مجله بیومکانیک ورزشی
سال چهارم شماره 2 (تابستان 1397)

High load and intensity exercises often begin in the early teenage years and therefore the risk of musculoskeletal and overuse injuries sush as spine injuries among young athletes increases in most sports fields, especially in young athletes at overhead and throwing sports. The purpose of this study was to review the kinesiopathology of thoracolumbar spine injuries in throwing and overhead young athletes. Articles on the topic in the past two decades were searched in sush databasesas in PubMed Medline and Science Direct and articles with keywords like “Pitchers Spine”, “Throwers Spine”, “Pitchers Injuries”, and “Overhead Throwers Injuries”. Finally 24 papers were selected from among 134 papers. Most of elbow and shoulder overuse injuries in throwing occur at preparation phase and deceleration phase. Muscle injuries in throwing and overhead young athletes, often include core muscle strain which includes internal and external oblique, transverse abdominal and in relatively high rates rectus abdominis and the core muscle strain rein jury. The damage to the posterior elements of the spine occur due to the rotation, hyperextension, and flexion during repetitive activities such as swing the bat and hitting. The incidence of scoliosis in throwing and overhead young athletes with asymmetric load distribution on the trunk and shoulders is very common. The discs of these athletes are prone to injury due to axial loading, hyperextension / flexion and rotation during the preparation exercises and also due to biomechanics of throwing, swing and services. Throwing skills can affect the entire kinetic chain. Force production in each segment of the body increases the load on the adjacent segments and ultimately injuries occurred in the weaker segments and joints of the body. Accordingly, it is recommended in assessing thoracolumbar injuries and development treatment plans for throwing and overhead athletes, dynamic stability of pelvis, lower back and core be evaluated. Following thoracolumbar spine injuries, the athletes should be allowed to return to play after achieving the free pain range of motion, and stability of lumbopelvic-hip complex, and progress in the rehabilitation plane to special sport exercise phase.

The link between frequency content of gait ground reaction forces and hearing loss is not well understood. The objective of this study was to investigate the effects of hearing loss on gait ground reaction force frequency content. Thirty male children were equally divided into a healthy group and a group with hearing loss problems (Deaf group). Frequency content of ground reaction forces were analyzed during barefoot walking. Independent samples t-test was used for between group comparisons. The significance level was set at p<0.05 for all analyses. The results indicated that hearing loss was associated with increased anterior-posterior frequency band amplitude in right limb (by 53%; p=0.020) and number of anterior-posterior essential harmonics in left limb (by 37%; p=0.000). Similar vertical and medio-lateral frequency content were observed in both groups (p>0.05). The results reveal that gait ground reaction force frequency content in deaf children may have clinical values for rehabilitation of these subjects.

Stiffness is a characteristic of viscoelastic structures and is an effective factor in sports movement biomechanics, which is an important factor in motion production and neuromechanical control of human body. The purpose of this study is to determine the relationship between lower extremity stiffness and selected biomechanical variables during vertical jumps. 20 male physical education students participated voluntarily in this study. They performed Vertical hopping tests in three styles, bilateral, unilateral on dominant leg and unilateral on non-dominant leg, with three strategies, preferred, controlled (frequency 2.2 Hz) and maximal to determine the stiffness of the lower extremity. They also performed Squat jump and Countermovement jump tests to determine the mechanical power, take-off velocity and the efficiency of the stretch-shortening cycle. Among the stiffness variables with different strategies, only the preferential lower extremity stiffness showed a significant and negative correlation with the velocity of the center of mass (p< 0.05). Bases on the research findings, it can be argued that lower extremity stiffness is not mush effective in vertical jumps. It is not effective in stretch-shortening cycle either but there may probably be some optimal value for it.

Genu Varum deformity is known as a factor disrupting gravity line and force patterns in lower limb and may make the individual more exposed to lower extremity injuries especially in repeated activities like running. The aim of this study was to investigate Ground Reaction Forces in subjects with and without genu varum deformity during running. Thirty active men were divided into two groups of genu varum (15) and normal (15) based on their knee posture. Ground Reaction Forces in three directions of anterior – posterior and medial-lateral and vertical using force plate was recorded and analyzed. Data were analyzed utilizing MANOVA for between-group differences and paired samples t-test for within-group differences at a .05 level of significance. The findings indicated that there was a statistically significant difference in peak of propelling anterior-posterior direction (p=0/044) and peak of medial-lateral ground reaction force (p=0/048) in dominant between normal and Genu varum groups during running. But the vertical directions of ground reaction force were not significantly different between the two groups (p>0/05). In addition, regarding the dominant and non-dominant limb, no significant difference was observed in any of the directions (p>0.05). Although mechanical departure resulting from genu varum deformity, will occure in frontal plate, the results showed that this complication might affect ground reaction force in other motion planes. Therefore, it is suggested that when designing balance schedules and exercising activities for those suffering from genu varum deformity, all motion planes be considered.

Obesity is associated with numerous health problems such as dyslipidemia, hypertension, type II diabetes, cerebrovascular diseases, and coronary heart diseases. Gait as an effective factor in controlling obesity is very important in human motor development. Thus, the purpose of this study was to examine the effects of obesity and slimming on the gait kinematics in children. Thirty student boys with the age of 7-9, based on weight –age percentile and body mass index were divided to three normal, thin and overweight groups. All the children were healthy and had no physical abnormality. The 3D motion analysis was used for measuring gait parameters such as walking speed, stride length, stride width, single support phase duration, double support and swing phase duration. ANOVA was run for the purpose of data analysis. The findings indicated that there not significant differences between walking speed (0/056), stride length (0/164) and stride width (0/126) in normal, thin and obese children, but there were significant differences in swing phase (0/004), single support (0/001) and double support (0/008) phases duration, between normal, thin and obese children and that obesity can affect some of the spatiotemporal parameters in children’s gait which can cause changes in obese children’s gait patterns. The results of this study have shown that when the movement system is under pressure, some kinematics gait factors may change which can help better movement control.

The purpose of this study was to investigate the effect of Kinesio Taping method and corrective exercise on Genu Varum and knee kinematics in adolescent soccer players. The present study was a quasi-experimental study with pretest-posttest design. The sample consisted of 30 soccer players with mean age of 16.66 ± 2.32 years with genu varum. Participants took part in this study voluntarity and were randomly divided into three groups including: corrective exercise, tapping and control groups. Q-angle and knee deformity were measured by caliper and universal goniometer. Gait analysis was measured by two cameras with 50 fps. The distance between internal epicondyl and Q angle was measured before and after 8 weeks of taping. The results showed that in Kinesio Taping group there was significant decrease on distance of internal epicondyl (p=0.001) and a significant increase on Q angle (p<0.001), knee angle in mid stance (p=0.008), heel contact (p<0.001), and toe off (p<0.001). Also, in corrective exercise group there was a significant decrease on distance of internal epicondyl (p<0.001) and a significant increase on Q angle (p=0.003), knee angle in mid stance (p=0.003) and heel contact (p=0.045). The finding suggest that both corrective exercise and kinesio taping will significantly affect effect of distance of internal epicondyl and can increase the Q angle. Therefore, it can be concluded that taping and corrective exercises help increase the Q –angle in players who have Genu Varum.