نشریه مطالعات طب ورزشی
پیاپی 28 (پاییز و زمستان 1399)

The purpose of this study was to investigate the effect of shoe type on muscles electromyography while descending stairs. The population of this study was 15 students aged 20 to 30 years. Co-contraction and peak muscle activity were recorded. The repeated measure ANOVA test was used.  The results showed that in both pre-activity and eccentric phases, the peak activity of tibialis anterior, internal and external gastrocnemius and soleus muscles significantly increased in the barefoot position compared to normal shoes. The co-contraction of the peronaeus brevis and gastrocnemius medialis muscles in the pre-activity phase had a significant difference between normal and minimalist shoes. In the eccentric phase, there was a significant difference between the co-contraction of the tibialis anterior and peronaeus longus muscles in barefoot and normal shoe states. It seems that the increased co-contraction of agonists and antagonists in barefoot and minimalist shoes compared to normal shoes may be an effective factor in maintaining joint stability.

The gastrocnemius muscle is one of the main muscles of the knee joint but its neuromuscular adaptations after ACL injury are poorly. The purpose of this study was to compare medial and lateral gastrocnemius preparatory and reactive activity patterns in the athletes with and without a history of ACL rupture. 15 ACL deficient, 15 ACL reconstructed and 15 control subjects participated in this cross-sectional study. ACL injured groups (ACLD and ACLR) had significantly lower lateral gastrocnemius muscle activity in the reactive phase compared to the control group. The gastrocnemius muscle is an antagonist of ACL and thus it seems that lower lateral gastrocnemius activity in ACL injured groups is a compensatory mechanism to decrease strain on ACL. .

Most of sport injuries occur during fatigue. The aim of the present study was to evaluate the effect ofMost sports injuries occur during fatigue. The aim of the present study was to evaluate the effect of fatigue protocol on lower limb muscular activities in individuals with genu varus during running with agility shoes. In this study, 14 individuals with genu varus and 15 healthy control ones aged 20-30 years volunteered to participate. Muscle activities were recorded using a Biometric system. Findings demonstrated greater gluteus medius activity in the healthy group compared to the genu varus group. The main effect of fatigue on tibialis anterior activity during the loading phase and mid-stance phase was significant. Overall, because of different tibialis anterior and semitendinosus performance in the genu varus group compared with the healthy group during running before and after fatigue protocol, rehabilitation of these muscles is essential in genu varus individuals.

The purpose of the current study was to determine allometric equations for leg stiffness, the main parameter of elastic behavior of human body. 30 young healthy men participated voluntarily in this study and performed vertical hopping test on a force plate and in front of a high-speed camera. Leg stiffness was calculated by a MATLAB program. The relationships between leg stiffness and individual characteristics such as body mass, height, BMI and age were determined by Pearson correlation test and the allometric equations were formed by regression analysis. Positive significant correlations were observed between leg stiffness of controlled hopping test and subjects body mass. Allometric scaling equations were Kbilateral=190M1.1 for bilateral leg stiffness, Kdominant=501M0.84 for dominant leg stiffness and Knondominant=549M0.82 for non-dominant leg stiffness. These equations can be the base of correct normalizing of human body elastic behavior and allow to leg stiffness estimation by body mass.

Performing dual task may impair balance and gait in cerebral palsy (CP). But the effect of dual task on the electromyographic activity of CP patients has not been well studied yet. The aim of this study was to investigate the electromyography (EMG) activity of the lower limbs and erector spinae muscles in CP patients and healthy controls during walking with and without a cognitive dual task. To do so, the EMG activity of biceps femoris (BF), rectus femoris (RF) and erector spinae at L3 level (L3) muscles of 10 CP patients and 10 healthy controls were recorded using an EMG USB2+ system and bipolar electrodes during walking with and without the cognitive task. Data were statistically analyzed using SPSS 22 and ANOVA for repeated measures with a significance level of 0.05. Results showed that during walking with the cognitive dual task, the EMG activity of the left L3, BF and RF muscles and right L3 and BF muscles was significantly higher than that of the normal subjects. The pattern of normalized EMG activity of L3, BF and RF muscles of CP patients and healthy control subjects differed during gait with and without the cognitive dual task, and there was a significant interaction between the group, muscle and task factors. Based on our results, cognitive dual task increases EMG activity of CP patients more than healthy subjects. This increase can be attributed to the effort of CP patients to [1]maintain posture and dynamic balance. Thus, it is recommended to pay attention to the cognitive dual task when evaluating and designing exercise programs for CP people with cerebral palsy.

The aim of this study was to investigate the effect of eight weeks of DNS training on dynamic and static balance, fall prevention and lower limb strength in healthy elderly women. This is a quasi-experimental research with pre-post-test. Thirty healthy elderly women (60-79 years old) selected purposefully and divided into two groups of exercise (DNS) and control randomly. Static balance were assessed by the Berg and Sharpendromberg balance test, dynamic balance by the Timed Up and Go test, prediction of fall risk by the Shumway-Cook model, and lower extremity strength by the Chair Stand test. Paired t-test and independent t-test were used to analyze the data. The training group showed a significant difference between pre and post-test and also compared to control group in all factors. According to the present findings, the effect of DNS in improving research variables is confirmed and its use in elderly care programs is recommended.

