本研究目的在運用表面肌電儀(electromyography, EMG)與自製足底感應器(footswitch)等儀器，針對正常無膝關節傷害之運動員，進行不同籃球動作測試：包括雙腳墊步急停(sudden stop, SS)、跳投(jump shot, JS)、單軸搖擺動作(twist, TW)、交叉步伐(cross over, CO)，以瞭解各動作之膝伸肌與膝屈肌，在離地前與著地瞬間之肌電活化動態徵召模式。研究對象以16位平均年齡18.3±2.78歲、身高184.5±5.35公分、體重74.2±6.43公斤之參與國內高中籃球聯賽之松山高中籃球代表隊球員，且經過四年以上籃球專業訓練，同時在過去半年，無下肢及膝關節前十字韌帶(anterior cruciate ligament, ACL)傷害參與本研究。在本實驗中以三個頻道作為肌電變化情形之訊號收集，其中二個頻道分別收集膝屈肌與膝伸肌肌電訊號，另一頻道運用本實驗自製的足底感應器，作為訊號起始之擷取方法，同時取樣頻率以1000Hz作為資料收集之依據。資料處理以單因子變異數分析與薛費氏事後多重比較法，分別探討不同動作之膝屈肌與膝伸肌，在離地前250ms與著地瞬間250ms之動態徵召模式。本研究結果發現：（一）隨不同籃球情境之需求，將透過不同騰空時間與跳躍高度，呈現出不同離地起跳與著地機制；（二）其次在離地前與著地瞬間之膝屈肌與膝伸肌中，以SS、JS動作，呈現較佳之肌電活化特性；（三）所有動作，在著地瞬間之膝屈肌肌電活化表現上，較膝伸肌明顯；且顯著優於在離地前之肌電活化特性。其本研究結果顯示經過不同動作測試後，SS與JS呈現出較佳之肌電活化機制，為神經肌肉控制系統的保護機制，並扮演著穩定膝關節重要的角色。

This study investigated the probe of knee muscles firing in different basketball movements (such as the sudden stop (SS), the jump shot (JS), the twist and cross-over). The electromyography (EMG) and foot-switch were used to measure the knee flexor and extensor muscle fining during the pre-landing and landing phases. Sixteen senior high school basketball team players voluntarily participated in this study (mean age: 18.3± 2.78 years, mean height: 184.5±5.35cm, and mean weight: 74.2±6.43kg). All subjects had six months before of knee ACL injury and had four years of basketball team experiences in high school. Three channels of electronic signals were measured in this study. Two channels of EMG were used to measure the knee flexor and the extensor. Another channel of foot-switch sensory was used to measure the foot-to-ground contact. All signals were simultaneously collected with a sampling of 1000Hz. The one-way ANOVA was used to examine the different movements in knee flexor, the extensor muscle firing during the pre-landing and landing phases. Scheffe's multiple comparisons were used to examine the differences between each test group. The results are as follows: First, with the different basketball situations, the flight time is different with the high jump; takeoff and landing show the difference from the mechanism. Second, in the pre-landing & landing phases, the sudden stops and the jump shots have more muscle firing activities in knee flexor & extensor of all movements. Third, in the pre-landing and landing phases, movements among activities fired from the knee extensor muscle are more active than from the knee flexor, especially at the landing phase. It was concluded that the SS and JS movements had more muscle firing activities which will be an important mechanism for the protection of the neuromuscular control system and play an important role in the stability of the knees.