مجله بیومکانیک ورزشی
سال هفتم شماره 4 (زمستان 1400)

Objective :

Excessive dynamic knee valgus, as a defective movement pattern, predisposes patients to lower limb injuries. Therefore, the aim of the present study was to study dynamic knee valgus in male soccer players.

Methods :

In this review article, an attempt was made to collect studies conducted on the subject of research from 2000 to June 2021. The websites Google Scholar, PubMed, Science Direct, SID, ISC and Magiran were used and keywords related to the topic were used to search for articles.  

Results:

 According to the search method, 50 articles were found, which were finalized according to the inclusion and exclusion criteria of 12 articles. Finally, 7 articles were reported in the present study. Dynamic knee valgus condition is more common in women than men, and varus are more common with increasing age of male soccer players. Different situations during the game such as tackling, jumping, imbalance after strike to the ball and landing after jumping are also among the situations that are associated with increased dynamic knee valgus and players are exposed to knee injury. The first minutes of the halves due to the lower angle of flexion of the knee and also late in the game due to fatigue can increase the dynamic valgus and increase the risk of knee injury. 

Conclusion:

 All studies have pointed to the role of dynamic valgus in the incidence of knee joint injuries, especially the anterior cruciate ligament, so it is necessary to identify the mechanism of injury and correct the direction of dynamic valgus among soccer players.

The purpose of this study was to the impact of an exhaustive exercise on static balance of freestyle wrestlers with flat foot.number of 15 freestyle wrestlers north khorasan province, the method semi-empirical and purposefully based on anthropometric variables with mean and standard deviation, BMI (kg/m2) (25.41±3.619) per square meter, Age (y) (22.8±2.833), Weight (kg) (79.9±1.837), Height (cm) (176.25±8.331) were intrant this studied.

The data analysis from descriptive statistical method (mean and standard deviation) and inferential statistics method (Shapiro-Wilk test dependent t-test was used to evaluate intragroup changes (P≤0.05).

The results this research showed, between static balance and wrestlers flat foot after an exhaustive practice a significant relationship and over affinity was between demographic characters with static balance in wrestlers with flat foot (P≤0.05).

Based on research results, it can be concluded that flat foot deformity associated with exhaustive exercise can on postural control and affected static balance freestyle wrestlers.

Objective :

The purpose of study was the effect of 8 weeks training shallow water on static balance of military with knee injuries.

Methods:

 Subjects of this research there were the Number of person 46 military in north khorasan province, They participated in this study purposefully and voluntarily. Subjects were randomly divided into two experimental groups of 23 people (Mean±SD, age (y) 33.65±6.62, height (cm) 183±6.95, weight (kg) 76.75±2.80) and a control group of 23 people (Mean±SD, age (y) 34.45±6.97, height (cm) 181±7.41, weight (kg) 71.66±3.20). To measure static balance were used the stork test. Were used For analyze the results of descriptive statistics (Mean±SD) and were used Inferential statistics method (Shapiro–Wilk test, dependent t and independent t).

Results :

The test results showed there is a significant difference between pre-test and post-test in the experimental group (P=0.001). So that was not observed significant difference between pre-test and post-test in balance (P=0.393), Also, a significant difference was found between the experimental and control groups (P=‌0.001).

Conclusion:

 Based on research results, it can be concluded that shallow water training is significant on the static balance of soldiers with knee injuries and this can indicate the greater effectiveness of exercises in shallow water so practice in the water it can be recommended as a way to improve static balance in people with knee injuries.

Objective:

 Genu valgum and genu varum are considered as the most common abnormalities of the knee joint in the lower extremity. Identifying of the mentioned abnormalities in the early stages of life can prevent the occurrence of later problems in the physical condition of a person's life. Therefore, the aim of the present study was to compare the kinematic pattern of knee joint flexion in healthy children and genu valgum and genu varum children during jumping.

Methods :

This study, 45 students in three groups (15 genu varum, 15 genu valgum and 15 healthy participated in the present study. Students performed long jump skills in front of a camcorder and measured information about the knee joint in three phases: take off, flight, and landing, using KINOVEA software. Data normality was investigated using Kolmogorov-Smirnov test and Mann- Whitney as well as kruskal-wallis nonparametric tests were employed for future analysis (P<0.05).

Results:

 There was a significant difference between healthy genu valgum and genu varum groups at take-off phase. No significant difference was observed between all three groups in the two other phases.

Conclusion:

 In genu valgum and genu varum groups the quadriceps muscles are affected to create dynamic stability in the frontal and sagittal planes.

Background and aim :

The sport of volleyball requires constant contact of sports balls with the hands of athletes, Therefore, the sports balls used in volleyball can play an important role in the performance of athletes. therefore, the aim of the present study is to compare the impulse of the new BETA volleyball designed with other samples volleyballs using the Bertak model force plate made in the United States.

Examples of Mikasa volleyballs, model V200W, made in Japan, Fox volleyball, model Spain, made in France and Old and new BETA volleyballs made in Iran with a weight range of 260 to 270 grams with a circumference of 66 cm were used in the present study, Finally, the impulses of volleyballs were compared using a Bertek model force plate machine.

Results:

 In line with the findings of the present study, there is a significant difference between the impulse of the sample of the new BETA volleyball ball designed at compared to the volleyball sample of the old beta design in the direction of the vertical axis (P = 0.014). in this regard, the post hoc test showed that there is no statistically significant difference between the sample of the new BETA volleyball at compared to the sample of Fox volleyball (P = 0.102) and Mikasa volleyball that is used in official competitions (P = 0.662).

Therefore, the use of a new BETA volleyball designed to reduce the rate of sports injuries is recommended to all coaches, referees, athletes and officials in the field of volleyball.

 Although most studies believe that the dominant hand performs better than the non-dominant hand in performing various tasks, there is still the challenge among researchers as to why the non-dominant hand performs better than the dominant hand in certain situations and tasks. The aim of this study was to compare dominant and non-dominant hand performance with force changes in a two-handed balance task.

 The samples of this study consisted of 30 male and female subjects with age (y) Mean±SD of 28±6.5. This research was conducted in Shiraz Health Center. In this study, a Huber device was used to measure hand function.

 The results of the independent t-test showed that when the force on the handle sensor was the same in both hands, the performance of the dominant and non-dominant hand did not differ significantly (P>0.05). However, the dominant hand performed better when the dominant hand-applied more force and the non-dominant hand performed better than the dominant hand when the non-dominant hand applied more force to the handles (P<0.05).

 The results of this study showed that the performance of the superior hand is not always better than the non-superior hand and the performance of both hands depends on the type of task, synthetic factors (force), and the amount of attention to each hand. These results support the theory of dynamic systems and the specialized hemisphere model in hand control.