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Background and Objective: Patellofemoral is a pain syndrome, common among athletes and the theraputic regiment based on the improvement of muscle involved in this disorder. This study was done to compare electromyography activity of the vastus medialis obliques and vastus lateralis longus during squat with isometric hip adduction in athletes with patellofemoral pain syndrome and healthy athletes.

Materials and Methods: This case – control study was carried out on 16 national team male athletes (volleyball, handball and taekwondo) aged 30-18 years with patellofemoral pain syndrome and 16 healthy male athletes. Subjects were matched based on weight, height, age, dominant of lower extremity and voluntarily participated. Electromyography activity of vastus medialis obliques and vastus lateralis longus muscles recorded by surface electrodes at 15, 30 and 45 knee flexion degrees. Paired t test was used to compare electromyography activities in each group and One-way ANOVA and Tukey post hoc test was used to compare each muscle in different angles.

Results: There was significant differences in the activity of vastus medialis obliques and vastus lateralis longus muscles in athletes with patellofemoral pain syndrome at 45 knee flexion degree (P<0.05). There were no significant differences between the muscle activities in healthy athletes at none of the knee flexion degrees. There were significant differences in the activity of vastus medialis obliques (P<0.05) and vastus lateralis longus (P<0.05) muscles at 45 degrees in comparison with muscle activities in each group in knee flexion degrees.

Conclusion: Electromyography activity of the vastus medialis obliques in healthy athletes during squat with isometric hip adduction at 45 knee flextion is greater than other degrees and in athletes with patellofemoral pain syndrome is greater than healthy athletes.

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Background and Objective: By increasing the number of athletes, sports-related injuries are increased and of those lower extremities injuries are more common. This study was done to evaluate the relation of sole arch index and static balance in female athletes with lower-extremity injury. Methods: This case – control study, was done on 18 female athletes without a history of lower extremity injury which were considered as controls and 18 female athletes with a history of lower extremity injury in past two years which were considered as cases. Static balance and sole arch index were evaluated using stork stand and Chippaux-Smirak index tests. Results: Static balance with open eyes was 16.10 seconds and 26.53 seconds in cases and controls (P<0.05), whereas, there was no significant difference in static balance with closed eyes and sole arch index between cases and controls. Conclusion: Poor static balance with neuromuscular control deficit can consider as lower extremity injury in female athletes.

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Background and Objective: Athletes suffer from poor physical fitness in some sports fields, which can cause long-term pain in their hands. This study was carried out to compare the musculoskeletal abnormalities in professional wushu athletes and wrestlers with non-athletes.
Methods: This descriptive-analytical study was carried out on 30 wrestlers, 30 Wushu athletes and 30 non-athlete subjects in Mazandaran province, north of Iran. Kyphosis and lordosis angles evaluation was performed by using flexible ruler. Evaluation of forward head and forward shoulders perform from side view with digital cameras and angles analyzed by AutoCAD 2010 software.
Results: The forward head in wushu athletes and wrestlers was significantly more than non-athletes (P<0.05). Also, forward shoulder in wrestlers and wushu athletes was significantly higher than non-athletes (P<0.05). In addition, kyphosis angle in wushu athletes and wrestlers were significantly higher than non-athletes. Also, Lordosis in wrestlers was higher than non-athletes (P<0.05). Uneven shoulder in wushu athletes was more than non-athletes (P<0.05).
Conclusion: This study showed that head, shoulder and spine status can be influenced by type of sport.

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Background and Objective: Creatine is one of the most important and commonly used supplements athletes, although the molecular mechanisms of creatine and its side effects are less understood. The high level of the ceratin kinase enzyme and lactate dehydrogenase enzymes are considered to be a sign of cell damage. This study was done to determine the effect of creatine monohydrate supplementation on creatine kinase (CK) and lactate dehydrogenase (LDH) enzymes following a severe muscle contraction in female athletes.
Methods: In this double-blind clinical trial study, 30 female athletes were randomly divided into intervention (creatine supplementation 0.3 grams per body weight for 4 times duing 7 days and control (placebo, starch powder) groups. Blood sample was collected before supplementation (pre-test) and 24 hours after Cunningham exercise test (post-test) to measuring CK and LDH in each subject.
Results: After intervention, the level of CK (323±63 IU/L) and LDH (119±13 IU/L) in intervention group had no significant difference in compared to control group (CK: 328±44 IU/L and LDH: 122±14 IU/L).
Conclusion: The usage of a 7-day course of creatine supplement did not significantly change the CK and LDH levels following a severe muscle contraction in female athletes.

