I feel as though “optimal flexibility” is forcing all of us to be stick insects. Is it really impossible to train ourselves to control flexibility beyond optimal flexibility without it leading to adverse adaptations?
In a word, Yes. In my humble opinion (based on the research and text currently available to me) you cannot train yourself to function optimally beyond a normal or optimal range of motion. You cannot push connective tissue to stretch beyond its elastic limit during a single exercise without tearing it anyway. If you reach the end of your available range, and push past it you are forced to compensate– this is known as “relative flexibility.” Compensation patterns will often lead to pattern overload and injury over time. You may use flexibility training to force adaptive changes that increase your range of motion beyond optimal, but it is important to consider the effect that will have on the rest of the human movement system. Hyper-mobility is just as dangerous as being tight. Muscle length has an effect on length/tension relationships, excitation threshold, joint kinematics, and proprioception. To alter Muscle length beyond optimal changes relationships between structures that are carefully balanced.
Another point that may help your perception of optimal flexibility - most people who have more than optimal range in one direction, lose range of motion in another. For example, an individual who has really flexible hamstrings will often have tight