Fencing equipment and skills
It is an established historical fact that Medieval and Renaissance fighting was highly systematized and incorporated a diverse range of personal combat skills and fencing equipment well outside that of the more limited craft of 18th and 19th century fencing. The full lunge as used in modern fencing was not heavily used until the end of the 17th Century. A lot of stances in fencing will cause you to act in such a way that you are isolating certain muscles to hold yourself in that stance, in order to free up other muscles to do other things or to just stay out of the way.