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Background and Objective: Vitamin D increases muscle strength through protein synthesis and myogenesis and may play an important role in anaerobic and aerobic activities. This study was done to determine the vitamin D status and its relationship with physical function indexes in young Taekwondo athletes.
Methods: This descriptive-analytical study was conducted on 75 young male Taekwondo athletes, aged 18-23 years that were selected using randomized sampling method. Serum 25-hydroxyvitamin D level was measured by ELISA method. The 20-meter shuttle run, running based anaerobic sprint (RAST), vertical jump, 36-meter sprint and Illinois agility tests were used to determine aerobic and anaerobic capacities, explosive anaerobic power of the lower limbs, speed and agility, respectively. Body mass index and percent body fat was measured for each subject. Level below 20, 20-30 and more than 30 ng/ml of serum 25-hydroxyvitamin D were considered as vitamin D deficiency, insufficiency and normal status, respectively.
Results: The results showed that 48% (36 athletes) and 42.66% (32 athletes) of taekwondo athletes had deficient and insufficiency levels of vitamin D, respectively. Also, a significant correlation was detected between serum 25-hydroxyvitamin D concentration and aerobic power (r=0.897), anaerobic power (r=0.901), vertical jump performance (r=0.855), fatigue index (r=-0.838), agility (r=-0.634) and 36 meters sprint (r=-0.793) times (P<0.05). However, this association was significant in athletes with lower than normal levels of vitamin D (P<0.05), no association was found in subjects with normal vitamin D levels.
Conclusion: Vitamin D of 90.66% of young taekwondo practitioners was lower than normal level. Increasing in vitamin D level can improve the physical performance of young athletes with vitamin D deficiency or insufficiency status.

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Background and Objective: Nutritional knowledge can affect food choices and, as a result, sports performance. The study of nutritional knowledge, attitude, and performance in athletes can play a fundamental role in choosing the type of training and adapting suitable dietary interventions. This study was done to evaluate the knowledge, attitude, and nutritional performance of male bodybuilding athletes in Gorgan, Iran.
Methods: This descriptive-analytical study was done on 104 male bodybuilding athletes over 18 years old with a history of at least three months of continuous bodybuilding who were randomly selected from 13 bodybuilding clubs in Gorgan, Iran during 2020. Parmenter and Wardle’s standard questionnaire measured athletes’ nutritional knowledge, attitude, and performance. The questionnaire was completed by the athletes with the guidance of the researcher. A trained nutritionist collected anthropometric and body composition data using an Omron BF511 device.
Results: Poor nutritional knowledge, poor dietary attitude and poor nutritional performance was observed in 67.3%, 33.65% and 77.88% of the athletes respectively. A significant correlation was observed between nutritional knowledge with weight (r=0.23, P=0.02), BMI (r=0.27, P=0.01), and body fat percentage (r=0.22, P=0.02). Also A significant correlation was determined between nutritional performance with body weight (r=0.31, P<0.001), BMI (r=0.27, P<0.001), exercise time per week (r=0.22, P=0.02), and exercise timespan (r=0.32, P<0.001).
Conclusion: The level of knowledge, attitude, and nutritional performance of bodybuilding athletes was weak.

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Background and Objective: Ankle instability is one of the most prevalent injuries among athletes. Biomechanical changes, sensory-motor impairments, and neuromuscular disorders have been reported in individuals with chronic ankle instability. The present study was conducted to compare the electrical activity of selected leg and thigh muscles during performing functional movements in female athletes with and without chronic ankle instability.
Methods: This case-control research was conducted on 40 female athletes in the age range of 18-30 years in two groups, including the case (with ankle instability, n=20) and healthy control (without ankle instability, n=20) groups. The electrical activity of selected leg and thigh muscles was recorded during three functional patterns, i.e., the overhead squat, overhead squat with heel lift, and single-legged squat, by electromyography apparatus. The investigated muscles consisted of the gastrocnemius medialis (GM) muscle, the gastrocnemius lateralis (GL) muscle, the tibialis anterior (TA) muscle, the fibularis longus (FL) muscle, the soleus (SO) muscle, the vastus lateralis (VL) muscle, the vastus mediali (VM) muscle, and the biceps femoris (BF) muscle.
Results: The activity of the VM, VL, BF, and TA muscles in the single-legged squat and the activity of the VM, VL, BF, SO, and TA muscles in the overhead squat showed a statistically significant increase in the case group compared to the control group (P<0.05). The highest difference in the muscle activity of the two groups was observed in the overhead squat with heel lift movement, which in this movement, except for the GL muscle, there was a statistically significant increase among all other muscles (P<0.05).
Conclusion: Functional movements culminate in increasing the electrical activity level of leg and thigh muscles in female athletes with ankle instability.