مجله بیومکانیک ورزشی
سال سوم شماره 1 (بهار 1396)

Talent identification reduces stint to achieve better sports performances by elite athletes and enables application of scientific training; and thereby sports science experts will continue their work with more motivation. The purpose of this study was the evaluation of the anthropometric, biomechanical and physical-fitness characteristics for talent identification and predicting the performance of the elite boys in 200m Backstroke swimming.
34elite young swimmers, age11-12 years, Which ranks top in the championship and earned his province had been entered in national competitions, completed the letter of satisfaction questionnaires. 3subject, due to lack of cooperation on the measurement of parameters and 4subject, due to measurement error, declines in the study. The anthropometrical, biomechanical and physical fitness-motion parameters from 27subjects were measured by Rydkv questionnaires. Data were analyzed using mean±SD and friedman test.
The most important anthropometrical parameters were subscapularis fat (8.32mm), triceps fat (8.93mm) and supraspinatus fat (9.15mm); the most important biomechanical parameters were elbow hyperextension (3.59degree), ankle dorsi flexion (6.50degree) and hip hyperextension (40.65degree); and the most important physical fitness-motion parameters were action and reaction velocity (20.76cm), left hand strength (23.56kg) and right hand strength (23.78kg) and flexibility (27.41cm) in 200m Backstroke swimming of the elite 11-12 year-old boys.
Anthropometrical, biomechanical and physical fitness-motion parameters for talent identification and predicting the performance of the elite 11-12 year-old boys in 200m Backstroke swimming, to be considered by authorities, practitioners and educators.

Poor dynamic balance may put a subject in falling risk. The role of proprioception systems have been well addressed in the literature. However, Majority of previous studies have been conducted in static conditions. The objectives of this study was to evaluate the dynamic postural control of healthy individuals during perturbation on their base of support in eyes opened and closed conditions.
Forteen healthy men participated in this study. To measure dynamic postural ability, subject stood on a four weel cart. Then using the force of a load equal to 10% of the subject’s body mass, the cart was moved to forward. A motion analysissystem with Falcon cameras (240Hz) was used to quantify the kinematic variables of the head, trunk, hip, knee and ankle joints during the test. Tests were repeated while the eyes were closed. For statistical analysis repeated measure analysis of variance was used with p The range of motion in head, trunk, hip, knee and ankle joints were 23.17º±1.8, 21.56º±3.51, 22.15 º ±2.16, 32.72º±3.29 and 19.93 º±2.18 respectively. Analysis showed that closing eyes resulted in the reduction of the range of motion in various joints.
the posture is controled mostly via the motion in knee joint rather than the hip or ankle joints. It is recommended to enhance the knee extensors to prevent falling in people with high risk of postural instability.

Parkinson Diseases (PD) is a progressive deficit of central nervous system. This disease affects gait performance. The objective of this study was to assessment the range of motion and muscle activity of lower limb in PD patient compared to normal elderly.
one patient with PD (height=173 cm, weight=63 kg, age 53 years) and one normal elderly subject (height=172cm, weight=70kg, age 51years) were participated in this study. VICON motion analysis system was used to measure kinematic variables. Moreover, MA300-16 was used to measure EMG activity of lower limbs muscles. Data were evaluated using Repeated Measure with significant point set at p The duration of mid stance and terminal swing phase of PD patient was greater than normal elderly in right limb 20.3% and 11.6 % and in left limb 19.4% and 2.3% respectively. The intensity and duration of muscle activity of tibialis anterior, vastu smedius and biceps femoris was significantly increased in PD patient compared to normal elderly.
The percent of gait cycle phases changes in PD patients. The intensity of muscle activity increases in PD patients than that of normal subjects that means PD patients’ muscles are weaker. So strengthen of ankle plantar-flexor, knee and hip extensor must be considered in rehabilitation programs

The purpose of this study was to compare vertical ground reaction force during forward and backward walking among the male Karates professional with genu varum and normal knee.
20 professional male Karates (in genu varum and normal groups) participated in this semi-experimental study. The vertical ground reaction force was measured using force plate system during forward and backward walking utilizing 250 Hz frequency. Mixed ANOVA test was used to analyze hypotheses.
The first force peak was significantly more during backward walking than forward walking ((p=0.00), (p=0.03)). The second force peak was significantly less in non-dominant limb during backward walking than forward walking (p=0.01). The first force peak in dominant limb during backward walking and in non-dominant limb during forward walking was significantly more in normal group ((p=0.00), (p=0.06)). Also, depth force during forward walking was significantly more in the normal group ((p=0.01), (p=0.01)). The second force peak in dominant limb during backward-forward-walking was significantly more in genu varum group ((p=0.04), (p=0.05)).
According to results of present study, genu varum can consider as an effective factor on vertical ground reaction force (as predictor factor of musculoskeletal injuries among the Karates professionals, and backward walking can cause a change in vertical ground reaction force than forward walking.

The purpose of this study was to determine the effect of eight weeks strength training on some chosen biomechanical properties of femur of old male rats.
in this experimental research sixteen old male Wistar rats with Twenty months old were assigned to sedentary control group (n=8) and strength training group (n=8). strength training group climbed from a ladder for 8 weeks, 4 times per week. Forty eight hours after last session of exercise training, animals were anesthetized and femur bones were removed. Three – point bending test was used to determine bone biomechanical properties. Our data was analyzed by independent t test (p≥0/05).
the results showed this training had no significant effect on bone stiffness, fracture energy and maximal load.
the probable cause of this object can be intensity, type and time of training or age of activity beginning .