| Summary: | 碩士 === 國立體育大學 === 運動保健學系碩士班 === 99 === Purpose: This study was to investigate the effects of dynamic and stretching on vertical jump SSC electromyographic(EMG) activity of the quadriceps. Methods: Sixteen healthy men(age22.37±2.12) took part in 3 conditions(static stretching[SS], dynamic stretching[DS], and no stretching[NS]) on separate days. During each condition, EMG of m. vastus medialis(VM) and lateralis(VL), rectus femoris(RF) were measured with ZEBRIS EMG system(1000Hz). The angle of knee joint using ZEBRIS ultrasound based three-dimensional motion analysis(100Hz) were recorded with three separated phase including eccentric, coupling, and concentric phase. The EMG values were averaged for three trials and analyzed with paired t-tests for pre- and poststretching(α= .05). Results: The EMG activity of RF, and VL were decreased 6.5%, 8.9% respectively in the eccentric phase. The EMG activity of VM, RF, VL were increased 14%, 16%, 26% respectively in the concentric phase of SS group. The EMG activity of VM was increased 12% in the eccentric phase and the EMG activity of RF, VL were increased 21%, 24% respectively in the concentric phase of DS group. The EMG activity of VM was decreased 8% in the eccentric phase of NS group. Conclusion: The results reveals that after static stretching have lower EMG activity in the eccentric phase, but after dynamic stretching, the EMG activity was increased. This imply that dynamic stretching may raise muscle spindle sensitivity and stretch reflex response to recruit more motor unit to promote vertical jump performance. Therefore, the results suggests that the warm-up by dynamic stretching will facilitate sports performance.
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