從不同頻率全身式垂直振動對運動員身體之響應

Resonance effect of athlete body part by applying varied whole-body vibration frequencies

目的：本研究就運動員在不同頻率垂直全身式振動下之身體響應加以探討，以了解振動訓練中適用之頻率。方法：共有55位運動員參與本研究，接受頻率為5，9，12，16，20，24和30Hz，振幅為4mm的垂直振動刺激，並透過10部鷹系列紅外線攝影機，取樣頻率為100Hz擷取各關節點的位置，計算出各關節點之運動學參數，以觀察身體各部位於各頻率下的傳遞比與振動強度；此外，以自我知覺努力程度量表來了解運動員之主觀知覺強度。結果：人體主要是透過膝關節與髖關節進行減振，以避免振動傳遞到上半身與頭部。但此彎曲膝關節的姿勢下，膝關節的共振頻率範圍可能在12到20Hz之間，因此無法以膝關節達成減振的效果。配合主觀知覺振動強度來看，振幅為4mm，頻率24Hz以上的振動刺激似乎強了一些，12Hz以下的振動刺激又顯得強度不足，而12到20Hz之間是人體的共振範圍，應予避免。結論：為避免振動刺激頻率在人體共振動範圍內，應考慮將振幅降低到2mm以下，頻率提高到20Hz以上，如此既可以避免危險，又能達到訓練效果。Whole body vibration exercise is more-and- more popularly used in training athlete's strength and power. However, inadequate researches have been documented in the relationship between applied frequencies and their body resonance responses. Purpose: To investigate the response of athlete's body during different frequencies of vertical whole-body vibration. Methods: this study used the Motion Analysis System and Borg 10 points scale to collect and calculate the transmissibility of different parts of body and intensity of vibration by subject's feel. Subjects included 55 athletes from weight-lifting, body building, Chinese Martial Arts, Wushu, Tai Chi, wrestling and Judo team. Results: we found that the knee and hip joint were used to damp the vibration and avoid the vibration to transmit to the upper body and head. There is a resonance of knee in 12 to 20Hz when subject kept the position that bent the knee and stood on the vibration platform. Therefore, subjects can't use the knee joint to damp the vibration. The vibration with 4mm amplitude and above 24Hz may be too strong for the subjects, below 12Hz was too weak to train. Concluded: The whole body vibration need to reduce the amplitude below 2mm and elevate the frequency above 20Hz to void the danger of resonance and to have training effect.