棒球投手模擬比賽之下肢肌電分析
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2011
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Abstract
目的:棒球投手重複性投球動作及投球球數逐漸增加後,對於下肢肌群從跨步期階段到手臂加速期階段之肌肉活化程度及疲勞情形。方法: 12名健康高中棒球投手(16.3±0.9歲、177.8±5.68公分、71.3±8.3公斤),各投100顆球(分5局,每局投20顆),以Noraxon無線肌電儀器(擷取頻率1500Hz)收取投手下肢肌群(股直肌、股內側肌、股外側肌、脛前肌、臀大肌、肌二頭肌、外腓腸肌)前(第1顆至第10顆)、中(第46顆至第55顆)、後(第91顆至第100顆)三個區段平均肌電振幅與中位頻率平均值,並同步利用高速攝影機(擷取頻率300Hz)取得投手投球過程中下肢動作運動學參數作為參考數據。以重複量數單因子變異數分析(One-way ANOVA with repeated measures)進行統計分析。統計顯著水準定為α=.05。結果:投手下肢肌群從跨步期到手臂加速期階段於前中後三個區段出現明顯活化程度,其中以手臂加速期前導腳肌群活化程度最為明顯;同時前導腳外腓腸肌中位頻率值在前(100.4Hz)、中(94.80 Hz)、後(90.65 Hz)三個區段隨投球數增加而降低。結論:投手經過持續且重覆投球動作後,前導腳外腓腸肌會有疲勞現象。
Purpose: To evaluate the muscle activation and fatigue conditions of the lower limbs from stride phase to arm acceleration phase after repeatedly pitching. Methods: The study recruited 12 healthy high school baseball pitchers (16.3 ± 0.9 years, 177.8 ± 5.68 cm, 71.3 ± 8.3 kg), were asked to pitch 100 balls (five set, 20 per innings pitched). The Noraxon wireless EMG devices (acquisition frequency 1500Hz) combined with high speed camera (capture frequency 300Hz) were used to captures and record the muscle activation and movement during pitching. The average of EMG amplitude and median frequency during the first (1-10 ), medium (46-55), and lest 10 balls pitching were calculated. The kinematic of lower limbs during pitching were also founded. One-way ANOVA with repeated measures was used to statistics. The significant level was set as α=.05. Results: The muscles of lower limbs were activated from the stride period to the arm acceleration phase, especially the muscle activation of the leading foot in the arm accelerated phase. The median frequency of the gastrocnemius were decreased while the number of pitching were increased (first:100.4Hz, medium:94.80 Hz, lest:90.65 Hz). Conclusions: After 100 pitches, the muscle fatigue was noted in the gastrocnemius in this study.
Purpose: To evaluate the muscle activation and fatigue conditions of the lower limbs from stride phase to arm acceleration phase after repeatedly pitching. Methods: The study recruited 12 healthy high school baseball pitchers (16.3 ± 0.9 years, 177.8 ± 5.68 cm, 71.3 ± 8.3 kg), were asked to pitch 100 balls (five set, 20 per innings pitched). The Noraxon wireless EMG devices (acquisition frequency 1500Hz) combined with high speed camera (capture frequency 300Hz) were used to captures and record the muscle activation and movement during pitching. The average of EMG amplitude and median frequency during the first (1-10 ), medium (46-55), and lest 10 balls pitching were calculated. The kinematic of lower limbs during pitching were also founded. One-way ANOVA with repeated measures was used to statistics. The significant level was set as α=.05. Results: The muscles of lower limbs were activated from the stride period to the arm acceleration phase, especially the muscle activation of the leading foot in the arm accelerated phase. The median frequency of the gastrocnemius were decreased while the number of pitching were increased (first:100.4Hz, medium:94.80 Hz, lest:90.65 Hz). Conclusions: After 100 pitches, the muscle fatigue was noted in the gastrocnemius in this study.
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棒球投手, 下肢肌群, 肌肉活化程度, 疲勞, baseball pitchers, lower limbs, muscle activation, fatigue