phase of gait in healthy males and females, by means of Pedar-X plantar pressure measurement apparatus.Methods: 15 healthy adult females who didn’t have any history of injury that altered their normal gait pattern and trajectory of COP, participated in this study. The coordinate of COP in transverse (X) and vertical (Y) axes were measured using Pedar-X system. The stance phase of gait divided into the four sections by key points of acceleration vector in Y direction and then position, velocity and acceleration of COP at these portions were computed. To statically analysis, Descriptive statistic (Mean and standard deviation), Pearson correlation coefficient and ICC coefficient were used  (P≤0.05). Results and Discussion: The results indicated that during stance phase of gait, COP moves forward and medial in Y and X axes, respectively. Significant, strong but negative correlation seen between COP coordinates in X and Y axes. High Inter Class Correlation also showed between trials reliability for Pedar-X system in estimation of COP coordinates. Conclusion:  The results of this study could be used as a standard norm of trajectory of COP in healthy adult subjects

The aim of the present research is comparing the effectof periodic trainingin hypoxic and normoxic conditions on anaerobic performance of athletes .Subjects of this research were 16 male volunteer students.Subjects were divided to two groups of eight by exercising in hypoxic condition(H 3300) normocytic.Anaerobic performance (peak power, average power) through the Wingate test and lactate concentration were measured before and after the Wingate test.After 24 hours in hypoxic condition,and after 48 hours in normoxic condition the measures of W _max  were determined.The intensity of exercises in both groups (one minute with intensity of 80% -85% W_max, and two minutes with 50% W_max) and exercise duration (30 minutes)were equalized. The training program consisted of 12 sessions in a row. After that the pre-test variables were measured again .After testing the normal distribution given by Kolmogorov – Smirnov test, dependent and independent t-Test with a confidence level of 0.05 ≥ p showed that this training improved aerobic performance in both groups, also five minutes after the Wingate test lactate concentration was decreased in both groups, but there was no difference between the 12 sessions of the periodic training in hypoxic and normoxic conditions on anaerobic performance. So it can be stated that the training used in this study can improve the anaerobic performance, but the severity and duration of hypoxia used in this study was not so much to improve anaerobic performance in hypoxic group more than normocyticone

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

Motion analysis systems are useful and effective equipment in biomechanics research. Unfortunately these systems are available for few researchers because these are expensive equipment. The aim of this study was to design and validation of a practical and inexpensive software, to determine the exact markers position in space and compute the kinematic of movement. In designing the software, the exact image processing algorithms and Direct Liner Transformation (DLT) method were used to calculate markers position in space. To validate the software, the markers position in static, dynamic, linear, angular, 2D and 3D conditions were calculateted by other standard tools and compared with software outputs using Mann-Whitney U test and no significant difference were observed. The validity and reliability of the software was assessed using Pearson Correlation Coefficient and Intraclass Correlations Coefficient and during all test conditions, very high levels of these coefficients were found (≥0.97). In a nutshell, present software, with features such as automatic tracking markers, inexpensive price, the possibility to outdoor use and image processing in 2D and 3D conditions, is valid and reliable software for kinematics analysis

Homocysteine and insulin resistance in postmenoupausal women rises due to decrease in estrogen, low mobility and weight gain which increase the cardiovascular diseases. The aim of this study was to examine the effects of aerobic exercise training status on response of homocysteine and insulin resistance to aerobic exercise in active and nonactive obese postmenopausal women. Therefore, 21 obese postmenopausal women with the age of 48 - 65 yrs voluntary participated in the study and assigned in active (n=11) and nonactive (n=10) groups. Aerobic exercise was performed with 70-75 percent of maximum heart rate. Blood sample was obtained before and after exercise, and 10 hours following fasting. Results showed that baseline levels of ​​homocysteine (p= 0.003) ​​and insulin resistance (p=0.003) were significantly lower in active subjects compared with inactive ones. However, homocysteine level was significantly (p=0.028) lower in active than to nonactive subjects following aerobic exercise. It can be concluded that regular aerobic training improves insulin resistance and homocysteine levels in obese postmenopausal women, however, a session of moderate aerobic exercise could not influence on insulin resistance. Although, homocysteine response was higher in active group. It seems that changes manner of two variable to aerobic exercise is different

