The length refers to the length of the arm; because the throwing motion is rotational from the shoulder out, the atlatl simply lengthens the arm to increase the throwing speed and force. 长度是指胳膊长度，因为抛扔运动是以肩膀关节为中心的旋转运动，这样一来，飞镖投掷器只不过是手臂的延长，因此，增加了投掷的速度和力量。