The aim of the present study was to compare sensory and motor function in female runners with and without Medial Tibial Stress Syndrome (MTSS). The present study was descriptive and comparative. Fifty female endurance runners with an age range of 20 to 30 years were divided in two groups MTSS and without injuries. Yates criterion was used to diagnose the injured group and to assess sensory function and motor function we used ankle and knee joint position sense and Functional Movement Screening(FMS) test respectively. The results showed significant difference between the two groups in the subscales and the overall score of the FMS test as well as knee and ankle joint position sense (P <0.05) and individuals in the group with MTSS had more deviation in the reproduction of the target angle. Therefore, it is recommended that endurance runners with MTSS pay attention to their weaknesses in their exercise program.

Frozen shoulder syndrome is one of the most common causes of shoulder pain and disability, which can be associated with poor posture and limited mobility of the shoulder girdle. The study compared upper body posture and shoulder range of motion in women with frozen and healthy shoulders. This study was conducted on 30 women with frozen shoulders and 30 healthy women in Ilam. In the present study, the head and shoulder angle was measured using imaging, the range of motion flexion, abduction and external rotation of the shoulder was measured through the goniometer and curvature of the thoracic kyphosis and a flexible ruler was used to evaluate the results of independent t-test at a significant level 0.05. The results showed a significant difference between head and shoulder angle in front, kyphosis, range of motion flexion, abduction and external rotation in patients with frozen and healthy shoulders. Findings indicated that people with frozen shoulders were more likely than healthy individuals to have anterior shoulder angle (P = 0.001), anterior head (P = 0.044) and kyphosis (P = 0.016). External Rotation Range of motion, flexion, abduction had less shoulder (P = 0.001). Therefore, it is suggested that in order to improve the range of motion of the shoulder in people with frozen shoulder, the posture of the upper body should be examined and a correction program should be considered to correct the anomaly of these people.

Multiple sclerosis (MS) is a progressive disease associated with the destruction of the myelin sheath of the central nervous system. The most common problems in these patients are muscle fatigue and balance disorders. Therefore, the aim of this study was to investigate the effect of 12-week yoga practice on fatigue and balance in male and female patients with MS. In this study, 22 men and women with MS, members of the Fars MS Association, were randomly divided into equally experimental (yoga exercises) and control groups. Muscle fatigue was measured by electromyography and balance index was measured by leaf balance test before and after yoga exercises. Data were analyzed using independent and paired t-tests. The results showed that after 12-week yoga practice, it had a significant effect on the amount of electromyography signal from muscle fatigue. Moreover, the results related to balance indicated an improvement in balance indices after 12 weeks of balance exercises in the experimental group compared to the control group. According to the results, this exercise method can be used to improve muscle fatigue and balance in these patients.

The trunk and its muscles play an important role in maintaining walking mechanics. Fatigue and weakness of these muscles could affect walking mechanics adversely. The trajectory of the center of pressure (COP) reflects whole body mechanics. The aim of this study was to investigate the effect of trunk muscles fatigue on the trajectory of the COP during walking. Totally, 20 female academic students participated in this study. Participants were asked to walk on the walkway before and after trunk muscles fatigue with self-selected speed. In the midway of the walkway, a footscan pressure mat was mounted. The COP trajectory, relative timing of stance phases and foot progression angle were recorded using footscan in pre- and post-fatigue conditions. After fatigue, the relative time of the initial contact phase increased and the relative time of forefoot contact phase decreased. Trunk muscle fatigue lateralized the COP trajectory in the Forefoot Flat Phase and Forefoot Push-off Phase and decreased foot progression angle. According to the results of the current study, it can be concluded that fatigue and weakness of trunk muscles lead to changes in walking mechanics. These changes could expose people to the risk of injury.

The aim of this study was to investigate the effect of lumbopelvic control (LPC) weakness on the symmetry of foot pressure distribution, vertical ground reaction force (GRF) and postural sways of athletes with frequent landings. In this case-control study, 34 professional players participated. LPC was assessed by Knee Lift Abdominal, Bent Knee Fall Out, Active Straight Leg Raising, and PRONE tests by Pressure Biofeedback Unit. Based on the results, participants were divided into two groups: appropriate LPC (n=17) and poor LPC (n=17). Foot pressure data were collected using PT-scan. The results showed that there was a significant difference between the mean scores of the foot pressure distribution symmetry, depth force, second peak force, area of sways, anterior-posterior and medial-lateral sways. Thus, poor LPC affects the symmetry of the foot pressure, GRF, and the postural sways of athletes with frequent landings, so can be a risk factor for lower limb injuries.

The purpose of this study was to determine biomechanical profile of wrestling holds based on fuzzy logic algorithm of 57 elite freestyle wrestlers in the city of Joybar . Dynamic posture stability index, time to stability, linear momentum, upper limbs mechanical power were determined as biomechanical variables for the analysis of wrestling holds. Findings were: (1) By designing new tests for analysis of holds such as rear throw, crotch lift, bridge, double leg pickup, flying mare, over under, and three types of stances was prepared the skill fitness profile of elite wrestlers into six weight classes; (2) fuzzy logic algorithm and principal component analysis could be used to score to the skill fitness of each wrestler . Generally, the results emphasize the necessity for the analysis of wrestling holds using the standard tests and design of scoring algorithm to compare the skill fitness of wrestlers in each weight class.