Objective: Considering the positions that the shooter chooses during shooting in different disciplines, it seems that the activity of deltoid and supraspinatus muscles which are common muscles during movement, varies in different disciplines. Therefore, the purpose of the present study was to evaluate and compare the electrical activity of deltoid and supraspinatus muscles between three shooting disciplines. Methods: 24 shooters (8 archers, 8 air pistol shooters, and 8 air rifle shooters) participated in the study. They performed shoulder abduction and scaption at 60 and 90 degrees. The electrical activity of deltoid and supraspinatus muscles was then recorded using surface electromyography. The data were analyzed by using ANOVA and Tukey’s test at the significance level of P<0.05. Results: The activity of anterior deltoid muscle at 60 and 90 degrees of abduction and the activity of middle deltoid and supraspinatus muscles only at 90 degree of abduction was significantly higher in the archery group than in the air pistol group (P<0.05). Conclusion: The higher electrical activity of deltoid and supraspinatus muscles in archery sport may be related to the tensile force of the bow and the greater arm angle at the shoulder joint during this type of shooting compared to air pistol and air rifle shooting.
Background and Aims: The morphology of knee joint extensor muscles including vastus medialis (VM) and vastus lateralis (VL), is one of the important and effective factors in lateral patellar compression syndrome (LPCS). This study aims to examine the morphological differences of these knee extensor muscles between women with and without LPCS. Methods: In this causal-comparative study, 15 women with LPCS aged 18-30 years and 15 women without LPCS as controls participated who were selected by a convenience sampling methhod. For muscle imaging, the anteromedial (VM) and anterolateral (VL) thigh distal ends were scanned by using a two-dimensional digital ultrasound device (SonoSite Co., USA). The muscles’ cross-sectional area at the patellar base was measured in square centimeters and the muscle-fiber pennation angles of these muscles was measured in degree. Independent t-test was used to compare the variables between the two groups. The significance level was set at 0.05. Results: The cross-sectional area of VM in the control group was significantly higher than in the LPCS group (P=0.001), while the cross sectional area of VL was not significantly different between the two groups (P>0.05). The muscle-fiber pennation angle of VM in the LPCS group was significantly lower than in the control group (P=0.016), while the muscle-fiber pennation angles of VL in the LPCS group was significantly higher than in the control group (P=0.021). Conclusion: The morphology of VM and VL in women with LPCS symptoms shows a significant muscle imbalance that can change the patella position from normal to a more lateral position and increase the contact between the lateral facet of the patella and the lateral femoral condyle, resulting in increased pressure on this area and eventually knee pain.Muscle morphology, Cross-sectional area, Muscle-fiber pennation angle, Lateral patellar compression syndrome, Knee extensors
Background and Aims Patellofemoral pain syndrome often results from misalignment of the patellofemoral joint that can affect lower limb function. Therefore, the present study investigated the relationship between patellar position and lower limb function and balance in athletes with patellofemoral pain syndrome. Methods In this exploratory analytical study, 39 male and female athletes with this syndrome with an average age of 25.6±4.7 years were selected by available sampling. Lower limb function and dynamic balance were measured by the Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) scale and Y balance test, respectively, and patellar position was assessed by digital radiology. The Pearson correlation test was used to analyze the data at a significance level of 0.05. Results The results showed that the position of the patella was significantly associated with lower limb function and dynamic balance (P<0.01). Accordingly, lower limb function on the WOMAC scale had a significant positive relationship with patellar tilt angle and patellar congruence angle (P=0.001). Also, dynamic balance showed a significant negative relationship with patellar tilt angle (P=0.007) and patellar congruence angle (P=0.002). Conclusion According to the results of the present study, the higher the tilt angle and patellar homogeneity, the weaker, the lower limb function and dynamic balance. Therefore, it is suggested that the position of the patella should always be considered and corrected to improve performance and balance and promote the record of sports activities of athletes with this disorder and facilitate their return to sports.
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