These nerves control muscular action, i.e. movement. Once the brain has determined what action is required, the motor nerves direct the muscles to contract and take action.
What Triggers a Reaction
While sparring, a fighter's reactions are usually triggered by what the fighter sees. Two major pathways lead from our eyes to our brains. The slower parvocellular (p) pathway carries complex information, such as colors, contrast, as brightness. The faster magnocellular (m) pathway transmits information about motion and triggers fast reactions. Therefore, if you can avoid triggering the m-pathway you may be able to strike before the opponent can react. By doing this, you may add about one-tenth of a second to the opponent's reaction time, which may mean the difference between a blocked attack and a point. To avoid triggering the opponent's m-pathway, an attacker should avoid any extraneous movement that signals an attack. A fist whose only movement is directly at the opponent's face provides little clues to its movement. To the opponent, the fist appears to be getting larger as it gets closer but this subtle change may not trigger the m-pathway. Whereas, if the fist makes any lateral movement, the m-pathway is sure to be triggered.
There is a time gap between detection, stimulus, and muscle contraction. This delay is called reaction time. Reaction time depends on the type of reflex action being used. There are three types of reflex action: unconditioned, conditioned, and trained.
- Unconditioned. These are instinctive natural reflexes, such as blinking when there is movement toward eyes or jerking back from a hot surface. This type of reflex has the shortest reaction time since the brain does not process it; however, it is the least useful to a Taekwondo student. Taekwondo students must train to resist some of these reflexes, such as blinking when a punch is approaching.
- Conditioned. These are reflexes that may be learned. An example of this is the classic experiment where Dr. Pavlov rang a bell when he fed his dogs. Over time, the dogs became so conditioned that they began to salivate anytime they heard a bell, even when food was not present. This type of reflex has the second fastest reaction time since the brain does not have to process sensory input; it is conditioned to respond directly to the input without conscious thought. Conditioned reflexes may also be learned unconsciously, so they are open to deception, therefore, they are not too useful to a Taekwondo student. An opponent may condition you to react to a feint, so you must train to resist this type of conditioning.
- Trained. These are reflexes that may be increased by repeated practice. It is a conscious reaction to a sensory input. This type of reflex has the slowest reaction time but, with continuous training over a long period, it may be developed to almost an instinctive reaction time. Since this reflex enables you to use judgment before action, it is the most useful reflex to a Taekwondo student.