Every Taekwondo basic movement should use reaction force. Reaction force is the action of using both sides of your body to work together thus maximizing your power. Next time you deliver a one handed technique don’t think about your weapon hand, think about pulling your spare fist back to your hip at the same rate as your delivery hand goes forward. The faster you simultaneously pull and deliver the more powerful your technique will be.
Remember: You must relax your body and breathe with your abdomen whilst delivering any powerful techniques. If there is any tension in your body, in particular your chest and shoulders, you may cause muscle damage. Remember that you should breathe out every single time you move in Taekwondo, this relaxes your body and maximises power.