Chronic ankle instability has defined as recurrent ankle sprain, so that 40% of injured athletes after acute injury despite of receiving of adequate rehabilitation, suffering from this instability. The purpose of this study is investigate of postural sway’s risk factors proportion in jump-landing and lateral hopping tasks, in prediction of chronic ankle sprain occurrence. 25 ankle sprain injured athletes and 25 healthy athletes participated in this descriptive-analytic study. Six variables (area of sways, path length and velocity of sways in jump-landing and lateral hoping tasks) were measured as predictor variables, and we used to Logistic Regression test for predicting. The results of study showed that path length and velocity of sways in jump-landing, area and path length of sways in lateral hopping had statistical significant proportion in classification of injured and healthy groups, and the model classified about 77% cases correctly. Therefore, athletes with ankle sprain history have less control of posture than healthy subjects in jump-landing and hopping tasks and have higher risk to getting recurrent ankle sprain. Also subjects with chronic ankle sprain have less control of posture in frontal plan

The aim of the study, study of Changes in adiponectin, leptin, and plasma lipid profile of Inactive men the  result 24 session, playing futsal. In this study, 20 healthy men 20 to 30 years old, the experimental group (age: 23/5±2/58, weight: 69/36±14/48, body composition: 22/82±4/41) of controls (age: 24/6±2, weight: 68/22±12/71, body composition: 21/99±3/58) inactive randomly divided into control and experimental groups. Experimental groups in each session, indoor futsal training program for eight weeks and will run three sessions per week, while the control group had normal activity. Before the training program, and 48 h after the last session of play, 5 ml blood samples for measurement of adiponectin, leptin, and plasma lipid profile, blood was collected from the participants. After 48 hours of the last training session before the test was re-sampled in the same conditions. T-test results showed that exercise increased adiponectin and high-density lipoprotein and decreased leptin, low density lipoprotein, lipoprotein (a), triglycerides and cholesterol are, however, differences in adiponectin was not significant (P≤0.05). Overall, this study can be taken that these exercises in a short period of eight weeks futsal, adiponectin does not cause significant changes but the significant changes in leptin, high-density lipoprotein, low density lipoprotein, lipoprotein (a), triglycerides and cholesterol in the blood plasma.
 

Support foot position is one of the important factors which can affect instep kick quality and ankle joint injury. The aims of this study were to examine the support foot parameters in maximal instep kicking with the preferred and the non-preferred leg and research on risk factors for ankle joint injury in amateur futsal players. In this semi experimental study, twelve young and novice futsal players performed maximal speed place kicks with the preferred and the non-preferred leg. Average of the subjects individual characteristic have contained, age : 21/2±1/5 years, weight : 67/6±5/5 Kg and height :176±4/2 cm. Athletes were kicking the ball towards the goal from 10 meters. amount of support foot pressure were calculated at 300 Hz. To calculate injury of ankle joint, Forces, impulses, position of the fixed leg and maximum pressure of the lateral and medial portions of the foots were determined. Results indicated a significant difference in amount of subtalar joint range of motion. Higher range of motion in dominant leg were caused by a greater flexibility and coordination in this side of the body. In addition there were no significant different in impact of anterior, middle and posterior portion of fixed legs between two support foot. In contrast the maximum pressure in lateral side of non-preferred leg, was significantly more than other foot. In addition, the maximum force in non-preferred leg occurred prior then other foot. These problems can exacerbate ankle injury risk. Because the subjects were novice and they do not have appropriate neuromuscular coordination, can’t show a good movement pattern in non preferred leg. Hence, the absence of neuromuscular coordination can lead to energy loss and high pressure coming into the body, especially the feet and it can exacerbate injuries.  In a nutshell, amateur subjects indicated higher quality of­ biomechanical parameters in support foot of the preferred leg. Also likelihood of ankle sprain in dominant foot was less than other. Also generalization of these results to semi-professional and professional players, need further research.

Specificity of physical exercises is one of the main factors which could affect musculoskeletal system. The purpose of this research is to make a comparison about postural abnormalities of the spine and lower limbs between female taekwondo athletes and non-athletes. Samples of current research were 50 female black-belt taekwondo athletes and 50 non-athletes. To measure kyphosis and lordosis, flexible ruler was used; also to determine the angle of forward head posture and scoliosis, photogrammetry was used, and to determine knee and foot deformities caliper and navicular drop methods were used respectively. To compare two groups, independent t test was used. The results of independent t test showed that amount of lumbar lordosis (47.90°) in taekwondo athletes is significantly higher than that of non-athletes (44.04°). Also amount of scoliosis (3.52°) in taekwondo athletes was significantly higher than that of non-athletes. Also distance of internal condyle )3/26 CM) of taekwondo athletes was significantly higher than that of non-athletes)1/91 CM)(P≤0.05). But no significant difference was observed between two groups in terms of forward head posture, kyphosis, distance of internal malleolus, and navicular drop. Based on the results of this research it is possible to express that taekwondo due to type of its common exercises and could have impact on posture of its athletes.

