There are also physiological reasons for using a single-lead. The right side of the brain controls the left side of the body and vice-versa. However, since the neural mechanisms for each side of the body are not identical, each side cannot achieve identical physical motions. Also, the body itself lacks identical symmetry. The length, mass, and thickness of practically every muscle on the one side are different from those on the other side. Most people were born with right or left side dominance and they reinforce this dominance with their daily actions. All these differences affect how you move, punch, and kick. Therefore, even though right and left side techniques may seem identical, there are actually quite different.
Therefore, with proper training, we may expect to be able to kick or punch from either side, but it is unrealistic to expect to be able to kick or punch equally from either side. Most people cannot write, throw a ball, or swing a bat or golf club equally on either side, so why should we expect to kick or punch equally from either side.
As we learn physical actions, we move from a level of conscious thought and effort to one of subconscious reflex while performing the actions. A right or left-handed person, with minimal practice, can drive a nail with a hammer while talking to a friend. However, it takes intense concentration and considerable effort to drive the nail with the opposite hand. Mastery (operating on the level of subconscious reflex) over a given task is directly related to the amount of conscious effort previously used to learn the task. With extensive training, you may learn to drive a nail equally well with either hand, but this still does not change your preference for the dominate hand. This may only be changed by consciously establishing a preference for the non-dominate hand by only using that hand. This normally occurs when a person loses the use of the dominate hand.