"In aikido, extending ki means extending energy. However, it does not mean to simply push with physical force. Rather it is a state of mind used to align the body to permit movement in a unified and calmly concentrated fashion...
This feeling of dynamic energy extension is used in all aikido techniques. Without it, throws quickly become exercises in muscular tension, largely dependent on mere mechanical advantage and bulk."
Koichi Tohei (1920-2011) 10th dan