This study aim to investigate the effect of different slops on mechanical lumbosacral angles and lumbar stability of healthy and mechanical low back pain (LBP) persons. This case- control study was performed on 38 females (18 LBP and 20 healthy subjects) who were referred to the Hospital in sari. At the beginning, Subjects’demographic data were recorded. In order to measure lumbosacral angles and  lumbar spine stability evaluation, three lateral radiography plots in state of standing on various slope (­ο, +3.7, -3.7) were prepared. There were no significant differences between the biomechanical lumbosacral angles by standing on the various slopes, within and between 2 groups (LBP and healthy females) (p≥0.05).There was more lumbar instability in females with LBP and lumbar mechanical stability was significantly difference between 2 groups in each slope (P +=0.023, P –=0.009, P 0=0.004). Although, lumbar stability was not significantly different within each LBP and healthy groups, on the various slopes (p≥0.05). It seems that lumbar instability may increases in mechanical LBP, that won’t manage by various levels of slop.

Since, sports activities are likely to be changes in various parameters of plantar pressure distribution during walking to create, This study compared patterns of plantar pressure distribution between right and left feet and their relationship with anthropometric parameters. 10 elite wrestler with the average and standard deviation of age: 23.6±3.33 yrs, height: 173.5±7.67 cm and mass: 83.3±21.8 kg voluntarily participated as subjects in this study. EMED-AT2 System for plantar pressure analysis, of parametric statistical methods paired t-test to compare parameters between the right and left leg and also of the Pearson methods for investigating correlation between variables was used. The only in the contact area parameter between the right leg and left at 4th mask significant differences were found (p≤0.05, ES=0.03). Also positive and significant correlation between height and mass with all the parameters were found (p≤0.01, p≤0.05) and in the heel area the correlation between maximum force in the right foot with height (medial heel r²=0.45 ; lateral heel r²=0.68) and weight (medial heel r²=0.56 ; lateral heel r²=0.8) and in the left foot with height (lateral heel r²=0.53) and weight (lateral heel r²=0.55) was reversed. (p≤0.05). Considering the lack of significant differences in plantar pressure parameters between the right and left foot, it could be argued, in wrestling foot demand function is the same. Also this research confirmed the results previous study indicating the absence of dominant leg in wrestling.

The incidence of lower extremity injuries in young soccer players is high, but the risk factors for injuries are unknown. Thus, the aim of this study was to investigate relationship between static lower extremity alignment and injuries in adolescent soccer players. Four teams (78 players) playing at Tehran Asia vision adolescence primer league (14-16 years old) participated in this study. Before entering the season Navicular drop, quadriceps angle, knee hyperextension, genu varum and body mass index was measured. Players were monitored for musculoskeletal injuries through a season (7-month period). overall injury rate was 8.7 injuries/1000 player-hours (95% CI=7.01-10.10). Logistic regression modeling indicated that Navicular drop in preferred foot (OR=4.5; p=0.001), Q angel in preferred leg (OR=2.77; p=0.048), and genu varum (OR=4.06; p=0.021) were all associated with injuries but no association was found in other parameters. Players had an approximately 3.47 times greater chance of suffering a lower extremity injury if they have Navicular drop greater than 1.5 centimeter and approximately 2.77 times greater chance of suffering injury if they have Q angel greater than 15.5 degrees. These findings show that multiple anatomic measures such as Navicular drop, genu varum and Q angle can predict soccer players’ injuries. Results of this study are valuable for coaches and players for injury prevention.

The aim of this study was to compare the profile of anthropometric, somatotype and body composition between novice and professional 6 to 8 years old gymnasts. A total of 40 gymnasts in tow group (20 novice gymnasts and 20 professional gymnasts) participated in this study. A total of 17 anthropometric, somatotype and body composition variables were recorded of each subject. The tools used in this study are: questionnaires (individual information and general health evaluation), chronometer, band meter, and movable weight scale, stadiometer, sliding calliper and somatotype software. In ferential and descriptive statistics and independent T test were used to analyze the obtained data. The level of significance was 0.05. There were significant differences in skinfold percentage (triceps, Supraspinatus and calf), total hand length, hip and calf, circumferences, BMI, endomorph and ectomorph between tow group) p<0.05). From an anthropometric stand point, 6 to 8 years old is a lowest and best age for select and talent identification. According to the results, between two groups, professional gymnasts exhibited lower BMI, circumferences (hip and calf), skinfolds, endomorphy and more total hand length, mesomorphy and ectomorphy than nivice gymnasts. On average, professional and novice gymnasts were in ectomorph-mesomorph and endomorph-mesomorph status respectively.