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Background and aim: Spinal injury especially during occupational lifting is one of the most common neuromuscular disorders in the general population of the world. Asymmetric motions of trunk frequent bending and twisting, lifting and forceful activities contribute to spine disorders. Sport as a comprehensive activity might be able to cause less force to the spine and decrease spinal injuries. The purpose of present study was to determine the effect of lifting on motor control pattern during combined symmetric and asymmetric trunk motions on athlete and non-athlete subjects.
Materials and Methods: Seventeen non-athlete female subjects and seventeen athlete female subjects performed to lift four loads ( 5,7,9 ,12 kilogram ) at symmetric and asymmetric conditions. Under each condition temporal parameters of motor control were measured on flexor and extensor of trunk muscles.
Result: In two groups of athletes and non-athletes with increasing load , muscles begin their activity faster ( P<0.05 ). No significant change was found at asymmetric condition. Also, in athletes premotor time of muscles during lifting was less than non-athletes.
Conclusion: With increasing load, according to the feed forward control mechanism and awareness of subjects from amount of loads, muscles quickly prepared to contract for starting the movement. It seems that the response of movement on the neuromotor system of athletes is preprogrammed and automatic due to sport experience. Actually muscles have anticipation activity.

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Background and Aim: Leg stiffness has recognized as a parameter related to sports performance and injury risk. The aim of the present study was to compare of leg stiffness during hopping test between female and male athletes.

 

Materials and Methods: Thirteen females and 12 males of the best Iranian racket-players participated in this study and<span style="font-family:;" dir="RTL" new="" b="" fa;="" mitra";="" roman";="" "times="" roman";"="" 12pt;=""> performed the bilateral hopping test at a frequency of 2.2 Hz. The subjects' leg stiffness was measured and was normalized through dividing by their body weights. Independent samples t-test was used to compare the mean of research variables between the female and male groups.

 

Results: Leg stiffness in the females was significantly lower than the males (p< 0.001), however the body mass-normalized leg stiffness was not significantly different between two groups (p = 0.290).

 

Conclusion: The lower leg stiffness observed in the female athletes may be a factor justifying their weakness in speed-based performances during horizontal movements. Furthermore, non-significant difference in normalized leg stiffness between two groups may indicate using a risky strategy by the females in vertical movement to compensate for the less inherent stiffness of their tendinous and muscular structures. Choosing the proper training programs to change the leg stiffness, may be an effective method to enhance the performance and to decrease the injury risk.

 

Keywords: Leg stiffness, Female and male athletes, Sports performance, Injury risk