Research in Sport Medicine and Technology

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Background: In sports such as handball, tennis and volleyball the player need to involve the great loads over his shoulders. In these sports, players are predisposed to overuse injuries. Infraspinatus syndrome’s meaning is the painless weakness and atrophy of this muscle that observe following Suprascapularis nerve neuropathy. In this investigation we want to survey the effects of a short term of progressive endurance-strengthening training and electrical stimulation on strength and electromyography in infraspinatus muscle. Method: 12 volleyball players with Infraspinatus syndrome were randomly divided to two groups: progressive endurance-strengthening training (6 persons, age 24/8±3/8, height 189/3±2/6, weight 83/8±7/9, sport background 9/4±2/5 and national team’s background 3/24±1/7) and electrical stimulation (6 persons, age 24/2±4/5, height 192/5±1/5, weight 86/2±6/4, sport background 8/5±4 and national team’s background 4/3±2/8). 20 persons of healthy players were considered to be as a control group (age 25/1±4/2, height 187/7±3/9, weight 75/6±7/1, sport history 9±3/8 and national team history 3/9±2/3), too. Therapeutic interventions performed for 8 weeks. Surface electromyography of infraspinatus and tress minor muscles and maximal isometric strength of external rotator muscles were measured before and after interventions. Data analyzing performed by SPSS.12 and we used of Paired sample T test and one-way ANOVA. Confidence level considered to be 95% (P<0.05). Results: After eight weeks, maximal isometric strength of external rotators in both experimental groups was increased significantly, but there were observed no significant changes in IEMG and RMSEMG. Conclusion: Progressive endurance-strengthening training and electrical stimulation can result in increase of maximal isometric strength of shoulder external rotator muscles. But both therapeutic methods have no effect onelectromyograghic parameters in infraspinatus and tress minor muscles. It seems that we can't use of surface electromyography for detecting the effect of these protocols on above muscles (P<0/05).

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The aim of the study was to compare the electrical activity pattern of major muscles involved in handball
triple shooting in two groups of adolescents and adults. Ten adolescent elite handball players playing in
national club league (16.4 ± 0.69) and 10 adult handball players (23.55± 2.69) participated in this research.
They performed triple shooting و assuming in a match situation and electrical activity of the Biceps brachii,
Triceps brachii, pectorialis major muscles and three anterior, middle and posterior parts of deltoid was
recorded using surface electromyography. Parameters related to the muscular activity pattern, including
time, peak, action amplitude and contraction sequences were obtained. The results of t-student statistical
test for two independent groups (p≤ 0.05) shown that there were no significant difference between time,
peak and electrical activity amplitude variables between groups. It seems the factors such as experience in
adolescent athletes, better utilization of muscle and being close to the end of puberty makes no difference
between adolescents and adults.

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The purpose of this study was to investigate the effect of different hip joint postures on electromyographic activity of selected lower limb muscles during squat's movement. Electromyographic activity of selected lower limb muscles of 15 healthy male students was recorded while performing a squat with neutral, 15°, 30°, 45° external and internal rotation of the hip. Friedman's nonparametric test was used to compare muscle activation at different angles of the hip rotation and the Wilcoxon test was used to determine within-group differences. The results of this study showed no significant difference in the activity of Vastus medialis (p = 0.052), Vastus lateralis (p = 0.102) and tensor fasciae lata (p = 0.193) in squat between different hip joint angles, but Significant differences were observed in gluteus medius muscle activation (p = 0.001) and biceps femoris (p = 0.015) in squat between different hip joint angles. Also, the results of this study showed that gluteus medius to tensor fascia lata activation ratio was significant in squat between different hip joint angles. squat with the external hip angles can be considered as an effective method to increase gluteus medius activation and gluteus medius to the tensor fasciae latae activation ratio. On the other hand, 45 ° external and 30 ° internal hip angles can be considered as an effective method to increase the biceps femoris activation.