مجله بیومکانیک ورزشی
سال یکم شماره 2 (پاییز 1394)

Resistance exercises improve muscle strength and joint's physical status. The aim of this study was to assess the effect of progressive resistive exercise on joint's physical characteristics and quality of life in hemarthrosis joint in severe haemophilic A patients.
Twenty-four severe haemophilia A patients (18-35 years old) with knee hemarthrosis, were assigned randomly to a resistance training (n=15) and control (n=12) groups. Resistance training group was required to perform six weeks trunk and lower limb exercises with low load and high repetition (40 min per session, three days per week). The control group was requested not to change their physical activity routines. Knee joint physical characteristics including joint range of motion (ROM), contracture, and crepitus were measured through Modified Colorado questionnaire and quality of life were investigated through SF-36 questionnaire before and after six weeks of training protocol.
six weeks resistance training significantly improved extension ROM (P=0.00), flexion contracture (P=0.02) and crepitus (P=0.03) in hemarthrosis knee joint compared to the control group. Quality of life also was significantly improved in the resistance training group compared to both the control group and baseline values (P=0.00).
Resistance training with low intensity and high repetition, can improve ROM, muscle strength, pain, and crepitus in hemarthrosis knee joint. This may be effective to improve the quality of life in hemarthrosis especially in patient with severe haemophilia A, in whom rebleeding is unavoidable.

A better understanding of the role of muscle fatigue in lower limb stiffness during performance will provide a strong foundation for the development of optimal training intervention programs. This study aimed to investigate the effect of fatigue on ankle and knee joints and leg stiffness during a 30-scontinuous vertical jump test.
Fifteen female volleyball players without history of lower extremity injuries were selected in this study. They performed a 30 seconds vertical jump test and kinetics and kinematics data were measured using a force plate and two video cameras, respectively. Lower limb, stiffness before and after fatigue (first 10 percent of the jump, 10% percent of the end jump) were compared using a paired samples t-test analysis. The amount of relationship between the height of the jump and leg, ankle and knee joints stiffness were measured by the use of Pearson test (P Results showed a significant reduction in knee and ankle joints stiffness (pknee= 0.00, pankle= 0.004) and leg stiffness (p=0.01) during the test. In other words, fatigue decreases leg stiffness and ankle and knee joints stiffness by 20%, 47% and 34%, respectively. It also decreases the jump height and ground reaction force.
As the height of the jump and stiffness changes in lower body parts is an important factor in fields such as volleyball, coaches need to pay due attention to stiffness changes and improve their training techniques.

The number of people suffering from Osteoarthritis (OA) is increasing. Treatment of OA can be done with or without surgery. The most common treatment is using orthosis. However, most patients with OA prefer not to use orthosis because of downward transition. Therefore, the objective of this study was to design new orthosis and to assess its effects on knee joint kinetics and kinematics during gait.
Ten subjects without any neuromuscular disease participated in this study. New orhosis with the same structure of Scottish rite orthosis was designed. Qualysis system analyses with seven cameras as well as a Kistler force plate were used to measure the kinematics and kinetics variables during the gait with and without orthosis. For statistical analysis independent student-t test was used. The significance level was set at p Mean walking speed with and without orthosis was not significantly different (p=0.42). Peak anterior- posterior forces applied on knee in the first half of stance phase and propulsion phase was the same during walking with and without orthosis (p>0.05). There was significant difference between peak medio-lateral forces applied on knee during walking with and without orthosis (p The new orthosis decreases the adductor moment on knee joint therefore, it can decrease the forces applied on medial compartment of the knee joint. This orthosis improves walking because it does not let inferior transition. This orthosis can improve femur alignment. It is recommended that physiotherapist prescribe this orthosis in order to decrease pain in patients with OA.

The purpose of this study was to evaluate the kinematics of liberation moment in the elite archers.
Ten elite archers (male = 5, female = 5), who were the members of the provincial and national teams, were studied. The trunk and upper extremities of the subjects were determined by 5 reflective markers. Each archer performed 10 successful trials. Using Motion Analysis System (150 Hz with a low pass filter having a cut-off frequency of 7 Hz) and based on markers’ coordination, the angles and angular velocities of the shoulder, elbow, and wrist of pulling hand in the sagittal plane at the moment of liberation were calculated.
Means (SD) of the shoulder, elbow, and wrist angles were 93.1 (4.0), 135.7 (5.7), 15.3 (2.8) °, respectively. Means (SD) of the shoulder, elbow, and wrist angular velocities were 55.4 (23.5), 38.4 (16.1), 81.9 (36.6) °/s, respectively.
The fast wrist extension causes a quick arrow release and enhancements in the results of archery. In addition, coordination between elbow flexion and shoulder extension assists the archer to pull the bow at its maximum range. These amounts and kinematic relations can serve as a criterion for coaches and elementary archers to enhance their level of performance.

The purpose of this study was to investigate the immediate effects of pre-made foot orthotics on rear-foot and tibia variability and joint coupling patterns during stance phase of gait in male athletes with pes planus.
Subjects of this semi-experimental research included 8 active men with pes planus. Kinematic gait data of these subjects were recorded by a motion analysis system with 8 cameras. After calculating three-dimensional angles, vector coding method was used for assessing coupling. Shapiro-Wilk test was used to test the normal distribution of data and dependent samples t-test was used to compare means in each sub-phase.
Results showed that in the first 3 sub phases of stance, there were no significant differences between joint coupling with and without orthotics (P>0.05), while in the fourth sub-phase the mean coupling angle decreased significantly by 19% (P=0.002-P0.05).
These results suggest that foot orthotics does not have an effect on rear foot and tibia joint coupling patterns in the first 75 percent of stance phase of gait, but leads to a decrease in these patterns in the last 25 percent. Thus, it seems that movements of the shank decrease relative to heel movements in terminal stance phase, and this change can explain reduction in knee pain and other beneficial effects of using foot orthotics in subject with pes planus.

The main objective of the study was to investigate the effect of factitious and true neurofeedback training on the balance performance of active males.
Twenty physical education male students were selected through purposive sampling and were randomly divided into real neurofeedback and sham neurofeedback groups (with mean age 21.38±1.32 years and mean weight of 71.01±3.58 and mean height 173.88±4.69cm). The participants attended neurofeedback training session 3 times a week for a period of one month. Prior to and after training, pre-test and post-test of static balance, semi balance and dynamic balance were administered using Bass Stick, Modified Romberg and Y test. Repeated measures ANOVA was run at a significance level of p Results showed that real neurofeedback training would have significant impact on static balance, semi balance and dynamic balance participants (Except for dorsolateral). The means of static balance and semi balance 4.19 and 3.72 seconds and dynamic balance on anterior direction 13.89 cm and on medial posterior 6.59 cm were increased, respectively.
Due to its positive impact on the balance of active males, neurofeedback training can be used as a complementary training program to increase their efficiency of such students in competitions.