internal skills in sport science are mental skills and mental toughness and developing these attributes. yoga is great form developing internal mental skills and putting an athlete into there IZOF - Internal/Individual Zone of Optimal Functioning. But it depends on the person, some people react better to higher or lower stress levels. I highly recommend you read some sport psychology, you may find some great stuff in the subject material Mr. Singh. Traditional Forms and Kata go a long way into skill learning - make fighter makes there own kata as a fight plan (some without knowing what kata is) e.g. BJJ flow plans. I know if i gain mount i should move to ezekiel, if that fails i have the option of snake choke or arm triangle, if the arm triangle fails i have the option of armbar or snake choke. That is very similar to the game plans set about in forms. Forms are pre-developed game plans.